Open Plant Breeding

This wiki provides extensive information and tutorials on open plant breeding methods. You don’t necessarily need all of this information in order to use the open breeding methods; it is here to give you as much background as you want in the science behind our techniques.

The wiki is a collaborative effort, meaning that you are welcome to add to and edit its content at any time. If you don’t already have a user account, it only takes a minute to sign up for one and start editing. Be bold!

If you are not comfortable adding or editing pages yourself, you can also submit your contributions to us via our contact form.

Please note that we have a zero-tolerance policy for spam and abuse; our system tracks all edits, and violators’ accounts will be permanently ban-hammered by IP address. But we don’t expect to ever have do that. :-)

The Open Breeding Method

Most organic growers know the benefits of heritage varieties: they are often hardier, higher in nutrient value, and more flavourful than modern hybridized crops. And because they are open-pollinated, they also have the genetic ability to adapt to changing environmental conditions.

But hardly any seed-savers realize that you can actually speed up a crop’s evolution, by using an easy breeding technique called mass selection. So when new pests and diseases become a problem, a breeder can create varieties that fight them off.

The method to do this was developed by Dr. Raoul Robinson as early as the 1960’s. But his work has not been widely accepted by conventional breeders, largely because it turns their entire knowledge-base on its ear. Instead of honing in on one gene at a time like most breeders have been trained to do, his technique uses a process of natural selection to find the best possible combination of all of the crop’s genes.

The process is very simple

One of the biggest benefits of Dr. Robinson’s technique is that it’s easy enough for anyone to do, without needing to have a scientific background. In a nutshell, here’s how you breed a crop with his method:

1. Put together a good selection of seeds of different varieties. Heritage seeds are recommended because they don’t have any single-gene breeding that would throw off your results. The idea here is to get a broad genetic base to breed from.

2. Plant out the seeds, and let all of the pests and diseases do their worst, until you can select a few plants that are most resistant to attack. The seeds can be planted with quite a close spacing since they will be thinned by disease pressure. It’s important to make sure that every plant gets infected, so that they all have an equal chance to show their resistance levels. Then, before the plants flower, you can rescue the best survivors. You may have to apply a little organically-approved crop protection to save them if they are badly infected.

3. Cross-breed the winners. If they are well separated from any other plants of the same crop, you can just remove the less hardy plants from your plot and let the best ones be naturally pollinated. The key is to make sure that they aren’t being crossed with plants from outside the selection group; keep in mind that bees can forage over a range of several kilometres if food is in short supply.

4. Keep the seeds from these plants, and use them to repeat the process next year.

Depending on how many seeds you start with – and how lucky you are – you might get an excellent variety right away, or it might take a number of generations of breeding. Statistically, there is a maximum of disease resistance that will be reached after ten to fifteen generations of mass selection. But it’s quite likely that you’ll get some good varieties much earlier in the breeding process.

The bigger your breeding population is, the better your chances are of developing a good variety. So the best way to succeed is to team up with other growers. A large number of seeds can be divided between the growers; then once they have been grown out and cross-pollinated, the results can be pooled for the next growing season.

The other advantage of distributing the seeds this way is that it protects our results. In case there is a complete crop failure in one of the breeding plots, there will still be a large enough population of plants in the other plots to continue the breeding process.

Plant breeding provides a number of benefits

Apart from the obvious advantages of producing disease-resistant crop varieties, there are also several other benefits. For one thing, as small-scale breeders start producing exceptional results, it will take genetic control of seeds away from corporate hands – which may have a vested interest in crops not being resistant to pests and diseases.

For another thing, even if a crop is originally bred for organic use, it can then also be used by conventional farmers, who won’t need to spray as many pesticides and fungicides – or perhaps they won’t need any at all.

And for organic growers, it will mean crops that are easier to grow, with less labour inputs and lower costs. If these costs are passed on to consumers, it will make organic foods more competitive with conventional foods, and help increase the rate at which the organic sector is growing.

Open breeding has already begun with potatoes

We chose potatoes for our first breeding project because they are easy to breed, and are one of the most heavily sprayed crops out there. They are affected by two relatively new problems: Colorado potato beetle, and genetically-variable potato blight. These problems have conventional potato growers spraying their crops up to 20 times a year, and organic growers are having a hard time producing high-quality potato crops at all.

We’re hoping to have some exceptional new potato varieties within the next few years, but we need your help to do it. We’d like to have around 100 volunteers growing test-plots this summer – so if you have some space that’s well-separated from other potato plants and you’re willing to help out, we’d love to hear from you.

General Concepts

Open plant breeding is a concept in which people share seeds for breeding, and volunteer to plant them out in field trials.

By exposing new varieties to every available pest and disease in an organic growing environment – and keeping seed from those plants that survive best – it is possible to develop new varieties that are best suited to growing without any need for pesticides and fungicides.

These techniques go against conventional plant breeding wisdom, but have been well established to work. In fact, the results of numerous projects to breed plants for disease resistance in this way have been well documented, and incredibly successful.

Introduction to Open Plant Breeding: Vertical and Horizontal Resistance Explained

This is a slideshow introduction of open plant breeding, explaining the difference between vertical and horizontal resistance.

Click to advance through the slides.

Basic Principles in Horizontal Resistance Breeding

This slideshow covers the basic principles in breeding crops for horizontal resistance.

Click to advance through the slides.

Biological Control and Biological Anarchy

In crop science, biological control has two distinct meanings. The first involves the deliberate importing of biological control agents to solve weed or pest problems. Classic examples are the control of weed cactus in Australia by insect parasites imported from Mexico, and the control of rabbits with the myxomatosis virus. This form of control can be extremely effective, but it is usually limited to the control of an imported, foreign pest by parasites from that pest’s centre of origin.

The second meaning refers to the use of the normal biological control agents of an indigenous pest or pathogen. These control agents may be predators, hyper-parasites, antagonistic micro-organisms, or organisms that trigger defence reactions in the host. The cultivation of such control agents for release into greenhouses can be an effective technique.

Biological anarchy is the converse of biological control. It is a situation in which biological control has failed, either because the control agents are absent from the area in which a foreign host species is growing, or because the control agents of an indigenous host have been largely destroyed with pesticides. The pest or pathogen then runs riot and can be an infernal nuisance. The best way to restore the indigenous biological control agents is with horizontal resistance. And the best way to enhance the effects of horizontal resistance is to restore the biological controls. The two phenomena are mutually re-enforcing.

Integrated pest management (IPM) is a technique used mainly by entomologists to enhance biological controls. It involves careful monitoring of insect populations in order to reduce insecticide applications to the absolute minimum.

Crop vulnerability and phytosanitation

One of the advantages of the Open Plant Breeding Foundation is that it can operate internationally with various members exchanging information and genetic material between countries. It is a great idea for amateur breeders to cooperate internationally but, before they do so, they must respect their countries’ phytosanitary regulations, which exist to protect against crop vulnerabilities.

Crop vulnerability means that a crop is susceptible to an epidemiologically competent pest or disease which is absent from the area in question. If that pest or disease is introduced, the vulnerability becomes real, and potential damage becomes actual damage. For example, although it has epidemiological competence in the United Kingdom, the Colorado beetle does not occur there, and the potato crops of that country are highly susceptible to it. This is a fairly extreme crop vulnerability. An even greater vulnerability is the area of wheat that is susceptible to the Ug99 strain of stem rust (see knowledge base)

The term phytosanitation (Gk. Phyto = plant; L. sanita = health) refers to the use of healthy planting material as a means of restricting the spread of dangerous crop pests and diseases. The primary purpose of phytosanitation is to prevent vulnerability threats from becoming reality. Phytosanitation can be used at the international, regional, and local levels, and it is usually backed by the force of law.

International phytosanitation involves international treaties and official certification of planting materials being transported across national boundaries. Your agricultural department can tell you the certification requirements for the material you wish to import. Bear in mind that some imports are totally forbidden.

International phytosanitation functions best with island nations, such as Japan, Australia, New Zealand, United Kingdom, Eire, Madagascar, and many smaller, islands, both tropical and temperate. Most of these islands are isolated from much natural dispersal, and they have complete control of all their air and sea ports. Understandably, their phytosanitationary regulations are usually quite strict.

The general rule is that true seeds are relatively safe, while vegetative propagation material (e.g., cuttings, tubers, rhizomes, bulbs, corms) are the most dangerous, particularly if they have soil adhering to them. Accordingly, vegetatively propagated crops are generally risky, while seed propagated crops are considerably less so.

Organic farmers should appreciate that many phytosanitationary regulations insist on seeds being dressed with a fungicidal and/or insecticidal seed dressing. If this flouts the organic status of their farms, they should arrange for that seed to be multiplied on a conventional farm.

Regional phytosanitation is the least effective because it is not feasible to check every car, plane, and train moving from one part of a country to another. Even when an international land border is involved, such as that between Canada and the USA, or that between France and Germany, an effective control of the transport of plant material is extremely difficult, and natural dispersal cannot be prevented.

Local phytosanitation functions best on an individual farm, because the individual farmer has control of everything that is brought on to his land. For example, he can take great pains to ensure that his new seed is not carrying a dangerous pest or disease that is absent from his farm.

Whatever amateur breeders may choose to do, they must stay legal. Quite apart from getting into trouble with the law, infringement of phytosanitationary regulations could cause devastation because of serious crop vulnerabilities that most people do not even know about. Please be responsible and consult your agricultural department.

Erosion of Horizontal Resistance

Even though horizontal resistance will not break down like vertical resistance, it can be eroded quantitatively. This is an alarming thought for anyone who values the idea that horizontal resistance is durable resistance. However, this erosion is easily avoided, and it is unlikely to be serious if it does occur, but it is still important to understand it.

There are four kinds of erosion of horizontal resistance:

Host erosion

A host erosion results from genetic changes in the host population. This can occur during the cultivation of a genetically flexible crop grown in the absence of the parasite, such as maize which is open-pollinated. But it does not occur during the cultivation of a genetically inflexible crop, such as a clone or pure line, even when the parasite is absent.

A host erosion can also occur during the breeding of any crop in the absence of a parasite, particularly if the screening population is protected by a functioning vertical resistance or by a pesticide. It is then known as the vertifolia effect.

Parasite erosion

A parasite erosion results from genetic changes in the parasite population. This is important only occasionally, and only with facultative parasites. For example, a soil-borne Fusarium or Verticillium wilt fungus might have a low parasitic ability. But that parasitic ability could increase if a susceptible host were grown repeatedly on the same land.

A parasite erosion was seen repeatedly in North America as settlers moved west and cultivated flax on virgin land. The native Fusarium wilt would gradually increase its parasitic ability until flax cultivation became impossible, and it moved west to new virgin land with new settlers. It was said that the linseed oil factories had a very high rate of being insured, and then burning to the ground, as flax cultivation moved west. Eventually, the flax accumulated so much horizontal resistance that this problem disappeared.

Environmental erosion

An environmental erosion results when a cultivar is taken from an area of low epidemiological competence, and is cultivated in an area of high epidemiological competence.

For example, bacterial wilt of potatoes lacks epidemiological competence entirely in temperate areas, and potatoes that have been bred in a temperate area are likely to be very susceptible to it. This lack of horizontal resistance becomes obvious only when those potatoes are grown in a tropical or subtropical country where the wilt has a high epidemiological competence.

False erosion

A false erosion results from sloppy experimental work, when a cultivar is thought to be resistant and is later found to be susceptible. It is very tempting to blame nature rather than oneself for this kind of error.

A false erosion can also occur over a long period of breeding when a cultivar used as a standard of susceptibility appears to become increasingly susceptible. This is an illusion resulting from the fact that all the other plants in the breeding program are becoming increasingly resistant, and the discrepancy between susceptible and resistant slowly widens.

Macro-evolution and micro-evolution

Darwinian evolution is usually divided into macro-evolution (Greek: macro = large) and micro-evolution (Greek: micro = small).

Macro-evolution has the following characteristics:
1. it requires periods of geological time
2. it functions primarily at taxonomic levels above that of a species
3. it leads to an increased complexity
4. it produces new genetic code
5. it produces new species
6. it is irreversible

Micro-evolution is the converse in all of these characteristics:
1. it requires periods of historical time
2. it functions at taxonomic levels below that of a species
3. it does not lead to an increased complexity
4. it does not produce new genetic code; it merely rearranges existing code
5. it produces differing ecotypes
6. it is reversible

Both ancient domestication and modern plant and animal breeding involve micro-evolution. But, in each case, the micro-evolution results from artificial selection rather than natural selection. Inevitably, the distinction between the two kinds of evolution is blurred. The artificial selection produced new agro-ecotypes, although taxonomists have dignified most of them as new species with their own Latin names, particularly when polyploidy was involved. However, if left to themselves in a wild ecosystem, most agro-ecotypes would either revert to their wild form, or they would become extinct. Natural selection would undo artificial selection quite quickly, within a short period of historical time.

New encounter, Old encounter, and Re-Encounter Parasites

Some important influences of the origins of crops on pest and disease susceptibility were first recognised by Buddenhagen (1977).

A new encounter parasite is one which evolved away from its agricultural host, usually on a closely related wild host species. A classic example is potato blight (Phytophthora infestans) which evolved in Mexico and was brought into contact with cultivated potatoes by people. Another example is the Colorado beetle (Leptinotarsa decemlineata) which occurs wild in Colorado, USA, and became a savage pest of cultivated potatoes. Similarly, bananas in Latin America came into contact with Fusarium oxysporum f.sp. cubense which is now a major infliction called Panama disease. When the old and new hosts are closely related, a new encounter parasite can be very damaging.

An old encounter parasite is one which had been in contact with is crop host ever since that crop was domesticated. Wheat rust (Puccinia graminis) is a typical example. Old encounter parasites are generally less damaging unless there has been a severe vertifolia effect.

A re-encounter parasite is one that is left behind when the cultivated host is taken to another part of the world. At a much later date, the parasite is also taken to the new location where it is often very damaging because the host has lost resistance during its cultivation and breeding in the absence of that parasite. The classic example of this was maize in tropical Africa which was re-introduced to the Central American tropical rust (Puccinia polysora) after about four centruies of cultivation in its absence.

Reference:

Buddenhagen, I. W. (1977): Resistance and vulnerability of tropical crops in relation to their evolution and breeding, in The Genetic Basis of Epidemics in Agriculture (P.R. Day, Ed) Ann. New York Acad. Sci., 287: 309-326

Parasite Interference

Crop scientists use statistically controlled field trials to make all sorts of comparative measurements such as the yields of cultivars, the best spacing between rows, and within rows, the optimum fertiliser applications, and so on. The statistics are mathematically quite complicated, but modern computer software has largely eliminated this difficulty. These statistically controlled trials can be very accurate. However, the statistics are not accurate and, indeed, are positively misleading, when it comes to measuring pests and diseases.

Vanderplank (1963) first recognised this problem, which he called the ‘cryptic error’ in field trials. The problem is caused by the fact that crop parasites can move from one plot to another within a field trial, and this can ruin statistical analyses. The phenomenon was renamed inter-plot interference and, finally, became parasite interference, when it was appreciated that it was also highly relevant to the screening of individual plants in recurrent mass selection. This is because parasites can also move from plant to plant, and a resistant plant surrounded by susceptible plants can have its resistance obscured by parasite interference. Parasite interference can increase the amount of damage by several hundred times (James, et al, 1973) and, if not recognised can be incredibly misleading .

Parasite interference is possibly at its most misleading in a wheat breeding technique known as ‘head to row’ screening, also known as family screening. In this technique, all the seeds from one head of wheat are sown in a single row, or family. The idea is to select the best families first, and then select the best individual in each family. Genetically, this makes a lot of sense but, in breeding for resistance, it is a disaster. Consider the following diagram.

Each of the boxes labelled A-E represents a single row, a single head of wheat. A red box has the maximum parasitism, while a green box has zero parasitism. A yellow box has a level of parasitism approximately halfway between the maximum and the minimum levels of parasitism. The red boxes A, C, & E all have vertical resistance gene 1 and their resistance has been matched. They have low levels of horizontal resistance and, consequently, they have the maximum parasitism. They are also interfering with Rows B and D, and are loading them with parasites in the process of parasite interference.

Row B also has vertical resistance gene 1 and the parasite interference is consequently matching allo-infection. But row B also has a high level of horizontal resistance. Unfortunately, this horizontal resistance cannot be observed because it has been swamped by matching parasite interference. This is the family that the breeder should have kept but which was invariably thrown out.

Row D, on the other hand, has vertical resistance gene 2 and the parasite interference is consequently non-matching allo-infection, and D looks perfect, except for damage due to hypersensitivity flecks (see below). But its very low level of horizontal resistance is completely obscured, and its vertical resistance is unstable. It is the very opposite of perfect. This is the family that the breeder should have thrown out but which was invariably kept.

When working with head-to-row plots, the parasite interference can be so intense that the hypersensitive flecks of non-matching allo-infection appear to be a serious disease. Small grain cereal breeders used to point out that this was not true disease, and that such damage would not occur in farmers’ fields, where the non-matching allo-infection was negligible. But, it seems, they never did consider the effects of a comparable interference on a high level of horizontal resistance, when the allo-infection was all matching infection.

These misleading effects of parasite interference are the main reason why crop scientists neglected horizontal resistance in favour of vertical resistance for most of the twentieth century.

Finally, when working with recurrent mass selection, it is imperative to use relative assessments of resistance. That is, the least parasitised individuals are selected, regardless of how severely parasitised they may be. Most of that parasitism will be the result of interference which will not occur in farmers’ fields.

References:

Van der Plank, J.E. (1963): Plant Diseases: Epidemics and Control. Academic Press, New York & London, 349pp.

James, W.C., Shih, C.S., Callbeck, L.C., & Hodson, W.A. (1973): Interplot interference infield experiments with late blight of potato (Phytophthora infestans), Phytopath., 63: 1269-1275.

Stable and Unstable Protection

All mechanisms of protection against crop pests and diseases can be classified into one of two categories. Stable mechanisms do not break down to new strains of the crop parasite. They provide durable protection. Unstable mechanisms do break down in this way, and they provide only a temporary protection.

Host Resistance

Vertical resistance involves single genes taken from a gene-for-gene relationship. Any combination of these genes operates against some strains of the crop parasite but not others. Its function is to reduce the frequency of matching allo-infections. Vertical resistance consequently fails to function on the appearance of a new, matching strain of the parasite. It provides an unstable protection.

Horizontal resistance, on the other hand, is the resistance that invariably remains after vertical resistance has been matched. Its function is to protect the host against matching allo-infections, and it operates equally against all matching strains of the parasite. It provides a stable protection.

Insecticides

Most natural insecticides provide a stable protection. In the Far East, rotenones (extracted from derris roots) have been used for centuries against body lice without any resistant strains appearing. Similarly, pyrethrins (extracted from the flowers of pyrethrum) have also been used for centuries to control fleas and bed bugs in Dalmatia without any resistance developing. Oils on water provide a stable protection of mosquitoes, and on beans a stable protection against weevils.

Most synthetic insecticides are unstable. DDT-resistant houseflies are the best known example.

Fungicides

The famous Bordeaux mixture is a stable fungicide as well over a century of use have demonstrated. So too are other copper formulations and the bisdithiocarbamate fungicides. But fungicides such as metalaxyl are unstable.

Antibiotics

It seems that all antibiotics are unstable, as our medical colleagues know to their cost.

The Advantages of Horizontal Resistance

Breeding plants for horizontal (i.e., many-gene) resistance is very easy, while breeding for vertical (i.e., single-gene) resistance is highly technical, very difficult, and very expensive.

Vertical resistance requires a ‘good source’ of resistance, which does not always occur. But it is possible to breed for horizontal resistance to any pest or disease, using only susceptible parents.

Horizontal resistance is durable resistance. It never breaks down to new strains of the pest or disease, as does vertical resistance. This means that the breeding is cumulative. A good cultivar need never be replaced, except with a better cultivar.

Horizontal resistance is a quantitative variable, and it exhibits every degree of difference between a minimum and a maximum. In the absence of crop protection chemicals, the minimum level of horizontal resistance usually leads to a complete loss of crop, while the maximum level of horizontal resistance leads to a negligible loss of crop. It is easy to breed for the maximum level.

Horizontal resistance can be accumulated for every locally important crop parasite. We can thus produce resistance that is durable, complete, and comprehensive. The need for insecticides and fungicides then disappears.

Most heirloom varieties have fairly high levels of horizontal resistance. But most modern varieties have rather low levels because horizontal resistance tends to be lost during breeding for vertical resistance, which has been the resistance of choice among professional breeders for the past century. This is because of the vertifolia effect.

The One-Pathotype Technique

This is a slideshow that introduces the one-pathotype technique, which is a way of making sure that no vertical resistances are throwing off the results of a breeding program. It is the only aspect of horizontal resistance breeding that can be difficult for amateurs.

Click to advance through the slides.

The Vertifolia Effect

The vertifolia effect was discovered by Van der Plank (1963) who named it after a potato cultivar of this name, in which the effect was very pronounced. The vertifolia effect is a loss of horizontal resistance which occurs during breeding for vertical resistance. Its meaning was later extended to include the loss of horizontal resistance that occurs during breeding under the protection of pesticides.

The level of horizontal resistance can only be assessed by the level of parasitism. Clearly, if there is no parasitism because of a functioning vertical resistance, or a pesticide, the level of horizontal resistance cannot be assessed. Because individual plants with a high level of horizontal resistance are rather rare in a mixed screening population, the chances are that individuals with a relatively low level of horizontal resistance will then be selected on the basis of their other attributes. The loss is usually quite small in a single breeding cycle but, after many cycles, it can become very serious indeed.

The prime example of the vertifolia effect is the loss of horizontal resistance to potato blight (Phytophthora infestans) that has continued ever since both the discovery of Bordeaux mixture in the late nineteenth century, and the discovery of vertical resistance in the twentieth century. A loss of horizontal resistance to cotton pests has continued ever since the discovery of DDT in the 1940s.

The vertifolia effect is a very modern phenomenon. Its overall consequences are seen in the high levels of horizontal resistance in heritage cultivars, when they are compared to modern cultivars. This is the main reason why heritage cultivars are so valued by organic farmers.

One of the main objectives of most amateur plant breeders will be to restore the horizontal resistances that were lost to the vertifolia effect.

Reference:
Van der Plank, J.E. (1963): Plant Diseases; Epidemics and Control. Academic Press, New York & London, 349pp.

University Plant Breeding Clubs

A special feature of university breeding clubs is the university ambience. Students are far more likely than amateurs to overcome the intimidation, and the initial hesitation, about breeding crops for horizontal resistance. The students would do all the work of breeding, supervised and guided by a professor. This would provide them with the initial ‘ice‑breaking’ and the essential ‘hands-on’ experience. The students would earn course credits from their club membership, and their teacher would earn teaching credits.

The main function of university breeding clubs is to teach. This teaching will promote a widespread proliferation of breeding clubs. Graduates, with life membership in their clubs, will most likely return to their family farms, or become agricultural scientists. If they become farmers, they might initiate one or more farmers’ breeding clubs in their own locality. If they become scientists, they might initiate one or more private breeding clubs among concerned amateurs in the vicinity of their work. Or they may become entrepreneurs themselves, relying on breeder’s royalties to earn a living.

In any event, both the concept and the practice of plant breeding clubs will begin to spread. As increasing proofs of the viability of horizontal resistance, and the ease and usefulness of amateur breeding, begin to accumulate, the proliferation of clubs will increase. The public interest in pure food, and a clean environment, to say nothing of the farmer interest in high yields and cheap production, is so strong that the process of growth and proliferation will increase exponentially.

That these developments have not occurred before now is due to a lack of knowledge. No member of the public was even aware of this possibility. The professional plant breeders, in their breeding institutes, have had no interest in promoting either amateur breeding or horizontal resistance. Indeed, they genuinely believed both to be impractical, if not impossible. And the chemical corporations, with their concept of crop protection chemicals substituting for host resistance, have also had no interest in promoting horizontal resistance.

The advantages of plant breeding clubs, particularly university clubs, over institutional and corporate plant breeding, are so marked that they merit emphasis.

Advantages for the students

Overcome the initial intimidation.

For anyone who has not tried it before, the very thought of plant breeding is somewhat intimidating, in the same way that the first use of a computer, or the first dive into deep water, is intimidating. Once this intimidation is overcome, plant breeding for horizontal resistance turns out to be very easy, and very rewarding. The ambience of a university breeding club is undoubtedly the best way of overcoming this intimidation, but this comment should not discourage other amateurs from starting their own clubs.

Learning to breed for horizontal resistance.

The use of computers cannot be learned from manuals, and ‘hands-on’ experience is essential. The techniques of breeding for horizontal resistance also require ‘hands-on’ experience and a breeding club is the best means of providing such experience. The students themselves would do all the work of breeding and they would gain practical experience in every aspect of the breeding process.

Improved participation and interest.

Many agricultural students, who grew up on a farm, find there is a gap between their own farming experience and the somewhat academic teaching within the university. A breeding club closes this gap very effectively, and it demonstrates the practical utility of various scientific concepts. The club also provides students with active participation, and a sense of achievement, as alternatives to passive learning.

Earn course credits.

As one of the inducements to join, students should earn course credits from their breeding club membership and participation.

Life-membership.

On graduation, students should be given life membership in their club or clubs. This would entitle them to consult the university experts, and to receive, test, report on, and utilise new lines coming out of their club(s) for the rest of their lives. They would also be encouraged to donate some of their best lines to the university club, and to attend club meetings.

Start new breeding clubs.

Having returned to their family farm, or arrived at their new place of work, graduates would be encouraged to start one or more new breeding clubs among farmers and other interested parties. This would lead to a proliferation of breeding activity. Their knowledge of breeding for horizontal resistance, as well as their life memberships in their university club(s) would be valuable assets in these activities.

Advantages for the professors

A new approach to teaching.

Plant breeding clubs would provide a new kind of teaching in which the students themselves are involved in the actual achievements of both demonstrating the value of horizontal resistance, and of producing new resistant cultivars.

Teaching credits.

Each club would have a professor in charge of it and the professor would earn teaching credits for this activity.

Long-term research.

Short-term research grants have no guarantee of renewal and our system of financing agricultural research discourages long‑term research projects, such as breeding for horizontal resistance. Because the breeding club work would be a teaching activity, its continuation would be secure, and the professor in charge could undertake long-term research in this topic. It need hardly be added that this is an area that has been seriously neglected, and that such research is urgently needed. In no small measure, this neglect has been due to the long-term nature of the research, and the insecurity of the research grant system.

Advantages for amateur breeding clubs

A scientific basis for amateur breeders.

Amateur breeding clubs that were initiated by a graduate with membership in his university club(s) would have the advantage of doing breeding that was technically sound. Their members could proceed with confidence.

Overcome intimidation.

Such a club would be the best method of over‑coming the intimidation that discourages an inexperienced amateur.

Rewards.

The club could provide very considerable rewards for its members. These include a sense of achievement, improved new cultivars for farmer-members, breeders’ royalties, and the satisfaction of participating in a successful communal activity.

Advantages for the university

A new approach to teaching.

In addition to the learning process, plant breeding clubs would provide advantages that the students would not obtain from the more conventional lab and field classes. These advantages include the actual participation in the production of new cultivars, and life membership in the club. Members of existing clubs have also discovered that their clubs provide a useful link between their practical experience on their family farm, and the relatively academic teaching of the university.

A new approach to research.

Most universities have abandoned research that involves plant breeding designed to produce new cultivars. Plant breeding clubs would provide new opportunities for providing farmers with the practical assistance that emerges from successful research.

Prestige from successful new cultivars.

The production of an assortment of valuable new cultivars in a range of locally important crops could provide valuable prestige for a university.

A renewal of the land-grant college concept.

The prestige earned from new cultivars would represent a return to the esteem that existed when the land grant colleges were first formed in the United States, with a really close co‑operation between agricultural scientists and farmers.

Advantages for the local farmers

Farmer-participation in research.

Institutional plant breeding has become so esoteric that farmers cannot understand it. Nor can they participate in it. Farmers should be encouraged to form their own clubs, assisted, no doubt, by some of their children who have graduated from a university that had plant breeding clubs. Equally, a university club might do well to instruct a few farmer-members who would themselves provide practical input.

Greatly increased breeding activity.

One of the chief criticisms of institutional and corporate plant breeding is that their work is so expensive, and that they are so specialised, and so technical, that their total breeding output is severely limited. A multiplicity of plant breeding clubs would provide a greatly increased amount of plant breeding.

Constructive competition between many breeding clubs.

If there were many plant breeding clubs, operated both by universities and farmers themselves, there would be constructive competition that would lead to an abundance of competing cultivars with gradually improving horizontal resistance to all locally important pests and diseases, as well as improving yield, quality of crop product, and agronomic suitability. This competition would continue until a ceiling was reached, when little further progress would be possible.

Cultivars suited to local agro-ecosystem.

These competing cultivars would all be the result of on-site selection in the local agro-ecosystem. They would be well balanced with all the variables in that agro-ecosystem.

Wide choice of new cultivars.

An abundance of good cultivars would give both farmers and consumers a wide choice of cultivars.

Freedom from the hazards, labour, and cost of pesticides.

Once adequate horizontal resistance had been accumulated, farmers would be freed from the environmental and human hazards, as well as the labour and costs of applying crop protection chemicals.

Reduction of crop losses.

As horizontal resistance accumulated, the crop losses from pests and diseases would decline.

Reduction of biological anarchy.

As horizontal resistance accumulated, the biological anarchy that was induced by crop protection chemicals would decline, as biological control agents returned and increased in numbers.

Cumulative crop improvement.

Because a good horizontally resistant cultivar need never be replaced, except with a better cultivar, breeding for horizontal resistance is cumulative and progressive. The overall effect of plant breeding clubs, therefore, would be a cumulative crop improvement.

Advantages for the environment

A return to resistance breeding.

Plant breeding clubs would lead to a return to the resistance breeding that was taken for granted before 1900.

Exponential increase in plant breeding expertise and activity.

Plant breeding clubs would lead to an exponential increase in the total plant breeding expertise and activity. This increase would be comparable to the exponential increase that we are witnessing now in both computer literacy and the use of the Internet.

Widespread reduction in pesticide use.

There would also be a widespread reduction in the use of crop protection chemicals, with a corresponding reduction in health and environmental hazards.

Improved bio-diversity.

An abundance of competing cultivars would provide a greatly improved bio-diversity. This diversity would occur between crops rather than within crops. Nevertheless, it is fundamental ecological principle that diversity provides stability.

Economic benefits

Cost of pesticides reduced.

The cost of crop protection chemicals, now running into billions of dollars annually, would be greatly reduced and, in some corps, largely eliminated.

Cost of pesticide application reduced.

The same is true of the costs of application of crop protection chemicals.

Crop losses reduced.

The pre-harvest crop losses from parasites average more than 20%, worldwide, in spite of the use of crop protection chemicals. These loses could be greatly reduced by the proper use of horizontal resistance.

Increased yields of a cheaper and healthier product.

The overall effect of a multiplicity of plant breeding clubs would be improved yields of crop products that were both cheaper to produce and healthier for the consumers.

Advantages for overseas aid organisations

New assistance technique.

Plant breeding clubs could provide an entirely new technique for overseas aid in agriculture. Overseas aid organisations could initiate these clubs in Third World universities, and support them with technical and financial assistance until they could stand on their own feet. If successful, these clubs could eventually prove to be the most effective agricultural assistance technique of them all. Overseas aid is often sub-divided into ‘soft’ and ‘hard’ aid. Soft aid consists or studies and research that result in advice and reports that are soon neglected and forgotten. Hard aid results in new physical entities that make a very real contribution to welfare, such as new roads, schools, or systems of communication. New, improved cultivars constitute hard aid.

Inexpensive technique.

These clubs could also prove to be one of the least expensive techniques of overseas aid.

Potato Breeding

Breeding potatoes for resistance to blight and Colorado potato beetle is the first project of the Open Plant Breeding Foundation.

OPBF maintains a bank of true potato seeds, which you are welcome to plant out in a field trial. Even a small plot of potato plants can help our breeding efforts to progress.

In simplest terms, the method is as follows:

Plant the potato seeds with about a 2” spacing.
As the potato plants grow, they can be thinned to around one per foot.
Allow any pests and diseases that may be present in your garden to do their worst.
Rescue the last few plants before they are killed off, and allow them to be cross-pollinated.
Save the seed-balls from these plants, and send them back to us. If the plants do not set seed, you can send us a few tubers from each plant.
These become the parents of the next breeding generation, and will be crossed with the results from the other participants in the project.

Potato Breeding Instructions

Once you volunteer to help the potato breeding project, you will be sent a packet of seeds. A few of these seeds will be the parents of a new blight & beetle resistant variety of potato, and your work will help by selecting which seeds are the best. Unlike seed potatoes, which are identical clones of their variety, each one of these seeds is genetically unique.

After you’ve selected the best plants from this batch of seeds, we’ll cross them with the results of our other test plots to produce another generation of seed. Every generation gets better than the last, and we hope to have a new disease-resistant variety within the fewest possible number of generations. When we do, we will happily share the results with you.

Seed Germination

You can treat these seeds the same way as tomato seeds. They can be planted in flats or in a seed bed, and then transplanted into the garden. If you are short of time, you can also sow them directly in the garden – this will save transplanting, but they will need careful attention for the first few weeks while they are very delicate.

The soil for germination should have a fine tilth which is neither too wet nor too rich in organic matter, otherwise the seedlings may die of stem rot. The young seedlings should be shaded, but mature plants like full sun. Germination time will be 1-2 weeks, and you can expect a germination rate of about 50%.

Planting

Because we actually want pests and diseases in this plot of potato plants, it’s best to plant them as far as possible from any potatoes that you are growing for food. Plant or thin them to about a 2-inch spacing – they will get thinned out more during the selection process. The more seedlings you’re able to plant, the better your chances of finding something really good.

The Selection Process

There are two stages to the selection process once the plants are in the garden. The first stage is to let pests and diseases destroy the most susceptible plants. Water them if needed, and remove the plants that are obviously dying, until there are only five to ten plants left.

The second stage is to rescue the survivors, and keep them alive as long as possible to collect their tubers. Beetles can be picked off; and blight can be minimized with a clear sheet-plastic roof, and/or organically-approved copper salts such as Bordeaux mixture. As soon as they are in danger of dying, dig up the tubers and keep them, no matter how small they are, in a dry place with subdued light. Don’t expect to see any large tubers from these plants, since they are grown from seed.

It’s very important to keep the tubers from each plant separate, to prevent genetic mixing. If possible, we’d like to have five tubers from each plant; you’re welcome to keep any others for your own investigations if you’d like to plant them out next year. Please pack the tubers carefully in a box, and mail it to us at: 445 Provost Lane, Fergus, Ontario, N1M 2N3. We’ll refund the cost of the postage.

Sarpo Potatoes

In Hungary, during the 1950s, Dr. Istavaán Sárvári led a potato research team working on resistance to both blight (Phytophthora infestans) and virus diseases. The communist government closed down his breeding program because of a dispute over his breeding methods. We do not know what this dispute was, but it was probably the old Mendelian-v-biometrician quarrel. Dr Sárvári then returned to the Sárvári family farm and he took many of his potato lines with him. His people have continued his breeding ever since. Recently, by special agreement, the Sárvári Research Trust was established at Bangor, in Wales, and various lines were introduced to Britain as Sárpo (i.e., Sárvári + potato) cultivars with high levels of horizontal resistance to blight and viruses.

In Britain, the National Institute for Agricultural Botany (NIAB) has a rating system for horizontal resistance to blight, where 9 = very resistant, and 1 = susceptible, when the crops are not sprayed with a fungicide. According to the British Potato Council, NIAB ratings of 6 or 7 (along with all other methods of control and avoidance) should prove sufficient, in most years, for organic growers to grow a crop with no copper sprays.

In 2004, nineteen clones of Sarpo potatoes were field tested in Wales for blight resistance, including the nationally listed cultivars, Mira and Axona. A further nine commercially available varieties were also tested. These included cultivars with high NIAB scores for blight resistance, namely Stirling (8), Lady Balfour (7) and Cara (6); and cultivars with low NIAB scores for blight resistance, namely King Edward (3), Wilja (3) and Pentland Crown (3).

The trials showed that all of the Sarpo lines have NIAB level 9 horizontal resistance to blight. With only one exception, all the Sarpo lines had higher yields than the commercially available varieties, when grown under organic farming conditions without fungicides.

Mira and Axona are registered main crop Sarpo cultivars in Britain and both have exceptional resistance to blight, viruses, and other pests and diseases. They are ideal for organic growers, and they have high yields of large tubers. They both have a red skin and a white flesh. They produce vigorous plants, with heavy yields of floury (high dry matter) tubers, excellent for fries, baking, roast and mash. At ambient temperatures, the tubers store well into spring without softening or premature sprouting.

Wheat Breeding

Breeding wheat for horizontal resistance is becoming an urgent necessity for the world’s food supply. Almost all wheat breeding during the last century has worked with single-gene vertical resistances. These can provide protection for some time, but they almost inevitably break down to new strains of diseases and parasites.

One of the worst diseases of wheat is stem rust, caused by the Puccinia graminis fungus. Most of the world’s wheat is protected against this fungus by a resistance gene called Sr24, and this gene has allowed wheat to be grown in relative safety from stem rust. But in 1999, a new strain of Puccinia graminis was discovered in Uganda which breaks down the Sr24 resistance. And this new strain of fungus is already spreading.

Ug99: a wheat fungus that is threatening the world's food supply

Virtually all wheat breeding during the past 100 years has employed single-gene (i.e., vertical) resistances which usually provide a complete protection, but which are liable to break down to new strains of wheat parasites. One of the worst diseases of wheat is caused by a fungus called ‘stem rust’ (Puccinia graminis) and much of the world’s wheat is protected against it by a resistance gene called Sr24.

In 1999, a new ‘strain’ (i.e., vertical pathotype) of the stem rust fungus was identified in Uganda and it is now known as Ug99. This strain is particularly dangerous because it can match Sr24 and, as a consequence, much of the world’s wheat is in grave danger. During the past few years, this rust spread to Kenya, Ethiopia, and the Yemen. It has now been recorded in Iran, and it is thought to have reached Pakistan. This is bad news indeed because it is only a matter of time before it reaches the Punjab and the ‘bread basket’ of Asia.

There is an urgent need for horizontal resistance breeding against wheat parasites but none of the professional wheat breeders seem prepared to tackle this. This reluctance to test anything new, and to stick with old concepts and techniques, is known as ‘scientific fundamentalism’, and it is much more common than most people realise. One of the more important objectives of the Open Plant Breeding Foundation is to promote horizontal resistance and to demonstrate just how easy horizontal resistance is to work with, and just how effective it can be.

Wheat is not the easiest crop to breed and it is not normally recommended for breeding clubs made up of amateurs. But it is a suitable project for university breeding clubs which are backed up by the university resources and expertise.

We beg agricultural colleges and universities in the countries where Ug99 is already present to establish wheat breeding clubs working with horizontal resistance to all the locally important wheat parasites. This may well prove to be the only means of overcoming the scientific fundamentalism within wheat breeding.

Glossary

This list of terms is both a useful reference, and a fun way of browsing through the terminology in order to learn more about plant species, plant breeding and agricultural techniques.

The original text was adapted from The Amateur Plant Breeder’s Handbook by Dr. Raoul A. Robinson. A free download of the handbook is available from www.sharebooks.ca.

As with any page in the Open Breeding Wiki, these glossary listings can be edited by anyone. If you notice any terms that still need to be added, or definitions that can be expanded, please sign up for an account and help make this resource even better.

Glossary: A

Abaca: See: Musa textilis.
Abelmoschus esculentus: Okra, previously called Hibiscus esculentus. This is an annual crop grown for its fruits that are cooked and eaten as a green vegetable. There has been considerable hybridisation with wild species and there is much genetic variation. Scope for amateur breeders working with horizontal resistance.
Abscission: The discarding of plant organs, such as leaves of deciduous trees in the autumn.
Acaricide: See: Miticide.
Acidity: See: pH.
Acre: A measure of land area. One acre is 4840 square yards, or 0.405 hectare.
Acropetal: Growing upwards so that the oldest parts are at the base and the youngest at the tip.
Adlay: See: Coix lachryma-jobi.
Adult plant resistance: Horizontal resistance in many crops, particularly the cereals, is often expressed more in mature plants, and less in young seedlings. This is to be expected because the epidemic intensifies as the growing season progresses. For this reason, horizontal resistance is often called adult plant resistance and, by implication, it is more difficult to observe it, measure it, or screen for it, in young plants.
Aerobic: Living conditions in which there is a plentiful supply of oxygen. Organisms which require oxygen are labelled as aerobic organisms, or aerobes. The converse, meaning without oxygen, is anaerobic.
Aestivation: An organism’s survival of a hot dry summer.
Aflatoxin: Toxins produced by Aspergillus flavus and related fungi. Mouldy feedstuffs contaminated with aflatoxins have caused severe disease and mortalities in livestock, particularly poultry.
African millet: See: Eleusine coracana.
Agaric: Any member of the Agaricaceae, a fungus family in which the fruiting bodies are mushroom shaped.
Agave sisalana: Sisal. Once an important bast fibre crop in its centre of origin in Mexico, and also in East Africa (Kenya and Tanzania), sisal has been largely supplanted by synthetic fibres. Seed set in sisal is extremely rare and breeding this crop is far too difficult for amateur breeders.
Agriculture: Agriculture was independently discovered and developed by many different groups of people in various parts of the world, the main centres being based on the crops wheat (Europe), maize (Central and South America), and rice (Southeast Asia).; Agriculture consists of the propagation and nurturing of domesticated animals and plants. The cultivation of crop plants is now divided into agricultural and horticultural crops. The latter involve a wide array of fruit and vegetables and offer great scope for amateur breeders.; Commercial agriculture is undertaken for financial gain, while subsistence agriculture, mainly in the tropics, is undertaken to feed the farmer’ family, possibly with the sale of some subsistence surpluses. Most subsistence crops also offer great scope for amateur breeders.; Forestry involves the cultivation of trees for timber and it too offers some scope for amateur breeders.
Agrobacterium: Agrobacteriium tumefaciens is the bacterium that causes a disease called crown gall on many different species of host, most particularly on temperate fruit trees. The galls can grow to the size of a soccer ball if left untreated.; Amateur breeders working with rootstocks of fruit trees may care to take resistance to this bacterium into consideration in their breeding. Genetic engineers use this bacterium as a means of introducing foreign DNA into a plant, but this is not a technique for amateurs.
Agro-ecosystem: The ecosystem of a cultivated crop. It differs from the surrounding, natural ecosystem because of the various artificial components of agriculture.
Agro-ecotype: The local landrace of an outbreeding crop is often called an agro-ecotype because, like a wild ecotype, it has responded to selection pressures within its own locality in the agro-ecosystem, and it is well adapted to that locality. In systems terminology, this adaptation is called local optimisation.; In a wide sense, any domesticated variety of plant or animal is an agro-ecotype. Amateur plant breeders may regard their work as improving the domestication of existing agro-ecotypes.
Agronomic suitability: The agronomic suitability of a cultivar is one of the four objectives of plant breeding (the others being yield, quality of crop product, and resistance to pests and diseases).; It is governed by a variety of traits such as plant shape and size (often called crop architecture), time of maturity, suitability for mechanical cultivation and harvesting, frost and/or drought resistance, yield potential, suitability to market requirements, and so on.; This is a factor that amateur breeders must always take into account.
Agronomy: That component of agriculture which is concerned with the theory and practice of growing crops, and with the management of soils.
Aguacate: See: Persea americana.
Air-borne parasites: Plant parasites can be air-borne, soil-borne, water-borne (mainly in irrigation water), and seed-borne. The air-borne parasites include fungi and flying insects, which can sometimes travel for hundreds of miles on prevailing winds.
Akee: See: Blighia sapida.
Aldrin: One of the dirty dozen chemicals called POPS. Aldrin is an insecticide, now banned by international treaty.
Aleurites spp.: Tung, an ancient crop in China, it is now grown in several warm countries. The seeds of A. fordii and A. montana yield a paint oil of exceptional quality. The market has declined from competition with cheaper paints, particularly plastics. Considerable scope for local amateur breeders who are not ambitious about their new cultivars.
Alfalfa: See Medicago sativa.
Alga: (Plural: algae). Primitive plants that have chlorophyll and can photosynthesise. They range in size from single-celled and microscopic, or many-celled and many feet long. They occur mainly in water, which may be either fresh or marine.
Alkaloid: An organic compound containing nitrogen, and with conspicuous physiological properties. Well-known alkaloids include nicotine, caffeine, quinine, morphine, cocaine, and strychnine.
Allele: The alternate copies of a single gene. Each gene normally consists of two alleles. Each allele occurs on one of the two matching chromosomes, one of which comes from the male parent, and the other from the female parent.; In one individual, the two alleles may be both dominant (AA), both recessive (aa), or one of each (Aa). The first two of these combinations are described as homozygous; the third is heterozygous.
Allelopathy: A mechanism that reduces or eliminates competition from other species by the production of toxins. The best known example is that of antibiotics produced by fungi to suppress the growth of bacteria. Equally familiar is the effect of a carpet of pine needles in suppressing the germination of other plants.
Alliaceae: The botanical family that includes the onions and their relatives. However, some taxonomists prefer to classify Allium spp. within either the Liliaceae or the Amaryllidaceae.
Allium ampeloprasum: Leeks and ‘elephant’ garlic. Leeks are tetraploids (4x) and set seed freely, while ‘elephant’ garlic is a hexaploid (6x) and is sterile. We can certainly consider the possibility of breeding leeks for horizontal resistance, but we should steer clear of ‘elephant’ garlic. The breeding procedures are those of open-pollinated crops.
Allium cepa: The common onion, including the shallot. This vegetable is an excellent subject for breeding by amateurs.; There are many different types of onion, ranging from sweet to pungent, and from deep red, and green, to white. And there are many parasite problems of onions, all of which can be either solved or greatly ameliorated by breeding for horizontal resistance.; Onions are open-pollinated but flower only in their second season. The parasite screening should be undertaken in the first season and it should be based on both yield and appearance after exposure to major infestations of parasites.; The best selections are stored, and this constitutes a second screening for resistance to storage rots and pests. The storage survivors are planted out and allowed to flower, but a negative screening decapitates the worst plants, and only the best individuals can form pollen and seed.; New varieties can consist of either improved populations (synthetic varieties) or hybrid varieties. The latter procedure requires more work but has the advantages of higher yields and complete protection of seed production.; The wild progenitors of onion are extinct.
Allium sativum: Garlic. This crop cannot be recommended for amateur breeders as it never sets seed, and it can be propagated vegetatively only. The flowers sometimes produce small bulbils, which can be used for propagation, but these are also vegetative and are not the result of pollination.; The formation of flowers and seeds is a major physiological sink that severely reduces the yield of vegetative parts of the plant. Ancient cultivators probably had a gut-feeling about this, and preferred clones that did not produce flowers or seed.; Garlic provides an excellent example of the durability of horizontal resistance because all the varieties are ancient clones that have been cultivated for centuries without crop protection chemicals, and without serious loss from parasites. Any modern problems with parasites are the result of an environmental erosion of horizontal resistance.
Allium schoenoprasum: Chives. The leaves are used as a garnish. This species is an outbreeder and is easy to breed. Chives can be propagated either vegetatively or from true seed. Chives do not have well-formed bulbs but they do form tillers to produce dense clumps of plant. Easy to breed.
Allogamy: Greek; allo = other, or different; gamy = marriage. The term means cross pollination. An allogamous plant or species is one in which cross-pollination is normal or even obligatory. Cultivated allogamous species include maize, sorghum, millets, and rye; members of the onion family, members of the cucumber family; and various pulses and vegetables.; The converse term, meaning self-pollination, is autogamy.
Allo-infection: Infection is the contact made by one parasite individual with one host individual for the purposes of parasitism. Allo-infection (Greek: allo = other or different) means that the parasite has arrived from somewhere else; it had to travel to its host. The first infection of any host individual must be an allo-infection.; The gene-for-gene relationship provides a system of locking which ensures that most allo-infections are non-matching infections. This is the sole function of vertical resistance in a wild pathosystem.; See also: Auto-infection, Allogamy.
Allopatric: Species, ecotypes, or pathotypes that come from another part of the world.
Allopolyploid: A polyploid has more than two sets of chromosomes (e.g., triploid, tetraploid). In an allopolyploid, the chromosomes are derived from two or more different species. In an autopolyploid, all the chromosomes are derived from the same species.
Allotetraploid: An allotetraploid has four sets of chromosomes derived from two different diploid species. For example, Coffea arabica is believed to be an allotetraploid derived from a cross of the two diploid species Coffea canephora and Coffea eugenioides.; An interspecific cross is usually sterile, but the cross can be made fertile by doubling its chromosome number, and making it an allotetraploid. However specialists should be consulted before such a breeding approach is attempted by amateur breeders in other crops.
Allspice: See: Pimenta dioica.
Alocasia macrorrhiza: One of the aroids, of minor significance, cultivated in S.E. Asia.
Almond: See: Prunus amygdalus.
Alternaria: This genus is an imperfect fungus (i.e., it has no sexual stage) with an extremely wide host range.; Various species of Alternaria cause leaf and fruit spots on citrus, brassicas, flax, potatoes, tomatoes, leeks, onions, and other crops. The spots form concentric rings of colonisation and the disease is often called ‘ring-spot’ or ‘target spot’.; It is easy to accumulate horizontal resistance to this fungus and plant breeders should take it into account when breeding many species of vegetables.
Amaranth: See: Amaranthus.
Amaranthus: Amaranth is an ancient crop of the Americas cultivated either as a grain crop or as a pot herb. It is now a popular ornamental. The Spanish tended to prohibit its cultivation as they believed it was associated with cannibalism, but its full potential is now being recognised.; The grain amaranths consist of three species, A. hypochondriacus and A. cruentas that originated in Mexico and Guatemala, and A. caudatus, which is native to Andean countries such as Peru. Vegetable amaranths are boiled as greens and include A. tricolor, A. dubius, and A. cruentus.; Most amaranths have high levels of horizontal resistance to all their pests and diseases but there is considerable scope for improvements in yield, quality, and agronomic suitability, including possible day-length changes.; The amaranths are wind-pollinated and should be subjected to open-pollinated breeding techniques. An attractive crop for plant breeders.
Amateur plant breeding: Plant breeding that is undertaken by people who are not professional plant breeders, and who may not have any formal training in plant breeding. Using the techniques of horizontal resistance breeding, amateur breeders can easily achieve outstanding results.; The Open Plant Breeding Foundation is here to support this type of breeding – both with information and practical assistance – as well as to encourage other plant breeders associations.
Ammonium nitrate: An artificial fertiliser that is exceptionally rich in nitrogen. Ammonium nitrate must be handled with care, as it is powerfully explosive when mixed with a combustible such as oil.
Amphidiploid: An alternative term for allotetraploid.
Amphimictic: The adjectival form of amphimixis.
Amphimixis: The converse of apomixis, and meaning reproduction by seed which has been produced by a normal sexual fusion.
Anacardiaceae: Family of tropical trees that includes mango and cashew.
Anacardium occidentale: Cashew nut. Although it is frost-susceptible, cashew is one of the hardiest of trees and, in warm countries, will grow on poor soils that are unsuitable for other crops. The nuts fetch a high price and the crop is about as valuable as arabica coffee. However, a factory is necessary for the specialised task of shelling the nuts.; Each nut is borne externally on the end of a fairly large fruit. The fruit is edible, but very astringent, and it can be utilised for the manufacture of alcohol. There is a correlation between total yield and quality, the highest yielding trees producing small nuts of low commercial quality.; But there is great variation among trees, and there is scope for selection within existing orchards, by amateur breeders, with a view to vegetative propagation of selected clones.
Anaerobic: Living conditions in which there is an absence of oxygen. Organisms which do not require oxygen are labelled as anaerobic organisms. The converse, meaning with oxygen, is aerobic.
Analogous evolution: Evolution in which similar features have different origins (e.g., the wings of birds, insects, and bats represent analogous evolution). This is the converse of homologous evolution, in which similar features have a common origin (e.g., all the plants in one family have a common ancestor).
Ananas comosus: Pineapple. This is a very difficult crop to breed and it is definitely not recommended for amateur plant breeders.
Anastomsis: Natural grafting that can occur in either stems or roots. For example, mango seeds contain both a nucellar embryo and a normal embryo that is the result of open-pollination. Trees growing from casually discarded seeds often consist of two trunks joined at the base by anastomosis. One trunk is the nucellar seedling and is identical to the maternal parent, while the other is an open-pollinated variant and is visibly different in many characteristics, including fruit quality and resistance to parasites.
Ancient clones: The importance of ancient clones is that they provide proof of the durability of horizontal resistance. Such clones may date from centuries, even millennia, ago.; They are common in figs (Ficus), olives (Olea), date palms (Phoenix), citrus (Citrus), horseradish (Armoracea), garlic (Allium), ginger (Zingiber), turmeric (Curcuma), saffron (Crocus), rhubarb (Rheum), etc.
Andromonoecious: Having both male and hermaphrodite flowers on the same plant.; See: Cucumis melo.
Anethum graveolens: Dill. See also: curry powders.
Angiosperm: Seed-forming plants whose seeds are protected by a seed-coat. This group includes the flowering plants, both monocotyledons and dicotyledons, and it provides virtually all human food, either directly as vegetable matter, or indirectly, as meat.; A few Angiosperms are parasitic on other plants. They lack chlorophyll and they include dodder (Cuscuta spp.), broomrape (Orobanche spp.) and witchweed (Striga spp.). It is possible to breed crops for horizontal resistance to these parasitic Angiosperms. See also: Gymnosperm.
Annual plant: A plant which flowers, fruits, and dies in one season.
Anther: The male reproductive part of a flower that produces pollen.
Anthesis: The time of pollen production.
Anthracnose: A plant disease caused by a species of the fungus called Colletotrichum (pronounced coll-ee-TOT-tree-coom). The symptoms are sunken lesions, several millimetres in diameter, with small, black, sporulating, fungal bodies on the sunken surface.
Antibiotic: A substance that inhibits the growth of micro-organisms, e.g., penicillin. It seems that all antibiotics provide an unstable protection when used singly, and that a cocktail of different antibiotics is much more stable.
Aphids: Plant parasitic insects of the Order Homoptera which are among the most common, and serious, of insect pests of crops.; Also known as greenfly or green bugs, aphids have several different forms, including winged females for allo infection; wingless, asexual, viviparous females for auto-infection; and winged males and females for sexual reproduction.; Many species of aphid are heteroecious. Many are vectors of virus diseases.
Apical dominance: The suppression of lateral branches by the apical shoot, or apex, of the plant.
Apical meristem: The meristem at the main growing point, or apex, of a plant.
Apis: The genus to which honey bees belong. These are stinging, social, hymenopterous insects, useful in the production of honey, and in the pollinating of many species of crop. Amateur breeders can often make use of them to produce a random polycross.
Apium graveolens: Celery and celeriac. An ancient domestication known to the classical Greeks. Celery is used for its green stems, mainly as a flavouring in soups and salads. Celeriac (var. rapaceum) is grown for its swollen, edible roots.
Apomictic: The adjectival form of apomixis.
Apomixis: Greek: apo = without; mixis = mixing. Asexual reproduction by seeds produced from the maternal tissue of a flower.; Apomictic seeds occur mainly in grasses, and they have the advantage of being the equivalent of vegetative propagation, being free of most vegetatively transmitted diseases (particularly viruses).; The so-called ‘apomictic gene’ is a topic of interest among molecular biologists because it could very easily preserve agricultural characteristics, including hybrid vigour, in heterozygous seeds of open-pollinated crops.
Apothecium: An open fruiting body shaped like a ‘dry martini’ glass, produced by some Ascomycetes, with asci on the open, upper surface. Sometimes called ‘cup fungi’.
Apple: See Malus.
Apple scab: See Venturia inaequalis.
Apricot: See Prunus armeniaca.
Araceae: The family to which the aroids belong; see Alocasia, Colocasia, Cyrtosperma, and Xanthosoma
Arachis hypogea: The peanut, also known as ‘monkey nut’, and groundnut, because the plant thrusts its pods underground as a method of self-sowing.; Originating in South America, ancient domestication produced non-fragile pods and shorter pod-bearing stems. Like the non-shattering character in cereals, these changes made harvesting much easier.; Most groundnut varieties are inbreeders and cross pollination is rather difficult. They are also allotetraploids and crossing with wild diploids is not easy. However, many interspecific crosses have been made and these offer considerable scope for development. A serious challenge for amateur breeders but one with great potential for the courageous.
Arachnid: A member of the Arachnida, the class of arthropods that includes spiders, mites, scorpions, and ticks.
Archetype: The wild ancestor of a modern cultivar.
Areca catechu: This palm is the source of the betel nut, which is chewed as a narcotic by more people than use chewing gum. It is chewed as a ‘quid’ of betel pepper leaves with a dash of slaked lime. This ‘quid’ turns the saliva red and this colours walls and sidewalks from spitting.; The young palm is also a popular houseplant. There is some scope for amateur breeders to select superior palms within existing populations in areca-producing countries.
Areca palm: See: Areca catechu above.
Armillaria: Armillaria mellea is known as the honey fungus, and it can cause a serous disease of many species of tree.; It produces long black rhizomorphs that look like boot-laces, and that can grow through the soil and spread the disease from tree to tree. Armillaria often produces toadstools on dead tree stumps.; In the tropics, it occurs only at high altitudes. It has even been postulated that a large network of rhizomorphs constitutes the largest living organism. Foresters often ring-bark trees about a year before felling them, and this denudes the roots of nutrients. The fungus is then unable to invade them.; Another defence is to dig trenches that the rhizomorphs cannot cross. However, many pathologists think that Armillaria will only attack trees that are weakened from some other cause such as waterlogging or shallow soil.; It is not feasible for amateurs to breed for horizontal resistance to this disease.
Armoracia rusticana: Horse radish. The roots are used to make a peppery condiment, but this species does not flower or set seed. It is definitely not recommended for amateur plant breeders.; There are many clones with widely varying degrees of pungency. These ancient clones have few pests or diseases and they are a good example of both the effectiveness and the durability of horizontal resistance.
Aroids: Aroids are a group of tropical root crops belonging to the family Araceae. See: Alocasia, Colocasia, Cyrtiosperma and Xanthosoma.
Arrowroot: See: Maranta arundunacea.
Arrowroot, Queensland: See: Canna edulis.
Arsenic: Compounds of this well-known poison were frequently used as an insecticide before the days of the much less hazardous modern synthetic insecticides.
Arthropod: An invertebrate animal belonging to the Phylum Arthropoda, which includes insects, spiders, crustaceans, centipedes, and millipedes. This is the largest phylum and it contains more than one million known species.; Arthropods are characterised by an exoskeleton with a segmented body and jointed limbs.
Artichoke, globe: See: Cynara scolymus.
Artichoke, Jerusalem: See: Helianthus tuberosus.
Artificial fertilisers: The term ‘fertilisation’ has two meanings in agriculture. It can mean sexual fertilisation of either plants or animals, or it can mean manuring of crops.; Fertilisers used for manure are divided into the two categories of organic and artificial. Organic manures are either the excrement of farm animals, usually known as farmyard manure (F.Y.M.) or stable dung, bone meal, or quarried deposits of fish-eating bird excrement, known as guano.; Artificial fertilisers are produced in factories, usually by a modification of natural products, such as atmospheric nitrogen, rock phosphate, or potash. Their constituents are known as N, P, and K, the symbols standing for nitrogen, phosphorus, and potassium. Other constituents may include calcium and magnesium, as well as various minor nutrients and trace elements.; Artificial fertilisers are not used in organic farming.
Artificial selection: Genetic selection which is controlled by people, within a genetically diverse population. Artificial selection is the basis of both domestication, and modern plant and animal breeding. See also: natural selection, agro-ecotype.
Artocarpus altilis: Breadfruit, which is an ancient domestication and is the staple food in a number of Pacific Islands.
Ascomycete: Fungi whose sexual reproduction is by means of an ascus. Many plant pathogens are Ascomycetes, such as the powdery mildews, and apple scab (Venturia inaequalis).
Ascospore: A spore produced within an ascus. Ascospores are haploid, being the result of the reduction division (meiosis) of a newly fertilised diploid cell, which is the only diploid component in the life cycle of an Ascomycete.; Being the result of meiosis, an ascus usually contains eight ascospores but, in some species, the ascus contains only four, or two ascospores.
Ascus: The microscopic reproductive organ of an Ascomycete fungus. The ascus consists of a tube containing eight, four, or two haploid ascospores that are the result of meiosis. When the ascospores are mature, the tube bursts at its tip, from internal pressure, and the ascospores are projected into the atmosphere like microscopic bullets.
Asexual reproduction: Reproduction without sex. Asexual reproduction prevents variation and it produces clones. Many microscopic organisms, such as viruses, bacteria, and imperfect fungi, have asexual reproduction only.; Many r-strategists plant parasites, such as fungi and aphids have both sexual and asexual reproduction. This has the advantage of speed and economy for the parasite, and it permits a population explosion.; If continued for too long, asexual reproduction in the higher organisms is a survival disadvantage in a wild population, but it can be very useful in agriculture. The asexual propagation of plants by cuttings, grafts, etc., is called vegetative propagation.; Some Angiosperms have asexual reproduction by apomictic or nucellar seeds.; See also: r‑strategists.
Asparagus officinalis: A dioecious vegetable that is perennial cultivated for its young succulent shoots. Difficult to breed and not recommended for amateurs.
Asparagus pea: See: Psophocarpus tetragonobolus.
Asynchronous flowering: The production of flowers at different times within one season. Asynchronous flowering assists cross-pollination. It also assists survival, if there is bad weather that hinders pollination.
Attention deficit hyperactivity disorder (ADHD): The syndrome in children which, as its name implies, exhibits hyperactivity and a very short attention span. It has been reported that about two million children suffer from this syndrome in the United States.; It is thought that the cause of the syndrome may be exposure to hormone mimics during foetal development and/or childhood. There have been numerous documented cases in which a switch to an organic diet has eliminated ADHD and other mental disorders.; See also: Dirty dozen, POPS.
Aubergine: See: Solanum melongena.
Austronesian family of languages: Also known as the Malayo-Polynesian family of languages, these are the languages of remote islands extending from Madagascar, in the West, to Easter Island, in the East, and from Hawaii, in the North, to New Zealand, in the South.; The Austronesian people spread these languages by their ability to make long ocean voyages long before either the Chinese or the Europeans developed ocean-going ships.
Autocratic plant breeding: The converse of the democratic plant breeding produced by self-organising crop improvement. Autocratic plant breeding is justified by the expense of breeding for vertical resistance, and by the relatively few cultivars produced by such breeding.; These cultivars have a very wide ecological adaptation and their widespread use justifies their cost. But the farmer has few choices of cultivar, and the breakdown of a vertical resistance can lead to widespread damage.
Autoecious: The converse of heteroecious, which means that a rust or an aphid is obliged to change its species of host in order to complete its life cycle. An autoecious rust is one that completes its entire life cycle on one species of host.; Entomologists use the term ‘monoecious’ in place of autoecious when describing aphids. Unfortunately, in botany, monoecious means that separate male or female flowers occur on a single plant (See also dioecious, hermaphodite).
Autogamy: (Greek: auto = self; gamy = marriage). Self-fertilisation, or self-pollination. An autogamous species is one in which individual flowers, or plants, are fertilised with their own pollen. However, some cross pollination always occurs in an autogamous species and variability is always maintained. (See also: allogamy).
Auto-infection: Infection is the contact made by one parasite individual with one host individual for the purposes of parasitism. Auto-infection (Greek: auto = self) means that the parasite was born on (or in) the host that it infects; it had no need to travel to its host.; Auto-infection is possible only after a matching allo-infection has occurred. The parasite then reproduces asexually to produce a clone in which all individuals are identical. It follows that, in terms of the gene-for-gene relationship, all auto-infection is matching infection. Consequently, vertical resistance cannot control auto-infection, which can be controlled only by horizontal resistance.; Because all parasitism involves auto-infection, it must be concluded that horizontal resistance occurs in every host, against every parasite of that host.; (See also: allo infection, autogamy).
Autopolyploid: A polyploid has more than two sets of chromosomes (e.g., triploid, tetraploid). In an autopolyploid, all the chromosomes are derived from the same species. In an allopolyploid, the chromosomes are derived from two or more different species.
Auxin: Auxins are plant hormones.
Avena fatua: Wild oats. This species can be a serious weed as it is difficult to control in cereal crops.
Avena sativa: Cultivated oats. This species is a hexaploid and the first controlled crosses were made by a Scottish farmer, Patrick Sheriff, in 1860.; Subsequently, most professional work has used pedigree breeding and back-crossing with a view to introducing vertical resistances. However amateur breeding for horizontal resistance is entirely feasible and a male gametocide, as used with wheat, will probably be effective.
Average: The mean. A figure obtained by dividing the total of given amounts by the number of amounts in the set.
Avocado: See: Persea americana.
Axil: The upper angle between a leaf and the stem.
Axillary bud: A bud that is located in an axil. Many axillary buds are suppressed by auxins emanating from the apical meristem, and they develop only if the apical meristem is damaged or removed.

Glossary: B

Back-crossing: A Mendelian breeding technique designed to transfer a single gene, usually a resistance gene, from a wild plant into a cultivar.; The cultivar and the wild plant are cross pollinated to produce a hybrid progeny. A hybrid individual that carries the resistance gene is then back-crossed with the cultivar parent to produce a second breeding cycle. This process of back-crossing is repeated for several breeding cycles until the hybrid is indistinguishable from the cultivar parent, except that it carries the resistance gene from the wild parent.; Note that back-crossing is an excellent technique when breeding for vertical resistance, but that it dilutes polygenically inherited characters, and it should not be used when breeding for horizontal resistance.; See also: Pedigree breeding.
Bacteriocide: A pesticide that kills bacteria.
Bacteriophage: A virus that attacks bacteria.
Bacterium: A bacterium (pl. bacteria) is the most primitive of the cellular organisms. About 1,600 species of bacteria are known to science and some of these are parasitic on plants.; Bacteria are prokaryotes. That is, although their cells do contain DNA, they do not contain a nucleus.
Bajra: See: Pennisetum typhoides.
Balanced science: Balanced science means two things. First, all systems levels are treated equally. Second, factual science and theoretical science are treated equally.; One of the reasons that twentieth century crop science has become unbalanced is because both the higher systems levels and theoretical aspects have been neglected. See also: Suboptimisation.
Bambara groundnut: See: Voandzeia subterranean.
Bamboo: See: Gramineae.
Banana: See: Musa.
Barley: See: Hordeum vulgare.
Barberry: See: Berberis.
Basidiomycete: A group of fungi whose microscopic spores, called basidiospores, are produced externally on microscopic structures called basidia. The basidium is the result of sexual recombination, and it usually produces four haploid spores by reduction division.; This group includes all toadstools and mushrooms as well as a number of plant pathogens.
Basidiospore: A microscopic spore produced at the end of a basidium by a Basidiomycete. These spores are usually produced in groups of four, and they are the result of sexual recombination followed by reduction division.
Basidium: A microscopic, club-shaped structure on which basidiospores are produced.
Bast fibre: Any coarse plant fibre used for making ropes, sacking, or mats (e.g., hemp, jute, sisal).
Batatas: See: Ipomea batatas.
Beans: See: Glycine (soybean), Phaseolus (haricot and other beans), Vicia (broad bean, or faba bean).
Bed bugs: A wingless hemipterous bug, belonging to the genus Cimex, which sucks human blood, and infests beds and dirty houses.; It is of interest because centuries of use of dried flowers of Chrysanthemum cineriifolium in Dalmatia have proved that natural pyrethrins are a stable insecticide.
Beech: See: Fagus sylvatica.
Beehives: Amateur breeders wishing to obtain a massive random polycross in an outbreeding species that is pollinated by bees, will usually benefit from placing a beehive close to their field plots.; If you do not wish to handle bees yourself, a friendly beekeeping neighbour can probably be found to assist.; Bees will also achieve a significant amount of cross-pollination in an autogamous species such as beans, but the use of a marker gene is recommended.
Bees: See: Apis.
Beet: See: Beta vulgaris
Beet, sugar: See: Beta vulgaris.
Beetles: Insects of the Order Coleoptera characterised by hard fore-wings which meet in a straight line down the back, and cover the hind wings. Many beetles are serious crop parasites, and others are serious parasites of stored food products.; Some beetles, such as ladybirds, are beneficial in that they eat other crop parasites.; There are some 300,000 species of beetles in the world, and this is by far the largest order of living organisms.
Bell-shaped curve: The graph that is produced when various levels of a quantitative character that has a normal distribution (e.g., horizontal resistance) are plotted against their frequency.
Benincasa hispida: The white, or wax, gourd, which is a member of the Cucurbitaceae.
Berberis spp.: The wild barberry that is the alternate host of the heteroecious wheat stem rust (Puccinia graminis). Barberry is the winter host in which sexual recombination occurs, and new vertical pathotypes are produced. See also: Saturation technique.
Bergamot oil: This essential oil is extracted from the rind of the Bergamot variety of Citrus aurantium, and is used to scent Earl Grey tea. The name derives from the town of Bergano in northern Italy. An inferior bergamot oil is obtained from the labiate herb Mentha citrata.
Berry: A fruit containing no hard parts except the seed, e.g., tomato, banana, grape, date, gooseberry.
Berry fruits: See: Rubus spp.
Bertholletia excelsa: Brazil nut. A young seedling of this tree takes at least twenty years to bear its first fruit, and may take as long as eighty years. The fruits take a year to ripen. Definitely not a crop for amateur plant breeders.
Beta vulgaris: This species, which belongs to the family Chenopodiacea, has been domesticated into sugar beet, garden beets (beetroots), fodder beet, mangolds, and chards. It is open-pollinated and breeding is based on recurrent mass selection.; The German chemist Marggraf first observed sugar in fodder beets and his pupil Achard started improving the crop and developing extraction techniques. Napoleon encouraged beet sugar production during the British naval blockade, which prevented the import of cane sugar from the West Indies. Subsequent tariff protection of various European and North American beet sugar industries did much to stimulate production. Beet sugar now makes up about half of the world supply of crystalline sugar.; The accumulation of resistance to ‘curly top’ virus in North America was a good example of very rare twentieth century breeding for horizontal resistance. Recent breeding has produced ‘monogerm’ varieties which have only one seed in each fruit. These are important as they eliminate the need for hand-thinning, and they allow the total mechanisation of the crop. However, this degree of technicality has taken the crop out of the hands of amateur breeders.; Beetroots, fodder beet, mangolds, and chards offer scope to the amateur breeder working with horizontal resistance.
Betula spp.: Birch trees, used in plantation forests to produce hardwood. Not recommended for amateur breeders.
Biennial: A plant which requires two seasons to flower, fruit, and die.
Biffin, R.H.: The scientist in Cambridge who first discovered single-gene resistance and initiated a century of professional plant breeding for vertical resistance.
Billion: The term billion should be used in the more logical American sense to mean one thousand million (10⁹), rather than the somewhat idiosyncratic British sense of one million million (10¹²) which is called one trillion in North America.
Bimli jute: See: Hibiscus cannabis.
Bimodal rainfall: A tropical pattern of seasons in which there are two rainy seasons, and two dry seasons each year.
Binomial coefficients: The numbers that make up the lines in Pascal’s triangle. The largest binomial coefficient for a gi