Phytosanitation
The national and international regulations that control the movement of plant propagating material around the world. The purpose of these regulations is to prevent the spread of dangerous crop parasites to those parts of the world that are still free of them. Phytosanitation can be international, regional, or local. International phytosanitation is usually effective because of border controls. Regional phytosanitation within a country is usually ineffectual because of the lack of border...
Ipomea batatas
The sweet potato. This crop originated in tropical South America. It was taken by Polynesians to Fiji and New Zealand, where it is known by its Peruvian name 'kumara'. The Portuguese took it to Africa and the Far East where it is known by its Caribbean name of 'batatas', which is the origin of the English word 'potato'. And the Spanish took it from Acapulco to the Philippines where it is known by its Mexican name of 'camote'. It is now one of the more important tropical food crops. Although it...
Phaseolus lunatus
The Lima or Sieva bean, also known as the butter bean. Named after the capital of Peru, archaeological remains of this bean have been found there dating from 6000BC. However, it is thought that this bean probably originated in the Guatemala area of Central America and was taken to South America by early travellers. The green shelled beans are eaten as a vegetable, and the dried beans are also cooked and eaten. The plant is self-pollinating, but some natural cross-pollination occurs. Of interest...
Plant quarantine
The isolation of newly imported plants to ensure that they are not introducing any foreign parasites. The term quarantine may refer to the quarantine station itself, or to the process of testing and purifying the plant material. Plantain In the tropics, a plantain is a starchy banana that is eaten cooked. In the industrial countries a plantain is a large sweet banana that is eaten raw. Plantation forest Man-made forest in the sense that the tree species used, their planting densities, and other...
Polygenic inheritance
Any inheritance that is genetically controlled by many genes of small effect, called polygenes. Polygenic inheritance is quantitative in its expression, and it exhibits every degree of difference between a minimum and a maximum, usually with a normal distribution. Polyphyletic A species that originated by hybridisation from more than one wild progenitor. Polyploid An organism, usually a plant, which has more than two basic sets of chromosomes. Thus triploid, tetraploid, etc. See also...
rstrategist
A species in which the population size is governed by the rate of reproduction, which is normally abbreviated to r. In its turn, the rate of reproduction is governed by the season. An r-strategist reproduces very cheaply, and very rapidly, with large numbers of very small offspring, whenever the weather and food supply permit. This behaviour produces a population explosion that is inevitably followed by a population extinction. Many plant parasites are r-strategists, and it is their population...
Brassica oleracea
Cabbages, Brussels sprouts, kohl rabi, cauliflower, broccoli, and kales. This is an ancient domestication, and many of these crops were known to the ancient Romans. It is a complex species probably derived from three wild species with a presumed doubling of chromosome number, followed by the loss of some chromosomes. The species is open-pollinated and requires recurrent mass selection, although some self-pollination occurs with sprouts, cauliflowers, and kohl rabi. Most of the crops are...
Hydroponics
The cultivation of plants in a nutrient solution instead of in soil. This technique is used mainly in greenhouses, and it is particularly useful for single seed descent. The plant roots can be suspended directly in the solution, or in inert gravel wetted with the solution, or inside flattened, plastic, tubular, film that is lying on the ground. In the last case, the plant grows through a small hole in the film, and nutrient solution is pumped continuously through the tube. The advantages of...
Chenopodium quinoa
Quinoa, the most important of the grain amaranths, is an extremely variable crop that was domesticated in Central America long before the Spanish conquest. The three main aspects of its domestication are seeds that are twice as large as the wild progenitors, the elimination of seed dormancy, and the retention of the seeds in the head. This pseudo-cereal is an interesting example of parallel domestication that is closely similar to that of the Old World true cereals. This is a minor crop but one...
Terracotta pots
Flower pots made of terracotta baked clay are more expensive than plastic pots, but they provide a superior aeration to plant roots. Tetraploid A cell or plant with four sets of chromosomes. A tetraploid usually develops from a more normal diploid , by an accidental doubling of its two sets of chromosomes. See also Doubled monoploid, Haploid, Auto-polyploid, Allo-polyploid. Thea assamensis Often called Camellia assamensis, this is the tea of India and Sri Lanka Ceylon . It contains considerable...
See Brassica alba Single seed descent SSD
A quick method of producing pure lines in crops that are inbreeding, and seed-propagated, such as many cereals and grain legumes. A breeding population may contain many individuals that are both genetically diverse and heterozygous. A single self-pollinated seed is taken from each individual and is grown to maturity. This process is repeated up to six times. Each individual becomes more or less homozygous, but the population is still diverse. The best individuals are selected and kept as new...
Panama disease of banana
See Musa sapientum. Panicum maximum Guinea grass. A tropical fodder grass native to East Africa. Panicum miliaceum This is the common millet. It is a cereal of ancient domestication, originating in eastern Asia. It was cultivated by the Chinese before the introduction of rice, by the pre-historic Lake Dwellers, and by the ancient Greeks and Romans. Its wild progenitors are extinct. It has a short growing season 60-90 days and it is drought-resistant. Some cross-pollination occurs, and this crop...
Recurrent mass selection
The breeding method of the Biometricians, designed to increase the levels of desirable, quantitative variables by changing the frequency of polygenes. In each screening generation, the best individuals are selected, and they become the parents of the next screening generation. This process is repeated for as many generations as necessary, but the rate of progress declines dramatically after a few generations. See also early selection, Family selection, Late selection, Pedigree breeding,...
Prunus armeniaca
The apricot, which originated in western China and, like the peach, is normally self-pollinated. Apricots can be hybridised with plums to produce 'plumcots'. Not recommended for amateur breeders . Prunus avium The sweet cherry, which is a diploid . There are also a number of other cherry species , some of which are tetraploid, including the sour cherry, Prunus cerasus. The commercial importance of cherries has declined with rising labour costs and the rewards for amateur breeders are unlikely...
Cimex lectularius
A flat, wingless, reddish-brown, hemipterous bug, known as the bed bug, of interest in that the natural pyrethins in Chrysanthemum cineriifolium have remained a stable insecticide after centuries of use in Dalmatia. CIMMYT Centro Internacional de Mejoramiento de Maiz y Trigo. Located near Texcoco, in Mexico, this is the home of the miracle wheats, and it is a bastion of pedigree breeding and single-gene resistances. With IRRI, these are perhaps the best examples of autocratic plant breeding, as...
Eragrostis tef
This cereal is unique to Ethiopia where it is used for the production of the staple dish 'njera'. It is also an excellent fodder crop. The self-pollinated flowers are very small and this makes cross-pollination extremely difficult. Not recommended for amateur breeders . Ergotism The human disease caused by the ingestion of poisonous ergots. The symptoms of ergotism are a constricting of the blood vessels which can lead to gangrene, abortion in pregnant women, and death. Before the discovery of...
Phaseolus angularis
The Adzuki bean, probably a native of Japan, has been established since antiquity in China. The plants are self-fertile when bagged but cross-pollination is frequent. This makes it an easy crop for amateur breeders . Phaseolus aureus The green or golden gram, Mung bean. A popular bean in China and India because it causes little flatulence. In China it is used for making 'bean sprouts'. This bean is self-pollinating and amateur breeders should commence by selection within existing populations....
Vanilla fragrans
This species is the only orchid grown for purposes other than ornamental. It originated in Mexico and the vanilla is extracted by fermenting the unripe pods and infusing them in alcohol. The main producer is now the Malagasy Republic Madagascar . The crop is propagated vegetatively and few clones are known to exist. There may be scope for selection by amateur breeders in the centre of origin. Variable ranking See Differential interaction. Variation Differences displayed by individuals within a...
See Allium sativum Gaumannomyces graminis
Previously called Ophiobolus graminis, this fungus causes 'Take-all' disease of wheat and other cereals. Gaussian curve The bell-shaped curve of a normal distribution. Gene The unit of inheritance which is carried on a chromosome. An inherited character may be controlled by a single gene i.e., a Mendelian gene , or it may be controlled by many genes polygenes . See also Allele. Gene banks The popular term for collections of plants made for purposes of genetic conservation. A gene bank may...
Saline
Salty, with reference to sodium chloride. Soils can become saline from inappropriate irrigation which allows excessive surface evaporation and salt accumulation. The ancient civilisations of the Tigris-Euphrates Valley declined, in part, from soil salination, but also from soil erosion. Sanitation Plant sanitation is generally taken to mean the use of clean seed, equipment, and soil, all with a view to reducing plant disease. Sapodilla Loosely, a saprophyte is an organism that derives its...
Inbreeding cereals
Cereals, such as wheat, rice, barley, and oats that are self-pollinating and are usually cultivated as pure lines. Inbreeding crops Many of the cereals and grain legumes are inbreeding and they require hand-pollination during the breeding process. See individual crops for details. Most tree crops are out-breeding, with the notable exceptions of arabica coffee and peach. Traditionally, during the twentieth century, inbreeding crops have been subjected to Pedigree breeding and the genetransfer...
Indigofera spp
Several species of this genus of the Leguminoseae are cultivated for a natural blue dye called indigo, or anil. This dye has been used for at least 4000 years, and it is superior to the European woad Isatis tinctora . However, with the development of analine dyes, the world market for natural dyes collapsed. Induced deficiencies Occasionally, a nutrient deficiency can be induced, in spite of the fact that there is an adequate amount of that nutrient available. For example, water softeners...
Amateur Plant Breeders Handbook
Raoul A. Robinson ISBN 0-9731816-2-1 This guide is intended for amateur plant breeders, usually members of a plant breeding club, who need a quick reference to terms that they may encounter in the course of conversation or reading. For readers who enjoy browsing, the guide should also be a source of information for anyone wanting to get away from the modern prejudices that favour single-genes, genetic engineering, and crop protection chemicals. It is also a guide for organic farmers, and for...
Cocoyam
See Xanthosoma sagittifolium and Colocasia esculenta. Codling moth See Carpocapsa pomonella. Coffea arabica Arabica coffee. This is the main coffee of commerce. It is an autogamous allotetraploid , 2n 44 believed to have been derived from an infertile cross between the two wild diploid , Coffea canephora and Coffea eugenioides 2n 22 , which subsequently doubled its chromosome number to become a fertile tetraploid. First cultivated in Ethiopia, it was taken to Arabia Felix Southern Yemen where...
Dactylis glomerata
A pasture grass grown mainly in the temperate regions of the Old World. Daktulosphaira vitifoliae The new scientific name for Phylloxera vitifoliae of grapes. Damping-off A disease of very young seedlings, which rots the stem at the soil surface. Affected seedlings then fall over like miniature, felled trees. The disease is caused by fungi such as Phytophthora, Pythium, and Rhizoctonia, and it is greatly aggravated by over-watering, which should be avoided. Otherwise, the best methods of...
Sorghum vulgare
See Sorghum bicolor. Source of resistance Mendelian breeders always need a source of resistance in order to undertake breeding for resistance to crop parasites. This source of resistance is usually controlled genetically by a single gene which is part of a gene-for-gene relationship, and which confers vertical resistance. If a source of resistance cannot be found, the breeding cannot be started. Biometricians working with polygenically controlled horizontal resistance do not need a source of...
Lime fruit
Tilia europaea. The lime tree, or linden tree. Linden In genetics, a line of descent. The term is used most frequently in the concept of a pure lines. Linear system The general systems theory originally concerned rather simple systems such as the solar system, and mechanical systems, such as clockwork. These are now called 'linear' systems, and they obey Newton's laws. Modern complexity theory concerns more complex systems, which are non-linear. Linear systems have parameters that are easy to...
Habgood nomenclature
This nomenclature uses the numbers of the binomial expansion i.e., 20, 21, 22, 23, etc., with arithmetic values of 1, 2, 4, 8, etc. . Each binomial number has an arithmetic value that is double that of its predecessor. The sum of any combination of binomial numbers is unique. For example, the sum 21 can be obtained only by adding 16 4 1, and no other combination of binomial numbers can add up to this sum. The nomenclature can be applied to matching pairs of vertical genes. Each pair of matching...
Saaz hops
This natural insecticide has the lowest known mammalian toxicity. However, it is difficult to obtain commercially. Saccharum officinarum Sugarcane. This giant grass is of very ancient domestication in New Guinea and it is derived from a continuous pathosystem. It consequently has no vertical resistance and it provides many magnificent examples of the utility and durability of horizontal resistance. There are about twenty-five cane breeding stations in the world and most of them still use...
Pure line
A cultivar of a seed-propagated, inbreeding species in which all the individuals are effectively identical and are almost homozygous. A pure line thus 'breeds true to type'. It is produced by self-pollinating the best heterozygous individual in a mixed breeding population for several generations. In each generation, the progeny show a reduced variability, and the process is repeated 4-6 times until no further variability is apparent. See also Single seed descent. Pyrenophora This is the Latin...
Nucellar seed
In most plants, seeds are produced as a result of fertilisation of an ovule by a pollen cell. In a few plants e.g., citrus, mango , embryos can also be produced directly from maternal tissue the nucellus , without any fertilisation by pollen. Seeds with nucellar embryos are called nucellar seeds, and they have two agricultural advantages. First, like true seeds, they do not carry virus diseases, or any of the other parasites whose transmission is blocked by seed propagation. Second, they are...
Humulus lupulus
Hops, which are now used almost exclusively for brewing beer. The plant is a perennial vine which dies back to ground level each fall. The above-ground parts thus have a discontinuous pathosystem and they have vertical resistance. It is a long-day plant and it is dioecious. It is propagated vegetatively, and only about eight clones dominated world production until quite recently. These include 'Fuggle' and 'Golding' in Britain, 'Hallertaur' in Bavaria, and 'Saaz' in Czechoslovakia. These clones...
Cholera
An intestinal diseases of humans caused by the bacterium Vibrio chlorae. This disease, and typhoid, caused by the bacterium Salmonella typhi, are spread by houseflies, and the Allied forces dusted the whole of Naples with DDT during World War II, in order to prevent major epidemics of insect-borne diseases, including malaria. DDT-resistant houseflies soon appeared and this was the first known example of the breakdown of an unstable, synthetic pesticide to new strains of the pests. It was this...
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 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...
Melinis minutiflora
A tropical fodder grass, called molasses grass, and native to Africa. Meloidogyne spp. A widespread genus of root feeding nematodes, that do not form cysts and which can be serious pests of crops. Melon See Solanum melongena. Mendel, Gregor Gregor Johann Mendel 1822-84 is often regarded as the father of genetics. More accurately, he is the originator of single-gene or Mendelian genetics, although his work was later used to explain the action of polygenes. This is an example of the time lag in...
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...
Commonwealth Institute Of Parasitology St. Albans Al4 0xu England
Commonwealth Agricultural Bureaux International. For a fee, the following institutes, which are part of CABI, will identify crop diseases, insects, and nematodes, respectively 1 International Mycological Institute, Bakeham Lane, Egham, Surrey, TW20 9TY, England 2 International Institute of Entomology, 56 Queen's Gate, London, SW amp 5JR, England 3 International Institute of Parasitology, 395A, Hatfield Road, St. Albans, Herts, AL4 0XU, England. Cacao
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...
Ribes grossularia
The gooseberry. An ancient crop known to the classical Greeks and Romans. A powdery mildew Sphaerotheca mors-uvae native to North America has prevented cultivation on that continent, and its introduction to Europe in 1905 caused severe damage. There is scope for breeding for horizontal resistance by amateurs. Ribes spp. The garden currants. There are a number of cultivated species of black and red currants, and white currants are a variety of Ribes sativum, the main red currant. Ribes spp., are...
Cucumis sativus
Cucumbers and gherkins. This species originated in India. There is a wide range of cultivar. The so-called 'English' cucumber has long fruits that are used mainly in salads and sandwiches. Pickling cucumbers have small fruits and are pickled as gherkins. The 'Sikkim' cucumber of India has reddish-brown fruits. All members of this species are monoecious, annual herbs, and some are parthenocarpic. There is considerable scope for recurrent mass selection by amateur breeders. Cucurbita maxima The...
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...
Alocasia macrorrhiza
One of the aroids, of minor significance, cultivated in S.E. Asia. Almond 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 breeding...
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...
Orange
A level in the taxonomic hierarchy. An order is a group of closely related families. Organ Any significant, macroscopic component of an organism. Organelles The internal, microscopic organs of a single cell. Organic chemicals Originally, chemical substances that had been produced by living organisms were called 'organic' chemicals, as opposed to the 'inorganic' chemicals such as rocks and water, which had not been produced by living organisms. Nowadays, the term 'organic chemical' refers to any...
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. However, 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...
Transpiration
The loss of water from a plant. The rate of transpiration is controlled by the stomata. See also Guttation. Tree Technically, any plant with woody tissues, as opposed to a herb that has no woody tissues. In practice, many of the smaller trees are called shrubs. Tree tomato See Cyphomandra betacea. Trifoliate This term means 'three leaves' and refers to the leaves of plants such as Trifolium spp., clovers , or Oxalis, that are divided into three leaflets. Trifolium spp. The clovers are important...
Prokaryote
Plant propagation may be by true seed sexual or it may be vegetative asexual . Seed propagation may involve segregating seed, which does not 'breed true', a pure line, which does 'breed true', or a hybrid variety, which has hybrid vigour. Vegetative propagation is achieved with tubers, rhizomes, cuttings, grafts, bulbs, corms, etc. Protective fungicide A nitrogenous organic compound that is an essential part of a living organism. Structural proteins form exoskeletons, hair, hoof and horn,...
Pimento
A compound leaf that has leaflets arranged on either side of a stalk. Pinus spp. The pine trees, which are members of the family Pinaceae, in the order Coniferae, which is one of the five orders of the Gymnosperms. These are particularly important timber trees that provide much of the world's soft wood. Selection within existing populations, particularly in North America, looking for horizontal resistance to white pine blister rust Cronartium ribicola would be an appropriate activity for a...
Cambium
A layer of active cells that separates the xylem and the phloem. These cells produce new xylem and phloem that are represented by the annual rings of trees. Camellia spp. A necrotic, sunken lesion on a thick part of a plant, such as a stem. Cankers are usually caused by fungi. Canna edulis Known as 'achira' in South America, where it originated, this crop is usually called Queensland arrowroot, or purple arrowroot, in English. It is grown commercially in Australia for extraction of starch from...
Seed production
Seed offered for sale is usually tested in a seed testing laboratory. The main test is for germination percentage, but other tests can include seed health, freedom from weed seeds, identity and purity of cultivar, etc. Seed-borne parasites Some parasites are carried in the seed, both true seed and vegetative seed tubers etc. True seed can be contaminated, infected, or infested. Contaminated seed carries pathogen externally and these can be destroyed by seed dressings. Infected seed carries...