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AmazonGlobal Ship Orders Internationally. Amazon Inspire Digital Educational Resources. Amazon Rapids Fun stories for kids on the go. Amazon Restaurants Food delivery from local restaurants. Farming systems in the tropics. Proceedings of the workshop on agroforestry systems in Latin America. Properties and management of soils in the tropics. John Wiley, New York. Pasture production in acid soils of the tropics. Research objectives in agroforestry - A conceptual approach. Research in silvopastoral systems. Paper presented at the International Symposium on Browse in Africa.
Expert Meeting on Tropical forestry. UN Environment Programme, Nairobi. President's Science Advisory Committee. The world food problem, vol. The White House, Washington, D. Vegetation of the earth in relation to climate and the ecophysiological conditions. Climate-diagram maps of the individual continents and the ecological climatic regions of the earth.
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Integrating forest and small-scale farm systems in Middle America. Photosynthesis of leaf canopies. Agri- cultural Research Report Centre for Agricultural Publications and Documentation, Wageningen. It is usually converted to flour and made into cake, porridge, pudding or gruel, and eaten with other foodstuffs. It is also used for malting and brewing. The grain is nutri- tious and is considered good for infants and invalids.
Its great advantage is that the grain can be stored without insect damage for several up to 10 years. It has a shallow, branched, fibrous, adventitious root system from the base of the main stem. The stem is noded, slender mm thick , erect and smooth and covered by the leaf sheath; leaves are cm long and often folded though with strong midribs.
The inflorescence is terminal and consists of digitally arranged sessile spikes, curved to inside and compact, often with an additional one or two spikes below the terminal whorl. Flowers are hermaphrodite and almost entirely self-pollinated within about days. Flowering takes place from top to bottom in the spike, but in the reverse direction in the spikelets. Seeds are very small, about mm in diameter. A number of cvs have been recognized, and many improved cvs have been selected and bred in India, for earliness in bearing as well as for higher yields. It does not tolerate heavy rainfall, and it requires a dry spell at the time of grain ripening.
However, the crop requires a well-distributed rainfall during the vegetative stages. Relatively fertile and free-draining soils are the most suitable. Photoperiod and temperature influence the time to maturity. While it does not tolerate waterlogging, it can tolerate dry spells during the early stages of growth.
The protein of the grain is of good biological value, and the grain is a good source of calcium. It consists of raising a broadcast crop of finger millet in the ash obtained by burning the trees and woodlands. Farmyard manure is incorporated into the soil at the time of seedbed preparation. The first needing is done along with thinning, which is followed by one or two more hand weedings. Thorough seedbed prepara- tion reduces the incidence of weeds, but drilling in rows is preferred because weeding in the broadcast crop is more diffi- cult than in the line-sown crop.
Ferilizer trials have shown good response to nutrients, especially N. Fertilizers are given as basal dressing except N, which is given in two equal instalments , one before sowing and the other when the plants are 6 weeks old. In India, the plants are cut close to the ground, tied into sheaves and stacked to dry, and threshed by beating with sticks or trampling by oxen or by stone rollers.
The crop does not attain maturity simultaneously, especially under irrigated conditions, when frequent harvestings may be necessary. Combine harvesting is also possible. Finger millet Eleusine coracana L Gaertn. It is a staple food, particularly in the tropics; is used as a livestock feed especially in temperate and advanced countries, and is a raw material for many industrial products such as starch, syrup or sugars, oil, alcohol etc. Over important products and byproducts are reported to be obtained from maize.
It is now cultivated throughout the world in areas with suitable growing conditions. However, most of the maize produced is consumed locally. It is usually single-stemmed but sometimes produces tillers, and grows up to 4 m tall. The adventitious roots develop about two weeks after germination, during which period the seminal roots are present. Roots are profusely branched and grow both vertically up to 2 m and horizontally.
Roots also grow from the lower nodes above ground level. These are called prop roots and they lend some support. Internodes are shorter and stouter at the base. Buds in the axils of the leaves of the three lowest internodes may produce tillers, but this is not a preferred character. Leaves are alternate, produced on either side of the stem at the nodes.
Leaf sheaths, usually with hairs along the upper margins, enclose internodes for varying distances. The leaf blade is linear- lanceolate; x cm. Both male and female inflorescences are produced separately on the same plant. The male inflorescence, called 'tassel', is a terminal panicle, about 40 cm long, with a central axis as the continuation of the stem and several erect or flexuous lateral branches.
Paired spikelets are borne in rows on the main axis and branches, each spikelet has two glumes of equal size, and two staminate flowers within the glumes. The female inflorescence called the 'ear' is a modified spike, produced from a short lateral branch in the axil of one of the largest leaves in the middle of the stem.
The ear has a central axis or cob, which is a thickened modified stem protec- ted by modified leaves from the lowest internode of the ear-bearing lateral branch, and these modified leaves become the husks of the cob. The cob bears paired spikelets in longitudinal rows. Each plant usually produces only one ear, but sometimes two or three. A mature cob is cm long, The kernel consists of a short spongy pedicel or tip, a smooth pericarp or hull which constitutes about 5. The tassel sheds its pollen within a period of over a week and the pollen remains viable for about 24 hours, viability being less in hot dry weather.
The pollen is produced in enormous quantities: The silks emerge during a period of days and remain receptive for about 14 days. The time to maturity of the crop varies greatly according to variety and altitude. At low altitudes and warm climates, it flowers in two months and matures in four, whereas at higher altitudes and colder climates, it takes about 6 months to flower and months to mature. Maize is the crop that has been subjected to maximum genetic and cytogenetic studies. Consequently tremendous advancements have been attained in improving the crop.
Mass selection, hybrid- zation, use of inbred lines, exploitation of cytoplasmic male sterility, development of synthetic cultivars etc. Thus, the type of cv. In low input systems of agriculture, a synthetic cv. However, it is essentially a crop of the warmer parts seasons of temperate regions and the humid tropics.
It is not suited to arid conditions and ever- wet tropical evergreen forests. In the tropics, maize grows best in areas with rainfall of mm during the growing period, but also grows in areas receiving as low as mm during the growing period. The young maize plant is The crop does not tolerate frost and waterlogging. It is highly susceptible to waterlogging; the crop can be killed if it stands in water for as long as a day. It can be grown on soils with a pH from 5. Maize is a plant with very fast rates of growth and photosythetic production during vegetative stages.
It is also grown mixed with legumes and low-growing vegetables. In Africa, many peasants still grow much maize by shifting cultivation and the 'shamba' taungya system. The coleoptile emerges from the soil days after planting. But of late, the tendency is to minimize the tillage operations to reduce the cost of cultivation and minimize soil erosion.
Depth of planting is Seeds are sown deeper in dry soils. Maize is usually sown early in the season, immediately after the danger of frost is over in temperate regions, and at the beginning of the rainy season in the tropics. It may be planted on ridges or hills or in rows. The spacing will depend upon the local climatic conditions and the cv. In drier areas, the spacing is wider.
When sown by hand, the plant population is adjusted to the required level by thinning, when the plants are about 15 cm tall.
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For best results, nitrogen is applied in three equal instalments at the time of sowing and one and two months after planting; sometimes two- thirds of the total quantity of nitrogen is given when the plants are knee-high. In commercial production, P and K, and secondary and micronutrients are also given, especially sulphur and zinc; but in tropical Africa, response to P is variable and there is little or no response to K. AFTERCARE During the pre-taeseling period, which varies from days depending upon genetic and environmental factors, the crop is kept weed- free either by hand-weeding and inter- cultivation or by the use of herbicides.
When fully mature, the leaves become yellowish and the husks papery, and the grains will be hard and shiny in appearance. When harvested by hand, the cobs are removed with as little stalk attached as possible. The grains do iot shatter. Cobs are stored in cribs made of wire mesh, or grains are stored in simple granaries. In the corn belt of the USA, they are much higher. The major fungal diseases are leaf blight Helrninthosporium turcicum, also known as Trichometasphaeria turcica , downy mildew saleroepova spp.
Stored grains are attacked by moths and weevils, and by rats, squirrels and other rodents. However, substitution of maize in borderline areas may be disas- trous in years with unfavourable climate. The widespread preference for maize in varied climatic and agronomic situations sometimes makes it imperative to grow maize in areas that are less than ideal. This is often the case when it is used in agro fores try. All the major maize-growing countries have their own national research and development programmes.
World Crops, 19, Nos. Advances in corn production: Iowa State University Press, Ames. Maize and beans with C. It is consumed mostly after husking. It may be cooked in the same way as rice, or ground into a flour and made into a porridge. The grain may be fed to poultry and other livestock or used to produce malt; in Africa, the malted seed is an important source of beer. The green plant is a good fodder. The straw, which is inferior to other cereal straws as a cattle feed, is also used for bedding, thatching, fencing and fuel.
The major producing regions are India and tropical Africa - especi- ally in the Sahel and Sudan zones. It is not a crop of international trade. Has a single seminal root, followed by fibrous- adventitious roots from lowest nodes of stem and tillers. Inflorescence is a contracted panicle or false spike, resembling a bulrush, and is terminal, dense, cm long, cylindrical, cm in diameter.
Spikelets usually borne in pairs, two- flowered , mm long, lower floret usually male. Fruit is a caryopsis, small, usually obovoid or elliptic, about 4 mm long, white, yellow or grey in colour. The plant is markedly protogynous and cross-pollinated. The spike emerges about 10 weeks after sowing and the grain begins to develop about a week after, and is fully developed about 30 days later.
Thus the total duration of the crop is about 4 months. A number of races and cultivars are recognized in Africa and India. Based on the total duration of the crop, these are short- 80 days , medium- days and long- days duration types. There is considerable variation in most cultivars as a mixture of cvs is usually planted and the crop is cross-pollinated. High-yielding hybrids have also been evolved. Early- maturing cultivars are found in lowest rainfall areas and late-maturing ones in areas with more rainfall.
The northern limit of pearl millet in West Africa is about mm isohyet. Even distribution of rainfall is more important than total precipitation. Its merit is that it can give economic yields in sandy and poor soils that are too poor for other cereals except a few minor millets. It is tolerant of weed competition and comparatively free from Striga hermontheca, the parasitic weed, whereas most other cereals are susceptible to it.
Its most serious disadvantage is its susceptibility to bird damage. The grains contain approximately Mostly grown in sole stands, but also grown on ridges, with sorqhum in the furrows between the ridges; also grown mixed with pulses. The crop may be grown on the flat or on ridges. Very rarely, 3-week old seedlings are transplanted. Farmyard manure is the most commonly applied manure. If tillers ripen unevenly, more thV. Fodder crop is usually harvested at milk stage. The seeds store well; they are usually consumed locally. It is grown under Aaaeia spp. Many Agricultural universities of India.
The West African millet crop and its improvement. Pearl millet Pennisetun typhoidee. Sorghum under Acacia albida. Brot Sorghum vulgare Pers. It is the world's fourth most important cereal crop after wheat, rice and maize. The grain is ground into a flour that is used for a variety of preparations; it may be cooked like rice; it is used for brewing beer especially in Afriea; and it is a valuable cattle feed in developed countries.
The plant residues and stems are used for fuel and sometimes for thatching huts. It is now cultivated in ovei 50 million hectares throughout the warmer parts of the world. In certain wetter parts, maize is replacing sorghum as the staple cereal. The stem is solid, erect, 0. Leaves vary from in number, erect when younc. The panicle is terminal, may be erest or goose-necked, densely packed with conical and short or long with primary, secondary or tertiary branching. The spikelets are borne in pairs, one of which is sessile and hermaphrodite and the other pedicelled and sterile or male.
The inflorescence begins to flower when elongation of the peduncle is completed; opening cf flowers begins at the top and continues downwards and is completed in days. Flowers remain open for about 2 hours in the fore- noon; pollination occurs from stamens in the same flowers, from other flowers of the same inflorescence or from other inflores- cences by wind. The fruit is a caryopsis; it matures within about days after blooming. The grain is partially covered by glumes; awns may be present or absent; the seed coat varies in colour from pale yellow to various shades between brown and red.
The crop matures in 2 J to 9 months depending upon the cv.
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A considerable amount of breeding and selection work has been done with sorghum. Moreover, sorghum is an extremely variable crop with a large number of cvs and varieties of different characteristics which cross readily. It can tolerate drouoht and dry conditions, but can also be grown in areas with high rainfall and occasional waterlogging. Being a crop of the warm regions, sorghum is usually cultivated in lower elevations, but high altitude cvs have also been developed.
Sorghum does not tolerate frost. SOIL Sorghum can tolerate a wide range of soil conditions. It grows best on reasonably fertile soils, but also grows well on heavy soils or on light sandy soils, in the pH range of 5. It will produce a crop on soils too poor for other crops? The drought resistance is due to a very efficient and well- branched root system which develops quickly before the above- ground parts, silica deposits on the roots, lesser leaf area compared to maize , waxy coating on the leaves, its ability to remain dormant during adverse periods etc.
In areas with more favourable growing conditions, maize is a better crop than sorghum, but under marginal conditions maize may be a disaster whereas sorghum will give a crop. Sorghum is a short-day plant, but cvs vary in their sensitivity to photoperiod. However, the length of the growing period is determined by the interaction of genotype , photoperiod, and temperature.
Lysine and methionine are the most limiting aminoa'cids. Sorghum shoots contain the cyanogenic glycoside dhurrin, which on hydrolysis produces HCN which is toxic in concentrations more than ppm. The quality of HCN varies with cv. HCN is destroyed when fodder is made into hay or silage. Grown in rotation with other crops, mainly cotton, groundnut, finger millet, tobacco, pulses, etc. Continuous cultivation in the same plot leads to heavy infestation of the parasitic weed Stviga. It is believed that sorghum depletes the soil of fertility "sorghum injury" , probably because of the high sugar content of its voluminous roots and depletion of soil moisture.
So it is usually the preferred crop in soils depleted by previous croppings. Also grown in admixture with other crops. Properly stored seeds remain viable for long periods. Usually no dormancy; germination within about seven days after sowing. Since the seeds are rather small, a firm fine seedbed is desirable, but in peasant farming this is seldom attained. Being a heavy feeder, sorghum should have a heavy dressing of farmyard manure which is usually incorporated into the soil at the time of seed-bed preparation. Before sowing seeds are treated with sulphur to protect the plants from smut disease.
Time of sowing depends on the conditions; in dry regions, the crop is sown at the time of onset of first rains. When grown in pure stand, x cm spacing is adopted depending upon moisture availability and soil fertility. Nitrogen is given in two instalments, half as basal dose and the other half at the time of flowering. Subsequent weedings, especially to control the parasitic weed Striga, are done with bullock- drawn hoes in row crops or hand-hoeing in broadcast crops.
Dried heads are threshed either by cattle- trampling or with stone rollers. Grain is well dried in the sun before storage.
Usually stored in earthen or metallic containers, closed tightly on the top. They are annual herbs with tubular corollas. Two major specie are S. Seeds of both are minute and are produced in large numbers. They remain viable in dry soils for several years and germinate while in proximity with host roots. The parasitic plants draw their requirements of water and nutrients mainly from the host roots, through haustoria. Severe attack by Striga causes drought-like conditions to the crop.
Careful weeding reduces the weed's population. INSECTS Sorghum shoot-fly, Antherigona varia soccata, the larvae of which burrow into the meris terns of young shoots and kill the shoots, is a serious pest. Many stem borers and sorghum midge Contarinia sorghiaola y are also major pests of sorghum. DISEASES Several diseases cause serious crop losses; most important are anthracnose Colletotrichwn graminicola , leaf blight Helmintho8popium turcimum , downy mildew Solerospova eorghi , and smut diseases Sphacelotheoa spp.
Voluminous research results are available on various aspects of sorghum. Some of the relevant compendiums are: Sorghum in West Africa. Field Crop Abstracts 18, They may be cooked together with vegetables, or the decorticated and dried seeds may be ground into a flour, or steamed. The young pods, stems, and leaves are used as a vegetable. Also grown as a fodder plant, and the residue of the grain crop is also used as an animal feed. Now it is cultivated through- out the tropics and subtropics. Erect, trailing, climbing and bushy forms exist.
Most cvs are indeterminate; life cycle varies from 60 to days or more. The tap-root is stout and well developed with numerous laterals spreading in surface soil, and large nodules, often collected in groups. The stem is rounded, thin and strong, sometimes with a purple tinge. Inflorescence is an axillary raceme having a long peduncle, with a few flowers' crowded near the tip in alternate pairs. Flowers are conspicuously coloured; they open early in the day, close around mid-day and fall off on the same day; self-pollinated.
Pods vary greatly in size, shape, colour and texture; they are linear, crescent-shaped, or coiled, cm long, seeded. They are indehiscent, usually yellow when ripe. Seeds also are very variable in size, shape and colour; mm long, globular to kidney-shaped; seeds weigh g. Several cvs are identified and numerous species names have been given to the various forms; a great deal of confusion and disagreement exist on the classification. The catjang pea and the asparagus bean, Vigna sesquipedalian widely cultivated in Asia, are also considered as forms of cowpea.
Numerous high- yielding hybrid strains have also been produced. It is sensitive to cold and killed by frost. Short-duration determinate types can be grown in areas of less than mm annual rainfall, whereas medium- and long-duration types are grown in areas of up to mm rainfall. Excessive rainfall and high humidity are not preferred.
It grows well in semi-arid climates. SOILS Cowpea can be grown on a wide range of soils if well- drained and not subjected to waterlogging. Optimum pH is 5. On heavy and highly fertile soil, excessive vegetative growth and poor grain yield occur. When grown for dry seeds, they are also drilled in rows cm apart, and In hill planting, as practised in francophone Africa, the recommended hill spacings are 50x50 - 50x60 cm.
Cowpeas must be kept free from weeds during the early stages, which is usually done by hand. Cowpeas are more sensitive to herbicides than many other crops. Early cvs mature in about 3 months and green pods will be ready for picking 50 days after sowing.
The pods tend to ripen unevenly. When grown as a grain legume, time of harvesting is critical as the mature pods shatter easily and the seeds germinate quickly if there is little moisture. When harvested manually, the nature pods are picked by hand at intervals of?
Cowpeas are extremely susceptible to insect damage while storing. The root-knot nematode Meloidogyne javanica also attacks the plant. However, it requires full sunlight for optimum grain production. The best possibility for c o. The International Institute for Tropical Agriculture, Ibadan, Nigeria, has since its establi- shment in been involved in research on the crop. Some of the notable literature references are: Commonwealth Bureau of Pasture and Field Crops. A bibliography of cowpeas. Tropical Products Institute, London.
Pulse crops of India-cowpea pp. Indian Council of Agricultural Res. Grain legumes of the lowland tropics. Dhal is made from the beans, or the dried beans are boiled and eaten. Flour is also made from the beans, and the green pods are used as a vegetable. Mung beans are also grown for hay and as a fodder crop. The tap-root grows very deep into the soil, and the laterals arising from it also extend obliquely downwards. The stem is nulti-b ranched and a few cvs have a spreading habit. Flowers are yellow to greenish, occurring in clusters; normally self-pollinated.
Toner and slender, with seeds. Seeds are small, globular, often green; seeds weigh g. Several cvs have been sorted out and high-yielding strains developed in India and to some extent in the USA. Two main types are aureus, yellow or golden gram, usually grown for fodder purposes, and typiaa, the green gram cultivated for grains. A black-seeded type, grandis, and a brown-seeded one, bruneus, are also grown in India.
The crop matures in days; longer-duration cvs have also been identified. Excessive rains prolong the vegetative phase. It is fairly tolerant of drought; does not tolerate frost. It can be grown on a wide range of soil types if they are well-drained and free from waterlogging.
It grows on clayey soils also. It is fairly tolerant of saline-alkaline conditions. Protein content as high as It is propagated by seeds; seeds retain viability for years. Seed rate is lower when sown in lines. The crop requires a good tilth. For best results, the phosphorus fertilizer is placed in bands below the seeds at the time of sowing. The crop matures in days, but shorter-duration cvs have also been developed. The serious pests include the Asian bea fly Qphiomyia lie ianagvoy. The cowpea weevil Callosobruchus ohinensis is the most serious pest of stored grains.
The root-knot nematode Heloidogyne spp. Numerous research reports on mung beans can be seen in Indian Farming and Indian J. Other major references are: Indian Council of Agric. Pulse crops of India Kachroo, P. Nutritional improvement of food legumes by breeding. Bibliography of mung beans research. Symposium on food legumes. Cent; Ministry of Agric. Stems are angular, hairy and branched; branching begins cm above ground, between 6th and 10th node.
Seeds vary in size, shape and colour; usually round or oval; seeds weigh g. Many cultivars over are recognized, and they are classi- fied into early-, medium-, and late-maturing types. Numerous improved high-yielding, short-duration, etc. The growth period varies considerably, from to days, according to the cv. Late- maturing cvs take over days, medium ones days and short-duration types less than days.
ECOLOGY CLIMATE Wide adaptability; grows well in semi-arid regions with less than 60 cm rain per year; best growth when there is good rainfall during the first 2 months followed by a dry period during flowering and harvesting; less suitable for very wet tropics; most cultivars are sensitive to frost. They are grown at a wide range of elevations, up to over m.
SOIL Can be grown on almost all soil types that are not very poor in lime and are not subjected to waterlogging. Optimum growth and yield are obtained in deep loam, with pH Saline-resistant cvs have been developed. Good growth in semi-arid regions, and during dry months in wetter regions. They are short-day plants; this affects time of maturity and height of plants according to date of sowing, and thus the ease of harvesting. For optimum yields, bright sunshine is essential.
The approximate composition of mature dry seed is: Pigeon peas are rich in Vitamin B, but are low in the essential aminoacids methionine and cystine. Also grown as a pure crop. Ridge plantin; recommended in areas liable to water- logging. SOWING When grown as a pure crop, the average spacing is cm between plants and cm between rows; wider spacings are also adopted, especially in East Africa. Spacing also varies depending upon the growth spreading habit of the plant. When grown with other crops, there is usually one row of pigeon pea for every rows of the main crop.
Seed rate is 1. The crop grows' slowly during the early stages, i. Weed control is essential at this stage. It also requires good supply of calcium, sulphur, and zinc. Finally when most of the leaves have dried and been shed, the plants are cut at the ground level, tied into bundles, left to dry for a few days, and then threshed. Dhal is prepared by the dry method drying the seeds in the sun for days and splitting them in a mill or by the wet method soaking in water for hours and then sun drying and splitting in a handmill.
The conversion ratio from fresh green pods to dried peas is about 3. Root- knot nematodes, mainly Meloidogyne javanioa, also attack the crop. The stored grains are infested by pulse beetles, Callo- eobPuahu8 ohineneie. Chemical treatments are recommended against all these pests, but most of them are not very effective. The most important disease is the soil-borne fungal wilt, caused by Fuearium oxyeporum sp. Crop rotations and mixed cropping are effective measures to control it.
There are a few minor diseases alsc. Even though it needs fu. Numerous research reports and data are available on pigeon pea and they have been compiled by: Crop and product digest No. Other major references include: International workshop on grain legumes. Pulse crops of India. Food crops of the lowland tropics. It has a high viscocity, it produces a very smooth jelly and it is used for certain types of glues. The fibrous residue, after extraction of starch, is fed to cattle.
It is also supposed to have medicinal value for healing wounds. Arrowroot is one of the most important export products of St. Roots are adventitious and fibrous, produced at the base of the plant Rhizomes are sympodial and distally swollen, cm long and cm in diameter. Stems are slender and erect; leaves distichous; lamina x cm, ovate to oblong; inflores- cence is borne terminally and branches are subtended by deciduous bracts.
Flowers are small 2 cm and borne in pairs; cross pollination is aided by ants and other insects. Fruits are very small about 7 mm and seeds are two-lobed. Seeds are seldom produced in some cvs. The rhizomes mature in months after planting. Fertile and friable sandy loams are preferred for better tuber development and easy harvesting.
Arrowroot starch retains its high viscocity on heating, unlike that of cassava and sago, whose viscocity falls when temperature increases. The crop is propagated by selected node-long tips of rhizomes known as "bits"; about kg are required to plant one hectare. Portions of rhizomes remaining in the soil after harvesting provide part of the ratoon crop. After thorough ploughing and forking, the bits are planted The crop is hand-weeded times.
Usually harvesting is by hand. Successive cropping on the same land is allowed for years. Yield varies considerably from t rhizomes per ha. The rhizomes contain the maximum amount of starch when the crop is 12 months old, but then they are more fibrous and the starch is difficult to extract. Cleaned and washed rhizomes are rasped, crushed, and mixed with water and the pulp is passed through a series of sieves. The starch settles in troughs and the fibrous tissue or bittie is separated.
The starch is then mixed with more watar and resettled which may be done by centrifuging , and dried in the air or in mechanical drisrs. Chlorination of water used for processing helps to prevent bacterial fermentation. It is graded on the basis of colour white is preferred , cleanliness, freedom from specks, pH, viscosity etc. However, 'banana' rhizomes must be processed within 48 hours after harvesting, whereas 'creole' rhizomes can remain before processing for several up to seven days.
In poor and infertile soils, long, thin rhizomes known as cigar roots are produced, which are useless. The Marantaceae of Malaya. In Root Crops, pp. Tropical crop and product digest No. Morphological and anatomical characte- ristics of the Marantaceae. Starch is also prepared from the tubers. Leaves are used as a pot-herb, and dried leaves as a fodder for cattle. Beer and other alcoholic drinks are also made from cassava. Tubers develop as swellings on adventitious roots a short distance from the stem by a process of secondary thickening.
There are usually tubers per plant, cylindrical or tapering, cm long, cm in diameter. The edible portion is the core or the pith covered by an outer skin periderm and a thin rind or cortex; it is rich in starch and usually white in colour. Old tubers become lignified. The stem varies greatly in length, branching habits, etc. Under natural conditions, germination is protracted and erratic. Usually plants are harvested months after planting, but long-season cultivars are left for longer periods. Many cultivars or clones are known. Generally they are divided into sweet cassavas, with low HCN content which are short- season cvs , and bitter Cassavas, which have more firm and yellow flesh than ; 'a.
It cannot with- stand frost or cold. It is grown in areas with to mm rains per annum; it can withstand drought except at planting , but not waterlogging. SOIL Generally cassava prefers a loose and friable soil, but it can be grown on diverse soil types that are not too shallow or stony. It will produce an economic crop on relatively poor soils that are unsuitable for other crops. However, heavy clays and saline and swampy soils are unsuitable.
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Highly fertile soils may result in excessive vegetative growth at the expense of tuber and starch formation. In sweet cassava, HCN is confined to the rind, whereas in bitter cassava it is more widely distributed, and must be destroyed by boiling, roasting, fermentation, etc. AGRONOMY Cassava is grown either as a pure crop or is interplanted with homestead horticultural crops T Propagation is by stem cuttings, cm long, taken from the middle of mature stems.
Usually land is prepared by a deep ploughing which facilitates maximum tuber development. The crop may be planted on the flat, on ridges, or on mounds; the usual spacing is 1 m x 1 m; may be planted at wider spacings also; sometimes cuttings are planted together. Adequate moisture is necessary at the time of planting, but after establishment the plant can withstand drought during which it will shed its leaves; the leaves reappear after rains. Weeding is done during the early stages. Earthing-up the soil around the stems months after planting favours tuber development and removes weeds.
Cassava is seldom manured in marginal areas and under suboptimal conditions of management. But optimal manuring can give good yields: Organic manures are applied in the planting pits at the tine cf planting and rertiiizers are applied after the crop's establishment at the time of earthing- up. Maturity is indicated by yellowing and shedding of leaves. Tubers cannot be kept for more than 48 hours after harvesting; therefore, harvesting is done as the demand or marketability is assured. Sweet cassava may be eaten raw after peeling; in bitter cassava, HCN is destroyed by washing and cooking.
Fresh tubers do not keep long, but may be sliced and dried in the sun with or without parboiling, the latter enhancing keeping quality. The nematodes Meloidogyne and Pratylenahus also are serious, especially in the Ivory Coast and Nigeria. Cassava mosaic virus, which causes mosaic and curling of.
Thus, cassava has excellent agroforestry potential. In Root crops, pp. The crop and product digest No. International Development Research Centre , Ottawa. Fig 14b Six month-old rubber tree intercropped with cassava Photo credit: It is the most important vegetable in the world today. Potatoes are eaten boiled, roasted, baked or fried and are processed into a wide range of products. Potatoes have subsidiary uses as stock feed and for preparation of large-grained starch, flour, and alcohol.
The root system consists of fine, fibrous, adventitious roots and swollen stem tubers. The stem is erect in early stages, but later becomes spreading or prostrate. Leaves are alternate and compound, irregularly odd-pinnate with petioled leaflets between the main pinnae. Many cvs produce a determinate flower cluster, consisting of white, red or purple flowers with five- lobed corolla.
Mostly self-pollinated, the fruit is a small spherical inedible berry. Considerable progress has been achieved in improving potatoes, and several cvs suited to specific growing conditions and with specific characteristics have been produced. In the tropics, the crop usually matures in months. However, the crop does not withstand frost. Rainfall of cm, evenly distributed throughout the growing period, is optimal. The crop does not tolerate drought. Under humid conditions, the control of late blight disease is difficult.
In the tropics the crop is grown in altitudes above m; the essential requirement is a marked cool season. Heavy clays and poorly-drained soils are unsuitable. Long-day cvs are unsuitable for the tropics. The crop grows under reduced light intensity, but for better yields the light intensity should be higher. Potatoes are also an important source of protein, iron, riboflavin and ascorbic acid in potato- rich diets. Propagation is by whole or, sometimes, cut tubers, known as "seed", weighing about 50 g. Good, healthy planting material is essential. Seed potatoes are treated with various fungicides before sowing.
Planting is done on ridges that are about 75 cm apart. When planted on the flat ground, soil is heaped around the stem during weeding, which facilitates tuberization. Usually, the seed is planted 10 cm deep, at a spacing of cm along the rows. Seed rate depends upon spacing, type of seed material whole or cut tubers etc.
The plants grow and cover the ground quickly so that weeding may not be necessary about six weeks after sowing. The crop is irrigated about once a week in dry weather. Potatoes respond well to manures and fertilizers. They are particularly heavy fetters of potassium, fertilizer require- ments vary considerably according to cultivar, soil type, and climatic conditions.
Potassium sulphate, rather than potassium chloride' is used as the source. Maturity is indicated by yellowing and drying of the foliage. Harvesting is done mechanically in commercial production, but can also be done manually, by digging. Prolonged storage favours the accumulation of excessive quantities of sugars.
Chemicals such as maleic hydrazide, iso-propyl phenylcarbamate etc. But the most widespread and serious malady is the fungal disease called late blight, caused by Phytophthora in fee tans. Early blight, Altevnaria eolani is another widespread disease. In addition, there are several other fungal, bacterial, and viral diseases and nutritional and physiological disorders. Publications from these institutes, the proceedings of the Symposia on Tropical Root and Tuber Crops, the American Potato Journal, and the common journals of agricultural sciences publish the research results.
Major books on potato are: Veenman and Zonen, Wageningen. The potatoes of Argentina, Brazil, Paraguay and Uruguay: The growth of the potato. Ministry of Agriculture, Fisheries and Food, U. The tubers are eaten boiled or baked, may be candied with syrup; also used for canning, dehydrating, and as a source of starch, glucose and alcohol.
The tender tops and leaves are used as a pot-herb in Africa and Southeast Asia. Now it is cultivated throughout the tropics, the largest area being in Africa. Outside the tropics, the major producers are Japan, China, the U. It has a vine-like, trailing, sometimes twining stem, mm in diameter and m long, with latex in all parts.
Internodes are cm long. The stem seldom rises more than 50 cm from the ground. An extensive, superficial, fibrous, adventitious root system is produced from the nodes of the planting material; stems in contact with the soil also produce roots at the nodes. Tubers, about 10 per plant, develop in the top 25 cm of soil by secondary thickening of some adven- titious roots, mostly from the original cutting, but also from the trailing vines. Tubers are smooth or ridged, globular; colour of the periderm and flesh varies depending upon the cultivar.
Yellow- and orange- fleshed cvs are rich in vitamin A. In freshly-cleared areas, sweet potato is the first crop, as it covers the ground quickly and smothers the weeds. It is also cultivated in steep slopes where it checks erosion better than most other crops, on small plots near the homestead, along roadsides where tall crops are prohibited by law and in valley bottoms. On homesteads, they are grown as intercrops under the perennial tree crops.