Choice of food crops in relation to actual and potential production in the tropics.

Abstract

Average world productions of the most important tropical and subtropical grain and non-grain staple crops (rice, wheat, maize, sorghum, cassava, sweet potato, yam, colocasia and banana) were compared. The results were expressed in kcal edible per hectare and per day of vegetation. The root crops produce more bulk but mainly because of their higher water content; their energy food value amounts to about 30% of the grain crops per unit weight. Taking into account the percentage edible matter and the average period of vegetation, the figures for average world production for root and grain crops were much closer. The differences in average world production between the 2 groups of crops did not show clearly, perhaps due to the fact that in rice, wheat and maize more breeding has been done, and also that these crops are mostly grown on better and usually irrigated soils. The figures for average world productions were compared with maximum productions reached in selected experiments in the tropics, and large discrepancies were found, showing that greater yields could be obtained by improved cultivation. The protein content, expressed per 100 kcal edible portion, of the root crops tends to be slightly lower than that of the grain crops, but the contents of Ca, Fe, vitamin A, thiamine, riboflavine, nicotinic acid and ascorbic acid are generally higher. Most root crops have also edible leaves with considerable protein content, and it is thought that selective breeding could increase the protein content of root crops. It was therefore concluded that root crops should play a more important role in increasing world food production. E. P. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Distributions, ex situ conservation priorities, and genetic resource potential of crop wild relatives of sweetpotato [Ipomoea batatas (L.) Lam., I. series Batatas]

“…( Huaman, 1987 ), and can translocate photosynthetic products to the storage roots throughout the growing season, thereby mitigating negative effects of temporary adverse conditions ( Kays, 1985 ). Sweetpotato produces among the highest amounts of edible energy per hectare of all major food crops ( De Vries et al, 1967 ), and is an important source of vitamin A and C, calcium, iron, and a number of essential amino acids ( Kays and Kays, 1998 ; Tumwegamire et al, 2011 ). In addition to human consumption of the storage roots and young leaves, the crop is utilized for animal feed, fuel, and starch production.…”

Genetic Variation Within Cassava Germplasm in Response to Potassium

“…Cassava (Manihot esculenta) is a very ecient tropical root crop in terms of the amount of energy produced per unit of land (Cock, 1982;De Vries et al, 1967), and in the absence of production constraints it compares favourably with other major staple food and energy crops grown in the tropics (El-Sharkawy, 1993). However, under stressful environments (low-fertility soils and prolonged water stress), cassava still produces reasonable yields where other food crops such as maize (Zea mays) and sorghum (Sorghum bicolor) would probably fail (Cock and Howeler, 1978).…”

Effects of Spacing on Cassava (Manihot Esculenta)

“…Comparisons between tropical crops have shown the great potential of cassava as a source of carbohydrate (Vries et al, 1967), which may be further increased with improved cultural practices. Since cassava is a root crop in which the marketable product is not used for planting, varying the amount of planting material does not reduce the amount of produce available for sale, so does not affect marketable yield.…”