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)