Demand-driven breeding of food legumes for plant-nutrient relations in the tropics and the sub-tropics: serving the farmers; not the crops!

A number of improved cultivars of food legume crops have been developed and released in the tropics and the sub-tropics. Most of these cultivars have been developed through conventional breeding approaches based on the development of crop varieties under optimum soil fertility levels. Nevertheless, it is hardly possible to say that the varietal provisions made by the past approach have been readily accepted, and properly utilized to boost productivity of food legumes grown by resource-poor farmers. The approach itself did not fully appreciate the actual circumstances of the resource-poor farmers where marginal production systems prevail and the poorest farmers could not afford to use cultivars developed under optimum soil fertility level. Therefore, the limitations and strategic implications of past experiences made to develop crop cultivars need to be analyzed in order to formulate better strategies and approaches in the future. The main purpose of this article is to review the efforts made, the technical difficulties associated with the genetic improvement in food legumes as related to plant-nutrient relations, causes of limited breeding success and thereby draw lessons useful to designing future breeding strategies. The scope of nutrient deficiency stress and the approaches to breeding for plant-nutrient relations are discussed and the need for refining the approach and better targeting of the breeding methodologies suggested.