STRATEGIES FOR IMPROVING DROUGHT RESISTANCE IN GRAIN LEGUMES

This review distills recent information on drought resistance characte ristics of grain legumes with a view toward developing appropriate gen etic enhancement strategies for water-limited environments. First, the possible adaptations that allow grain legumes to better cope with dro ught stress are summarized. It is suggested that there are considerabl e gains to be made in increasing yield and yield stability in environm ents characterized by terminal drought stress by further exploiting dr ought escape, by shortening crop duration. Many traits conferring dehy dration avoidance and dehydration tolerance are available, but integra ted traits, expressing at a higher level of organization, are suggeste d to be more useful in crop improvement programs. Possible genetic imp rovement strategies are outlined, ranging from empirical selection for yield in droughted environments to a physiological genetic approach. It is suggested that in view of recent advances in understanding droug ht resistance mechanisms, the latter strategy is becoming more feasibl e. It is concluded that use of this recently derived knowledge in a sy stematic manner can lead to significant gains in yield and yield stabi lity of the world's major grain legumes, as they are mainly grown (and will continue to be grown) under rain-fed conditions.