GENETICS AND GENETIC MODIFICATIONS OF PLANT ARCHITECTURE IN GRAIN LEGUMES - A REVIEW

Crop architecture may be modified to improve the adaptation of the cro ps to different environments and to increase the seed yield and its st ability. The main peculiarities of the grain legume architecture are t he indeterminate growth habit, which may lead to a prolonged growth cy cle with consequences on the maturation and strong within-plant compet ition between the reproductive and vegetative growth and the fleshy po ds. The principal reasons are presented as to why modifications of the grain legume architecture and the genetic strategies could contribute to increasing the seed yield. The main components of the crop archite cture are analyzed. The flowering date is of major importance for the adaptation of a crop to the environmental conditions. The branching pa ttern may be directly affected independently of other architectural mo difications. The leaf size and structure contribute to the leaf area i ndex of the crop and may influence the light interception efficiency. The determinate growth habit modifies the duration of the growth cycle and the assimilate partitioning while the dwarfism may improve the ad aptation to a range of environments through the reduction of the lodgi ng risk. The pod walls may contribute to the pod photosynthesis but th ey account for a large proportion of the pod weight at harvest. This r educes the crop harvest index. For each of these traits, the genetic m odifications that have been observed in the different grain legume spe cies are presented as well as their genetic control. The consequences on the seed yield elaboration and the adaptation of the crops are asse ssed. The limitations of the architectural modifications are also inve stigated and the interest in combining morphogenetic and functional ap proaches is discussed. ((C) Inra/Elsevier, Paris.).