Plastochron index for detecting juvenility and deciding the components of maturity period in cowpea

Abstract

Growth of nine field grown cowpea genotypes was characterized using plastochron index. Attainment of the final plastochron index was considered as a point of completion of a vegetative phase. The population under study completed a vegetative phase within 50 d and exhibited flower initiation in 55 d. The gap between completion of the vegetative phase and flower initiation indicated the prevalence of juvenility in cowpea. The maturity period was found to be a sum of the periods for plastochron completion, lag I, pod development and lag II. Lag I and Lag-II periods existed due to variation in the relative sensitivity of successively formed leaves to the normal inductive conditions. A high genotypic variation for the two lag periods indicated a scope for designing an efficient plant architecture of cowpea either for grain or for vegetable purpose.