Performance of cowpea Recombinant Inbred lines for grain yield and stability under low soil moisture conditions in Northern Ghana

Abstract

Drought is more prevalent in the semi-arid areas where cowpea has the greatest potential. Drought is unpredictable in occurrence. Drought affects both the vegetative and reproductive phase resulting in significant yield losses. The objective of this study was to determine grain yield and stability of cowpea inbred lines under low soil moisture conditions. Four hundred and fifty (450) F₂:₆ inbred lines were developed through single seed decent from drought parent (IT 93K-503-1) and susceptible parent (IT 97K-279-3). Populations were initially screened, and further evaluation was done under field conditions using split plot design. Inbred lines were completely randomized in three replications. Moisture stress was imposed 10 days after planting and watering resumed at 40 days after planting. Physiological and agronomic data were collected during moisture stress at vegetative, flowering and at harvest. Analysis of variance was performed using GenStat discovery edition 12. Quantitative indices of stress tolerance were calculated using grain yield data. The results obtained indicated that, water stress caused percentage yield reduction for most of the inbred lines and the parental checks. The highest percentage yield reduction was observed for inbred line F20 (57.83%). Inbred lines F142, F408, F398, and F38, had their yields reduced under stress conditions whilst inbred lines F131, F186, F406 and F255 were less affected. Inbred line F84 rather had yield increase under drought (10.57%). The use of two contrasting parents in generating the inbred lines for the study revealed classes of maturity groups for drought tolerance. This aided the test of superiority for the inbred lines in relation to the parental performance across the environments used for the study. Further research using quantitative trait loci analysis will be required to enable the identification of loci responsible for drought and its relationship to maturity period.

Key words:  Cowpea, drought tolerance, quantitative indices, Stability analysis, Recombinant inbred lines