Genetic Analysis of Vegetative-Stage Drought Tolerance in Cowpea

Abstract

The continued improvement in the yield of cowpea for the semi-arid regions where it is a dominant crop will record rapid progress if the genetic basis for yield under different moisture regimes is better understood. This study investigated the genetic combining abilities and heterosis for grain yield, yield components, flowering and biomass production among diallel hybrids derived from nine cowpea genotypes. Results showed that moisture stress significantly reduced grain yield, biomass production, and number of pods per plant. Only for grain yield was a significant interaction observed for moisture regimes. Genetic control for grain size, number of seeds per pod and days to flowering was dominated by additive genetic effects. For grain yield, both additive and non-additive genetic effects were dominant. The genetic control of yield under the two soil moisture conditions indicated that grain yield improvement will be more challenging for drought prone regions. Nonetheless, careful selection of genotypes that have complementary but different alleles for yield under different soil moisture conditions might permit yield improvement through recurrent selection. This study has identified parental lines, developed populations, and provided a breeding strategy for developing cowpea cultivars with higher grain yield for Guinea and Sudan savannah regions of West Africa.

Estimates of combining ability and heritability in cowpea genotypes under drought stress and non-stress conditions in Uganda

“…Improvement for these traits therefore requires a recurrent selection procedure that allows for favorable gene recombination in later generations before a final selection is made. Similar results on moderate to low narrow sense heritability estimates for grain yield, 100 seed weight and number of pods per plant were reported by Alidu et al (2013). However, these results contradicted with Chiulele (2010) findings, possibly due to the differences in the population studied, multilocationality of the study as Chiulele's study was conducted across locations while this study was done in one location.…”

“…Gene action studies conducted elsewhere have reported the predominance of additive genetic effects over non-additive genetic effects in controlling yield components such as days to flowering, number of seeds per pod, number of pods per plant and hundred seed weight (Chiulele, 2010;Romanus, 2008). Non-additive genetic effects were, however, more important for seed yield (Chiulele, 2010;Alidu et al, 2013). Thus, information regarding combining ability and nature of gene action governing the inheritance of desirable traits are basic requirements for breeding high yielding drought tolerant cowpea genotypes.…”

Response of Cowpea Genotypes to Drought Stress in Uganda

“…Cowpea is sensitive to soil moisture stress during the vegetative and reproductive growth stages [9]. Drought stress during flowering and pod filling impacts negatively on flower development, pollination, pod setting and grain filling leading to reduced number of pods per plant, reduced seed weight and low seed yield [10].…”

Breeding and genetic management of drought in cowpea: Progress and technologies

“…The additive gene action was also identified as more important in the inheritance of yield related traits, 100-seed weight, number of seeds per pod, Normalized Difference Vegetation Index (NDVI) measured at three different growth stages and the number of pods and seeds per plant under drought stress. High GCA effects were also reported for hundred seed weight, pod per plant and grain yield in cowpea progenies grown under water stress (Carvallo et al, 2012;Alidu et al, 2013). Information on gene action controlling drought tolerance, yield and its associated traits is scarce in cowpea.…”