Drought is the most important abiotic constraint limiting groundnut production and yields across the world, including the three Northern Regions of Ghana. There is limited information about inheritance of drought tolerance genes in groundnuts. Genetic development of varieties that have the ability to better use limited available water is needed. Therefore, the current study sought to estimate the heritability and genetic variability of some selected parents of groundnut for drought tolerance traits to aid in their effective selection and utilization. The North Carolina II mating design was adopted, and whiles the variance component method was used to estimate heritabilities in the narrow and broad sense as well. Also, Chlorophyll content (greenness of leaves) was recorded at 60 and 80 DAP. The objective was to measure the chlorophyll content, and hence the drought tolerance performance of the entries. Mean squares caused by differences among crosses was partitioned into difference due to male parents and female parents, which was attributed to general combining ability (GCA), as well as difference due to male x female interaction, which was attributed to specific combining ability (SCA). Evaluation of Estimates from the Narrow Sense Heritability from the variance components for different traits varied under both water regimes, ranging from 12.2% to 95.7%. The most heritable traits were; dry biomass weight (95.7%), days to 50% flowering (91.0%), seed yield (90.0%), plant height at harvest (76.0%), SCMR60DAP (71.7%), days to maturity (67.0%) and SCMR80DAP (66.0%). Pod yield (12.3%) and harvest index (12.2%) exhibited low narrow sense heritability estimates, but scored high estimates for broad sense heritability at 98.0% and 69.5% respectively. Additive gene effects largely controlled the inheritance of pod yield, seed yield and biomass weight. Positive association between most yield and yield components as well as higher heritabilities shows that selection for higher yield and maturity is conceivable in improving groundnuts. SPAD-CMR is a very good measure of drought and heritability because of its high heritability and ease of data collection as well as positive association with yield traits. Marker assisted selection procedures could help enhance the process based on the availability of QTLs and genes for the drought traits and markers developed to that effect.
Keywords: Abiotic, constraints, Chlorophyll content, drought, genetic, groundnut, heritability, North Carolina II mating design, tolerance, yield