In this study, seven maize inbred lines representing different tropical,
drought tolerant populations and two adapted temperate maize inbred lines
were crossed in a half-diallel mating design to determine combining
abilities. The genotypes were tested in well-watered (WW) and managed water
stressed (WS) conditions in 2013 and 2014. General combining ability (GCA)
and specific combining ability (SCA) mean squares were significant for all
investigated traits and demonstrated both additive and non-additive genetic
effects in both conditions. Higher desired leaf rolling, leaf senescence,
stomatal conductance and leaf chlorophyll content GCA effects of tropical
inbreds under WS conditions showed the presence of the valuable allels
related to drought stress. SCA analysis revealed that the best hybrids for
water use efficiency and irrigation water use efficiency were tropical x
temperate crosses. Stress tolerance index and drought resistance index
identified G5 x G9, a tropical x temperate hybrid, as the most tolerant
hybrid to drought. Our study suggests that tropical drought tolerant
germplasm has the potential to contribute useful genetic diversity to
temperate maize breeding programs.
Combining ability and testcross performance of drought-tolerant maize inbred lines under stress and non-stress environments in Kenya
