The feasibility of improving tropical maize for tolerance to post-emergence drought stress was examined. In 1992, CIMMYT initiated a divergent S1 recurrent selection program in the tropical maize population 'DTP1' for survival and biomass production under post-emergence drought stress. The present study examined (i) broad-sense heritabilities and genetic correlations between survival, biomass, leaf rolling and leaf ABA concentration in two progeny trials evaluated in different seasons under post- emergence drought stress, and (ii) progress resulting from selection in survival, biomass, leaf rolling, and leaf ABA concentration after two selection cycles. Apart from leaf rolling, selection for improved survival and biomass production under post-emergence drought stress did not result in any significant differences compared with the original population, whereas selection for decreased survival and biomass production resulted in poorer survival under post-emergence drought stress. The progeny trials confirmed low broad- sense heritabilities for survival and biomass production. Heritabilities were higher for leaf rolling and leaf ABA concentration, but there was no obvious relationship between these secondary traits and survival or biomass production. it was concluded that (i) selection for improved survival and biomass production under post-emergence drought stress is difficult because environmental variation is high under field conditions and because natural selection may have already exploited all positive genetic variation, and (ii) agronomic solutions may lead to more short-term impact than genetic solutions in reducing yield losses in tropical maize-growing areas due to post-emergence drought stress.

Research and Partnership Program

English

9802|AGRIS 9702|anterior|R97-98PROCE|FINAL9798

Jose Juan Caballero

INT1888

CIMMYT Publications Collection