Combining ability of maize inbred lines for performance under low nitrogen and drought stresses
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Drought and infertile soils are increasingly the most important stresses affecting maize (Zea mays L.) and causing substantial yield losses in Sub-Saharan Africa. Varieties with improved water use efficiency and/or N would be beneficial for subsistence farmers in the region. The objective of this study was to assess yield potential of F1 hybrids, estimate the General and Specific Combining Ability (GCA &SCA) and the degree of transmissibility of performance of selected maize inbred lines under drought stress and low nitrogen. Twelve parents were crossed in a half-diallel mating design. The resultant hybrids were evaluated in four environments; namely, optimum N and low-N, well-watered and managed drought-stress. There were significant variations among the hybrids for grain yield. Additive genetic effects for grain yield, EPP and ASI were generally more important than were nonadditive. The narrow-sense coefficient of genetic determination was low for grain yield in stress environments. Inbreds with good potential for hybrid production included CZL 02004, CZL 03002, CML 78, and CML 379. Selection for performance in drought and low-N stresses should focus on high yielding hybrids from parents with desirable GCA values for yield, ASI, and EPP under drought stress.