Drought tolerance at flowering and cross-over interactions for yield of three maize populations grown in two agro-ecological zones of Zimbabwe
1997
Magorokosho, C. | Pixley, K.V.
Development of drought tolerant maize cultivars is a high priority in Zimbabwe, where an average of 77 Per cent of the arable land is droughty. Two experiments involving random S1 lines from three maize populations were conducted at three locations in the semi-arid agro-ecological zone Natural Region (NR) IV and one location in the humid zone NR II, to compare grain yield and various secondary traits that might be related to drought tolerance at flowering. Experiment 1 compared 143 lines from ZM601 (selected for drought tolerance for three cycles) with 94 lines from ZM607 (selected for three cycles for high yield under adequate moisture conditions). Experiment 2 compared 162 lines from ZM601 with 154 lines from TSEQ (selected for high yield and drought tolerance for six cycles). Yield responses in experiment 1 showed no advantage for ZM601 over ZM607 in semi-arid, stressed environments. In experiment 2, yield responses were of a cross-over nature; TSEQ out-yielded ZM601 by 33 Per cent under stress, while under no stress ZM601 out-yielded TSEQ by 15 Per cent. Yield under stress was strongly correlated .with anthesis-silking interval (ASI) (r=-0.27** and -0.25** for the two populations) in experiment 1, and for ZM601 in experiment 2 (r=-0.43** ), but not for TSEQ (r=-0.13). Days to flowering was negatively correlated with yield, except for TSEQ, indicating that earliness and, hence, drought escape was important for ZM601 and ZM607 but not for TSEQ. Drought tolerance resulted in higher grain yield than drought escape for the experiments in NR IV of Zimbabwe.
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