Articles

Genetic variability for drought tolerance in early-maturing maize inbreds under contrasting environments


Abstract


Drought severely constrains maize (Zea mays L) production in the savannas of West and Central Africa (WCA). Understanding the levels of drought tolerance in early-maturing maize inbreds is crucial for the development of drought-tolerant maize hybrids for the sub-region. A total of 156 inbred lines were evaluated under drought and well-watered conditions at Ikenne and Bagauda in Nigeria for 2 yr. The objectives were to (i) determine the levels of drought tolerance in early-maturing inbreds, (ii) assess the performance of the inbreds and relationship among traits under the contrasting environments, and (iii) identify the most stable inbreds across environments. Inbreds differed significantly (p < 0.01) in grain yield and other measured traits under drought and well-watered conditions. Grain yield of inbreds was significantly (p < 0.01) correlated with ears per plant (r = 0.50), anthesis-silking interval (r = -0.55), plant aspect (r = -0.57), ear aspect (r = -0.35) and stay-green characteristic (r = -0.28) under drought. Forty-eight percent of the lines were identified as drought tolerant with tolerance indices ranging from 0.17 to
15.31. Broad-sense heritability estimate was 43% for grain yield under drought and 47% under well-watered con- ditions. Drought reduced grain yield of the inbreds by 3-88%, averaging 52%. Biplot analysis identified inbreds TZEI 18, TZEI 56, TZEI 1, and TZEI 19 as the most stable across environments. The inbreds with high levels of drought tolerance could be utilised for the development of drought-tolerant hybrids and synthetic varieties as well as for introgression of tolerance genes into tropical maize breeding populations.

Keywords

drought, early-maturing inbred lines, heritability, maize, tolerance indices

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