Effects Of Three Cycles Of S1 Family Selection On Genetic Variances and Correlations Of An Early White Maize Population Under Drought and Well-Watered Environments.

Drought is the most important factor limiting maize (Zea mays L.) production and productivity in  savannas of West and Central Africa. Two hundred and forty S₁ families derived from four cycles of recurrent selection were evaluated under drought and well-watered conditions at two locations in Nigeria for 2 yr to determine relative changes in genetic variances, heritabilities, and genetic correlations for grain yield and other traits. Under drought, yield was significantly correlated with days to silking, anthesis-silking interval, plant and ear aspects in C₀ to C₂ but not with any other trait in C₃. Under well-watered conditions, yield was significantly correlated with plant and ear aspects in all cycles except for ear aspect in C₁ and C₃. Yield was not correlated with plant height in C₀ and C₁ but was significantly correlated with plant height in the advanced cycles under well-watered conditions. Genetic variances and heritabilities generally decreased for yield and other traits in advanced cycles under drought and well-watered conditions except for yield and ear height under well-watered conditions. Heritability for yield ranged from 0.40 for C₃ to 0.69 for C₀ under drought and 0.46 for C₀ to 0.65 for C₁ under well-watered conditions. Realized gain from selection for yield was 955 kg ha^-1, corresponding to 30.5% cycle^-1 under drought and 352 kg ha^-1 with a corresponding gain of 16.7% cycle^-1 under well-watered conditions. Predicted gain based on C₃ was 282 kg ha^-1 and 583 kg ha^-1 under drought and well-watered conditions, respectively. Yield ranged from 1081 kg ha^-1 for C₀ to 2018 kg ha^-1 for C₃ under drought and 2280 kg ha^-1 for C₀ to 3507 kg ha^-1 for C₃ under well-watered conditions. The low genetic variances, heritabilities, and predicted gain cycle⁻¹ for grain yield and other traits suggest the need to introgress drought tolerant genes into the population.