Baffour Badu-Apraku, PMB 5320, Oyo Road, International Institute of Tropical Agriculture-Nigeria, Ibadan, Oyo State, NIGERIA, Muhyideen Oyekunle, Maize Improvement, International Institute of Tropical Agriculture, Croydon, United Kingdom, Morakinyo A.B. Fakorede, Department of Crop Production & Protection, Obafemi Awolowo University, Ile-Ife, Nigeria and Michael Aderounmu, Maize Improvement Unit, International Institute of Tropical Agriculture, Ibadan, Nigeria
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 droughtand 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.