Low maize yields and the impacts of climate change on maize production shows the need to improve yields in Sub-Saharan Africa. Thus the objective of this study is to evaluate DT maize hybrids under heat and combined heat and drought stresses and to determine the relationship between grain yield and other agronomical trait. In this study two groups of hybrids were used. Eighteen top cross maize hybrids, one local check and a standard check laid-out in alpha lattice of 5x4 with two replicates, the second group was thirty four three way cross maize hybrids, one local checks and a standard check laid-out in alpha lattice of 6x6 with two replicates, which was evaluated for grain yield and other agronomic traits under heat and combined heat and drought stresses conditions over two seasons (2018 and 2019) at Kadawa, Kano state, Nigeria. At two weeks prior to flowering, drought stress was imposed on the trials by withdrawing irrigation for three weeks, to coincide with high temperature. Irrigation was resumed after three weeks, and thereafter the trials received irrigation only once per week. Also to access the effects of heat stress, frequent irrigation was supplied. The trial received irrigation after every four days till two weeks prior to flowering. Thereafter the trial received irrigation once per week till physiological maturity. This ensured the effect of heat stress only. Base on the combined analysis of year 2018 and 2019, mean performance of top cross hybrids varied from 3452 to 5850 kg ha−1 and 199 to 1976 kg ha−1, respectively under heat and combined heat and drought stress also for three way-cross the yield for heat was 706.55 to 5882.93 kg ha−1 and that of combined heat and drought was 485.65 to 4018.99 kg ha−1. Hybrids differed significantly for grain yield in the two season and other measured traits under both heat and combined heat and drought stresses. For top cross DT maize hybrids obasuper II, Sammaz 51, M0926-9, M1526-2, M1426-3 (heat stress), M1526-2, M0926-9, M1026-3 (combined heat and drought stress) and for three way DT hybrids M1627-4, M1427-3, M1427-8, M1124-27, M1627-6 (heat stresses) local check, M1627-2, M1627-5, M1627-6, Obasuper II (combined heat and drought stresses), combines tolerance to heat, combined heat and drought stresses with high yield, which is an indication that grain yield can be used to measure the effect of both stresses and tolerance to either stress alone did not confer tolerance to combined drought and heat stress.

I thank God almighty for life and for making this work a reality. Special thanks to my supervisors, Dr. A. Abe, Dr. A Menkir, Dr. S. Meseka for their support, guidance, corrections and adjustments. My appreciation goes to Mr. I .Innocent, Late-Mr O.Femi, Ayodeji Julius, Mr O. Abiodun for their support, constant advice and words of encouragement. I’m grateful to Maize Improvement Program for the provision of maize genotype and resources for this research. Special thanks to the staff at MIP unit, ...

Nutrition; Pests of Plants; Plant Genetic Resources

Maize; Hybrids; Drought; Genetic Variation; Stress; Tolerance; Heat Tolerance; Heat Stress; Drought Tolerance

Africa; West Africa

Nigeria

Headquarters and Western Africa Hub