Abstract

Development of drought tolerant maize cultivars is prerequisite to achieving stable grain yield in drought–prone ecologies of Nigeria’s Guinea savanna. However, success has been limited mainly due to lack of maize genotypes that show clear differences in response to well defined moisture deficit condition. Two sets of drought tolerant (DT) maize germplasm were evaluated under screenhouse and field conditions between 1999 and 2002. In the screenhouse study, performances of the genotypes were compared under well-watered condition and moisture deficit imposed at different growth stages. Under field conditions, the first set comprising 11 accessions along with a check were evaluated for 4 growing seasons while the second set which comprised 3 DT varieties were evaluated along with 2 check varieties using monthly plantings between April and August of 2001 and 2002, respectively. In the first set, post anthesis moisture deficit significantly reduced grain yield by 25 to 73.5% in the open pollinated varieties (OPVs) and by 20 to 64% in the hybrids. Grain yield under field conditions ranged from 2.48 to 3.49, 2.82 to 3.73 and 3.58 to 4.76 tons/ha^-1 for 1999, 2000 and 2001 full growing seasons, respectively, and 2.03 to 2.50 tons/ha^-1 for 2000 late growing season. In the second set, pre and post anthesis moisture deficits reduced grain yield by 77.6 and 95.8%, respectively, of well watered condition while in the field, grain yields in the genotypes were highest for plantings made in April and July (1.90 - 2.5 t/ha), lowest for August (0.7 -1.8 t/ha) when moisture deficit coincided with reproductive phase. Yield stability exhibited under moisture deficit and on the field by 8522-2, Oba super 2 and AK9943-DMRSR in the first set as well as DT-SR-Y C0 and DT-SR-W C0 in the second set, indicates their suitability either as cultivars per se or as potential source of DT alleles for development of DT maize varieties for Nigeria’s savanna ecologies.

Key words: Drought tolerance, moisture deficit, germplasm accessions, planting dates, grain yield.