Screening Maize Germplasm for Drought -Adaptive Traits in the Rainforest Ecology of Sw Nigeria.

The rainforest agroecology of south west Nigeria is characterized by bimodal rainfall pattern that fall during the early and late cropping seasons for maize. Planting maize (Zea mays L.) in the late season is normally done from mid to late August, and the crop is frequently affected by terminal drought occurring as from November. Manipulation of planting dates could thus permit exposture of maize to drought at the flowering and grain-filling stages of the crop. Several studies were conducted from 2001 to 2010 at the Teaching & Research Farm of Obafemi Awolowo University, Ile-Ife, representing the rainforest ecology in south west Nigeria. The objective of the studies was to evaluate maize populations and varieties for traits that could be used as indices of drought tolerance under natural conditions. In Experiment 1, 20 early and extra-early varieties were evaluated in 36 trials. Experiment 2 involved 36 intermediate-to-late maturing varieties grown in four trials while Experiment 3 consisted of 100 varieties also evaluated in four trials. In each experiment, planting dates were manipulated to expose the varieties to normal rainfall conditions throughout the season in some of the trials while others were planted to allow flowering to occur under natural drought stress conditions. Several varieties that performed very well under drought were identified, including Pool 16 DT, TZE Comp 4, and TZL COMP 1-W. Number of ears per plot was consistently associated with high grain yield performance under drought.