Abstract

Sixteen upland rice varieties, comprising of some interspecific New rice for Africa (NERICA) hybrids, established varieties and some breeding lines, were raised in the greenhouse and used to expound drought response under varying moisture conditions, as a guide for breeding genotypes with appreciable drought tolerance and grain yield. Varieties were subjected to different levels of drought stress through different combinations of moisture regime and times of water application at different stages of growth. Varieties, moisture regime and times of water application espoused significant mean squares (MS) for root, vegetative and grain production. Times of water application consistently accounted for the largest percentage of mean squares (PMS) for most characters. Significant interaction was also obtained between variety, moisture regime and times of water application for most of the characters. There were significant correlations between times of water application and all the root, shoot and grain yield character. Fresh shoot weight, dry shoot weight, tiller number and leaf number were also positively correlated to moisture regime. WAB 880 recorded the largest mean value for root volume and thickness and hence better drought adaptation but this failed to translate to superior grain production. ITA 150, an established variety, however recorded the highest panicle number and grain production compared to WAB 880 and the NERICA varieties. The need for further introgression of genes from ITA 150 into newly developed NERICA varieties through an intricate combination of favourable genes for improved drought tolerance and better grain production was canvassed.

Key words: Drought tolerance, interspecific hybrids, root and vegetative traits, grain yield.