Effect of Water Stress Duration on the Growth Characteristics and Yield Components of Upland Rice Varieties in Kenya

Drought stress is a major problem in upland rice grown areas under rainfed conditions. It affects plant growth and development, and eventually leads to a considerable yield reduction. The study was carried out with the aim of evaluating the effect of drought stress duration on the growth characteristics and yield components of upland rice varieties. The experiment was conducted at the University of Eldoret with Sixteen upland commercial and local rice varieties were used in the study obtained from Kenya and Liberia. Rice plants were subjected to drought stress treatments at tillering and flowering stages in the green house. The experiment was layout in a complete randomized design (CRD) in a split plot arrangement with five treatments and replicated three times. The results of leaf rolling, plant height, days to 50% flowering, days to maturity, panicle number, spikelet sterility, biological yield, leaf relative water content,1000-grain weight, harvest index and grain yield revealed that there were significant differences as a result of water stress on the treatments (p≤0.001) and rice varieties (p≤0.05). All the sixteen varieties were significantly affected by the treatments when compared with the control. The results also revealed that MWUR, Dourado, L-22, Komboka, Jaowo, LAC-23, Kpatawee, MWUR, White rice and Red Youmo varieties were significantly affected by the water stress treatments at leaf rolling, flowering and maturity then that of NERICA 1,2 ,3, 4, 10,11 and 14 at tillering and flowering stages. The findings of this study indicated that NERICA 1, 2, 3, 4, 10 varieties were less affected by soil water stress treatments amongst the tested varieties, followed by NERICA 11 and14 respectively. Thus, NERICA varieties had the best performance in most of the parameters that were measured. Therefore, these varieties can thus be used by breeders to develop varieties adapted to areas with limited rain fall and insufficient soil moisture for rice production.