Response of Bread Wheat Genotypes to Drought Simulation under a Mobile Rain Shelter in Kenya

Selection of drought tolerant wheat genotypes for Arid and Semi-arid lands (ASALS) of Kenya, which consist of 83% of total land area, can provide alternative agricultural land for expansion. To reduce cost of dryland research, simulated drought under a rain shelter offers a good alternative for screening because marginal areas are vast and widespread. Four moisture regimes which simulated terminal, early, midand lateseason droughts were created under the mobile rain shelter at Njoro in 1998/99, by applying drip irrigation (i) up to seedling stage (70 mm) (ii) through tillering (82 mm) (iii) up to anthesis (94 mm) and (iv) grain filling (106 mm), respectively, to determine drought responses of five wheat varieties (Duma, R748, R830, R831 and R833) and identify drought tolerant genotypes. Control watering regime had 118 mm applied at all stages. Yield and yield components in each season and the two seasons combined showed significant difference (P<0.05 and 0.01, respectively). Early drought during seedling stage and tillering caused significant reduction in plant heights, tiller number and number of reproductive tillers. However, drought from anthesis and grain filling to maturity caused significant (P<0.05) reduction in ear length (16.9%), spikelets/head (14.3%), 1000-kernel weights (22.4%) and an increase in the number of sterile florets/head (28.3%), compared to control. Seedling and reproductive stage (anthesis and grain filling) droughts caused the highest grain yield reduction (25 and 67%, respectively), indicating that they were the most critical stages in moisture requirement compared to control. Genotype R748 out-performed Duma (check) in all moisture regimes, and was recommended for field testing and participatory evaluation. From this study, it is possible to select drought tolerant cultivars using mobile rain shelters by drought simulations in Kenya.