ORIGINAL ARTICLE

Morphological Response and Yield of Rice Cultivars to Water Deficit Condition at Different Growth Stages on Sandy Loam Soil in Ibadan 

Drought is a major abiotic constraint in upland rice field, causing severe yield loss of more than 50%. Southwestern Nigeria, which covers almost 30% upland rice fields are purely rainfed and rainfed farming is no longer reliable due to fluctuation in rainfall pattern and volume causing drought in rice field. The need to understand response of upland rice cultivars to moisture deficit at different phenological stages is important to device appropriate drought management strategy in upland rice field. Information on response of upland rice cultivar to water deficit condition at different growth stages is scanty. Therefore, response of 12 Rice Cultivars (RC) to water deficit condition at tillering, panicle initiation and grain filling on sandy loam was investigated. The study was a 4×12 factorial, arranged in completely randomized design with six replicates was conducted in a screenhouse during the early and late dry seasons of 2018 in Ibadan. Treatments included twelve RC: OFADA, IGBEMO, FARO-16, FARO-44, FARO-60, IR-64, APO, NERICA-4, NERICA-5, NERICA-7, NERICA-8, water stressed at tillering, Panicle Initiation (PI) and Grain Filling (GF) and Well-Watered Soil (WWS, served as control). Three weeks old rice seedling was transplanted into pot containing 5 kg soil. Data were collected on plant height (cm), leaf area (cm2), number of leaves and tillers, leaf roll and dry, dry matter and yield components. Data were analyzed using analysis of variance (ANOVA) and means separated with LSD (p<0.05). APO had significantly taller plant (99.42 and 113.18) at tillering and GF than other cultivars. However, at PI, OFADA was taller (143.26 cm) than other cultivars. Similarly, IR-64 had significantly higher number of leaves (13.67, 17.38 and 17.54 cm) and tillers (3.17, 3.75 and 4.17) at tillering, PI and GF, respectively than other cultivars. Similarly, IR-64 had highest unfilled grain weight (1.67 g). VANDANA had significantly higher filled grain (3.71 g) and grain weight (3.93 g) over other cultivars. Drought stress retarded growth and reduced yield of upland rice cultivars severely at tillering and panicle initiation stages than at grain filling stage, while VANDANA produced the highest grain relative to other cultivars predisposed to drought.