Response of upland rice agronomic parameters to variable water supply

Rice response to water application is necessary for increased productivity; hence, this study was aimed at establishing the agronomic responses of rice crop to differential water supplies. A two-year dry season experiment was conducted on the research farm of International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria. Two upland rice varieties (NERICA 2 and NERICA 4) were planted on a 5 m×5 m plot in a randomized complete block design with four treatments and two replicates based on different water application. Irrigation scheduling was designed as 100%ET, 75%ET, 50%ET and 25%ET for the treatments weekly. Agronomic parameters such as plant height, root depth, canopy shading (CS), leaf area index (LAI), panicle and tiller configuration, biomass and grain yield in relation to crop water use were obtained and the results were subjected to statistical analysis. Average values of highest plant height (89.0 and 100.3 cm), deepest root depth (22.1 and 23.8 cm), panicle diameter (3.9 and 4.5 cm), panicle length (26.1 and 25.7 cm), LAI, 3.27 and 3.95, CS, 0.22 and 0.99 were obtained for both NERICA 2 and NERICA 4 respectively. Leaf width (1.3 and 1.4 cm), total tillers (14 and 12) and leaf length (36.9 and 38 cm) were also observed for the two varieties respectively. The highest total grain and biomass yields of 1.94 t/ha and 1.95 t/ha were observed in 100%ET treatment for NERICA 2 while the least values of 0.29 t/ha and 1.09 t/ha were observed in 25%ET treatment. As for NERICA 4, the highest values (1.90 t/ha and 2.27 t/ha) were from 100%ET and the least (0.38 t/ha and 2.29 t/ha) in 25%ET. The result of ANOVA showed significant differences in biomass and grain yield, LAI, CS, plant height and root depth among treatments stressing the domineering influence of water in agronomic response of rice.