PERTANIKA JOURNAL OF TROPICAL AGRICULTURAL SCIENCE

Water-wise rice cultivation is a growing concern in rice production. We justified the effects of different water levels on rice production of upland variety. A completely randomised design was arranged with four treatments (T1: flooding at 5 cm depth, T2: flooding at 1 – 3 cm depth, T3: saturated to 1 cm flooding, and T4: alternative wetting and drying, or AWD) with five replications. Yield, plants and soil parameters were evaluated. Upland rice variety showed improved yields and yield parameters under flooding at 5 cm depth treatment than alternative wetting and drying treatment. Flooding water significantly increased plant height, tiller numbers, panicle numbers, panicle height, grains per panicle and yield compared to AWD treatment. Chlorophyll (Chl) content increased gradually with increasing plant age but flooding at 5 cm treatment increased Chl content after the secondary tillering. Net photosynthesis rate (Pn) and relative water content (RWC) decreased in plants under alternative wetting and drying treatment than control treatment. Saturated to 1 cm flooding treatment saved 42% of water used in the treatment of flooding at 5 cm depth, which showed a similar water use efficiency (WUE) to alternative wetting and drying treatment. However, treatments of flooding at 1 – 3 cm depth and saturated to 1 cm flooding showed a similar effects on rice yield. Meanwhile, saturated or above soil water condition did not affect soil pH, soil electric conductivity (EC) and phytoavailability of nutrients in the soil. These results suggested that saturated to 1 cm flooding irrigation could increase rice yield of upland variety and save fresh water for other purposes at the same time.