Effect of Shallow Water Management on Growth and Yield of Rice

Abstract

Rice, the most staple food crop of the world has been cultivated about 157 million hectares of land (FAO, 2008). Irrigated rice ecosystem contributes 75% of global rice production. Growing rice using conventional irrigation (continuous flooding) requires a tremendous amount of water. The high water demand of irrigated lowland rice mainly arises from keeping the field continuously submerged. There is decreasing trend in water resource availability year by year due to various reasons. The shortage of water resources for rice production has now become an important issue worldwide. It indicates that a reduction in water input without compromising yield and optimization of scarce water in rice production are required. Shallow water management can be one of the alternatives to use water efficiently, achieve good yield and minimize the methane emission from the rice fields. However, information about growth and yield of rice grown under shallow water management are limited. Therefore, this study was conducted to investigate whether shallow water could influence plant growth and yield of irrigated rice under field conditions. Materials and Methods A field experiment was conducted at Yamagata University Experimental Farm, Takasaka, Tsuruoka, Japan in 2009. Two plant spacings – [30*30cm (wider) and 30*15cm (narrow)] and water managements shallow and conventional were practiced .The four treatments were set up as conventional wider (CW), conventional narrow (CN), shallow wider (SW) and shallow narrow (SN). In conventional method, five to six cm water ponding depth was maintained throughout the growing period except for mid season drainage and totally drained out 15 days before the harvest. For shallow water ,ponding water depth of 1-2cm with wetting and drying was done till panicle initiation stage and then 1-2 cm was maintained and totally drained out 30 days before harvesting. Transplanting of 28 days old (3.5leaf age) seedlings of Sasanishiki variety was done on12th May and harvested on 1 st October 2009. The total dry matter & nitrogen (N) uptake by plant was measured at 37, 44, 51, 58, 65, 77, 91 and 122 days after transplanting (DAT). The yield was estimated by both yield components (10hills) and yield examination (50hills).This preliminary experiment was carried without replication. Results and Discussion Comparing with water management practices, aboveground biomass was higher in shallow than conventional. Interestingly, wider spacing of shallow water management showed almost same as to conventional narrow spacing (fig.1).