The effects of irrigation method, age of seedling and spacing on crop performance, productivity and water-wise rice production in Japan

Abstract

A field experiment using system of rice intensification (SRI) techniques was conducted in Chiba, Japan during the 2008 rice-growing season (May-September) with eight treatment combinations in a split-split plot design (S-SPD) to observe the potential of SRI methods under the temperate climatic conditions in Japan. Intermittent irrigation with alternate wetting and drying intervals (AWDI) and continuous flooding throughout the cropping season were the two main-plot factors, while the effects of age of seedlings and plant spacing were evaluated as sub and sub-sub plot factors, respectively. The experiment results revealed that the proposed AWDI can save a significant amount of irrigation water (28%) without reduced grain yield (7.4 t/h compared with 7.37 t/h from normal planting with ordinary water management). Water productivity was observed to be significantly higher in all combinations of practices in the intermittent irrigation plots: 1.74 g/l with SRI management and AWDI as compared to 1.23 g/l from normal planting methods with ordinary water management. In addition, the research outcomes showed a role of AWDI in minimizing pest and disease incidence, shortening the rice crop cycle, and also improving plant stand until harvest. Synergistic effects of younger seedlings and wider spacing were seen in tillering ability, panicle length, and number of filled grains that ultimately led to higher productivity with better grain quality. However, comparatively better crop growth and yields when using the same SRI practices with ordinary water management underscore a need for further investigations in defining what constitute optimum wetting and drying intervals considering local soil properties, prevailing climate, and critical watering stages in rice crop management.Keywords System of rice intensification (SRI) Á Alternate wet and dry irrigation (AWDI) Á Water savings Á Water productivity Á Split-split plot design (S-SPD)

Early growth stage water management effects on the fate of inorganic N, growth and yield in rice

“…Our study, which was conducted under controlled irrigation without standing water (Non-flooding) or shallow water depth (0.02 m, SWD), was same as SRI. Our total water use ratio was similar to that reported in Chapagain and Yamaji (2010); the water management techniques associated with from the SWD and Nonflooding treatments decrease water consumption. Soil moisture (v/v) for all treatments and both years exhibited the same trends and no statistically significant differences in the early to maximum tillering stages.…”

“…The total water use reported for conventional practices is two times higher than for modified system for rice intensification (SRI) irrigation in India (Satyanarayana et al 2007) and 1.4 times higher in Japan (Chapagain and Yamaji 2010) because of the low percolation rate. It is possible that leaching losses increased with the depth of submergence during all growth stages in a paddy field as a consequence of an increased percolation rate (Magdoff and Bouldin 1970).…”

Towards an understanding of the high productivity of rice with System of Rice Intensification (SRI) management from the perspectives of soil and plant physiological processes

“…For example, total water used in conventional practices was 2 times higher than modified SRI irrigation in India (Satyanarayana et al 2007) and 1.4 times higher in Japan (Chapagain and Yamaji 2010). Consequently, water productivity in SRI irrigation was higher than in conventional irrigation.…”

“…SRI was based on a set of practices to manage plants, soil, water and nutrients, and increased yields of rice grown under SRI were found only when several SRI components were used in good combination (Chapagain and Yamaji 2010). They conducted the combination experiment and the highest yield (8.1 t ha…”

Comparative Evaluation of Seed and Grain Quality Parameters of Rice (Oryza sativa L.) Varieties under SRI and Conventional Methods of Rice Cultivation

“…In recent years, water table has depleted at a very rapid rate throughout the globe, thus, posing alarming threats and limiting the scope for cultivation of high water consuming crops especially rice. Challenges in maintaining the sustainability of rice farming have been increasing with the increased scarcity of water and competition for water resources, declined yield levels with low grain quality and increasing the production costs due to more use of agriinputs (Chapagain and Yamaji, 2010). Therefore, it is very much important to search for water saving technologies without reducing the yields.…”