Effects of seedling treatment with System of Rice Intensification management and with conventional management of transplanted rice.

Many benefits of inoculation for improving crop production have been documented, including growth and yield enhancement and the alleviation of biotic and abiotic stresses. However, because rice is usually cultivated under continuous flooding that creates anaerobic soil conditions, this limits the benefits of these beneficial fungi. Cultivating rice with the methods of the System of Rice Intensification (SRI) provides rice plants with a more favorable environment for their colonization by beneficial microbes in the soil because the soil is more aerobic under SRI management and contains more organic matter. This study evaluated the effects of inoculation of rice plants under SRI management compared with transplanted and flooded rice plants, considering also the effects of different means of fertilization and different varieties in rice. Experiments were conducted in 2015 and 2016 under the tropical climate of Nepal's western terai (plains) during both the rainy season (July to November) and the dry season (March to July). The results indicated significantly better performance ( = 0.01) associated with inoculation for both seasons and for both systems of crop management in terms of grain yield and other growth-contributing factors, compared to non-inoculated rice cropping. Relatively higher effects on grain yield were recorded also with organic compared to inorganic fertilization; for unimproved (heirloom) varieties compared with improved varieties; and from SRI vs. conventional flooded crop management. The yield increase with treatments across all trials was 31% higher than in untreated plots (4.9 vs 4.5 mt ha). With treatment, yields compared with non-treated plots were 24% higher with organic SRI (6.38 vs 5.13 mt ha) and 52% higher with non-organic SRI (6.38 vs 3.53 mt ha). With regard to varietal differences, under SRI management inoculation of the improved variety Sukhadhan-3 led to 26% higher yield (6.35 vs 5.04 mt ha), and with the heirloom variety Tilkidhan, yield was 41% higher (6.29 vs 4.45 mt ha). Economic analysis indicated that expanding the organic cultivation of local landraces under SRI management should be profitable for farmers where such rice has a good market price due to its premium quality and high demand and when SRI enhances yield. These varieties' present low yields can be significantly increased by integrating bio-inoculation with SRI cultural methods. Other recent research has shown that such inoculation can be managed profitably by farmers themselves.