Evaluation of system of rice intensification in a high rainfall area of North- Western Himalayas

Field experiments were conducted during 2002-2004 to evaluate SRI in a high rainfall area of north-western Himalayas. Effects of age of seedlings (7-12-d old i.e. SRI vs 22-28-d old i.e. conventionally transplanted rice (CTR), plant-hill spacing (15x15 and 30x30 cm) and water regime (continuous, CF vs intermittent flooding, IF) on plant height, rice yield and yield parameters (tillers, grains panicle-1 and 1000-grain weight),  and water use efficiency (WUE) in rice (cv. RP 2421) were investigated. Younger seedlings produced plants taller than older seedlings on average by 14.1 cm. Effective tillers hill-1 increased from 10 to 25 while effective tillers m-2 decreased significantly from 413 to 277 with the increase in plant-hill spacing. The 30 x 30 cm spacing produced higher grains panicle-1 (79) and 1000- grain weight (21.67 g) than the 15 x 15 cm spacing (70 grains panicle-1 and 20.42 g 1000-grain weight). Grain yield was statistically the same under all treatments (3.24-4.05 t ha-1), except CTR-30 with significantly lowest grain yield of 2.84 t ha-1. Numerically, SRI-15 (CF) and SRI-30 (CF) produced 20 and 13%, respectively, higher grain yield than CTR-15 (CF) i.e. the farmers’ practice. Total water use was higher by 80-634 mm in SRI than CTR. The WUE under CTR and SRI varied with the water regime; under CF, it was significantly higher with CTR-15 (1.87 kg ha-1 mm-1) than SRI-15 (1.69 kg ha-1 mm-1), and under IF, it was significantly higher at 15x15 cm (1.64-1.75 kg ha-1 mm-1) than at 30x30 cm spacing (1.48-1.51 kg ha-1 mm-1) under both SRI and CTR. SRI at 30x30 cm spacing required 222 man-days ha-1 compared to 833 man-days ha-1 with CTR-15; SRI required 19-11% more time for transplanting than CTR irrespective of hill-spacing. Compared with CTR-15, the SRI-30 showed advantage in terms of higher rice yield (13%), lower seed rate (1/10th of CTR) and lesser time and labour requirement during transplanting (1/4th of CTR).