Performance of rice (Oryza sativa) varieties at different spacing under system of rice intensification (SRI) in mid hill acid soils of Sikkim Himalayas

Abstract

Field experiments were conducted at the ICAR Sikkim Research Farm, Tadong located at an altitude of 1450 m amsl in the per-humid mid hill acidic soils during kharif (rainy season) of 2008 and 2009 to evaluate the perfor- mance of four rice ( Oryza sativa L.) varieties viz., RCPL 1-87-8 (medium-duration, 125 days), Pusa Sugandh-2 (medium-duration, 130 days), RC Maniphou-7 (long-duration, 150 days) and one local cultivar Thulo Attey (long- duration, 155 days) under different spacing in system of rice intensification (SRI) compared with conventional rice cultivation. RC Maniphou-7 recorded the highest grain yield (6.73 t/ha), N uptake (124.8 kg/ha), P uptake (40.5 kg/ha), K uptake (84.3 kg/ha), water use efficiency (2.879 kg/ha-mm), net return (Rs. 72,750) and benefit: cost (2.09) at 20 cm 20 cm spacing under SRI. Total N, P and K uptake was the highest in SRI with a spacing of 20 cm 20 cm in RCLP 1-87-8, RC Maniphou-7 and local cv Thulo Attey over conventional rice cultivation. The