Performance of rice (Oryza sativa) varieties at different spacing under system of rice intensification (SRI) in mid hill acid soils of Sikkim Himalayas
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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 performance 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’ (longduration, 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 optimum spacing under system of rice intensification for ‘RCPL 1-87-8’, ‘RC Maniphou-7’ and local cv ‘Thulo Attey’ was 20 cm × 20 cm. ‘Pusa Sugandh-2’ recorded a 2.0% yield decrease at 20 cm × 20 cm and 23.0% yield decrease at SRI 10 cm × 10 cm, as compared to conventional rice cultivation and did not respond to SRI.
Acid soils, Long duration rice, Manure, Mid-hills, Mountain regions, Medium duration rice, Nutrient uptake, Water use efficiency.