Evaluation of rice (Oryza sativa) under double transplanting in rainfed lowland rice ecosystem of Asom

A field experiment was conducted during the rainy (kharif) season of 2011 and 2012 at Gerua, Hajo, Asom to assess the performance of high-yielding varieties of rice (Oryza sativa L.) under double-transplanting method in rainfed lowland rice ecosystem of lower Brahmaputra Valley of Asom. The experiment consists of 10 treatment combinations, viz. 2 plant stand establishment methods (normal transplanting and double transplanting) in main plots and 5 rice varieties 'Ranjit', 'Swarna', 'Swarna Sub 1', 'Sabita' and 'Pooja' in subplots. Double transplanting recorded significantly increase in grain yield by 9.4% over normal transplanting. The increase in grain yield was owing to increase in number of panicles/unit area, number of grains/panicle, grain filling percentage and 1,000 grain weight. Among the rice varieties 'Swarna' recorded significantly higher grain yield of 6.16 t/ha followed by Ranjit' (5.67 t/ha) and 'Swarna Sub 1' (5.65 t/ha). Under double transplanting, 'Swarna' recorded the highest benefit cost ratio of 2.03 and least production cost of '5.03/kg of grain, while 'Sabita' recorded lowest benefit: cost ratio of 1.10 due to lowest yield (4.20 t/ha) and poor market price.