Effect of seedlings age and plant spacing on growth, yield, nutrient uptake and economics of rice (Oryza sativa) genotypes under system of rice intensification

Abstract

A field experiment was conducted during the rainy ( kharif) season of 2008 and 2009 at Varanasi, to evaluate the effect of seedlings age and plant spacing on growth, yield, nutrient uptake and economics of rice ( Or yza sativa L.) under system of rice intensification (SRI). Sixteen treatments were laid out in a split-plot design, keeping com- binations of 2 genotypes (PHB 71 and NDR 359) and 2 spacings (25 cm 25 cm and 30 cm 30 cm) in main- plots and 4 seedlings age (8, 10, 12 and 14 days old) in sub-plots with 3 replications. The rice hybrid PHB 71 showed significantly higher growth, yield attributes and 12.6% higher yield than NDR 359. This hybrid also gave the highest net monetary returns ( 46,700/ha) and benefit: cost ratio (1.56). Wider spacing i.e. 30 cm 30 cm gave significantly more tillers/hill (22.7), panicles/hill (21.9) and grains/panicle (168.1) than other spacing. How- ever, plant height (116 cm), leaf-area index (5.0), net monetary returns and yield were significantly higher in closer spacing of 25 cm 25 cm. The closer spacing resulted in around 12.30% higher grain yield over wider spacing. Amongst the ages of seedlings, 10 days old seedlings resulted in significantly higher growth, yield attributes, net monetary returns and yield than 8 and 14 days old seedlings but remained at par with 12 days old seedlings. The 10 days old seedlings gave 12.8 and 17.6% more grain yield than 8 and 14 days old seedlings, respectively.