Spikelet sterility in hybrid rice (Oryza sativa) as influenced by sources and levels of nutrients

An experiment was conducted for two years during kharif 2009 and 2010 at College Farm, College of Agriculture, Rajendranagar, Hyderabad, India to study the effect of organic sources and fertilizer levels on spikelet sterility in hybrid rice (Oryza sativa L.). The experiment was laid out in split plot design with three replications. The treatments included organic manures (control – no organic manuring, subabul incorporation @ 5 t ha⁻¹, rice straw incorporation @ 2.5 t ha⁻¹) as main plot treatments and fertilizer levels comprising of N:K₂O kg ha⁻¹ (150:75, 175:50, 175:25, 200:50, 200:25, 225:0) as sub plot treatments. Among the organic sources, incorporation of subabul @ 5 t ha⁻¹ recorded the highest number of total grains panicle⁻¹, filled grains panicle⁻¹, lowest number of unfilled grains panicle⁻¹ and spikelet sterility in both the years. Among the fertilizer levels tested, 200:50 N:K₂O kg ha⁻¹ recorded the highest number of total grains panicle⁻¹, filled grains panicle⁻¹, while 150:75 N:K₂O kg ha⁻¹ recorded the lowest spikelet sterility. The highest spikelet sterility was recorded with the application of 225:0 N:K₂O kg ha⁻¹ in both the years. Interaction effect was found significant on total grains panicle⁻¹ and filled grains panicle⁻¹. Subabul incorporation @ 5 t ha⁻¹ + 200:50 N:K₂O kg ha⁻¹ recorded the highest number of total and filled grains panicle⁻¹ and was comparable to subabul incorporation @ 5 t ha⁻¹ + 200:25 N:K₂O kg ha⁻¹.