Directorate of Rice Research Rajendranagar, Hyderabad-500 030 (A. P.), India.
An experiment was conducted during dry season of 1994–95 and wet season of 1995 in clay loam soils. Recently released rice hybrids viz., DRRH-1 and APRH-2 alongwith check variety Jaya were tested under three levels of N (0, 60 and 120 kg/ha) and three levels of weed competition viz., high weed competition (unweeded control), medium weed competition (two hand weedings at 20 and 45 days after transplanting-DAT) and weed free. Mean grain yield of hybrids and inbred variety Jaya was higher by 53.37 and 90.90% during dry and wet seasons, respectively, under weed free treatment over higher weed competition treatment. Hybrids responded differently to application of N levels and weed interference. DRRH-1 recorded significantly higher mean grain yield of 4.42 and 3.91 t/ha over Jaya during dry and wet season, respectively. The maximum grain yield of 6.90 and 6.03 t/ha during dry and wet season, respectively, was obtained under high N level (N 120 kg/ha) in least weed competition with DRRH-1. Weed biomass was significantly higher under APHR-2 hybrid as compared to DRRH-1 during wet season. Based on these preliminary results, it can be inferred that rice hybrids should be selected based on their response to applied N level and their ability to tolerate weed competition.
