EFFECT OF PLANT GROWTH REGULATOR APPLICATION AT DIFFERENT GROWTH STAGES ON THE YIELD POTENTIAL OF COARSE RICE

The study was conducted to find out the growth behaviour of transplanted coarse rice (IR-6) as influenced by plant growth regulator (NAA 4.5 % as sodium salt) under the agro climatic conditions of Dera Ismail Khan, Pakistan during 2004 and 2005. The experiment was laid out in randomized complete block design with split plot arrangements, replicated 4 times. Main plot consisted of three growth stages of rice that is tillering (S1), panicle initiation (S2), and grain formation stage (S3), while subplots included four levels of plant growth regulator viz. 0, 60, 90 and 120 ml naphthalene acetic acid (NAA) ha^-1. Data on plant height (cm) at maturity, number of panicles m-^2, number of spikelets panicle^-1, 1000-grain weight (g) and paddy yield (Mg ha^-1) were recorded. The data revealed that application of growth regulator (NAA) data at the rate of 90 ml ha-1 at panicle initiation stage resulted in highest number of 340 and 342 panicles m^-2, 182 and 187 spikelets panicle^-1, 88 and 90 % normal kernel, 23.00 and 23.20 g 1000-grain weight, 9.00 and 9.20 Mg ha^-1 paddy yield during 2004 and 2005, respectively.