EFFECT OF N LEVELS AND SOME PLANT GROWTH REGULATORS ON HYBRID RICE (ORYZA SATIVA L.) SEED PRODUCTION

The aim of the present investigation is to identify the suitable N application rates and gibberellic acid to enhance hybrid rice seed production in Egypt. The experimental material comprising of both the parent Giza 178R and CMS line G46A was treated with different N levels and foliar Gibberellic acid (GA(3)). Treatments were arranged in a split-plot design with three replications. The main plots were devoted to the four N fertilizer levels (0, 55, 110 and 165 kg N ha(-1)), while, the doses of foliar GA(3) + boric acid were 0, 150, 150 + 0.5%, 200, 200 + 0.5%, 300 and 300 + 0.5% g ha(-1) arranged in the sub plots. Application of 165 kg N ha(-1) produced the highest seed yield in both seasons. The application rates of 300 g GA(3) + 0.5% boric acid ha(-1) produced the highest seed yield. The interaction between N levels and doses of GA(3) was highly significant for duration of spikelet opening, spikelet opening angle, stigma exsertion, plant height, panicle exsertion, panicle length, number of fertile tillers, panicle weight, seed set, harvest index and seed yield. It is concluded that, the treatment combination of (165 kg N ha(-1) and 300 g GA(3) ha-1 + 0.5% boric acid) gave the best effects for most of the rice characteristics.