Development of some high yielding rice lines tolerant to drought stress conditions

In Egypt ,rice is one of the major water consuming crops and continuous flooding is the most common methods for irrigation. The water requirement for the rice crop cause nowadays an acute problem because of the limited irrigation water available from the River Nile.The present study was carried out to develop new promising lines produce more rice with less water to be grown to the drought affected areas due to the shortage of irrigation water and at the end of the terminals which receives irrigation water irregularly. Some promising lines were derived from IET 1444/ Sakha 102, Sakha 101 / IR 65600 and Sakha 101 / Gaori populations. Attentions were paid to the traits more associated with drought tolerance among segregants, to identify genotypes that confer drought resistance through selection procedures. The progenies from each cross were advanced under drought conditions from F2 generation using the pedigree method technique until F6 generation. The best ten selected lines from Fn generation were promoted to the yield trial experiments during 2007 and 2008 seasons. Randomized complete block design with three replications was used. The amount of irrigation water applied was determined by using flow meter. In 2009 season, the lines were evaluated under different irrigation intervals (irrigation every four, eight and twelve days) to test their yield potential. These lines were found to be tolerant to drought conditions at different growth stages i.e. early and late vegetative stage, reproductive and ripening stage. These lines proved to possess useful traits associated with drought tolerance such as early maturity, medium tillering ability, intermediate plant height, deep and thick roots, high root volume, high root: shoot ratio, plasticity in leaf rolling and unrolling, in addition to high water use efficiency. Water saving ranged 50-55 % as compared to continuous submergence, with a rice yield of 7-9 tons/ ha. So, by using such lines, the total water requirements will be significantly reduced without significant reduction in the yield. Also these lines can be used as donor parents at reproductive stage to solve the problem of a lack of the donor parents in breeding rice for drought tolerance.