Abstract

In Egypt, water requirement for the rice crop is a problem because of the limited irrigation water available from the River Nile. To solve that problem, a breeding program for drought tolerance, starting from hybridization until yield trials experiments, was designed. Ten 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. The progenies from each cross were advanced from F₂ until F₆generation. F₇ seeds were collected and bulked to provide the seed source for yield trial experiments. The best selected lines from Fn generation were evaluated under normal and drought conditions (flush irrigation every 12 days) during 2007 and 2008 rice growing seasons. 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 4, 8 and 12 days). Each experiment was designed in a randomized complete block design, with three replications.  These lines were found to be tolerant to drought conditions at different growth stages, that is, seedling stage, early and late vegetative stage, panicle initiation stage and ripening stage. Water saving ranged from 50 to 55% as compared to continuous submergence, with a rice yield of 7-9 t/ha. So, by using such lines the total water requirements might be significantly reduced without significant reduction in the yield. Also, these lines could 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.

Key words: Drought stress, rice, high yielding lines, saving irrigation water.