BEHAVIOR OF EGYPTIAN HYBRID RICE CULTIVAR (EHRI) UNDER DIFFERENT IRRIGATION REGIMES AND HARVESTING TIMES

Abstract

These studies were carried out at the Experimental Farm of Rice Research and Training Center (RRTC), Sakha, Kafr El-Sheikh, Egypt, during 2007 and 2008 summer seasons. The purpose was to investigate the effect of irrigation intervals, cut-off irrigation and harvesting times on grain yield and its attributes as well as grain quality characters and water relations of Egyptian hybrid rice cultivar (EHR1). A split split–plot design, with four replicates, was used. The main plots were devoted to three irrigation intervals namely: continuous flooding (CF), irrigation every 6 (6D) and 12 days (12D). The sub-plots were assigned to five times for cut-off irrigation, i.e. cut-off irrigation after complete heading (ACH), 1-, 2-, 3- and 4- weeks after complete heading (WACH). However, the sub-sub plots were consisted of three harvesting times, i.e. harvest rice plants at 10-, 15- and 20- days after cut-off irrigation (DACI). The main resultsshowed that grain yield and its attributes, as well as milling recovery and protein content, were significantly decreased as irrigation intervals increased from CF up to twelve days, but, unfilled grains (%) and amylose content were increased. Irrigation every six days came in between with insignificant difference with CF in most of previously mentions traits. Delayed cut-off irrigation up to 3- and 4-WACH significantly increased grain yield and most of its attributes, as well as grain quality. However, it reduced amylose content in 2007 and unfilled grains (%) in both seasons, as compared with cut-off irrigation ACH. Harvesting rice plants 10 and 15 DACI recorded the highest number of grains/panicle, panicle weight, 1000 grain weight and grain yield. However, the lowest values of milling recovery and protein content were recorded when plants were harvested at 10 DACI. Continuous flooding consumed the highest amount of irrigation water, while increasing irrigation intervals up to six and twelve days tended to decrease the amount of water used. Furthermore, 6D treatment recorded the highest water productivity (0.796 and 0.798 kg/m3) and minimum grain yield reduction (4.54 and 3.64 %) with water saved about 8.04 and 7.08 %, compared to CF in both seasons, respectively. Delay cut-off irrigation recorded higher water productivity than early cut-off irrigation after complete heading. Generally, in case of water shortage, it was concluded to use irrigation every six days and cut-off irrigation 3-WACH with harvest plants 10 DACI for the highest water productivity and grain yield, as well as acceptable grain quality characters, of Egyptian hybrid rice cultivar (EHR1).