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, cutoff 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 cutoff irrigation, i.e. cutoff 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 cutoff irrigation (DACI). The main results showed 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 cutoff 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 cutoff 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/m 3) 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 cutoff irrigation recorded higher water productivity than early cutoff irrigation after complete heading. Generally, in case of water shortage, it was concluded to use irrigation every six days and cutoff 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).

No abstract

Aerobic rice cultivation progresses water productivity, and it can save almost 50% of irrigation water compared to lowland rice with the appropriate development of genotypes and management practices. Two field trials were conducted during 2020, and 2021 seasons to determine the validation of different rice varieties under aerobic cultivation based on their plant defense system, physio-morphological traits, stress indices, grain yield, and water productivity. The experiments were designed in a split-plot design with four replications. Two planting methods, transplanting and aerobic cultivation, were denoted as the main plots, and ten rice genotypes were distributed in the subplots. The results revealed that the planting method varied significantly in all measured parameters. The transplanting method with well watering had the highest value of all measured parameters except leaf rolling, membrane stability index, antioxidant, proline, and the number of unfilled grains. EHR1, Giza179 and GZ9399 as well as A22 genotypes a chief more antioxidant defense system that operated under aerobic conditions. Giza179, EHR1, GZ9399, and Giza178 showed high cell membrane stability and subsequently high validation under such conditions, and also showed efficiency in decreasing water consumption and improving water use efficiency. In conclusion, this study proves that Giza179, EHR1, GZ9399, Giza178, and A22 are valid genotypes for aerobic conditions.

Two field experiments were conducted at the experimental farm of Sakha Agriculture Research Station, Sakha, Kafr El-Sheikh, Egypt during 2017 and 2018 seasons. The aim of the current investigation was to study the effective of bio and organic fertilizers in declining the mineral nitrogen fertilizer in rice fields (Sakha 108 cv.). The treatments were: T1: 165 kg N/ha as recommended nitrogen rate (RN), T2: ⅔ RN, T3: ⅔ RN + 5 t/ha poultry manure as organic fertilizer, T4: ⅔ RN + Anabaena oryzae (N-fixing anabaena) as bio-fertilizer, T5: ⅔ RN + organic manure + bio-fertilizer, T6: ⅓ RN, T7: ⅓ RN + organic manure, T8: ⅓ RN + bio-fertilizer and T9: ⅓ RN + organic manure + bio-fertilizer. The obtained results revealed that the integration among mineral, organic and biofertilization of T5 (110kg N/ha + 5 t/ha poultry manure + 600 g/ha N-fixing anabaena) gave the maximum values of tillers number m-2 , days to heading, dry matter accumulation, flag leaf chlorophyll content, flag leaf area, leaf area index, panicles number m-2 , panicle weight, 100-grain weight, grain yield, straw yield, milling percentage and grain protein content, as well as, the lowest number of unfilled grains panicles-1. However, the differences between T5 and T1 (165 kg N/ha as recommended mineral N level) in panicles number m-2 , number of unfilled grains per panicle, straw yield, milling percentage and grain protein content were insignificant. In addition, T1 gave the tallest plants and the maximum values of number of filled grains per panicle and hulling percentage, but the differences with T5 in number of filled grains panicle-1 and hulling percentage were insignificant. Number of branches panicle-1 , panicle length, harvest index and head rice had insignificant response. It could sum up that adding ⅔ of the recommended mineral nitrogen plus of 5 t/ha of poultry manure plus 600 g/ha of N-fixing anabaena could be the recommended for reducing mineral nitrogen fertilizer and brining high grain yield of Sakha 108 rice variety.

Field experiments were conducted during the 2019 and 2020 seasons at The Experimental Farm of Sakha Research Station, Kafr El-Sheikh, Egypt, to study the impact of different irrigation regimes, potassium silicate on growth, grain yield, and water productivity of some rice genotypes. The experiments were laid out in a strip-split plot design, with three replications. The vertical plots contained four irrigation regimes, i.e., irrigation every 4-day (I1), alternate 4-day on and 4-(I2),6-(I3), and 8-(I4) days off. However, the horizontal plots consisted of four potassium silicate rates, namely, 0, 1, 2, and 3 % potassium silicate. Meanwhile, the sub-sub plots consisted of three rice genotypes (Sakha 108, Giza 178, and Egy-Kor 27). The main results revealed the growth characteristics, grain yield, and its components were significantly decreased with increasing period from I1 up to I4. The potassium silicate at 3% followed by 2 % registered high values of the study traits. Giza 178 had the highest values of the study traits except for panicle length, panicle weight, and 1000-grain weight which recorded the highest value with Sakha 108. Irrigation every 4-day consumed the highest amount of irrigation water while the lowest amount was received by I4. The treatment I3 irrigation recorded the highest water productivity as compared to other treatments. Generally, under the same conditions, it is possible to cultivate Giza 178 rice cultivar and alternate irrigation as 4-day on + 4-day off with spray 2 % of potassium silicate for highest grain yield and acceptable water productivity.