The Mutual Effect of Irrigation Intervals and Weed Control for Enhancing Yield and Productivity of Irrigation Water for Two Rice Cultivars

Two field experiments were conducted through 2018 and 2019 summer growing seasons at Sakha Agricultural Research Station, Kafrelsheikh, Egypt to study effect of irrigation intervals and weed control for maximizing yield and productivity of irrigation water on Sakha 107 and Giza 179 rice cultivars. A strip split-plot experimental design, with three replications was used in both seasons. Three irrigation intervals i.e; irrigation every three days, every six days and every nine days were assigned in horizontal plots. Two rice cultivars viz; Sakha 107 and Giza 179 were randomly distributed in vertical plots. Six weed control treatments i.e., Saturn 50% EC (thiobencarb), Ronstar 25% EC (oxadiazon), Saturn followed by (fb) Granite 24% SC (penoxsulam), Ronstar fb Granite, hand weeding and weedy check were allocated in the sub-plots. The resultsof both seasons showed that, irrigation every 3-days recorded the lowest dry weights of E crus-galli and total weeds while, irrigation every 9-days recorded the lowest dry weights of A. baccifera and C. difformis. The highest rice dry weight, number of panicle m^-2, number of filled grain panicle^-1, panicle weight and rice grain yield were recorded by irrigation every 3-days as compared to 6 and 9 days. Rice cultivar Giza 179 exceeded Sakha 107, it recorded the lowest dry weights of A. baccifera, E crus-galli and total weeds in addition, increased number of panicle m^-2, number of filled grain panicle^-1 and rice grain yield while, the highest panicle weight was recorded by Sakha 107. Application of Ronstar fb Granite at recommended dosesachieved the best weed management, the highest weed control efficiency (%), rice grain yield and its attributes as well as productivity of irrigation water (PIW) compared to other treatments. The amount of irrigation water applied was decreased by 15% and 31% for six and nine days compared to three days, while productivity of irrigation water was taken the descending order six > three > nine days. To achieve the best weed control efficiency (%), yield and its attributes as well as save irrigation water and promote PIW, it could be apply irrigation every 6-days with Giza 179 cv treated by Ronstar fb Granite at recommended doses. But in case of water shortage, it could be apply irrigation every 9-days with Sakha 107 cv treated by Ronstar fb Granite at recommended doses.