Efficacy of weed control and irrigation intervals on productivity of rice and water under direct seeding on furrows

Abstract

A field study was conducted at Rice Department Experimental Farm, Sakha Agricultural Research Station, ARC, Egypt during 2020 and 2021 summer seasons, to investigate the best chemical weed control treatment of direct seeded-rice on furrows as innovative method under different irrigation intervals. A strip plot design with three replications was used. Irrigation intervals every 4 (I1), 8 (I2) and 12 days (I3) were assigned in horizontal plots and six weed control treatments were allocated in the vertical plots which contained (W1): Saturn 50% EC (thiobencarb) at 3.57 kg ai ha -1 at 4 days after seeding (DAS), (W2): Stomp 50% EC (pendimethalin) at 2.023 kg ai ha -1 at 4 DAS. (W3): Saturn followed by Repair 18% TB as a ready-made of quinclorac 16.5% + bensulfuronmethyl 1.5% at rate of 0.491 + 0.0446 kg ai ha -1 at 25 DAS. (W4): Stomp followed by Repair 18% at 0.536 kg ai ha -1 (W5): weed free and weedy check (W6). The obtained results showed that I1 treatment exceeded the other irrigation intervals and recorded the lowest dry weights of grassy weeds as well as total weeds, in spite of gave the highest dry weights of broad leaf weed, in addition to the highest rice dry weight, grain yield and its attributes in the two seasons. Irrigation every 8 and 12 days saved about 17.95 and 23.1% of applied irrigation water as compared to irrigation every 4-day. W4 treatment achieved the best weed control as well as improved water productivity and rice vegetative growth which produced grain yield of 8.14 and 8.58 t ha -1 in 2020 and 2021 seasons, respectively, in addition to reduced yield losses to 4.1% as an average of the two seasons. While weeds caused 93.2% losses in rice grain yield in weedy check plots. The combination of irrigation every 4-days with pendimethalin at 4 DAS followed by ready-made of Repair18% at 25 DAS achieved the best chemical weed control treatment and increased rice vegetative growth and yield as well as minimize yield losses of Sakha super 300 as new released Egyptian rice cultivar. While under water scarcity, the interaction of irrigation intervals every I2 and W4 that recorded water productivity (0.79 kg m -3 ), grain yield (8.89 tons ha -1 ) and saved 17.95% of applied water as an average of the two seasons. The highest water productivity was recorded by I2 x W5 (0.81 kgm -3 ) with no significant differences with I2 x W4 (0.79 kgm -3 ).