Integrated weed management in lowland rice

Abstract

A field experiment was conducted at Cropping Systems Research Centre (CSRC), Karamana, Thiruvananthapuram to evolve a suitable integrated weed management practice for lowland nee. The study was conducted during the viruppu season of 2003. The field experiment was laid out in randomised block design having three replication with twelve treatments. The treatments include different herbicides in combinations, herbicides + hand weeding, hand weeding twice and unweeded control. Butachlor, 2,4~D, pretilachlor, anilofos + 2,4-DEE, anilofos, ethoxysulfuron, metsulfuron methyl and chlorirnuron- ethyl were the different herbicides used in the experiment. The rice variety used for the experiment was Kanchana. The results of the study revealed that grasses, broadleaved weeds and sedges competed with the rice crop. Different weed management practices significantly influenced the intensity and distribution of weeds ... The lowest dry matter of weeds was recorded by anilofos + ethoxysulfuron followed by one hand weeding which was on par with anilofos -+ ethoxysulfuorn alone. All the weed management treatments resulted in improved yield attributes and higher grain yield compared to weedy check. The plots treated with anilofos + ethoxysulfuron followed by hand weeding at 40 DA T recorded the highest grain yield. This treatment resulted in enhanced plant height, number of productive tillers un', LAI and nutrient uptake of rice. The yield attributes and grain yield were significantly increased by this treatment. The total weed population, weed dry matter production and nutrient removal by weeds were also reduced and weed control efficiency was increased by this treatment. Unweeded control recorded the lowest

gram yield. No herbicide used in this experiment resulted m residual toxicity after the cropping season. Manual weeding is expensive, laborious and time consummg. Labour non-availability at peak crop season for weeding also poses great threat. Readymix application of anilofos + 2,4-DEE (T3) resulted in highest B:C ratio of 1.41 and butachlor + 2,4-D (T,) with 1.40. Pre-emergence application of anilofos + ethoxysulfuron followed by one hand weeding at 40 DA T (T 8) was the most remunerative treatment.