Sarmah, M.K.M, Vigneshwaran2021-01-122021-01-122020-06https://krishikosh.egranth.ac.in/handle/1/5810159927A field experiment entitled “Performance of direct seeded sali rice under two different crop establishment methods and weed management practices” was carried out at the Instructional-cum-Research (ICR) Farm, Assam Agricultural University, Jorhat during the sali season of 2018-19 with a view to study the growth and yield behaviour of direct seeded sali rice under two different crop establishment methods and to find out the appropriate weed management practices for direct seeded sali rice. The experiment was laid out in a factorial RBD with three replications. The treatments consisted of two methods of sowing i.e., dry seeding (M1) and wet seeding (M2) and seven different weed management practices viz., two hand weedings at 20 & 40 DAS (W1), preemergence herbicide application of pretilachlor @ 0.75 kg a.i./ha (W2), pre-emergence herbicide application of pretilachlor @ 0.75 kg a.i./ha + one hand weeding at 40 DAS (W3), pre-emergence herbicide application of pyrazosulfuron ethyl @ 20 g a.i./ha (W4), pre-emergence herbicide application of pyrazosulfuron ethyl @ 20 g a.i./ha + one hand weeding at 40 DAS (W5), weed free check (W6) and weedy check (W7). The experimental field was infested with different types of grasses viz., Panicum repens, Leersia hexandra and Eragrostis unioloides, sedges viz., Cyperus rotundus L., Fimbristylis littoralis, and broad leaved weeds viz., Ageratum conyzoides, Alternanthera philoxeroides., Ludwigia decurrens and Acmella ciliate. The method of sowing brought significant influences on weed density and weed dry weight in all the growth stages. The wet seeding proved statistically superior in regards to growth attributes i.e. number of tillers/m2 and plant height at all growth stages compared to dry seeding. Similarly, wet seeding recorded significantly highest yield attributes i.e. number of panicles/m2 (160.11), panicle length (26.32 cm), number of filled grains/panicle (118.83) of sali rice followed by dry seeding. The wet seeding also recorded significantly highest grain yield (31.27 q/ha) and straw yield (49.04 q/ha). Higher uptake of nitrogen, phosphorus and potassium in grain, straw and total uptake by sali rice and lower uptake by weeds were recorded in wet seeding. Among the different weed management practices, weed free plot recorded the lowest weed density and weed dry matter, highest weed control efficiency and highest weed control index at all growth stages as well as recorded the highest growth characters, yield attributes, grain yield and straw yield. Results indicated that apart from the weed free plot, pre-emergence herbicide application of pretilachlor @ 0.75 kg a.i./ha + one hand weeding at 40 DAS and pre-emergence herbicide application of pyrazosulfuron ethyl @ 20 g a.i./ha + one hand weeding at 40 DAS shown the lowest weed density, dry weight, highest WCI, highest WCE at 45, 60 DAS and at harvest stage as well as it recorded the highest yield attributes, grain yield and straw yield. At 30 and 60 DAS, lowest uptake of nutrients by weeds were recorded in weed free check followed by two hand weedings at 20 & 40 DAS. At harvest, lowest uptake by weeds were recorded in weed free check followed by pre-emergence herbicide application of pretilachlor @ 0.75 kg a.i./ha + one hand weeding at 40 DAS. Significantly higher uptake of nitrogen, phosphorus and potassium in grain, straw and total uptake by sali rice was recorded in weed free check followed by pre-emergence herbicide application of pretilachlor @ 0.75 kg a.i./ha + one hand weeding at 40 DAS and pre-emergence herbicide application of pyrazosulfuron ethyl @ 20 g a.i./ha + one hand weeding at 40 DAS. The treatment combination of wet seeding (M2) combined with the weed free check recorded the highest grain yield (41.33 q/ha) and straw yield (59.33 q/ha) and it was statistically at par with the treatment combination of wet seeding along with preemergence herbicide application of pretilachlor @ 0.75 kg a.i./ha + one hand weeding at 40 DAS. An economic analysis showed that treatment combination of wet seeding combined with pre-emergence herbicide application of pretilachlor @ 0.75 kg a.i./ha + one hand weeding at 40 DAS (M2W3) recorded the highest net return (Rs. 63,089/ha) and benefit cost ratio (1.76).EnglishThesis