Studies on weed dynamics in different rice establishment methods under rice wheat system

Abstract

newline Field experiments were conducted during Kharif and Rabi seasons of 2020-21 and 2021-22 newlineat N. E. Borlaug Crop Research Centre of G.B. Pant University of Agriculture and Technology, newlinePantnagar entitled quotStudies on weed dynamics in different rice establishment methods under ricewheat newlinesystemquot. The soil of the experimental site was slightly alkaline in nature (pH), high in organic newlinecarbon (0.87 %), low in available nitrogen (227 kg ha-1), and medium in accessible phosphorus newline(19.6 kg ha-1) and potassium (202 kg ha-1). Rice variety PD-24 and wheat variety UP 2572 were newlineused in the study. Rice was grown under 3 establishment methods [Transplanted (TPR), Direct newlineseeded rice (DSR) and wet-direct seeded rice (WDSR)] and 4 weed management practices viz., newlineWeed free (3 times hand weeding), Mechanical weeding (2 times conoweeder), Chemical weeding newline(use of pre and post emergence herbicides) and Weedy check (control). The experiment was done in newlinesplit plot design with three replications. During rabi season, wheat was taken with standard practices newlinein all 3 main plots, while subplots (weed management practices) were similar to that of rice. newlineDuring both the years of study, direct seeded rice recorded the highest number of tillers m-2 newlineas well as dry matter accumulation upto 90 DAS/DAT fb WDSR. The other growth indices were newlinefound superior with transplanted rice. The yield attributes (number of panicles m-2, panicle length, newlinegrains panicle-1, grain weight panicle-1 and 1000 grain weight) were significantly higher with newlinetransplanted rice during both the years. The grain, straw as well as biological yields were newlinesignificantly highest with TPR, while WDSR and DSR were at par. The gross returns and net newlinereturns were also found higher under TPR method during both the years. However, the B: C ratio newlinewas more with DSR. The grain yield of wheat after DSR was higher by 11.6% in 2020-21 and newline14.9% in 2021-22 over TPR and 5.3% in 2020-21 and 4.5% in 2021-22 after WDSR. The highest newlineNPK content and uptake by rice was found with TPR method. newlineFor rice the growth parameters, yield attributes and yield parameters were found to be the newlinehighest in weed free treatment fb mechanical method. Further, mechanical and chemical weed newlinecontrol treatments found at par with each other. The species wise weed density, total weed density, newlinetotal weed dry weight and NPK depletion by weeds was found to be maximum under weedy check newlinetreatment and minimum under weed free treatment fb mechanical and chemical treatments. newlineWheat gave better yield response when planted after DSR. Growing wheat after puddled newlinerice (TPR or WDSR) recorded lower yields compared to after DSR. For wheat also mechanical and newlinechemical weed control were found at par with weed free treatment. Different rice establishment newlinemethods and weed management practices did not have significant influence on soil organic carbon, newlineavailable nitrogen, phosphorus and potassium during both the years. newlineThus, direct seeding of rice and mechanical or chemical practice for weed management newlinecould be followed for higher productivity and profitability of rice-wheat cropping system.