T.K. DasJITESH KUMAR BAGHEL2018-08-312018-08-312017http://krishikosh.egranth.ac.in/handle/1/5810070375t9606Conservation agriculture (CA)-based rice (Oryza sativa L.) - wheat (Triticum aestivum L. emend Fiori&Paol.) cropping system (RWCS) can be the possible option for higher productivity and sustainability of the RWCS in the North-western Indo-Gangetic plains of India. But, weed infestation is the most important constraint towards its adoption. The CA influences weed species dynamics and competition in RWCS and affects the productivity of crops. A suitable integration of CA and weed management option can lead to a viable and sustainable RWCS through effective weed management that leads to higher productivity and resource-use efficiency. Therefore, field experiments were carried out at the ICAR-Indian Agricultural Research Institute, New Delhi during 2012-13 and 2013-14 to find out best weed control option for reducing crop-weed competition in RWCS, and to evaluate the effects of CA and weed control measures on resource-use efficiency, crop productivity and economics. The experiment was laid out in a split plot design, keeping CA practices in main plots and weed control measures in sub-plot with three replications. The CA treatments were: direct-seeded rice (DSR) - zero till wheat (ZTW), DSR - ZTW + rice residue retentions (RR), DSR + BM (brown manuring) - ZTW, DSR + BM - ZTW + RR, Mungbean residue (MR) + DSR – ZTW - zero till summer mungbean (ZTSMB), MR + DSR – ZTW + RR – ZTSMB + wheat residue retentions (WR), transplanted puddled rice (TPR) - ZTW and TPR – conventional till wheat (CTW). Weed control treatments in rice comprised of unweeded control (UWC), pre-emergence applications of pendimethalin at 1.5 kg/ha followed by postemergence applications of bispyribac-Na at 25 g/ha at 25 DAS/DAT, and these combination also integrated with one hand weeding (HW); and in wheat: unweeded control (UWC), preemergence application of pendimethalin at 1.0 kg/ha applied alone at 2 DAS; and sequenctional applications of pre-emergence pendimethalin at 1.0 kg/ha alone at 2 DAS followed by post-emergence applications of sulfosulfuron at 25 g/ha at 30 DAS. CA practices like brown manuring, summer mungbean and rice residue retention and zero till wheat influenced the growth, yield and yield attributers of rice and succeeding wheat. Higher rice yield was recorded in TPR than DSR practice. Among DSR practices, the triple cropping system including a legume (i.e. mungbean), MR + DSR – ZTW + RR – ZTSMB + WR combined with sequenctional applications pendimethalin followed bispyribac supplemented with one HW was found best treatment. It was next to TPR practices (TPR - ZTW & TPR - CTW) on the growth, yield, and yield attributes of rice. On the contrary, ZTW performed better than CTW. Higher growth and yield of wheat were recorded in ZTW. In wheat, the MR + DSR – ZTW + RR – ZTSMB + WR (with residues of three crops) and MR + DSR – ZTW– ZTSMB (without residue) and the applications of pendimethalin fb sulfosulfuron resulted in higher values of growth parameters, yield and yield attributes compared to the TPR - ZTW and TPR - CTW systems. The overall system productivity and monetary benefit were higher with treatments, MR + DSR – ZTW + RR –ZTSMB +WR combined with pendimethalin fb bispyribac along with one HW in rice, and pendimethalin fb sulfosulfuron in wheat. DSR was infested with diverse weeds in large numbers than TPR. Grassy weeds were more dominant than others in rice. Among DSR practices, the DSR - ZTW and DSRZTW + RR had maximum weed infestation. In wheat, broad-leaved weeds were more dominant, and higher weed infestation was observed in conventional till wheat practices, i.e., TPR-CTW and TPR-ZTW. The applications of pendimethalin fb bispyribac along with one HW in rice and pendimethalin fb sulfosulfuron in wheat effectively controlled weeds and provided higher weed control efficiency (WCE). The populations of plant-parasitic nematodeswere higher in DSR and ZTW practices than conventional practices. Treatments, DSR + BM - ZTW and DSR + BM – ZTW + RR resulted in higher number of nematodes in both rice and wheat. Weed density and nematode population were positively correlated. Herbicide application significantly reduced nematodes population. Higher values of microbial biomass carbon (MBC) and soil dehydrogenase activity (DHA) were associated with DSR and ZTW practices. Weed control measures did not affect microbial activity. CA practices had significant impacts on C pools, available NPK and soil organic carbon. The treatments,MR + DSR – ZTW + RR – ZTSMB + WR, MR + DSR – ZTW – ZTSMB, and DSR + BM - ZTW + RR resulted in higher very labile C and available NPK. Weed control measure did not influence C pools and soil organic carbon. Thus, based on the two-year studies, a combination of the CA-based triple cropping system that involves summer mungbean residue retention in direct-seeded rice, followed by zero till wheat with rice residue, and zero-till summer mungbean with wheat residue retention, and the applications of pre-emergence pendimethalin 1.5 kg/ha alone followed by postemergence bispyribac-Na 25 g/ha at 25 DAS/DAT supplemented with one 1 hand weeding in rice, and the applications of pre-emergence pendimethalin 1.0 kg/ha at 2 DAS alone followed by post-emergence applications of sulfosulfuron 25 g/ha at 30 DAS in wheat, may be recommended for better weed management and higher crop productivity, profitability and resource-use efficiency in the North-western Indo-Gangetic Plains of India.en-USnullThesis