Kumar, AnilSharma, Jyoti2024-08-052024-08-052024-07-03Sharma. J. Effect of Sowing Window Crop Ecologies and Herbicides on ACCase Resistant Phalaris minor in Wheat under Irrigated Conditions. Ph.D/ thesis 202437207https://krishikosh.egranth.ac.in/handle/1/5810212815The present study entitled “Effect of Sowing Window Crop Ecologies and Herbicides on ACCase Resistant Phalaris minor in Wheat under Irrigated Conditions” was conducted at the Research Farm, Division of Agronomy, SKUAST- J, Chatha during Rabi season of 2021-22 and 2022-23. The experiment-I entitled “Effect of normal sowing window crop ecologies and herbicides on ACCase resistant Phalaris minor in wheat under irrigated conditions was laid out in split plot design with sowing window viz. (5th Nov, 15th Nov and 25th Nov) as main plot treatments and weed management as sub plot treatments which were replicated thrice. The different pre, early-post and post emergence herbicides were applied for control of ACCase resistant Phalaris minor in wheat. The application of fertilizers were done in accordance with the recommended package and practices of SKUAST-J, Chatha. The experiment results revealed that wheat crop sown on 5th November sowing window recorded significantly lowest Phalaris minor density and biomass at different growth stages of wheat which leads to enhancement in yield attributes, yield and net returns and B:C ratio. Among the various weed management practices, weed free recorded significantly higher yield attributes and yield. However, among the various herbicidal treatments, pre-emergence application of Pyroxasulfone @127.5 g ha-1 recorded significantly lowest Phalaris minor density, biomass and higher yield attributes and yield, gross returns, net returns which was statistically at par with the early post emergence application of Pyroxasulfone 127.5 g ha-1, post-emergence application of Pinoxaden 40 g ha-1and pre- emergence application of Flumioxazin 125 g ha-1 while post-emergence application of Pinoxaden 40 g ha-1 recorded higher B:C ratio. Similarly, another field experiment was conducted under late sowing window with 3 different sowing window (15th Dec, 25th Dec and 5th Jan) and having similar weed management treatments as experiment- I. Among the late sowing window, 15th December sowing window recorded significantly lowest Phalaris minor density, biomass which leads to significant higher yield attributes, yield and net returns and B:C ratio. By and large similar results were obtained with respect to weed management treatment as experiment-I. A pot bioassay experiment for “Evaluation of different herbicides on ACCase resistant strains of Phalaris minor” was conducted in completely randomized block design consisting of seven treatments which were replicated thrice for three P. minor biotypes keeping Sundarbani, Rajouri biotype as susceptible (control). The P. minor biotypes were evaluated against seven recommended herbicides (flumioxazin, pyraxasulfone, metribuzin, clodinafop, fenoxaprop and pinoxaden) with their graded doses (0, 1/4X, 1/2X, X (Recommended dose), 2X and 4X) respectively. Pot experiment results revealed that three P. minor biotype i,e Karnal Kothi, Suchetgarh, Jammu, Sangyal, R.S. Pura, Jammu and Bera, R.S. Pura, Jammu were found resistant to ACCase herbicides like Clodinofop propargyl, fenoxaprop and pinoxaden than flumioxazin and pyraxasulphone. The development of resistance among these three P. minor biotypes were also confirmed by the higher GR50 (g/ha) values and resistant index compared with susceptible biotype during both the year of cropping. Resistant P. minor also recorded numerically morphological characteristics as compared to susceptible biotype of P. minor during both the year. Henceforth, based on the two years of investigation it can be concluded that wheat crop sown on 5th November and 15th December along with the pre-emergence application of pyroxasulfone @127.5 g ha-1 beside better management of weeds achieved with respect to lower P. minor density and dry matter thus leading to relatively higher wheat productivity for resource poor farmers. Pre-emergence application of Pyroxasulfone @127.5 g ha-1 can be recommended for higher wheat productivity. Whereas, for resource rich farmers Pursuit viz. post-emergence application of pinoxaden @ 80 g/ha at 3-4 leaf stage weed management treatments could also be taken up along with wheat crop sown on 5th November and 15th December thus providing the diverse nature of herbicidal weed management options under scarce labour availability condition to different economic strata of farmers of subtropical irrigated conditions of Jammu. Pot bioassay revealed that P. minor biotype collected from Karnal Kothi, Suchetgarh, Jammu, Bera, R.S. Pura, Jammu, Sangyal, R.S. Pura, Jammu was found to be resistant to ACCase inhibitors clodinafop and fenoxaprop and pinoxaden. The selection pressure exerted by continuous use of herbicides in wheat might have led to the development of herbicide resistance in P. minor. This necessitated the use of ACCase resistant herbicides like pyraxasulfone and flumixazin for P. minor. These promising herbicidal management options in respect of three location specific diverse biotypes can be safely recommended to target farmers on the premise that the germplasm doesn’t spread further over larger pockets of wheat growing areas.EnglishThesis