TY - BOOK AU - Bokka Navyashika AU - Jacob D (Guide) TI - Directed application of pre and post-emergence herbicides for weed management in sesame (Sesamum indicum L.) U1 - 630 PY - 2023/// CY - Vellayani PB - Department of Agronomy, College of Agriculture KW - Agronomy N1 - MSc N2 - The study entitled “Directed application of pre and post emergence herbicides for weed management in sesame (Sesamum indicum L.)” was undertaken during 2020-2022 at College of Agriculture, Vellayani, Thiruvananthapuram, Kerala, with the objective to evaluate the efficiency of pre and post-emergence directed application herbicides for weed management, and their effect on growth, yield and phytotoxic effect on sesame crop. Field experiment was laid out at Onattukara Regional Agricultural Research Station, Kayamkulam in Randomized Block Design with twelve treatments and three replications during summer 2022 (02/02/2022 to 30/04/2022). Per emergence (PE) oxyflourfen 80 g ha-1 at 2 DAS fb carfentrazone ethyl 20 g ha-1 at 25 DAS (T1), PE oxyflourfen 80 g ha-1 at 2 DAS fb imazethapyr 50 g ha-1 at 25 DAS (T2), PE oxyflourfen 80 g ha-1 at 2 DAS fb mechanical weeding with wheel hoe weeder at 25 DAS (T3), PE pendimethalin 500 g ha-1 at 2 DAS fb carfentrazone ethyl 20 g ha-1 at 25 DAS (T4), PE pendimethalin 500 g ha-1 at 2 DAS fb imazethapyr 50 g ha-1 at 25 DAS (T5), PE pendimethalin 500 g ha-1 at 2 DAS fb mechanical weeding with wheel hoe weeder at 25 DAS (T6), PE diclosulam 12.5 g ha-1 at 2 DAS fb carfentrazone ethyl 20 g ha-1 at 25 DAS (T7), PE diclosulam 12.5 g ha-1 at 2 DAS fb imazethapyr 50 g ha-1 at 25 DAS (T8), PE diclosulam 12.5 g ha-1 at 2 DAS fb mechanical weeding with wheel hoe weeder at 25 DAS (T9), Mechanical weeding with wheel hoe weeder at 15 and 30 DAS (T10), Hand hoe weeding at 15 and 30 DAS (T11) and weedy check (T12) constituted the treatments. Herbicides were applied using crop protective herbicide applicator, and sowing was done with seed cum fertilizer drill. The sesame variety used for the study was “Thilak”. Weed management practices had significant effect on growth parameters viz.,plant height at 40, 60 DAS and at harvest, number of branches at 60 DAS, and leaves and leaf area per plant at 40 and 60 DAS, and DMP at 40, 60 DAS and at harvest. At 40, 60 DAS and at harvest, the treatment T10 recorded the highest plant height. However, at 40 DAS, T6 and at 60 DAS T10 recorded the highest number of leaves per plant. The treatment T10 recorded the highest leaf area per plant at 40 DAS, and at 60 DAS T4 recorded the highest. At 60 DAS, T10 recorded the highest number of branches. However, DMP was found to be the highest in T10 at all stages of observation (40, 60DAS and at harvest). Among physiological parameters viz., RGR at 20-40 DAS and 40-60 DAS, CGR at all time intervals, and LAI at 40 and 60 DAS were significantly influenced by weed management practices. At 20-40 DAS and 40-60 DAS time interval T6 and T4 recorded the highest RGR. However, T10 recorded the highest CGR at all time intervals. The highest LAI was observed in T10 at 40 DAS and T4 at 60 DAS. Days to 50 per cent flowering did not vary significant effect. The treatment T10 recorded the highest number of capsule per plant (43.8) and T6 recorded the highest number of seeds per capsule (64.95). Seed yield and haulm yield were significantly influenced by weed management. The treatment T10 resulted in the highest seed yield (478 kg ha-1 ) and haulm yield (1177 kg ha-1 ) which was comparable with T6 and T4. Weed index was the lowest in T10 which was followed by T6 and T4. Organic carbon content, soil available N, P and K status of post harvest soils and nutrient uptake by crop at harvest were significantly influenced by weed management. The treatment T10 recorded the highest organic carbon content, soil available N, P and K and also the highest total N (53.64 kg ha-1 ), P (11.04 kg ha-1 ) and K (31.67 kg ha-1 ) uptake by the crop at harvest. Weed dry management profoundly influenced the nutrient uptake by weeds at 20, 40 and 60 DAS. The treatment, T11 recorded the lowest N removal by weeds (1.14 kg ha1 ) at 20 DAS, T10 (4.16 kg ha-1 ) at 40 DAS and T4 (6.46 kg ha-1 ) at 60 DAS. The treatment T10 recorded the lowest P removal by weeds at 20, 40 and 60 DAS (0.03, 0.17 and 0.48 kg ha-1 ). The treatment T10 recorded the lowest K removal by weeds at 20, 40 and 60 DAS (0.25, 2.05 and 2.91 kg ha-1 ). The predominant weeds associated with sesame in the experimental field were Echinochloa colona, Eleusine indica, Melochia corchorifolia and Cleome viscosa. Weed dry weight was also significantly influenced by weed management. The treatment T10 recorded the lowest weed dry weight at 20 and 40 DAS (13.64 g m-2 and 21.48 g m-2 , respectively). However at 20 DAS, T10 was statistically on par with T11 and T6 and at 40 DAS T10 was statistically on par with T6 and T4. At 60 DAS, T6 recorded the lowest weed dry weight (32.65 g m-2 ) which was on par with T10 and T4. Among the treatments, T10 recorded the highest weed control efficiency at 20 and 40 DAS which was followed by T11 and T6 at 20 DAS, T6 and T4 at 40 DAS. At 60 DAS, T6 (77.19 %) recorded the highest WCE which was followed by T10. The highest gross income was observed in the treatment T10 (Rs. 71,726 ha-1 ) which was comparable with T6, T4 and T11. However, the net return and B: C was recorded highest in T6 (Rs. 37,070 ha-1 and 2.09) and remained at par with T4 and T10. The yield and economics of treatments T10 , T6 and T4 were comparable. Hence the study revealed the possibility of three weed management options for sesame. Mechanical weeding with wheel hoe weeder at 15 and 30 DAS (T10) could be recommended as a non chemical weed management practice. Pre emergence pendimethalin 500 g ha-1 at 2 DAS fb wheel hoe weeding at 25 DAS (T6) could be recommended as an integrated weed management practice and pendimethalin 500 g ha-1 at 2 DAS fb post directed application of carfentrazone ethyl 20 g ha-1 at 25 DAS (T4) could be recommended as a chemical weed management practices for higher yield and return in sesame ER -