Weed management in finger millet (Eleusine coracana L. Gaertn) intercropped in coconut

Abstract

The study entitled “Weed management in finger millet (Eleusine coracana L. Gaertn) intercropped in coconut” was undertaken during 2020-2022 at College of Agriculture, Vellayani, Thiruvananthapuram, Kerala, with the objective to assess the cost-effective weed management practice for finger millet raised as intercrop in coconut. Field experiment was laid out at Coconut Research Station, Balaramapuram in Randomized Block Design with 12 treatments and three replications during Summer 2021 (6/01/2022 to 4/04/2022). The treatments adopted for the study were T1: PE pretilachlor + bensulfuron methyl 495 g ha-1 0 DAS fb WHW at 25 DAS, T2: PE pretilachlor + bensulfuron methyl 495 g.ha-1 0 DAS fb bispyribac.sodium 20 gpha-1 at 25 DAS, T3: PE pretilachlor + bensulfuron methyl 495 gpha-1 0 DAS fb penoxsulam+ cyhalofop butyl 125 g ha-1 at 25 DAS, T4: PE pyrazosulfuron ethyl 20 g ha-1 0 DAS fb WHW at 25 DAS, T5: PE pyrazosulfuron ethyl 20 gpha-1 0 DAS fb bispyribac sodium 20 g ha-1 at 25 DAS, T6: PE pyrazosulfuron ethyl 20 g ha-1 0 DAS fb penoxsulam+ cyhalofop butyl 125 g ha-1 at 25 DAS, T7: PE oxyfluorfen 50 g ha-1 0 DAS fb WHW at 25 DAS, T8: PE oxyfluorfen 50 gpha-1 0 DAS fb bispyribac.sodium 20 gpha-1 at 25.DAS, T9: PE oxyfluorfen 50 g ha-1 0 DAS fb penoxsulam+ cyhalofop-butyl 125 g ha-1 at 25 DAS, T10: WHW at 15 and 30 DAS, T11: HW at 15 and 30 DAS andT12: weedy check. The finger millet variety used for the study was PPR 2700 (Vakula). Weed management had significant effect on growth attributes, viz., plant height at.20, 40 and 60pDAS, leaves per plant at 20 DAS, tillers m-2 and DMP at 20, 40 and 60 DAS and at harvest. The treatment T11 resulted in taller plants at 20, 40 and 60 DAS. However, T4 noted the highest number of tillers m-2 at all stages of observation and the highest number of leaves per plant at 20 DAS. The treatment T10 recorded the highest DMP at 20 and 60 DAS, T6 at 40 DAS and at harvest T4 recorded the highest DMP per plant (27.50 g per plant). Weed management had significant impact on chlorophyll content at 20 and 60pDAS. At 20 DAS, T10 recorded the highest chlorophyll content and at 60 DAS, 156 T6 resulted in the highest chlorophyll content. Relative growth rate and CGR was found significant only at 20-40 DAS and 40-60 DAS. At 20-40 DAS, the highest RGR and CGR were observed in T6. However, at time interval 40-60 DAS, treatment T4 resulted in the highest RGR and T10 recorded the highest CGR. Leaf area index was found to be the highest in T10 at 20 DAS and T4 at 40 DAS. Yield parameters viz., productive tillers m-2 , fingers per ear head and ear head weight were significantly influenced by weed management and the treatment T4 resulted in higher productive tillers m-2 (93.3), fingers per ear head (13.3) and ear head weight (12.8 g). Weed management profoundly influenced the grain and straw yield and harvest index. The highest grain yield (2072 kg ha-1 ), straw yield (3670 kg ha-1 ) and harvest index (0.380) were noted in T4. Weed index was also found to be the lowest in T4 (0.0). The quality attributes, viz., protein and starch content of grain were significantly improved by weed management. The highest protein content was observed in T4 and the starch content in T6. Available N, P, K and organic carbon status of post-harvest soil and total N, P and K uptake by crop were markedly influenced by weed management. The highest soil available N was observed in T1, available P in T3 and T4 recorded the highest soil available K and organic carbon. The highest total N and K uptake were observed in T4 (65.87 and 67.03 kg ha-1 , respectively) and P uptake in T10 (25.22 kg ha-1 ). Weed management had significant impact on nutrient uptake by weeds. The treatment T8 at 20.DAS (0.43 kg ha-1 ), T11 at 40.DAS (0.23 kg ha-1 ) and T10 at 60 DAS (8.72kg ha-1 ) resulted in the lowest N uptake by weeds. The lowest P uptake by weeds was observed in T6 and T9 at 20.DAS (0.01 kg ha-1 ), T11 at 40.DAS (0.04 kg ha-1 ) and T4 at 60 DAS (0.02 kg ha-1 ). The treatment T9 recorded the lowest K uptake at 20 DAS, T11 at 40 DAS and T4 at 60 DAS. The highest dehydrogenase enzyme activity was reported in T4 at 20 DAS and T6 at 40 DAS. However, T6 resulted in the highest urease enzyme activity at 20 DAS and T4 at 40 DAS. 157 In comparison to weedy check, significant reduction in total weed density and weed dry weight were observed in weed management treatments. The lowest total weed density at 20, 40 and 60 DAS were observed in T7 (12.0 no.m-2 ), T1 (12.0 no. m-2 ) and T2 (8.0 no.m-2 ), respectively. However, the lowest weed dry weight was observed in T8 at 20 DAS (1.04 g m-2 ), T11 at 40 DAS (1.41 g m-2 ) and T4 at 60 DAS (32.40 g m-2 ). Weed control efficiency also followed the same trend of weed dry weight. Gross return ((Rs. 82, 888ha-1 ), net return (Rs. 40, 974 ha-1 ) and BCR (1.98) were found to be the highest in T4. Considering the dry matter production per plant, total chlorophyll content, CGR, RGR, total weed dry weight, WCE, yield attributes, grain yield, gross return, net return and BCR, the treatment T4 (PE pyrazosulfuron ethyl 20 g ha-1 on the day of sowing fb wheel hoe weeding at 25 DAS) could be recommended as the best weed management practice for higher yield and net return from finger millet intercropped in coconut garden.