Fishery and stock structure of Thunnus albacares (Bonnaterre, 1788) off Andhra waters along western Bay of Bengal

537-542The fishery and stock structure of Thunnus albacares off Andhra waters along western Bay of Bengal was studied from 2012 to 2015. The average annual landing of the species during the study period was 5,952 t contributing 32.9 % of the total tuna landings. Gill nets contributed 59 % of the catches, followed by hook and lines (34 %). Von Bertalanffy growth equation was Lt = 196.35 [1 – e–0.23 (t+0.0546)] and natural mortality, fishing mortality and total mortality was 0.4, 0.71 and 1.11 with exploitation ratio of 0.64 and exploitation rate of 0.43. Annual average stock, standing stock biomass and maximum sustainable yield were 13,879 t, 8,383 t and 4,653 t, respectively. Yield per recruit and biomass per recruit estimated were 2584.7 g and 3640.4 g. The exploitation rate, yield and yield per recruit indicate the stock of T. albacares to be overexploited. To sustainably and optimally harvest the species, reduction in the present fishing effort by 60 % is necessary, thereby increasing the yield by 35.31 %. With overcapacity in the number of gillnetters and hook and line units operating in the waters off Andhra Pradesh, implementation of the recommended fleet size proposed by Central Marine Fisheries Research Institute by means of buy-back measures and strict adherence to Minimum Legal Size at harvest would ensure sustainable and optimum exploitation of the resource

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A three-year study was carried out at six locations in three agro-ecologies representing the areas of irrigation water availability at critical stages during kharif maize (Zea mays L.) in North Western Plain Zone (NWPZ), North Eastern Plain Zone (NEPZ) and Peninsular Zone (PZ) for optimizing the nutrient requirement and realizing potential yield of the popular genotypes. The study included five popular genotypes/hybrids with three nutrient management practices of RDF, 50% RDF/Farmer Fertilizer Practices (FFP) and nutrient expert based site-specific nutrient management (NE-SSNM) in the split-plot design and replicated thrice. The grain yield of maize was significantly higher at four locations with NE-SSNM however; it was at par with RDF at two locations. The gross returns followed the same trend as of grain yield but the returns over fertilizer cost (ROFC) were significantly higher with NE-SSNM which indicates that the use of these nutrient management practices has the potential to rationalize the nutrient management practices in maize. Hence, it was concluded that the NE-SSNM could be an effective strategy for realizing the potential yield and enhancing net returns of maize production in NWPZ, NEPZ and PZNot Availabl

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Not AvailableA three-year study was carried out at six locations in three agro-ecologies representing the areas of irrigation water availability at critical stages during kharif maize (Zea mays L.) in North Western Plain Zone (NWPZ), North Eastern Plain Zone (NEPZ) and Peninsular Zone (PZ) for optimizing the nutrient requirement and realizing potential yield of the popular genotypes. The study included five popular genotypes/hybrids with three nutrient management practices of RDF, 50% RDF/Farmer Fertilizer Practices (FFP) and nutrient expert based site-specific nutrient management (NE-SSNM) in the split-plot design and replicated thrice. The grain yield of maize was significantly higher at four locations with NE-SSNM however; it was at par with RDF at two locations. The gross returns followed the same trend as of grain yield but the returns over fertilizer cost (ROFC) were significantly higher with NE-SSNM which indicates that the use of these nutrient management practices has the potential to rationalize the nutrient management practices in maize. Hence, it was concluded that the NE-SSNM could be an effective strategy for realizing the potential yield and enhancing net returns of maize production in NWPZ, NEPZ and PZ.Not Availabl

Sustainable intensification of climate-resilient maize–chickpea system in semi-arid tropics through assessing factor productivity

Abstract Global trends show that the rapid increase in maize production is associated more with the expansion of maize growing areas than with rapid increases in yield. This is possible through achieving possible higher productivity through maize production practices intensification to meet the sustainable production. Therefore, a field experiment on “Ecological intensification of climate-resilient maize–chickpea cropping system” was conducted during consecutive three years from 2017–2018 to 2019–2020 at Main Agricultural Research Station, Dharwad, Karnataka, India. Results of three years pooled data revealed that ecological intensification (EI) treatment which comprises of all best management practices resulted in higher grain yield (7560 kg/ha) and stover yield compared to farmers’ practice (FP) and all other treatments which were deficit in one or other crop management practices. Similarly, in the succeeding winter season, significantly higher chickpea yield (797 kg/ha) was recorded in EI. Further EI practice recorded significant amount of soil organic carbon, available nitrogen, phosphorus, potassium, zinc, and iron after completion of third cycle of experimentation (0.60%, 235.3 kg/ha,21.0 kg/ha,363.2 kg/ha,0.52 ppm and 5.2 ppm respectively). Soil enzymatic activity was also improved in EI practice over the years and improvement in each year was significant. Lower input energy use was in FP (17,855.2 MJ/ha). Whereas total output energy produced was the highest in EI practice (220,590 MJ ha−1) and lower output energy was recorded in EI–integrated nutrient management (INM) (149,255 MJ/ha). Lower energy productivity was noticed in EI-INM. Lower specific energy was recorded in FP and was followed by EI practice. Whereas higher specific energy was noticed is EI–INM. Each individual year and pooled data showed that EI practice recorded higher net return and benefit–cost ratio. The lower net returns were obtained in EI-integrated weed management (Rs. 51354.7/ha), EI-recommended irrigation management (Rs. 56,015.3/ha), integrated pest management (Rs. 59,569.7/ha) and farmers’ practice (Rs. 67,357.7/ha) which were on par with others

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Not AvailableMaize mostly cultivated in tropical conditions suffers from various biotic and abiotic stresses. Granted, while crop improvement has led to less disease and pest losses due to host plant resistance in maize hybrids, these factors still cause substantial yield losses of maize in India. In the event of incessant rains and unavailability of herbicides, farmers are not able to control weeds through pre-emergence herbicides and manual weeding. Such circumstances, compounded by escalating labor prices, demand effective post-emergence herbicide to manage weeds for sustainable and profitable maize production. To find effective post-emergence herbicides, field experiments were conducted at 20 locations in various agro-ecologies of India for three consecutive years (2015-2017). It was found that weeds caused 32.1 to 59.4% grain yield losses of hybrid maize in the kharif season in India. The losses from the weed in absence of weed management in hybrid maize were maximum in Central Western Zone (55.4 to 60.8%), followed by Northern Hill Zone (43.0 to 49.4%), North Western Plain Zone (44.1 to 49.1%), North Eastern Plain Zone (36.4 to 48.8%); and least in Peninsular zone (26.9 to 40.3%). These losses indicate that the rainfed ecosystem has the maximum yield reduction in kharif maize in central and northern India. The application of Atrazine (1.5kg a.i./ha) as pre-emergence followed by Tembotrione (120ml a.i./ha) at 25 DAS as post-emergence gave the best weed control and higher yield as well as net returns compared to the other pre- and post-emergence herbicide-based management practices at most of the locations. The study suggests that the Tembotrione at 120 ml a.i./ha at 25 DAS could be a better option for weed management in maize in India and similar agro-ecologies.Not Availabl