Weed management in rainfed pearl millet [ Pennisetum glaucum (L.) R. Br. emend Stuntz] under conservation agriculture

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Date
2020
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DIVISION OF AGRONOMY ICAR-INDIAN AGRICULTURAL RESEARCH INSTITUTE NEW DELHI
Abstract
A field study entitled “weed management in rainfed pearl millet (Pennisetum glaucum (L.) R. Br. emend Stuntz) under conservation agriculture” was conducted at the research farm of ICAR-Indian Agricultural Research Institute, New Delhi during rainy season of 2019. The experimental site is situated at 280 40’N latitude and 770 12’E longitude at an elevation of 228.6 m above mean sea-level, which is characterized by semi-arid climate. The soil of the experimental site was sandy loam in texture (sand 63.1%, silt 19.7% and clay 17.2%) with pH 7.79 in the top 15 cm of soil. The soil was low in available nitrogen (152 kg ha-1 ), organic carbon (0.38%), medium in available phosphorus (12.26 kg ha-1 ) and potassium (245 kg ha-1 ). The experiment was laid out in a split plot design with three replications keeping three tillage practices (conventional tillage, zero tillage, zero tillage + residue 3t ha-1 ) in main plots and seven weed management treatments [Weedy check, hand weeding at 30 and 50 DAS, atrazine 0.75 kg ha-1 (PE) + 2,4-D 0.75 kg ha-1 (PoE), atrazine 0.75 kg ha-1 (PE), atrazine 0.75 kg ha-1 (PE) + tembotrione 0.05 kg ha-1 (PoE), atrazine 0.75 kg ha-1 (PE) + tembotrione 0.075 kg ha-1 (PoE) and atrazine 0.75 kg ha-1 (PE) + tembotrione 0.10 kg ha-1 (PoE)] in sub plots. Pearl millet cv. ‘Pusa composite 443’ was planted in rows, 45 cm apart using 5 kg seed ha-1 on 16 thJuly and harvested on 3 rd October, 2019. Data on weed species showed that experimental pearl millet crop was infested with 6 species of grasses, 2 of sedges and 5 of broad-leaved weeds species in weedy check plots. Results of the study indicated that different tillage and weed management practices significantly influenced weed density, dry weight of weeds and weed control efficiency recorded at 30, 60 DAS and at harvest. The lowest weed density, dry weight of weeds as well as highest weed control efficiency was recorded with Zero tillage + residue 3 t ha-1 , which were significantly better than zero tillage and conventional tillage. This treatment also registered the lowest N, P and K removal by weeds and enabled the crop to take up the maximum N, P and K. In addition, zero tillage+ residue 3t ha-1 lowered 1.30 and 2.310C temperature at 8 AM and 2 PM, respectively compared to conventional tillage. Results also revealed that zero tillage + residue 3 t ha-1 caused minimum consumptive use of water and moisture use rate, thereby maximum water use efficiency (6.54 kg ha-mm-1 ). However, zero tillage proved to be significantly superior to zero tillage + residue 3 t ha-1 to maximize net energy, energy productivity and energy efficiency. Significantly highest growth and yield attributing parameters, grain yield (2.40 t ha-1 ), stover yield (7.90 t ha-1 ) and biological yield (10.3 t ha-1 ) were recorded with zero tillage + residue 3 t ha-1 . The yield advantage of 9.17 and 13.3 per cent was registered with zero tillage + residue 3 t ha-1 over zero tillage and conventional tillage, respectively. The maximum net return (₹23847 ha-1 ) and net B:C ratio (0.86) were fetched by zero tillage + residue 3 t ha-1 . It gave ₹ 523 and ₹ 3568 ha-1 higher net return than that of zero and conventional tillage, respectively. Results further revealed that all the weed management practice led to significant reduction in density and dry matter of weeds compared to weedy check. At 30 DAS, pre-emergence application of atrazine resulted in lowest weed density and dry weight of weeds with higher weed control efficiency. Data recorded at 60 DAS and at harvest showed that two hand weeding at 30 and 50 DAS recorded significantly lowest weed density, dry weight of weeds coupled with highest weed control efficiency, but remained at par with those of atrazine 0.75 kg ha-1 (PE) fb 2,4-D 0.75 kg ha-1 (PoE), atrazine 0.75 kg ha-1 (PE) fb tembotrione 0.10 kg ha-1 (PoE), atrazine 0.75 kg ha-1 (PE) fb tembotrione 0.075 kg ha-1 (PoE) and atrazine 0.75 kg ha-1 (PE) fb tembotrione 0.05 kg ha-1 (PoE). However, phytotoxicity effect was observed by slight stunting at 45 DAS due to atrazine 0.75 kg ha-1 (PE) fb tembotrione 0.10 kg ha-1 (PoE). Significantly maximum depletion of N, P and K by weeds was registered under weedy check, whereas nutrient depletion was recorded minimum with two hand weeding. Significantly higher N, P and K uptake by the grain and stover, and available N,P and K, and SOC in soil were noted with two hand weeding at 30 and 50 DAS followed by atrazine 0.75 kg ha-1 (PE) fb 2,4-D 0.75 kg ha-1 (POE). Soil temperature and consumptive use of water did not differ significantly due to different weed management treatments. Net energy (111046 MJ ha-1 ), energy productivity (0.21 kg MJ-1 ) and energy use efficiency (11.9 %) was recorded highest under atrazine 0.75kg ha-1 (PE) fb tembotrione 0.05 kg ha-1 (PoE) followed by atrazine 0.75 kg ha-1 (PE) fb 2,4-D 0.75 kg ha-1 (POE). Two hand weeding at 30 and 50 DAS resulted significant improvement in most of the growth and yield attributing characters and produced significantly maximum grain (2.53 t ha-1 ), stover (8.13 t ha-1 ) and biological yield (10.66 t ha-1 ) with 34.8 per cent more grain yield than control. Pre-emergence application of atrazine 0.75 kg ha-1 (PE) fb 2,4-D 0.75 kg ha-1 (POE) was registered to be next best treatment for producing higher grain, stover and biological yield. Highest Cost of cultivation (₹ 34134 ha-1 ) and gross return (₹ 57386 ha-1 ) was recorded with two hand weeding at 30 and 50 DAS. Application of atrazine 0.75 kg ha-1 (PE) fb 2,4- D 0.75 kg ha-1 (PoE) recorded significantly highest net return (₹ 29201 ha-1 ) and net B:C ratio (1.08). However, it has been concluded that growing of pearl millet in zero tillage+ residue 3 t ha-1 along with application of atrazine 0.75 kg ha-1 (PE) fb 2, 4-D 0.75 kg ha-1 (PoE) found effective for controlling weeds and achieving economically higher grain yield under rainfed condition of semi arid tropics.
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