Weed Management under Phosphorus Enrichment in Groundnut (Arachis hypogaea L.)

Background: Weeds infestation is one of the major threats to crop production and leads to severe crop-weed competition which finally reduce the crop productivity in term of quality and quantity. To enhance crop productivity therefore efficacy of various pre and post-emergence herbicides were evaluated on the basis of Amaranthus viridis, Commelina benghalensis and Cynodon dactylon population reduction, nutrient concentration and their uptake by groundnut. Methods: The present investigation was conducted consecutively for two kharif seasons of 2016 and 2017, at Instructional Farm, CTAE, MPUAT, Udaipur with six weed management practices and four phosphorus levels thus, 30 treatment combinations; all were evaluated in split-plot design with three replications. Result: The experimental results revealed that all herbicidal treatments as well as weed free recorded significantly lowest weed density as well as highest weed control efficiency, nitrogen, phosphorus and potassium concentration and also their uptake by groundnut as compared to weedy check except quizalofop-ethyl at 30 DAS in respect to control Cynodon dactylon. Further, pod yield response to phosphorus was found quadratic. The results also showed that phosphorus exhibit significantly increase nutrients concentration and their uptake by groundnut over control during the experimentation.

Impact of integrated weed management on growth, yield and economics of onion (Allium cepa L.)

An experiment was conducted in the Rabi season of two consecutive years of 2019-20 and 2020-21, respectively to determine find out practically convenient and economic weed control measure for the onion growers. Treatments comprised T1 Farmers’ practice (pendimethalin 30% EC 1 kg ai/ha before transplanting+ 1HW at 25 DAT) and T2 (oxyflurofen 23.5% EC @ 0.10 kg ai/ha + quizalofop ethyl 5% EC @ 0.05 kg ai/ha at 25 DAT + 1 HW at 45 DAT) replicated at ten farmers’ field. Treatment T2 (oxyflurofen 23.5% EC @ 0.10 kg ai/ha + quizalofop ethyl 5% EC @ 0.05 kg ai/ha at 25 DAT + 1 HW at 45 DAT) recorded significantly lowest weed density (32.59/m2), highest plant height (52.50 cm), neck thickness (1.12 cm),bulb diameter (6.38 cm), bulb weight (92.57 g) and bulb yield (304.85 q/ha) as compared to treatment T1. The highest net returns (Rs 2,04,391/ha) and B:C (3.04) were obtained with T2.

Effect of Seasonal Variation on the Persistence and Dissipation Behaviour of the Herbicide Mixture of Fomesafen + Quizalofop-Ethyl in Tropical Soybean Agroecosystem and Safety Risk Assessment

Weeds are the major limiting factor for optimum soybean production in India. The herbicide mixture of fomesafen and quizalofop-ethyl provides effective control of a broad spectrum of weeds, but its fate in the tropical soybean ecosystem is unknown and also the risks involved to the consumer and the environment are still unexplored. Hence, a supervised field trial was conducted following the post-emergence application of fomesafen 12% + quizalofop-ethyl 3% in two consecutive seasons. The dissipation of fomesafen followed biphasic double first order in parallel kinetics, whereas quizalofop-ethyl dissipation followed first order kinetics. A significant difference in the persistence of fomesafen was observed due to seasonal variation of meteorological parameters. However, the variation was significant only in plant, but non-significant in soil, in case of quizalofop-ethyl. The overall shorter persistence of both fomesafen and quizalofop-ethyl was recorded in warmer climatic conditions of Season I than Season II. The results thus indicated that care must be taken during application of this herbicide mixture in cold climatic regions, since both the herbicides may exhibit higher stability. The absence of end-point residues at harvest concluded that the formulation is safe for application in tropical agroclimate. The low chronic dietary toxicity and low soil ecological toxicity indicated that the herbicide mixture will offer no threat against consumer health and soil ecosystem. However, there was a concern about the toxicity against soil algal population which needs to be reconfirmed by further studies.

Synthesizing Nanoencapsulated Sulfentrazone Herbicide and Optimizing Time and Dose for Season Long Weed Management in Irrigated Blackgram (Vigna mungo L.)

Background: Pulses are nutritious edible seeds of leguminous plants, have become an essential part of the human diet. Among the pulses, blackgram (Vigna mungo L.) is an important legume crop cultivated in tropical and subtropical regions of the world. Even though there are so many factors responsible for the lower yield of blackgram, weeds play a major role. Sulfentrazone is a broad spectrum herbicide belongs to the family of phenyl triazolinone. Sulfentrazone has high persistence and mobility with mean partition coefficient Koc = 43 and sorption coefficient Kd less than 1 and also has high horizontal and vertical leaching potential. Even though generally used herbicides in blackgram like pendimethalin, imazethapyr and quizalofop-ethyl are helpful in managing weeds, they have to apply multiple times or have to integrate with other methods of weed management which is expensive. So as to reduce the usage of multiple herbicides, to avoid manual weeding and to achieve season long weed control without affecting the environment the nano-encapsulated sulfentrazone is the better alternative and it gives better solution for the above constraints besides increasing the productivity.Methods: Laboratory and field experiments were conducted in the Department of Agronomy, Tamil Nadu Agricultural University, Coimbatore during 2019-2020. Laboratory experiment was conducted to prepare nano-encapsulated sulfentrazone herbicide using solvent evaporation method. Screening trial was conducted in field with 17 treatments in randomized block design. Main trial was conducted with nine treatments of randomized block design by selecting the best performing treatments in screening trial. A confirmatory trial was also conducted by using same treatments.Result: The encapsulated sulfentrazone particles were characterized in SEM (Scanning electron microscope) and also analysed with EDAX (Energy dispersive X-ray analysis) for elemental analysis, which is followed by particle size analysis and zeta potential to know the size and stability respectively. All these tests concluded that the sulfentrazone particles were encapsulated correctly and might be useful for slow release of the particle and also for reducing vertical and horizontal leachability. The field trials revealed that sulfentrazone @ 0.30 kg a.i. ha-1 with encapsulation applied at 1 DBS is better alternative for the season long weed management in blackgram without affecting the soil and ground water, as well as increasing the productivity.

Effect of Chemical Herbicides on Weed Management in Allium sativum L. (Garlic) and Its Yield

A field experiment was conducted during 2015-16, 2016-17 and 2017-18 at Agricultural Research Station, Hanumanamatti, Ranebennur (Tq), Haveri (Dist.) Karnataka, to study the effect of chemical herbicides on weed management in garlic. The treatments consisted of pre emergent application of Pendimethalin, Oxyfluorfen, Quizalofop ethyl and Butachlor. The pooled mean results indicated that, pre-emergent application of Butachlor 50 EC @ 1.0 kg ai/ha + one hand weeding + second spray at 30 days after planting (B1HW2S:T7) recorded the least weed density (82.83, 89.67 monocot weeds and 8.15, 6.34 dicot weeds), weed bio-mass (80.99g, 93.33g fresh weight of monocot weeds and 8.48g, 1.82g fresh weight of dicot weeds, 32.40g, 37.33g dry weight of monocot weeds and 3.39g, 0.73g dry weight of dicot weeds), the highest garlic plant height (4.34cm, 16.17 cm), number of leaves (3.55, 6.57) at 30 and 60 days after planting respectively. Treatment with Butachlor 50 EC @ 1.0 kg ai/ha + one hand weeding + second spray at 30 days after planting (B1HW2S:T7) also recorded the highest hundred bulb weight (912.98 g), yield per plot (2056.63g) and yield/ha (41.13 Q) followed by Oxyflurofen 23.5 EC @ 0.15 kg ai /ha + one hand weeding + second spray at 30 Days after planting (O1HW2S:T4) compared to farmer’s practice (2HW:T8) and untreated control (WC:T9).

Influence of Pre-Emergence Weedicides on Turmeric (Curcuma longa L.) Growth and Yield

A field experiment was conducted during 2015-16, 2016-17 and 2017-18 at Agricultural Research Station, Hanumanamatti to study the effect of chemical herbicides on weed management in turmeric. The treatments consisted of pre emergent application of Alachlor, Butachlor, Pedimethalin, Atrazine and Quizalofop ethyl. The pooled mean results indicated that, pre-emergent application of Alachlor @ 1.50 kg ai / ha + one interculture + one hand weeding (A1IC1HW) recorded the least weed density (13.67, 68.11 monocot weeds and 2.67,12.36 dicot weeds), weed bio-mass (32.33 g, 43.67 g fresh weight of monocot weeds and 5.68 g, 26.05 g fresh weight of dicot weeds, 17.50g, 7.68g dry weight of monocot weeds and 2.34 g, 10.69 g dry weight of dicot weeds), the highest turmeric plant height (11.35 cm, 32.49 cm), number of leaves (4.92, 8.39), leaf length (5.08 cm, 18.91cm), leaf breadth (2.21 cm, 7.25 cm) and number of tillers per plant (1.01, 4.34) at 30 and 60 days after planting respectively. The treatment with Alachlor @ 1.50 kg ai / ha + one interculture + one hand weeding (A1IC1HW) also recorded the highest yield per plot (65.03 kg), rhizome yield/ha (43.36 tonnes) and processed rhizome yield (8.67 t/ha) followed by Pendimethalin @ 1.00 kg ai/ha + one interculture + one hand weeding (P1IC1HW) compared to farmer’s practice (2HW1IC) and unweeded control (WC).

Yield Analysis of Chickpea (Cicer arietinum) with Mustard (Brassaca juncea) Intercropping System as Influenced by Weed Management Practices

Background: Intercropping is the more profitable cropping system in Agriculture for marginal hold farmers. In this system risk cover in abiotic stress and farmers have gain one crop mostly who are using herbicide to control weeds. Crops raise fast and with controlled weeds. Scientific approach of intercropping increases the productivity per unit area and per unit time under a situation where two crops are grown in a certain row proportion. The selection of compatible crops is one of the important considerations, in deciding economically viable and feasible intercropping system. Chickpea with mustard is a prominent intercropping system in Indian subcontinent. The majority of the farmers adopt this system under recourse constraint conditions. Since Chickpea is a poor competitor for weeds because of its slow growth and limited leaf area development at early stages of crops growth and establishment.Methods: An experiment was conducted at College of Agriculture Farm Gwalior during Rabi season of 2011-12 and 2012-13. The experiment was laid out in Split-Plot Design with three replications. Eighteen treatment combinations comprising three intercropping systems, viz, chickpea (sole), mustard (sole) and chickpea with mustard were taken as main plot treatments and six weed management practices viz, weedy-check, weed free, fluchloralin@ 1.0kg/ha pre-plant incorporation (PPI), pendimethalin @ 1 kg/ha as pre-emergene, (PE), Isoproturon 0.75 kg/ha as post emergence (POE) and quizalofop -ethyl @50 ml/ha (PoE) as sub plot treatments. The recommended dose of fertilizer in chickpea 18 kg/ha of nitrogen and 46 kg/ha of P2O5 were applied with equal distribution to both the crops through 100 kg /ha diammonium phosphate as basal application at the time of sowing in rows below the seed. A seed rate of 70 kg and 5 kg/ha for chickpea and mustard was used in their sole crops respectively. Result: Chickpea with mustard intercropping system proved to be the most promising system which obtained more net returns and benefit: cost ratio. So for realizing higher net returns and benefit: cost ratio, chickpea with mustard may be recommended to farmers who are interested in taking both the crops instead of their pure stands as it proved to be economically better and feasible in generating more monetary benefits by spending fewer amounts for their better lively hood security as well as land use efficiency.