Weed-Free Durations and Fertilization Regimes Boost Nutrient Uptake and Paddy Yield of Direct-Seeded Fine Rice (Oryza sativa L.)

Under the changing climate, fertilization regimes and weed infestation management in aromatic direct-seeded fine rice (DSR) remain vital for curbing environmental hazards and ensuring food security. A multi-year field study was undertaken to appraise the influence of fertilization techniques and weed-free periods on weed dynamics, nutrient uptake and paddy yield in a semi-arid environment. Treatments included two fertilization methods (broadcasting and side placement) and five weed-free durations (20, 30, 40, 50 post-seeding days, DAS) along with a weed-free crop for a whole season. Weed competition for a season-long crop (weedy check) was maintained for each fertilizer application method. Our results revealed that the side placement of fertilizers resulted in a significantly lower weed density and biomass, even under season-long weed competition. The highest paddy yield was recorded for a crop without weeds, while weed-free duration of up to 50 DAS followed it. The uptake of nitrogen (N), phosphorus (P) and potassium (K) for a weed-free duration of up to 50 DAS were only 19%, 9% and 8%, respectively, as compared to the weedy check. The uptake of N, P and K by weeds in the broadcast method was 18%, 30% and 24% higher, compared to side-placed fertilizers. The period of 20–50 DAS remained critical in DSR as far as weed control was concerned. Thus, the side placement of fertilizers and controlling weeds for up to 50 days after rice sowing can be recommended for general adoption in semi-arid agro-ecological conditions.

Effect of Crop Establishment Methods and Weed Management Practices on Weed Density and Productivity of Basmati Rice (Oryza sativa L.)

Aim: Present experiment was conducted to study the effect of crop establishment methods and weed management options on weed dynamics and performance of Basmati rice. Study Design: Split plot design. Place and Duration of Study: Iinvestigation was conducted during the kharif-season of 2019 and 2020 at Crop Research Center, S.V.P.University of Agriculture &Technology, Meerut (U.P.), India. Methodology: Mainfactors consist of the crop establishment methodsviz.(1) Conventional Puddled Transplanting, (2) Unpuddled Flat and (3) Furrow Irrigated Raised Beds, the sub factors consist of five weed management options viz., (1) Pretilachlor @ 0.75 Kg ha-1 PE fb Bispyribac sodium @ 20 g a.i. ha-1 POE at 20 DAT, (2) Almix 4 g a.i. ha-1 + Bispyribac sodium @ 20 g a.i. ha-1 POE at 20 DAT, (3) Bispyribac sodium @ 25 g a.i. ha-1 POE at 20 DAT, (4) Two hand weedings and (5) Weedy check. Results: Minimum total weed density was recorded under CPT (E1) followed by FIRB(E3) while itwas maximum under UPF(E2). Two hand-weedings effectively reduced total weed density. In herbicides, application of pretilachlor @ 0.75 Kg ha-1fb Bispyribac sodium @ 20 g a.i. ha-1 (W1) was found most effective in reducingtotal weed density.Higher yield and yield attributes were found under CPT which was significantly higher than the UPF and at par with FIRB. Amongweed management practices highest yield and yield attributes were obtained with pretilachlor @ 0.75 Kg ha-1fb Bispyribac sodium @ 20 g a.i. ha-1.Lowest yield and yield attributes were obtained in weedy check. Conclusion: Puddled transplantation in rice might be the best option to get higher yield and for weed control, application of Pretilachlor @ 0.75 Kg ha-1 PE fb Bispyribac sodium @ 20 g a.i. ha-1 POE at 20 DAT may be done to get higher yield.

Effects of Narrow-Windrow Burning on Weed Dynamics in Soybean in Louisiana

The soil seedbank allows for long-term persistence of weed species in agricultural fields. Some weed species can persist in the soil seedbank for extended periods. Restricting inputs into the weed seedbank has a large impact on future population density and influences management practices of these weeds in soybean production systems. Harvest weed seed control (HWSC) tactics incorporate mechanical and cultural management strategies to target weed seeds present at harvest. A 3-year trial was initiated to determine if continual use of the HWSC method, narrow windrow burning, selects for earlier seed set and shattering in Louisiana soybean. No shifts in weed populations or shattering time were observed. However, there was a significant reduction in weed density and the weed seed present in the soil seedbank when HWSC and robust herbicide programs were used in combination. Therefore, utilizing multiple effective weed management strategies is imperative in reducing the soil seedbank.

Efficacy of Pre and Post Emergence Application of Imazethapyr and its Ready Mix Herbicides on Growth, Weed Dynamics and Productivity of Chickpea (Cicer arietinum L.)

Background: Weeds are major constraints in chickpea production. This crop is highly susceptible to weed competition owing to slow initial growth thus weeds cause up to 75% yield loss. Methods: Treatments comprised of imazethapyr 50 g/ha as PE (pre emergence), imazethapyr 70 g/ha as PE, imazethapyr 50 g/ha as PoE (post emergence), imazethapyr 70g/ha as PoE, imazethapyr + imazamox ready mix (RM) 50 g/ha as PE, imazethapyr + imazamox (RM) 70 g/ha as PE, imazethapyr + imazamox (RM) 50 g/ha as PoE, imazethapyr + imazamox (RM)70 g/ha as PoE, pendimethalin 1 kg/ha PE, imazethapyr + pendimethalin (RM) 1 kg/ha PE, hoeing at 20 and 40 DAS and weedy check. Result: Application of imazethapyr + pendimethalin (RM) 1 kg/ha as pre emergence recorded maximum plant dry matter accumulation at 60, 90, 120 DAS and at maturity stage and also higher CGR at 60-90, 90-120 and120 DAS - maturity of crop. Application of imazethapyr + pendimethalin (RM) 1 kg/ha as pre emergence was most effective in producing higher seed yield (1749 kg/ha), weed control efficiency (87.28%), net return (` 77,136), reduced weed management index 5.15 and 3.90 at 30 and 60 DAS respectively.

Influence of Pre and Post Emergence Herbicides on Weed Dynamics, WCE and Yield of Pigeon Pea under Rainfed Conditions

A field experiment was conducted at ICAR-KVK, Kalaburgi, during Kharif seasons of 2018-19 and 2019-20 to adjudge the efficacy of pre and post emergence herbicides against diverse weed flora in pigeonpea ecosystem. The experiment was laid out in RCBD with 11 treatments comprising of different pre-emergent herbicides viz., Pendimethalin, Pendimethalin 30 EC + Imazethapyr 2 EC and post-emergence premix product herbicides such as Imazamox 35 WG + Imazethapyr 35 WG, Propaquizafop 2.5% + Imazethapyr 3.75%w/w ME and their different dosages with cultural methods were compared with weed free check and weedy check treatments. Among the different pre and post emeregent herbicides tested against different weed flora, post emergent application of Propaquizafop 2.5% + Imazethapyr 3.75% w/w ME @ 2000 ml ha-1 at 20-25 days recorded significantly lower weed density, weed dry weight, highest weed control efficiency (91.36%) and lowest weed index (8.78%) and higher grain yield (1209 kg ha-1 ), net returns (` 43,036 ha-1) and benefit cost ratio (2.35) followed by Propaquizafop 2.5% + Imazethapyr 3.75% w/w ME @ 1500 ml ha-1 at 20-25 DAS, Imazamox 35 WG + Imazethapyr 35 WG at 100 g ha-1 at 20-25 DAS and HW at 20 and IC 40 and 60 DAS.

Effect of Barley Sowing Density on the Integrated Weed Management of Lolium rigidum (Annual Ryegrass) in Mediterranean Dryland: A Modeling Approach

Population models are particularly helpful for understanding long-term changes in the weed dynamics associated with integrated weed management (IWM) strategies. IWM practices for controlling L. rigidum are of high importance, mainly due to its widespread resistance that precludes chemical control as a single management method. The objective of this contribution is to simulate different IWM scenarios with special emphasis on the impact of different levels of barley sowing densities on L. rigidum control. To this effect, a weed–crop population model for both L. rigidum and barley life cycles was developed. Our results point out: (i) the necessity of achieving high control efficiencies (>99%), (ii) that the increase of twice the standard sowing density of barley resulted in a reduction of 23.7% of the weed density, (iii) non-herbicide-based individual methods, such as delayed sowing and weed seed removal at harvest, proved to be inefficient for reducing drastically weed population, (iv) the implementation of at least three control tactics (seed removal, delay sowing and herbicides) is required for weed infestation eradication independently of the sowing rate, and (v) the effect of an increase in the sowing density is diluted as a more demanding weed control is reached. Future research should aim to disentangle the effect of different weed resistance levels on L. rigidum population dynamics and the required efficiencies for more sustainable IWM programs.