Weed Dynamics Research Articles

Crop establishment methods and herbicide mixtures induced weed dynamics, productivity, and profitability of summer rice

Rice farmers face challenges in achieving higher yield and profit during the summer season due to improper establishment and weed control. To address this, a study was conducted to assess the effects of herbicide combinations on the growth and yield of CR Dhan 206 (Gopinath), a high-yielding rice variety. The research took place from January to May 2022 at the PG Research Farm of M. S. Swaminathan School of Agriculture, Centurion University of Technology and Management, Paralakhemundi, Odisha. The experiment followed a split plot design with two main plots (transplanted rice and wet seeded rice) and five subplots (fenoxaprop-p-ethyl + ethoxysulfuron (Tank mix) @ (50+15) g ha-1 at 18 days after transplanting/sowing (DAT/S); triafamone + ethoxysulfuron (Ready mix) @ (45+22.5) g ha-1 at 12 DAT/S; pretilachlor + bensulfuron-methyl (Ready mix) @ (600+60) g ha-1 at 4 DAT/S; weed-free (Hand weeding at 20,40,60 DAT/S); and weedy check) replicated thrice. The dominant weeds observed were Echinochloa colona, Leptochloa chinensis, Cyanotis auxiliaris, Physalis minima, Ludwigia parviflora, Cyperus iria, and Fimbristylis miliacea. Results indicated that the establishment methods did not significantly affect crop growth, yield attributes, crop yield, and weed infestation. However, the application of triafamone + ethoxysulfuron in both transplanted and wet seeded rice demonstrated superior growth, yield, weed control, and comparable results to the weed-free check. The combination of wet seeded rice and triafamone + ethoxysulfuron showed the highest net return and benefit-cost ratio, suggesting its recommendation for effective weed control and profitability in rice farming in summer season.

Assessment of weed dynamics under different sowing dates and weed management practices on the irrigated field pea (Pisum sativum L.)

Assessment of weed dynamics under different sowing dates and weed management practices on the irrigated field pea (Pisum sativum L.)

Influence of Weed Management Practices and Biochar on Weed Dynamics of Fenugreek (Trigonella foenumgraecum L.)

A field experiment was conducted at Instructional farm, Rajasthan College of Agriculture, MPUAT, Udaipur (Rajasthan) during rabi season 2021-22 and 2022-23 to study the influence of weed management practices and biochar on weed dynamics of fenugreek. The experiment consists of eight weed management treatments and three biochar levels thereby involving 24 treatment combinations replicated thrice in factorial randomized block design. The pooled results revealed that pre-emergence application of oxyfluorfen 120 g ha-1 recorded significantly lowest density and dry matter of narrow-leaved, broad-leaved and total weeds and highest weed control efficiency (78.28%).

Weed communities after decades of mineral fertilization and tillage treatments in a corn–soybean rotation

Abstract Soil fertility and disturbance can potentially modify weed dynamics in a corn–soybean rotation. Knowing how added mineral fertilizers and tillage influence weed populations in the long term can provide insight into weed community shifts, which may affect future weed management requirements. The first objective of this study was to evaluate the effect of 24 to 25 years of nitrogen and phosphorus fertilization treatments and tillage (moldboard vs. no-till) on weeds (density, biomass, and composition) before and after herbicide applications in 2016/corn and 2017/soybean. The second objective was to evaluate the effect of the same treatments 6 yr after no postemergence weed management in 2022/corn. Since the last evaluation performed in 2004, weed density, richness, and diversity increased, and more annual grasses were observed under both tillage regimes. No fertilization effect was observed on any weed variables, including composition, except for increased biomass when left to grow all season after crop planting. In managed plots, the density and biomass of annuals and perennials were generally higher in no-till, and discrepancies were highest for annual grass densities before herbicide application. Weed species richness and diversity based on counts were equivalent between tillage regimes, but total biomass was distributed between more species in no-till. Higher weed densities and concurrent weed biomass, observed in no-till, reduced crop yields in 2016/soybean only. The combination of low crop diversity and low use of residual herbicides during the trial potentially led to the observed species shifts and increased weed density.

Evaluation of weed management approaches on weed dynamics, yield and economics of puddled rice under different plant techniques

A field experiment was conducted in January to May, 2022 (Navarai) to find out the effective weed management practices in puddled rice. The experiment was carried out in a split-plot design, which included two planting techniques viz., drum seeded rice and system of rice intensification (SRI) in main plot, as well as eight weed management practices viz., hand weeding, cono weeding, pretilachlor, bispyribac sodium and fenoxaprop - p - ethyl as pre and post emergence application in sub plot. The results of the experiment demonstrated that among the planting techniques and weed management practices tested, the system of rice intensification and sequential application of pretilachlor @ 0.5 kg a.i ha-1 fb bispyribac sodium @ 20 g a.i ha-1 has revealed lowest weed density (39.67, 71.25 and 17.02, 33.97 no m-2) and highest weed control efficiency (55.89, 65.78 and 84.99, 82.33 %) grain yield (4.55 and 5.47 t ha-1), gross and net income (Rs. 12116 and Rs. 64336 ha-1). However, drum seeded rice resulted higher return-1 rupee invested due to lower cost of cultivation. Hence, the SRI planting method with sequential application of pretilachlor @ 0.5 kg a.i ha-1 followed by bispyribac sodium @ 20 g a.i ha-1 has proven to be effective in controlling weeds and achieving higher grain yield and net income.

Effect of fire on weed dynamics and behavior of pre-emergent herbicides in Eucalyptus spp. plantations

The forest fires that occurred during summer 2021-22 in Uruguay generated concern in several areas, including silvicultural systems. The fire could generate changes at the flora level by changes in the dormancy of soil bank seeds, and in the behavior of frequently used pre-emergent herbicides due to inactivation by ashes. These possible changes impose a challenge in connection to weed control. In this study, an attempt was made to provide an answer to the problem by evaluating the dynamics of weeds and the behavior of pre-emergent herbicides in post-fire Eucalyptus plantations. The evaluations were carried out in two sites previously burned —one of them previously harvested and the other one not, being able to obtain data in different conditions. The weed dynamics was evaluated through the observational study of the percentage of total weed cover and present species were identified. With the data obtained, the parameters frequency, diversity and richness were calculated to analyze the different properties separately. Pre-emergent herbicides were evaluated in a randomized block experimental design: S-metolachlor, flumioxazin + S-metolachlor , isoxaflutole + S-metolachlor, oxifluorfen + S-metolachlor . Proposed treatments were assessed for possible interactions with fire and removal of the first cm of soil and ashes. Weed density was evaluated by characterizing and quantifying how many weeds could emerge in a square 30cm×30cm. While one of the fields was evaluated 8, 23, 31, 41, 61, and 82 days post application (DPA), the other was evaluated 8, 20, 31, 41, and 61 DPA. On both experiments the fire showed an increase in the weeds. In one experiment the weeding percentage increment was 64.9% on the burned area, while on the other it was 54.3 %. In addition, in the non-harvested field there were no large amounts of weeds on both treatments due to the conditions that standing trees generated. The results of weed control did not show interaction between efficiency and ashes presence, and were related to the species present in the weed bank, not showing a clear trend among the herbicide treatments. The S-metolachlor treatment was always the highest in number of weeds. The number of weed|m2 was about 17-25 on the harvested field, and 3-4 weed|m2 on the non-harvested one. The fire generated changes in the expression at seed bank of soil. This study was an important development in the generation of knowledge for future production.

Effects nursery media on Irvingia gabonensis and Dacryodes edulis seedlings and weed dynamics of the media

A field experiment was conducted to assess the effect of different nursery media on performances of Bush mango (Irvingia gabonensis) and African pear (Dacryodes edulis) seedlings. Five nursery media were formulated from topsoil, poultry manure and river sand in the following ratios; 0:3:3, 1:2:3, 1:3:2, 2:3:1 and 3:2:1. The media formulated were analyzed for the physico-chemical properties and seeds of the test crops were sown in each filled polythene bags with the formulated media. The experiment was arranged in a completely randomized design (CRD). The results obtained show significant (P≤0.05) media effects on days to first and 50% seedling emergence and percentage total emergence in Bush mango but non-significant in African pear. Number of days to last seedling emergence was significantly (P≤0.05) influenced by media in African pear leaf number and plant height for 10 weeks were responsive to differences in media in both crops. Media influenced total dry weight only in Bush mango while dry matter distribution pattern varied significantly in African pear. In both crops, percentage total seedling emergence and seedling vigour were better in medium 1:2:3. Therefore, from the results, the differential influence of media on seedling growth as evidence in the study suggested the need for broader evaluation of media for different tropical tree species to identify the most appropriate medium for each species that will ensure better vigorous seedling production for plantation and/or orchard establishment. Also, the results showed significant variation in weed flora composition, comprised of 35 species made up of 14 families. The families of Asteraceae, Gramineae, Amaranthaceae and Acanthaceae were predominant. Annual weed species and broadleaf were predominant.

Tillage and Crop Residue Management on Weed Dynamics and Productivity of Direct Seeded Rice

A field experiment was conducted during 2019 and 2020 to evaluate the effect of tillage and residue management on weed dynamics and productivity of direct seeded rice with four tillage systems; Conventional tillage in rice and wheat, Zero tillage in rice and wheat and two rotational tillage sequences that alternated between Conventional tillage and Zero tillage whereas four residue management practices; residue applied in both season, residue applied in kharif season only, residue applied in rabi season only and without residue in both season. The experiment was carried out at research farm of Birsa Agricultural University, Ranchi, Jharkhand. Results revealed that in direct seeded rice having highest grain yield (10%), straw yield (8%) and yield attributes (10-15%) as well as lesser weed density and weed dry matter found under Conventional tillage during both the seasons of experiment but performance of zero tillage was slightly better (3-4%) in second year as compared to all treatments. Whereas surface retention of residue @5 tonne/ha was significantly more effective in controlling different category of weeds, it decreased up to 60-75% weed population, resulting increment in grain yield up to 19% and 23% during first and second year, respectively, as compared to plot receiving no residue.

Effect of residue and weed management practices on weed flora, yield, energetics, carbon footprint, economics and soil quality of zero tillage wheat

A two-year field study was conducted during Rabi 2018–2019 and 2019–20 to find out the influence of different residue and weed management practices on weed dynamics, growth, yield, energetics, carbon footprint, economics and soil properties in zero-tilled sown wheat at Research Farm, AICRP-Weed management, SKUAST-Jammu. The experiment with four rice residue management practices and four weed management practices was conducted in a Strip-Plot Design and replicated thrice. The results showed that residue retention treatments recorded lower weed density, biomass and higher wheat growth, yield attributes and yields of wheat as compared to no residue treatment. The magnitude of increase in wheat grain yield was 17.55, 16.98 and 7.41% when treated with 125% recommended dose of nitrogen + residue + waste decomposer (RDN + R + WD), 125% RDN + R, and 100% RDN + R, respectively, compared to no residue treatment. Further, all three herbicidal treatments decreased weed density and biomass than weedy treatments. Consequently, a reduction of 29.30, 28.00, and 25.70% in grain yield were observed in control as compared to sulfosulfuron + carfentrazone, clodinafop-propargyl + metasulfuron, and clodinafop-propargyl + metribuzin, respectively. Moreover, 125% RDN + R + WD obtained significantly higher energy output (137860 MJ ha−1) and carbon output (4522 kg CE/ha), but 100% RDN had significantly higher net energy (101802 MJ ha−1), energy use efficiency (7.66), energy productivity (0.23 kg MJ−1), energy profitability (6.66 kg MJ−1), carbon efficiency (7.66), and less carbon footprint (7.66) as compared to other treatments. Despite this, treatments with 125% RDN + R + WD and 125% RDN + R provided 17.58 and 16.96% higher gross returns, and 24.45% and 23.17% net outcomes, respectively, than that of control. However, compared to the control, sulfosulfuron + carfentrazone showed considerably higher energy output (140492 MJ ha−1), net energy (104778 MJ ha−1), energy usage efficiency (4.70), energy productivity (0.14 kg MJ−1), energy profitability (3.70 kg MJ−1), carbon output (4624 kg CE ha−1), carbon efficiency (4.71), and lower carbon footprint (0.27). Furthermore, sulfosulfuron + carfentrazone, clodinafop-propargyl + metasulfuron, and clodinafop-propargyl + metribuzin recorded 29.29% and 38.42%, 27.99%, and 36.91%, 25.69% and 34.32% higher gross returns and net returns over control treatment, respectively. All three herbicides showed higher gross returns, net returns, and benefit cost ratio over control. The soil nutrient status was not significantly affected either by residue or weed management practices. Therefore, based on present study it can be concluded that rice residue retention with 25% additional nitrogen and weed management by clodinafop-propargyl + metasulfuron herbicide found suitable for zero tillage wheat.

Crop–weed dynamics, nutrient uptake, and soil microclimate in elephant foot yam under conservation agriculture

Conservation agriculture (CA) is a sustainable option to adapt to climate change. Weed management is one of the most important challenges faced by CA. Information on CA in cropping systems involving elephant foot yam (Amorphophallus paeoniifolius (Dennst.) Nicolson), an important tuber crop, is lacking. Hence, this study aimed to determine the effect of CA in elephant foot yam on crop–weed dynamics, nutrient uptake, and soil microclimate. Field experiments were conducted in randomized block design over two seasons at ICAR-Central Tuber Crops Research Institute, Thiruvananthapuram, Kerala, India, in elephant foot yam (var. Gajendra) intercropped with banana (var. Robusta) with five treatments viz., conservation organic, conservation chemical, conventional chemical, existing conventional [package of practices (POP) as control], and existing organic package. The weed flora was dominated by broad-leaved weeds. By the fourth month, conservation chemical practice reduced the weed density by 58.8% and weed biomass by 55% over existing POP. The total biomass production and its partitioning to corms, uptake of nitrogen (N), phosphorus (P), and potassium (K), crop growth rate, corm bulking rate, and harvest index of elephant foot yam did not differ significantly under conservation or conventional practices but were higher in conservation chemical practice. The N, P, and K physiological efficiencies were higher in conventional chemical treatment. The soil microclimate was improved, with higher soil CO2 flux and soil moisture in conservation organic or organic plots. The study proved that conservation practices involving reduced tillage, residue retention, and use of herbicides was a viable alternative in banana + elephant foot yam system.

Site-specific herbicide spraying can control weeds as well as full spraying in the long-term. A simulation study

Site-specific herbicide spraying reduces herbicide use as it sprays only where weeds are detected. We studied the long-term impact of this weed-control measure on weed-impact indicators (crop yield loss, biodiversity, …). We developed a submodel to simulate the effects of site-specific spraying on weed floras and included this into the existing FlorSys model. The latter simulates multiannual multispecies weed dynamics and crop canopies at a daily time-step from cropping system, weather and soil. Global sensitivity and uncertainty analyses, based on 30-year-long simulations of different rotations and weather series, identified the most influential inputs and the most sensitive outputs. The cropping system (rotation with associated sowing patterns, herbicide products and treatment dates) was more influential than the spraying system (geometrical spraying pattern, weed detection). Finally, a real-life case study was simulated to demonstrate the feasibility of reconciling crop production with reduced herbicide use, thanks to site-specific spraying.

Weed Dynamics and Crop Productivity as Influenced by Weed Management Practices and Fertility Levels in Groundnut (Arachis hypogaea L.)

Background: Groundnut or peanut (Arachis hypogaea L.) is known as the “King of Oilseeds” which belongs to family Fabaceae (Leguminosae). It is highly susceptible to weed infestation because of its slow initial growth up to 40 DAS and small foliage cover. However, study on use of mechanical weed control methods with different fertility regimes for improving the productivity of groundnut was limited. Therefore, the objective of this study was to find a suitable method for optimising the productivity of groundnut. Methods: A field experiment was conducted at Odisha University of Agriculture and Technology, Bhubaneswar for two consecutive years of 2020 and 2021. The field experiment comprised 16 treatment combinations of four weed management practices and four fertility levels. The weed management practice included W1-Pre-emergence (PE) application of pendimethalin @ 0.75 kg ha-1, W2-Pre-emergence (PE) application of pretilachlor @ 0.5 kg ha-1, W3-Manual weeding (20 and 40 DAS), W4-Twin wheel hoe at 20 DAS followed by (fb) hand weeding at 40 DAS and four fertility levels includes T1-100% RDF (20:40:40) (N: P205: K2O kg ha-1), T2- 75% RDF + 5 tonnes FYM ha-1, T3- 50% RDF + 10 tonnes FYM ha-1, T4- without fertilizer + without FYM. Result: Amongst the weed management practices, use of twin wheel hoe at 20 DAS followed by hand weeding at 40 DAS significantly reduced the weed density, weed dry weight, weed index and recorded the highest weed control efficiency (69.8%). Highest weed index (32.9) was recorded with the application of pretilachlor @ 0.5 kg ha-1 (PE), which was followed by weed index of (28.5) with application of pendimethalin @ 0.75 kg ha-1 (PE). The fertilizer management practice with application of 50% RDF + 10 tonnes FYM ha-1 gave the highest yield and considerably reduced the total weed density, weed dry weight and recorded the maximum weed control efficiency (71.8 % at harvest). We suggest that weed management with twin wheel hoe at 20 DAS followed by hand weeding at 40 DAS along with application of 50% RDF + 10 tonnes FYM ha-1 as the most effective strategy for controlling the weed menace in groundnut with the highest weed control efficiency.

Effect of Spacing and Weed Management on Weed Dynamics of Summer Blackgram [Vigna mungo (L.) Hepper] under Nagaland Conditions

Background: A study was conducted during Zaid season of 2021 on response of summer blackgram [Vigna mungo (L.) Hepper] to planting geometry and weed management under Nagaland conditions. Methods: The experiment was laid out in Factorial Randomized Block Design (FRBD) with three replications and comprised of three levels of planting geometry viz., S1-20 × 10 cm2, S2-30 × 10 cm and S3-40 × 10 cm and four different levels of weed management viz., W1-Weedy check, W2-Two hand weedings at 20 DAS and 40 DAS, W3 = Pendimethalin @ 1 kg a.i ha-1 + Imazethapyr @ 100 g ha-1 at 30 DAS and W4= Pendimethalin @ 1 kg a.i ha-1 + one hand weeding at 30 DAS. Result: The highest seed and stover yields (739 kg ha-1, 2068.2 kg ha-1) were recorded at 30 x 10 cm2 spacing and it was at par with 20 × 10 cm2. Pendimethalin @1 kg a.i ha + one hand weeding at 30 DAS recorded lowest weed population, weed dry weight and highest weed control efficiency. Combination of 30 × 10 cm2 and Pendimethalin @ 1 kg a.i ha-1 + one hand weeding at 30 DAS recorded highest B:C ratio (1.32) among all the treatments and was found to be an economically achievable treatment combination for summer blackgram.Background: A study was conducted during Zaid season of 2021 on response of summer blackgram [Vigna mungo (L.) Hepper] to planting geometry and weed management under Nagaland conditions.

Exploring the interplay between Arbuscular Mycorrhizal Fungi and weed dynamics in agricultural ecosystems.

Weeds are responsible for major crop losses worldwide but can provide beneficial agroecosystem services. The present study aimed to study the association of arbuscular mycorrhizal fungi in common weeds found in agro-ecosystem. Around 19 weeds were collected from various locations of eastern dry zone of Karnataka. The mycorrhizal association was determined by root staining technique. Of the 18 weed samples, AM fungal association was found in 17 weed species and the percent root colonization ranged from 10-68 %. Highest root colonization was found in weeds belongs Graminaceae family. The result of the study concludes that, AM fungi colonizes the weeds and they may act as host during the off seasons.

Weed dynamics and productivity of wheat (Triticum aestivum) under various tillage and weed management practices

The reduced yield under conventional tillage is due to more crop-weed competition and more dry matter accumulation by the weeds(Kumar et al. 2018). Due to zero weed competition, weed-free treatments yielded the highest grain yield of all weed managementpractices. In contrast to this, the lowest grain yield was obtained in weedy treatment due to season-long weed competition. Maximum yield under W8 is due to broadspectrum activity of these herbicides (Sharma et al. 2014, Sunil et al. 2021). The use of zero tillage reduced weed incidence and suppression, leading to higher grain yields. Therefore, zero tillage and metsulfuron 20% wp 4 g a.i./ha + clodinafop propargyl 15% wp 60 g a.i./ha should be practiced for minimizing weed growth and maximizing the yield.

Weed dynamics under diverse nutrient management and crop rotation practices in the dry zone of Sri Lanka

Integrated weed control strategies are essential for organic and integrated nutrient management, where both systems are progressing with a fundamental of zero or minimum synthetic chemical cultivations. For optimizing the outcome of weed management, a better understanding of the weed dynamic is needed. Especially, with the absence of herbicides, weeds are expected to be controlled by the system itself, during the transition period under rice-based crop rotation systems. This study was conducted to estimate the weed abundance, growth, and composition during the transitional period with conventional (CONV), integrated (INT), and organic (ORG) nutrient management under four crop diversification intensities in a dry zone of Sri Lanka. Monocrop rice and a rice-maize rotation were the starting point. After 1 year, the diversification intensity was increased by adding interseason sunnhemp (rice-sunnhemp-rice and rice-sunnhemp-maize). Weed density and weed biomass were measured at 20 DAS and 60 DAS intervals. Weed density was higher in ORG during the early growth stages of monocrop rice rotation in the 1st cycle, and monocrop rice and rice-sunnhemp-rice rotation in the 2nd cycle while didn’t show any changes during the later growth stage of all systems in both cycles. The total weed biomass in ORG increased with increasing crop diversification. Overall, crop rotation in INT reported the lowest weed density and biomass after two cycles. In the CONV with rice-sunnhemp-maize rotation, weed biomass had declined, while in ORG grass biomass decreased only in sunnhemp cultivated rotations. Overall, INT was the best for weed suppression irrespective of crop rotation intensities. Monoculture with rice in the INT was able to suppress weed more effectively than rice-maize rotation.

Modelling weed seed predation by carabids and its effects on crop production under contrasted farming systems

To reduce herbicide use, different avenues of biological weed regulation are currently investigated. Among these, weed seed predation by carabid beetles appears promising. Though observed in different cropping systems and conditions in fields, there was to date no demonstration that this process actually influences weed dynamics over time and reduces weed harmfulness for crop production. Consequently, the objective of the present paper was to (1) model the impact of cropping system, field margin and pedoclimate on weed seed predation by carabids to complete the FlorSys model, which simulates weed dynamics and crop production from cropping systems, soil and weather, (2) evaluate whether including seed predation is needed to correctly predict weed dynamics in different cropping systems, (3) which components of the seed predation submodel are the most influential. The new seed-predation submodel calculates the daily predation rate for each weed species from seed traits, weather data, canopy state variables and management operations. In FlorSys, this predation rate is applied to the newly shed weed seeds on the soil surface. The equations and parameters were based on past publications from our team and other literature. Then, simulations were run with FlorSys over 13 years, with and without the seed predation submodel, using weather data and management operations from 10 fields from the INRAE Dijon-Epoisses experimental station. The resulting output in terms of weed and crop state variables (plant density, biomass, seed bank, yield) were compared to measurements from the 10 fields, showing that including weed seed predation in the simulations improved the model's prediction quality, by reducing the overestimation in weed-variable predictions. Finally, a sensitivity analysis to the components of the predation submodel was run, by repeating the simulations after successively switching off individual components of the submodel. This showed that daily incident radiation, light interception by plant canopy, harvest, carabid reproduction and daily temperature had the most influence on seed predation rates. The simulations showed that weed seed predation by carabids can indeed contribute to managing weeds, by reducing field infestation and improving crop yields, but with large variations among crops. However, to determine which cropping systems and field margins favour weed seed predation enough to noticeably contribute to biological weed regulation, a larger diversity of cropping systems and weather series needs to be explored by simulation.

Effect of Irrigation and Sowing Techniques on Weed Dynamics in Alfalfa under South Saurashtra Agro-Climatic Zone of Gujarat, India

A field trial was conducted during winter cycle of November to April 2022-23 at Farming system research station, College of Agriculture, JAU, Junagadh to study the effect of irrigation and sowing method on alfalfa. The treatments given were: I1: 0.6 IW/CPE, I2: 0.8 IW/CPE, I3: IW/CPE ratios and two sowing methods, M1: Line sowing and M2: Broadcast. The combination of treatments were tested in split plot design with three replications. The experimental field was heavily infested with mixed flora of sedge, grasses and broad-leaved weeds, viz. cypers rotundus L., Echinocoloa coloa L., Chinopodium album L., Chinopodium murale L., Digera arvensis L., Commelina benghalensis L., Cleome viscose L., Euphorbia spp. L. Results showed that the irrigation scheduling and sowing method had significant effect on the weed density and dry weight of weed during the study. Significantly higher weed density and dry weight of weed was obtained with broadcasting as compared to line sowing at 25 cm apart.

Effect Of Sequential Application Of Pre And Post-Emergence Herbicides On Dynamics Of Weeds Associated With DSR System Andrice-Growth And Sustained Yield

The sustained rice yield plays an important role in the country’s GDP. The diverse weed flora is a potential biotic threat to the sustained yield in the DSR system. The crop faces severe competition the resources from its beginning (germination of crop seedlings) to the panicle initiation with the diverse weeds flora as it grows quickly in moist conditions, resulting in severe yield losses up to 65 per cent. Thus, an effective and economical weed control strategy in DSR is often required to overcome the losses. In such situations, sequential application of herbicides may provide broad-spectrum weed control in DSR. A field experiment was conducted on silty loam soils to assess the herbicidal effects on weed dynamics and growth & yield productivity of direct-seeded rainy (Kharif) rice at Agronomy Research Farm of Narendra Deva University of Agriculture and Technology, Kumarganj, Ayodhya (U.P.) during the years, 2016 and 2017. The field trial was carried out in Randomized complete block design (RCBD) with three replications and twelve treatments. The treatments consisted of nine pre & post-emergent herbicide combinations along with three distinct controls, i.e. a) Hand weeding (at 20 & 40 DAS), b) Weed Free (weeding at every 15 days interval from seedling to the PI stage), and c) Weedy Check. The results of the field study revealed that the weed-free plots recorded the highest weed control efficiency, and they registered the least weeds density and dry weight of weeds associated with direct seeded rice fields. However, the application of herbicides, namely, pendimethalin (1000 g a.i. ha-1) as pre-emergent and Bispyribac-Na (1000 g a.i. ha-1) as post-emergent coupled with a hand weeding at 40 DAS provided the statistically comparable results to weed-free and is effectively controlled the diverse weed flora by 81.9-84.5 per cent in DSR system. And both the treatments gave significantly better growth (plant height, number of tillers, dry matter, LAI) and yields (grain and straw) of rice as compared to the weedy-check. Among the diverse weeds associated with the DSR fields, sedges were dominant as compared to broad leaves and grasses. The study also recorded the rice-grain yield reduction by 40.9 per cent due to the presence of diverse weed flora in weedy check plot as to weed-free plot.

Assessment of weed dynamics in different rice farming systems and assessment weed management practices

Assessment of weed dynamics in different rice farming systems and assessment weed management practices