Direct-seeded Rice Production Research Articles

A comparative assessment of polymer-coated and non-coated urea in direct-seeded rice: agronomic, economic, and environmental performance and sensitivity analysis

The application of polymer-coated urea (PCU) to crops is likely restricted because the product’s capsules cause plastic pollution. Although conventional fertilizer use reduces plastic pollution, it may increase nitrogen (N) pollution owing to its lower N recovery than that of PCU. Therefore, we need to develop optimal N application methods to reduce both plastic and N pollution. Here, we aimed to (1) compare the agronomic, economic, and environmental outcomes of PCU application with those of conventional urea application and (2) provide quantitative targets for developing alternatives to PCU application in dry direct-seeded rice production. We developed a model incorporating yield, brown-rice protein content, farmer profit, and environmental damage cost due to N and polymer loss according to N fertilizer application. Data were collected from field experiments at a farm in Iwate, Japan, from 2020 to 2022. The average apparent N recovery was 0.43 for PCU and 0.37 for conventional urea. Despite the plastic damage cost, the estimated total environmental cost of PCU was lower than that of normal urea owing to the former’s higher N recovery. However, our ability to simulate plastic pollution is limited, as few of the environmental effects of microplastics are understood. If new N application methods with N recovery above 0.5 are developed, an N fertilization cost within $5 × 10–3 g N–1 can maintain the same benefit as that obtained here. This model can be used to evaluate the quantitative relationships among N recovery, benefits, and implementation costs of each candidate N application method.

Investigating the Impact of Climate Change Impacts on Direct-seeded Rice Production in Middle Gujarat Using the InfoCrop-rice Model

Rice (Oryza sativa L.) is a global food staple, essential for human nutrition and calorie intake, particularly in low- and middle-income countries. This study assesses the impact of climate change on direct-seeded rice (DSR) production in Middle Gujarat (India) using the InfoCrop-Rice model. The study evaluates potential climate scenarios under Representative Concentration Pathways (RCP) 4.5 and RCP 8.5, focusing on projected changes in temperature, rainfall, and sunshine hours, and their effects on rice yield and phenology. Field data from Kharif 2023 were used to calibrate the model, which projected significant increases in maximum and minimum temperatures, variable changes in rainfall, and consistent reductions in sunshine hours. By 2100, maximum temperatures are expected to rise by up to 6°C under RCP 8.5, and minimum temperatures could increase by as much as 7.5°C. Rainfall projections show high variability, with potential reductions and increases depending on the scenario and time period. Sunshine hours are projected to decline by approximately 6.6% under both RCP scenarios. The model simulations indicate a notable decline in rice yields, with reductions ranging from 18% to 36% by 2100. These results underscore the severe impact of climate change on DSR productivity. The study highlights the need for adaptive strategies, including improved water management, resilient crop varieties, and sustainable agricultural practices, to mitigate the adverse effects of climate change and ensure the sustainability of direct seeded rice production in Middle Gujarat.

Insights into the effects of anilofos on direct-seeded rice production system through untargeted metabolomics

Weed infestation is the major biological threat in direct-seeded rice production and can cause significant yield losses. The effective use of herbicides is particularly important in direct-seeded rice production. Anilofos, a pre-emergence herbicide, has been shown to be effective against the weed barnyardgrass. However, its impacts on crop yield and the direct-seeded rice production ecosystem remain underexplored. In this study, we conducted field trials and used untargeted metabolomics to investigate systemic effects of two different treatments (40 g/acre and 60 g/acre) on rice shoot and root as well as the rhizosphere soil during the critical tillering stage. Here, a total of 400 metabolites were determined in the crop and soil, with differential metabolites primarily comprising lipids and lipid-like molecules as well as phenylpropanoids and polyketides. Spearman correlation network analysis and a Zi-Pi plot revealed 7 key differential metabolites with significant topological roles, including succinic acid semialdehyde and riboflavin. KEGG pathway analysis showed that anilofos downregulated the amino acid metabolism while mainly promoted carbohydrate metabolism and secondary metabolites biosynthesis of the crop, which made minimal disruption on soil metabolism. Notably, we found 40 g/acre anilofos application could significantly improve the rice yield, potentially linked to the improved activity of flavonoid biosynthesis and starch and sucrose metabolism. This research provides a comprehensive evaluation of anilofos effects in the direct-seeded rice production system, offering new insights into optimizing herbicide use to improve agricultural sustainability and productivity.

Optimizing Nutrient and Energy Efficiency in a Direct-Seeded Rice Production System: A Northwestern Punjab Case Study

This study was carried out in Amritsar, Punjab, to find out how efficiently nutrients were used and how much energy was employed in direct-seeded rice (DSR) production. In this study, four levels of nitrogen (0, 40, 50, and 60 kg N ha−1) and three levels of phosphorus (0, 37.5, and 45 kg P2O5 ha−1) were tested. In a rice production system, the energy indices of various inputs and outputs were evaluated through the application of energy equivalency. The nutrient-use efficiencies in rice were assessed using different efficiency indices. The maximum grain yields of 38.9 q ha−1 and 36.9 q ha −1 were recorded at 50 kg N ha−1 and 45 kg P2O5 ha−1, respectively. On the other hand, application of nitrogen at 60 kg N ha−1 and phosphorus at 45 kg P2O5 ha−1 resulted in maximum straw yield of 57.1 q ha−1 and 51.1 q ha−1, respectively. In comparison with the control, application of 60 and 50 kg N ha−1 resulted in 161.9% and 151.0% higher grain yield, respectively. On the other hand, with applications of 45 kg P2O5 ha−1 and 37.5 kg P2O5 ha−1, an increase in the grain yield of 17.3 and 28.6%, respectively, over the control was recorded. Moving further towards nutrient-use efficiencies (NUEs), the highest values of partial factor productivity of nitrogen (PFPN), agronomic efficiency of nitrogen (AEN), partial nutrient balance of nitrogen (PNBN), and recovery efficiency of nitrogen (REN) were 89.1, 50.4, 1.78 and 0.72, respectively, which were obtained at 40 kg N ha−1, after which the values started decreasing steadily. In the case of phosphorus, the partial factor productivity (PFPP) of 88.6 was the maximum at 37.5 kg P2O5 ha−1, but partial nutrient balance (PNBP) of 0.36 and recovery efficiency (REP) of 0.08 were highest at 45 kg P2O5 ha−1. The main results revealed that the farmer field had an excessive amount of non-renewable energy inputs. The experimental field depicted greater energy-usage efficiency (EUE) of 4.5, energy productivity (EP) of 0.14, and energy profitability (EP1) of 3.5. These results were primarily ascribed to a significant drop in energy inputs under direct-seeded rice (DSR). In the case of non-renewable energy inputs, fertilizer made the maximum contribution to energy input (47.9%) in the farmer’s field. We conclude that nutrient-use efficiencies and energy-use efficiency were highest at 50 kg N and 45 kg P2O5 ha−1. This recommendation is beneficial for farmers because lower inputs and higher outputs are the main objective of every farmer.

Weed growth and productivity of direct-seeded rice under different weed management practices

Weed growth and productivity of direct-seeded rice under different weed management practices

Integrated Weed Management Practices on Productivity and Profitability of Direct Seeded Rice under Aerobic Condition

At the research farm of RPCAU, Pusa, Samastipur, Bihar, a field experiment was carried out during the 2017 kharif season to examine the effects of integrated weed control on the profitability and productivity of direct-seeded rice grown in aerobic conditions. The experiment was laid out in Randomized Block Design having ten treatments with three replications. Both hand weeding and herbicidal treatments, out of all the weed control techniques, had noticeable effects on crop development and yield as well as their superiority to the weedy check. Hand weeding at 20, 40 and 60 days after sowing was found significantly superior over all the integrated weed management practices on productivity and profitability of dry direct seeded rice. Pendimethalin @ 1 kg/ha at 0–2 days after sowing, followed by two hand weedings at 20 and 40 days after sowing, outperformed the other herbicidal treatments in the trial for dry direct seeded rice.

Irrigation Management Strategies to Increase Crop-Water Productivity and Grain Quality of Direct Seeded Rice in North West IGP: A Review

Due to its great productivity and profitability, rice (Oryza sativa L.) is farmed in alluvial irrigated tracts of northwest India. For half of the world's population as well as in our country, rice serves as the main source of calories. However, excessive groundwater use in rice farming has resulted in an alarming decline in water table, indicating overuse of groundwater. Therefore, it is necessary to investigate alternative, resource-conserving methods that can sustain rice production. Direct seeded rice presents a compelling option when the future of rice production is in jeopardy due to worldwide water constraint and rising labour costs. The oldest method of crop establishment in this regard, direct seeded rice (DSR), is becoming more and more well-liked constraints minimal input requirements. It has certain benefits, including labour savings, a reduction in water and manpower requirements, early crop maturity, cheap production costs, improved soil physical conditions for crops, a reduction in methane emissions, and greater options for being the best match in various cropping systems. For dry-seeded rice, management strategies that cut irrigation water use and boost crop-water production are needed. Some of the interventions in this respect include cultivars with short growing seasons, tillage, and irrigation scheduling. High crop-water productivity is ensured with optimal yields thanks to irrigation scheduling that aims to eliminate over- or under-irrigation. Tillage changes the edaphic environment of the soil, which impacts crop development. Because of their shallow root systems, rice plants are unable to use the water in the deeper layers of the soil. In order to increase the deep root growth of rice cultivars, deep tillage has become the preferable method. The present research evaluates irrigation management options to raise crop-water productivity and grain quality of DSR in northwest IGP based on the available evidence.

Efficacy of Pendimethalin Rates on Barnyard Grass (Echinochloa crus-galli (L.) Beauv) and Their Effect on Photosynthetic Performance in Rice

Pendimethalin herbicide toxicity to rice plants and barnyard grass invasion have increasingly affected the productivity of direct-seeded rice (DSR) in the fields. Whether and how to promote DSR productivity and sustain weed management depend on the appropriate pre-emergence herbicide application rate to minimise its toxicity in the rice ecosystem. Pot experiments were conducted to determine the effects of pendimethalin rates (1.5, 1.75, 2.0 kg a.i. ha−1, two control treatments include the untreated control and the treated control with 1.5 kg a.i. ha−1 S-metolachlor) on barnyard grass (Echinochloa crus-galli (L.) Beaux) and their potential toxicity risk to photosynthetic performances of rice (Topaz and Sen pidao). All the pendimethalin treatments provided excellent control of barnyard grass. Among the treatments, 1.5, 1.75, 2.0 kg a.i. ha−1 pendimethalin and 1.5 kg a.i. ha−1 S-metolachlor (treated control) decreased leaf area of barnyard grass significantly by 38.9, 49.6, 49.6 and 46.2%, respectively, compared with the untreated control at 40 days after sowing (DAS). The above-ground biomass of barnyard grass significantly decreased by 40% (1.48 g plant−1) with 2.0 kg a.i. ha−1 pendimethalin and by 46.2% (1.33 g plant−1) when 1.5 kg a.i. ha−1S-metolachlor was applied at 40 DAS compared with the untreated pots. Higher pendimethalin rates increased toxicity in Topaz and Sen pidao varieties, and 2.0 kg a.i. ha−1 pendimethalin significantly reduced effective quantum yield (light-adapted) of photosystem (PS) II by 18% (0.58) and 19% (0.52), respectively, compared with the untreated control. Application of 2.0 kg a.i. ha−1 pendimethalin rate significantly decreased the maximum quantum yield (dark-adapted) of Sen pidao (0.66) compared with 1.5 kg a.i. ha−1 pendimethalin (0.68) including the untreated control. All pendimethalin treatments suppressed above-ground biomass at 55 DAS, but above-ground biomass of barnyard grass significantly decreased by 59.9% when 2.0 kg a.i. ha−1 pendimethalin was applied compared with the untreated control. Although application of 1.5 kg a.i. ha−1 pendimethalin rates reduced the effective quantum yield (light-adapted) of photosystem II of Sen pidao (0.55) by a small percentage (8%) than Topaz (0.65), it was non-toxic for both varieties compared with 2.0 kg a.i. ha−1 pendimethalin. Therefore, the use of 1.5 kg a.i. ha−1 pendimethalin can be used for effective weed management in the direct seeding of rice at an early growth stage.

Co-implementation of conservation tillage and herbicides reduces weed and nematode infestation and enhances the productivity of direct-seeded rice in North-western Indo-Gangetic Plains

Direct-seeded rice (DSR) can be a resource-efficient alternative to puddled transplanted rice (PTR), but weeds and nematodes pose severe challenges. Conservation agriculture (CA)-based DSR may inhibit/influence weeds/nematodes, which can be further intensified by adopting better weed control. Hence, this experiment was undertaken. Five CA-based DSR practices involving zero tillage, residue retention, brown manuring, and superimposed with four weed control/herbicide options were compared with PTR in a split-plot design replicated three times. All DSRs encountered more weeds and plant parasitic nematodes (PPNs) than PTR. Root-knot nematodes (RKN) infested five among 14 weeds present in rice and was first time found inDinebra retroflexa. A CA-based zero till (ZT)DSR+ mungbean residue – ZT wheat + rice residue – ZT mungbean+wheat residue system reduced weeds significantly. It reduced RKN galls inEchinochloa colona, Echinochloa crusgalli, and rice plants by 72, 58, and 56%, respectively. In soil too, RKN and other PPNs, namely,Tylenchorhynchus brevilineatusandPratylenchus thorneiwere reduced by 39%, 32%, and 26%, respectively, which gave a 6.3–22.7% higher yield in this CA practice than other DSRs. Pyrazosulfuron-ethyl, cyhalofop-butyl, and bispyribac-Na applied sequentially reduced weeds and PPNs, increased rice yield by 176.1%, and were at below detectable levels in soil, rice grains, and straw, and were safe for rotational crops. The above ZT-based triple cropping with residue supplemented with herbicides through better weed and nematode control would be an alternative to PTR in the North-wester Indo-Gangetic Plains of India and in similar agroecologies of the tropics/sub-tropics. This study would help farmers and policymakers to design integrated weed and nematode management modules using tillage, crop residue, and herbicides/pesticides for higher DSR yield and income.

Seeding rate, fertiliser and herbicide effects on canopy growth and productivity of direct-seeded rice (DSR) under different management practices

A low seeding rate with seed drill is a good management practice to promote good canopy growth and increase yield of direct seeding rice (DSR) in lowland rice fields. Many studies did not evaluate seeding rates in an integrated way under different management practices in smallholder farmers’ fields. Estimating canopy cover from Canopeo and normalised vegetation difference index (NDVI) may offer a non-destructive, rapid way to assess crop growth and productivity under different field conditions. On-farm field experiments were conducted comparing the yield and canopy growth in response to seed drilled seeding rates of 20, 40, 60 and 80 kg ha −1 and hand-broadcast seeding rates of 180 kg ha −1 (farmers’ practice) grown under different management conditions in Cambodia. In the first experiment, different seeding rates were compared in two villages, Kork Ton Loab (KTL) and Svay Cheat (SVC), in the 2018 growing season. In the second experiment, seeding rates and fertiliser application rates were compared at Kork Ton Loab location in the 2019 cropping season. The third experiment compared seeding rates and pre-emergence herbicide options at Oroung village in the 2018 and 2020 cropping seasons. In experiment 1, sowing at 20 and 40 kg ha −1 consistently decreased mean canopy cover with Canopeo index at Kork Ton Loab and Svay Cheat locations. In experiment 2, sowing at 80 kg ha −1 significantly increased the mean canopy cover compared with 20 and 40 kg ha −1 seeding rates with Canopeo index at 60 and 75 DAS at the Kork Ton Loab location. The low seeding rates of 60, 80 and 180 kg ha −1 increased in canopy cover at 60 DAS with NDVI compared with the lower seeding rates at Kork Ton Loab and Svay Cheat locations. Seeding rates had significant effects on grain yield and gross margin only for experiment 1 and experiment 3 in the 2020 cropping season. For experiment 1, the seed drill rates of 60 and 80 kg ha −1 did not significantly differ in grain yield or gross margin compared with broadcast of 180 kg ha −1 in both locations. Sowing at 20, 40, 60 and 80 kg ha −1 produced similar yield and gross margin at Kork Ton Loab except for the 20 kg ha −1 seeding rate that significantly reduced yield and gross margin at Svay Cheat. For experiment 3, the seed drill of 80 kg ha −1 and 180 kg ha −1 by broadcast (Farmer’s Practice) significantly increased yield up to 3.5 t ha −1 compared with 40 and 60 seeding rates in the 2020 cropping season. Increasing fertiliser rates (high fertiliser; N-100, P-80, and K-50 kg ha −1 ) by two times increased grain yield by 12.8% compared with the low fertiliser rate of N-50, P-40, and K-30 kg ha −1 . Pre-emergence herbicide application significantly increased mean grain yield by 16% and 15% in the 2018 and 2020 cropping seasons, respectively. Therefore, the seed drill of 80 kg ha −1 , high fertiliser rate and pre-emergence herbicide interventions improved uniformity in canopy growth and increased grain yield of DSR. This information can be incorporated into integrated crop and weed management programs for the productivity of direct-seeded rice in the lowland ecosystem. • Low seeding rates (60–80 kg ha -1 ) with seed drill provide similar yield and gross margin as hand-broadcast of 180 kg ha -1 . • The use of vegetation-derived information from reflectance sensors estimates canopy growth in dynamic field conditions. • Sowing at 60 and 80 kg ha -1 with seed drill reduced undesirable agronomic traits compared with hand-broadcast of 180 kg ha -1 .

Energy Assessment of Manual Transplanting Rice and Dry Direct Seeding Rice Production Systems in Combined Nalgonda District, Telangana

Background: Rice is the major crop in India in terms of area, production and consumption. Rice occupies about 23% of the gross cropped area and 35% of the total area under food grains in the country. Rice is of one key importance to the economy as well as a staple food for Telangana people, requiring about 50 lakh tons annually to feed the state population. In recent times the area under rice cultivation has been increased and is expected to hit the one crore acre mark by rabi season 2022. In any type of crop production system an accountability of inputs, energy spent, yield and costs must be monitored, by that one can modify it or substitute it for obtaining the better results. Methods: Due to decline in the share of agriculture workers in the country, there is a need to adopt new technologies in rice cultivation. Dry direct seeding of rice refers to direct sowing of rice seeds in the dry field rather than by transplanting seedlings from the nursery. A study was conducted to compute the inputs and energy consumptions in manual transplanted rice production (MTR) and dry direct seeding rice production (DDSR) methods of paddy cultivation in the combined Nalgonda district of Telangana State, during 2020-21. Firstly, the different operations performed in these two methods were listed out, then by using suitable energy equivalents total energy consumed in two methods of operations were calculated. Result: The human energy spent in the manual transplanted rice production and dry direct seeded rice productions were 506 and 92.84 MJ/ha respectively. Specific energy noted for dry direct seeded rice production and manual transplanted rice productions were 2.10 and 2.28 MJ/kg respectively. A total saving of Rs. 16,000/- ha-1 was recorded by practicing the dry direct seeded rice production method over the manual transplanted rice production method. On comparing both the methods for overall energy consumption, manual energy consumption and cost of cultivation DDSR method was found to be more efficient than MTR method in the district.

Germination and Growth Performance of Water-Saving and Drought-Resistant Rice Enhanced by Seed Treatment with Wood Vinegar and Biochar under Dry Direct-Seeded System

Dry direct-seeded rice (dry-DSR) is an efficient, resource-saving and environmentally friendly cropping system. The employment of water-saving and drought-resistant rice (WDR) for dry direct-seeding can better meet the needs of dry-direct seeding systems. However, the decline in seedling emergence rate and poor seedling growth are the main bottlenecks under current direct-seeded rice production. Seed treatment is a sustainable and effective technique to overcome these issues. Therefore, growth chamber and field experiments were conducted to assess the impact of poplar wood vinegar (WV) priming and rice straw biochar (BC) coating on emergence, establishment, growth, physio-biochemical events, and ultimate yield. We treated the seeds of WDR viz., Hanyou 73 with WV, BC, and co-treatment WV + BC. The results showed that seed priming with 1:50 WV concentration and coating with 20% BC content was the optimal ratio for promoting germination and seedling growth. The field evaluation indicated that individual WV and BC markedly promoted the final emergence by 58% and 31%, respectively, while co-treatment WV + BC increased by 67%. Likewise, WV and BC significantly enhanced total seedling biomass by 26% and 10%, respectively, and the respective enhancement of WV + BC was 31%. For ultimate yield, WV and BC produced 12% and 19% higher grain yield, respectively, whereas WV + BC yielded 20%. The above results revealed that WV and WV + BC were the most effective treatment. Our findings may provide new avenues for advancing pre-sowing seed treatments facilitating the stand establishment and grain yield of dry direct-seeded rice.

Weed Management Practices on Crop Productivity and Economics in Dry-Direct Seeded Rice under Hill and Plateau Region of Eastern India

In direct seeded rice, weeds are the major problems limiting the crop productivity. Sesbania with direct seeded rice (DSR) as well as seeding rates of rice affects the weed density by smothering effect and therefore, it can be a better weed management practice. Two year on farm trials were conducted at the Kusma, Boarijore Block and Bhaluka, Sundarpahadi block of Godda from 2020 and 2021 to assess the effect of weed management on yields and economics in DSR. The results revealed that significantly the lowest density of grasses, broad leaved weeds (BLWs), sedges, total weed density, total weed dry weight and the highest weed control efficiency were recorded with the treatment of DSR + Sesbania over DSR (pre-sowing irrigation followed by tillage and rice seeding) followed by first post-sowing irrigation at 15 DAS and the farmer’s practice. Weed management practice, DSR + Sesbania was found significantly higher grain yield, gross returns, net returns, B: C ratio, production efficiency and economic efficiency over to followed by first post sowing irrigation at 15 DAS and farmer’s practice. While the farmer’s practice was recorded higher weed index and lowest weed control efficiency. Thus, on the basis present study it is concluded that weed management practice i.e. DSR + Sesbania could be a better option to reduced the weed infestation as well as improves the productivity of DSR in rainfed agro-ecosystem of Jharkhand.

A preliminary study of ‘Tidy Field Technology’ to assess growth, development and weed control in direct-seeded rice

Direct-seeded rice (DSR) is an important method to achieve simplified and mechanized rice planting in economical manner. However, proper weed management is a major limiting factor in the development of DSR. ‘Tidy field technology’ (TFT) is a new non-transgenic herbicide-resistant (HR) cropping technology, which refers to ‘herbicide-resistant crops combined with broad-spectrum herbicide’, and has been widely confirmed to effectively suppress weed populations in agriculture. However, it is rarely applied in DSR production in China. Therefore, field experiments were conducted to determine the effects of TFT on rice growth and weed control in 2019 and 2020. In this study, two rice varieties, Huanghuazhan-HHZ (Vc) and herbicide-resistant HHZ (Vr) were adopted and practiced with broad-spectrum herbicide management (Hb) and conventional herbicide management (Hc). An equal amount of water was sprayed on Vc as a control (CK). Thus, there were five treatments: VrHb, VrHc, VcHb, VcHc and CK. The grain yields of VrHb was increased by 8.4% and 160.3% in 2019, and 16.0% and 226.6% in 2020 compared with VrHc and CK, respectively. Furthermore, there were no significant differences in grain yield between VrHb and VcHc, but the total economic benefit of VrHb was significantly higher than that of VcHc. In addition, the tiller number, leaf area index (LAI), and aboveground total dry weight (TDW) of VrHb were significantly higher than VrHc, VcHc and CK. In contrast, weed species and density under VrHb were significantly lower than those under VrHc, VcHc and CK. Overall, TFT (VrHb) could replace conventional weed management for DSR due to a better weed control effect and higher economic benefit with similar or even higher grain yield. However, it is necessary to explore the effects of TFT residue on soil physical and chemical properties, microorganisms and the growth of subsequent crops in the near future. • Tidy field technology (TFT) was a new non-transgenic herbicide-resistant technology. • Direct-seeded rice (DSR) had the highest yield and net economic benefit under TFT. • High yield of DSR under TFT was due to better weeds control and crop establishment. • High economic benefit of DSR under TFT was due to the reduced cost of weed control.

Effect of Sunflower Crop Residue on Weed Suppression in Direct-Seeded Aus Rice Under Rice – Sunflower-Rice Cropping Pattern

In Bangladesh direct-seeded Aus rice is a conventional rice cultivation practice and weed infestation is a severe problem in direct-seeded rice production due to the existence of favorable environment during this period. So, by minimizing the use of herbicides and replace them with eco-friendly and environmentally sustainable herbicides based on natural plant products or allelochemicals, a factorial experiment based on randomized complete block design with three replications was performed at the research field of Bangladesh Rice Research Institute (BRRI), Gazipur, Bangladesh from July 2018 to August 2019 to evaluate effect of sunflower crop residue on weeds growth and yield of direct seeded Aus rice in Transplanting Aman-Sunflower-Aus cropping pattern. Weed population and weed dry weight were significantly affected by crop residues treatment. Weed population was significantly lower in C3 (Direct sowing of Aus after 7 days of Sunflower residue incorporation) treatment than the control C1 (Direct sowing of Aus without Sunflower residue incorporation) treatment. The lowest weed dry weight (90.5 g m-2) was also obtained from C4 (Direct sowing of Aus after 14 days of Sunflower residue incorporation). The highest reduction of grain yield was obtained from without crop residue and no weeding treatments. The highest number of effective tillers m-2 (403.33), grain panicle-1 (114.67), tillers hill-1 (16.36), and grain yield (3.32 t ha-1) were observed from the treatments where sunflower residue was incorporated and the plots that were weed free. Results of this study indicate that sunflower residues showed potentiality to inhibit weed growth and it has a significant effect on the yield and yield parameters of direct seeded rice. Again weeds played a significant role in the reduction of yield of direct seeded rice. Thus, sunflower residues might be substitute for weed management practice as well as obtaining higher yield of direct seeded rice.
 Bangladesh Agron. J. 2021, 24(2): 115-125

Effect of crop establishment and weed management methods on weed dynamics and productivity of direct-seeded rice in middle Indo-Gangetic Plains

A field experiment was conducted during rainy seasons of 2018 and 2019 at the ICAR-Research Complex for Eastern Region Patna, Bihar to evaluate the effect of crop establishment methods and weed management treatments on weeds and productivity of direct-seeded rice (DSR). The treatments consisted of three upland DSR establishment methods, viz. zerotill direct-seeded rice:(ZT-DSR); conventional-till (CT)-dry DSR (CTDSR) and CTDSR-dust mulching, and three weed pressure maintenance treatments including: low weed pressure: maintained with pre-emergence (PE) application of pendimethalin (1.0 kg/ha) at 2 days after seeding (DAS) followed by (fb) post-emergence (PoE) application of bispyribac–Na (30 g/ha) PoE at 20 DAS fb hand weeding (HW) twice at 30 and 50 DAS; medium weed pressure: maintained with pendimethalin (1.0 kg/ha) PE at 2 DAS fb bispyribac–Na (30 g/ha) PoE at 20 DAS, and high weed pressure: maintained with pendimethalin (1.0 kg/ha) PE alone, in upland DSR under the middle Indo-Gangetic Plains (MIGPs). The major weeds recorded with upland DSR were Cyperus rotundus, Cynodon dactylon, Echinochloa colona, Brachiaria ramosa, Caesulia axillaris and Physalis minima. Significantly the lowest relative weed abundance, weed density and biomass were recorded in CT-DSR-dust mulching compared to ZT-DSR and CTDSR. Among the weed management treatment, maximum weed suppression was recorded in low weed pressure in comparison to medium and high-weed pressure management practices. Significantly higher grain yield (2.14 t/ha) and net returns (₹ 20869/ha) were obtained with CT-DSR-dust mulching. Hence, it may be concluded that for better rice productivity and weed management in upland DSR, CT-DSR-dust mulching with low weed pressure maintenance is the most potential and viable practices under the MIGPs.

An impact of agronomic practices of sustainable rice-wheat crop intensification on food security, economic adaptability, and environmental mitigation across eastern Indo-Gangetic Plains.

In the eastern Indo-Gangetic Plains (EIGP), conventional rice-wheat system has led to a decline in productivity, input-use efficiency, and profitability. To address these, a four-year field study was conducted to evaluate the performance of tillage and crop establishment (TCE) methods in rice-wheat-greengram rotation. The treatments included: 1) random puddled transplanted rice (RPTR) - conventional-till broadcast wheat (BCW) - zero-till greengram (ZTG); 2) line PTR (LPTR) - conventional-till drill sown wheat (CTW) - ZTG; 3) machine transplanted rice in puddled soil (CTMTR) - zero tillage wheat (ZTW) - ZTG; 4) machine transplanted rice in zero-till wet soil (ZTMTR) - ZTW - ZTG; 5) system of rice intensification (SRI) - system of wheat intensification (SWI) - ZTG; 6) direct-seeded rice (DSR) - ZTW - ZTG; and 7) zero-till DSR - ZTW - ZTG. During the initial two years, conventional rice system (PTR) recorded a 16.2 % higher rice grain yield than DSR system. Whereas in the fourth year, the rice yields under DSR and PTR were comparable. As compared to SRI/SWI, the average wheat yield in ZT system was significantly high, whereas in rice, SRI/SWI system was comparable with CT system. ZTW after non-puddled rice was at par to CTW after PTR. The ZT wheat produced 4.6 % more yield than CT system. DSR production system consumed 6.8 % less water compared to transplanted system. On the system basis, 10.8 % higher net returns were recorded with CA-based system compared to conventional system. The system energy productivity under CA-based production system was 14-36 % higher than PTR-based systems. CA-based system also led to 8-10 % lower global warming potential (GWP) than conventional methods. The current study indicated that as compared to conventional system, a significant gain in productivity, profitability and energy-use efficiency, and reduction in the environmental mitigation are possible with emerging alternative TCE methods. Long-term expansion and further refinement of these technologies in local areas need to be explored for the second green revolution.

Crop Establishment and Weed Control Options for Sustaining Dry Direct Seeded Rice Production in Eastern India

Dry direct seeded rice (DSR) has emerged as an economically viable alternative to puddled transplanted rice to address emerging constraints of labor and water scarcity and the rising cost of cultivation. However, wide adoption of DSR is seriously constrained by weed management trade-off. Therefore, the availability of effective weed control options is critical for the success and wide-scale adoption of DSR. A field study was conducted at ICAR-National Rice Research Institute, Cuttack, India, in the dry seasons of 2015 and 2016 to evaluate the performance of three crop establishment methods and five weed control practices on weed management, productivity, profitability and energetics of dry DSR. The results demonstrated that weed density and weed dry weight was lower in drill seeding than broadcast seeding by 26–36% and manual line-seeding by 16–24%, respectively, at 30 and 60 days after crop emergence (DAE). Among herbicides, post-emergence application (17 DAE) of azimsulfuron was most effective in controlling weeds compared to early post application of bispyribac-sodium and bensulfuron-methyl+pretilachlor. Weed competition in the weedy check treatment resulted 58% reduction in rice yield. Among establishment methods, drill-seeding was most profitable with US $ 685 ha−1 higher net income than broadcast seeding primarily due to higher yield. Among weed control treatments, azimsulfuron was most profitable resulting in US $ 160 and 736 ha−1 higher net income than weed free and weedy check, respectively. The specific energy was lowest for drill seeding among establishment method and azimsulfuron among weed control practices, suggesting lowest energy consumed in producing per unit of grain yield.

Potassium application in split can boost up the vegetative growth and economic productivity in direct seeded rice

Potassium (K) deficiency in direct seeded rice is very common occurrence and split application of K eventually leading the soil available K in economic output. The study investigated the effect of split application of K at basal and active tillering stage on direct seeded rice production. The experiment included ten treatments of K application doses in combination with vermicompost and potassium solubilizing bacteria (KSB). The recommended dose of K was kept as 40 kg K2O ha−1 and increased up to 80 kg in two equal splits. The double split application of K resulted the higher yield over the single split against the 40, 60 and 80 kg K2O ha−1 through the continuous higher soil available K. In this study 60 kg K2O ha−1 in two equal split and the same amount in single split with KSB (Frateuria aurantia) inoculation of seedling recorded 17.14% and 17.29% more yield, respectively over the recommended dose of K management (40 kg K2O ha−1 in single split). Study confirmed that not only split application of K but also an increment of 50% higher dose of K over the standard recommendation can be benefited economically. The use of KSB as seed inoculation was also found useful to obtain the better growth and higher productivity in direct seeded rice.

Grain yield and N use efficiency of direct-seeded rice under different N management practices aimed to reduce N input

ABSTRACT The objective of this study was to determine whether integrated N management strategies can be used to increase yield and N use efficiency (NUE) of direct-seeded rice. Field experiments were conducted in the Chengdu Plain in China. Super hybrid, ordinary hybrid and inbred rice were grown under four N management practices, namely N0 (zero N), N1 (fix-timing N management), N2 (reduced basal N combined with SPAD-based N management [SBNM]), and N3 (no basal N fertilization combined with SBNM). Although total N application rate was 13%-40% lower under N2 and N3 than under N1, grain yield under N2 and N3 was equal to that under N1. Rice grown under N2 and N3 had higher NUE than under N1. Super hybrid rice had 11% higher grain yield than ordinary hybrid and inbred rice. The higher grain yields of super hybrid rice were attributed to higher biomass, larger panicle size and lower temperatures during grain filling period. Our results suggest that it is feasible to improve grain yield and NUE by growing rice under SBNM with a reduced basal N application rate, and that breeding cultivars with large panicle size may be an effective approach to achieve high yield in direct-seeded rice production.