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The use of allelopathic bacteria to combat weed infestation in crops is regarded as an effective technology for sustainable agriculture and environment. In this regard, six bacterial strains from the genus Pseudomonas were selected for their ability to inhibit the germination and growth of Leptochloa chinensis (L.) and Dactyloctenium aegyptium (L.) while promoting the growth of rice. These strains were applied to the target weeds and rice using different application methods viz. seed priming, liquid application, and foliar application. The results showed that all strains possessed herbicidal activity and significantly reduced growth of L. chinensis. Shoot length, root length, and fresh biomass of D. aegyptium were also significantly reduced in all strains by 60, 55, and 76%, respectively, with the exception of R15-4. Additionally, the growth suppression of both weed species was more prominent in the liquid application. The selected allelopathic strains also demonstrated plant growth-promoting traits and improved the growth and physiological parameters of rice in all three application methods, with the best results achieved with liquid and foliar applications. The survival efficiency of the bacterial strains was also tested using four different carrier materials, where the press mud was found the best carrier for controlling L. chinensis and D. aegyptium. [ABSTRACT FROM AUTHOR]

Background: Weeds are the key pest, which reduce crop productivity. Direct-seeded rice is very prone to early-stage weed infestation during initial crop development. Cultural and mechanical methods are difficult due to unavailability of labour and poor work efficiency. Hence, use of herbicides is an effective method for timely weed control. However, the efficacy of agrochemicals depends on the efficiency of spraying equipment. Conventional knapsack sprayers are used most often to spray herbicides but they are highly time-consuming, labour intensive and labour drudgery practices. Hence, the current experiment was aimed to study the efficiency of unmanned aerial vehicles (UAVs) on weed management. Methods: A field experiment was conducted at Tamil Nadu Agricultural University, Coimbatore during summer, 2022 to evaluate the efficacy of UAV-based herbicide application in direct-seeded rice. The study comprised of five weed management treatments such as pre emergence application of pretilachlor with safener and pyrazosulfuron through both UAV and knapsack sprayer and unweeded check as control. The experimental plot was laid out in a randomized block design with four replications. Result: The experimental findings showed that the application of pre-emergence pretilachlor significantly reduced the density and dry weight of grasses, sedges and broad leaved weeds in knapsack application. Moreover, it was found on par with UAV application of same herbicide without any phytotoxicity to rice seedlings. From the experiment, the application of pre-emergence pretilachlor through UAV is found to be more effective for timely weed control during early stages in direct-seeded rice, which reduce the labour intensity and drudgery than knapsack application. [ABSTRACT FROM AUTHOR]

Weeds are a major obstacle in the widespread implementation of direct seeding of rice (DSR). Traditional weed control methods have raised serious environmental and health concerns. In this study rhizobacterial strains were assessed for the growth inhibition of Leptochloa chinensis, Dactyloctenium aegyptium, and promotion of rice. For initial screening, hydrogen cyanide (HCN) and Escherichia coli (E. coli) was employed. After screening, plant growth-promoting traits were assessed, and two in vitro growth reduction and growth promotion trials were conducted on weeds and rice. Based on 16S ribosomal RNA (16S rRNA) gene sequencing, all selected rhizobacteria belonged to Pseudomonas spp. The results of the laboratory experiment showed that strains R4-1 (Pseudomonas plecoglossicida) and R16-10 (Pseudomonas fluorescens) exhibited significant ability to inhibit the growth of selected weeds, while potential to enhance the growth of rice. Further evaluation in pot trial under ambient light and temperature conditions showed that the selected strains significantly reduced weed growth and yield parameters of both weeds compared to the control. Strains R16-10 and R4-1 decreased the biomass of Leptochloa chinensis and Dactyloctenium aegyptium by 20% and 15%, respectively. The trial confirmed that strain R16-10 significantly increased DSR growth traits infested with Leptochloa chinensis and Dactyloctenium aegyptium, including grain yield (10% and 12%) and photosynthetic rate (9% and 7%). Furthermore, strain R4-1 was also effective in promoting the growth, yield, and physiological attributes of DSR. These results suggest that the strain R16-10 and R4-1 can reduce Leptochloa chinensis and Dactyloctenium aegyptium growth while promoting DSR growth. [ABSTRACT FROM AUTHOR]

Weed menace is the major biotic constraint in direct-seeded rice (DSR) cultivation as they cause higher yield loss. Hence, exploring different weed management options along with intercropping could be promising practice for improving crop productivity. Keeping this in view, an experiment was conducted at Pantnagar, Uttarakhand, India in 2015 and 2016 to evaluate the effect of different weed management practices in the DSR + Brahmi intercropping system for providing farmers with a practical and economically viable weed control solution. Two intercropping ratios along with four weed management practices in sole rice and sole Brahmi as control were evaluated. The results revealed the significant effect of weed management and intercropping on weed control efficiency (WCE) and different competition indices. The highest WCE (73.3 and 83.3%) was recorded with pendimethalin (pre-emergence) + cyhalofop-butyl (post-emergence) + 1 HW (hand weeding) at 45 DAS (days after sowing) in 2:1 ratio treatment. Similarly, significantly minimum density and weed biomass were also recorded under the same treatment. However, significantly higher values of relative yield total, aggressivity, relative crowding coefficient, and competition ratio were recorded in a 1:1 ratio of DSR + Brahmi. In conclusion, using Brahmi as an intercrop with DSR can help with weed management, reduces the use of pesticides, and increases profitability. [ABSTRACT FROM AUTHOR]

A field experiment was conducted during kharif 2016 and 2017 at the Main Research Station, Hebbal, Bengaluru to study the effect of different weed management treatments in dry direct-seeded rice (upland condition) on weed density, yield and soil weed seed bank as measured by emergence of weed seedlings. Among various weed management treatments hand weeding at 20, 40 and 60 DAS recorded significantly highest paddy grain and straw yield in hand weeding at 20, 40 and 60 DAS (5.50 and 7.22 t/ha, respectively) and found at par with application of bensulfuron-methyl + pretilachlor as pre-emergence fb bispyribac-sodium (5.39 and 7.16 t/ha, respectively). After the harvest of the crop a kilogram of soil (0-10 cm and 10-20 cm depth) was taken in a tray from each plot and observations were recorded on germination of weed seeds and weed seedling emergence at various intervals. At different intervals significantly the lowest weed seedlings emergence was noticed from the soils collected from different depths in hand weeded plots during both the years. Among various herbicide combinations, pre-emergence application of bensulfuron-methyl + pretilachlor followed by bispyribac sodium recorded the lowest germination of weed seeds and weed seedling emergence followed by bensulfuron methyl + pretilachlor and triafamone + ethoxysulfuron. Significantly the highest weed seed germination and seedling emergence was noticed from soil collected from weedy check. [ABSTRACT FROM AUTHOR]

Weeds are serious pests in rice sown under direct-seeded rice (DSR) technology. Herbicide-based weed management is becoming increasingly popular, but there is a dire need to choose appropriate herbicides and their effective dose for controlling weeds in DSR fields. A field trial was conducted to appraise the comparative efficacy of three post-emergent herbicides applied at different doses [Clover 20% EC (bispyribac sodium) at 39.54, 59.30, and 79.07 g a.i. ha-1, Pyranex Gold 30% WDG (bispyribac sodium + bensulfuron methyl) at 74.13, 111.20, and 148.26 g a.i. ha-1, and Puma Super 7.5% EW (fenoxaprop-p-ethyl) at 46.33 and 92.66 g a.i. ha-1] at 20 days after sowing (DAS) for weed control and paddy yield performance under DSR system. A weedy check was retained as control. Results revealed that Clover and Pyranex Gold applied at either dose significantly (p≤0.05) reduced the population and growth of Cyperus iria (90-97% weed density and 93-97% weed dry biomass) and Echinochloa colona (94-97% weed density and weed dry biomass) weeds over control, while Puma Super proved efficient in suppressing Leptochloa chinensis and Echinochloa colona weeds. Among all the tested treatments, application of Puma Super at 92.66 g a.i. ha-1 furnished the highest number of tillers (137.3 in 2014 and 141.3 in 2015), grains panicle-1 (77 in 2014 and 79 in 2015), final paddy yield (1983.8 and 1570 kg ha-1 in 2014 and 2015, respectively), and net economic returns (Rs. 95915 ha-1), followed by the use of Puma Super at 46.33 g a.i. ha-1 which offered the next best economic benefits (Rs. 81906 ha-1). Thus, applying Puma Super at 92.66 g a.i. ha-1 is appeared viable approach to control grassy weed flora and ensure higher paddy yield with higher economic returns when rice is sown under DSR technology. [ABSTRACT FROM AUTHOR]

Direct-seeded rice (DSR) is an emerging resource-saving rice production practice. It can be alternative to input-intensive conventional transplanted puddled rice, which has encountered problems, relating to water, nutrients, energy, and environment. DSR can save water, labour, and energy, reduce greenhouse gases emission and improve soil properties. But, weeds are major constraint, which can cause complete failure of rice. Effective weed management is essential to achieve higher yield and resource-use efficiencies. Herbicide is a more effective and economical option than other weed control methods. But, its efficacy is influenced by herbicides and their use rates, and the weed species that vary across locations, depending on climate and soil. Therefore, this field experiment was carried out to evaluate the combinations of pre-emergence (~ PE) and post-emergence (~ PoE) herbicides as sequential applications, and their impacts on weeds, crops, economics, water productivity, and major nutrients-use efficiencies. It was observed that weed control treatments reduced weed density by 68–84.5% and weed dry weight by 71.6–86.7% at 60 days after sowing (DAS) compared to unweeded control (UWC). Among them, the pendimethalin 1000 g ha–1 PE at 1 DAS followed by (~ fb) penoxsulam + cyhalofop-butyl 130 g ha–1 (pre-mix) PoE at 25 DAS resulted in significant reduction in weed density (~ 84.5%) and weed dry weight (~ 86.7%) at 60 DAS. These sequential herbicides application increased effective tillers (233.3 m–2), grains weight per panicle (2.54 g), and grain yield (3.92 t ha–1) of rice, and irrigation (0.87 kg m–3) and total water productivity (0.31 kg m–3) by 288.2%, 75.2%, 378.9%, 378%, and 380%, respectively, than those in UWC. This resulted in 17.9% and 73.3% higher net returns and net benefit: cost, respectively, than even weed-free control (WFC) and was superior to all. Contrast analysis revealed that the brown manuring (BM) fb almix 20 g ha–1 (pre-mix) applied at 40 DAS was similar to it, reducing weed density by 82.7% and dry weight by 83.3%. This study suggests that the sequential applications of herbicides or integration of herbicides with BM would provide broad-spectrum weed control and higher productivity and profitability in DSR. Controlling weeds may also reduce/economize water use and increase use efficiencies of N, P, and K in DSR. [ABSTRACT FROM AUTHOR]

Performance of eight rice (Oryza sativa L.) genotypes (‘Swarna Shreya’, ‘IR84899-B-179-13-1-1-1’,‘IR83929-BB- 291-2-1-1-2’,‘DRR-42’,‘IR84899-B-183-20-1-1-1’,‘IR84894-143-CRA-17-1’,‘DRR-44’,‘Rajendra Bhagwati’) was evaluated in three weed management practices, i.e. application of pendimethalin @1.0 kg/ha as pre-emergence (PE) at 2 days after sowing (DAS) followed by (fb) bispyribac-Na @30 g/ha as post-emergence (POE) at 20 DAS and two hand weedings (40 and 60 DAS)-low weed pressure; application of pendimethalin @ 1.0 kg/ha as PE fb bispyribac- Na @ 30 g/ha as POE at 20 DAS-medium weed pressure and pendimethalin @ 1.0 kg/ha alone-high weed pressure during rainy seasons of 2016 and 2017 at Patna, Bihar. Application of pendimethalin (PE) followed by bispyribac-Na (POE) and two hand weedings (low weed pressure) significantly reduced weed infestation compared to pendimethalin alone (medium weed pressure). Markedly lower weed density was recorded with ‘IR84899-B-179-13-1-1-1’. Low weed pressure produced 90 and 26% more grain yield (2.53 t/ha) compared to medium (2.01 t/ha) and high weed pressure (1.33 t/ha).Significantly higher grain yield was recorded with ‘IR84899-B-179-13-1-1-1’ (2.32 t/ha) followed by ‘Swarna Shreya’ (2.18 t/ha). Low weed pressure had significantly higher gross returns (45.9×103 `/ha) and net returns (14.1×103 `/ha). Amongst genotypes, ‘IR84899-B-179-13-1-1-1’ had the highest gross returns (44×103 `/ha) and net income (17.6×103 `/ha). Hence, it may be concluded that application of pendimethalin (PE) fb bispyribac-Na (POE) along with hand weeding had significant impact on reduction of weed infestation and helps in achieving the higher grain yield of direct-seeded rice genotypes in eastern India.

Parthenium weed (Parthenium hysterophorus L.) is an emerging weed species in direct-seeded aerobic systems of rice production. This two-year field study was conducted to evaluate the effect of five different densities (0, 5, 10, 15 and 20 plants m−2) of parthenium weed on rice yield and yield-related attributes. Parthenium weed produced ca. 38 to 178% higher biomass at its densities of 10 to 20 plants m−2 as compared to the lowest density of 5 plants m−2. The paddy yield and yield-related attributes were negatively affected with an increase in the parthenium weed density. In both years, the highest reductions in number of rice panicles (14 to 17%), panicle length (10 to 11%), number of grains per panicle (11 to 18%), 1000-grain weight (8 to 21%) and paddy yield (30 to 35%) were recorded at the highest parthenium weed density (20 plants m−2) tested. However, the lower densities of 5 to 15 parthenium weed plants m−2 also caused 11 to 24% and 12 to 26% losses in paddy yield during the years 2016 and 2017, respectively. Therefore, this weed species should be controlled below the density of 5 plants m−2 to avoid the substantial yield losses (over 15%) in direct-seeded rice. [ABSTRACT FROM AUTHOR]

Direct seeding of rice (Oryza sativa L.) has since long been viewed as a potential alternative to unsustainable water-intensive transplanted rice (TPR) world-over, but heavy infestation of a variety of weed species limits the large-scale adoption of direct-seeded rice (DSR) cultivation. Hence, a 2-year field investigation was carried-out in a spilt-plot design, at Banaras Hindu University, Varanasi, during rainy seasons of 2016 and 2017 to assess the influence of various crop establishment methods (CEMs) and weed management options (WMs) on diverse weed-flora, nutrient removal by weeds, weed-control efficiency (WCE) and yield of DSR (cv. Rajendra Kasturi). The results revealed that zero-till DSR + residue + Sesbania brown manure (ZTDSR + R + SBM) was most effective in containing crop-weed competition, lowered density of Echinochloa colona (L.) Link , Echinochloa crusgalli (L.) Beauv. , Cynodon dactylon (L.) Pers. , Eclipta alba (L.) Hassak. , Caesulia axillaris Roxb., Cyperus rotundus L., Cyperus iria L., Fimbristylis miliacea (L.) Vahl. by 63.4% and enhanced grain yield by 22.8%. Further, applying pendimethalin at 1000 g ai ha−1 as PRE. and later post-emergence (POST) spray of chlorimuron + metsulfuron at 4 g ai ha−1 each 20 days after sowing (DAS) supplemented with 1 hand-weeding (HW) 45 DAS was found to be a better weed management option as this treatment recorded the lowest density and nutrient depletion by above mentioned weeds and higher WCE, thereby improving rice yield by 3–19.5% over other studied WMs. Also, the combination of this weed management option with ZTDSR + R + SBM suppressed weeds to a greater extent, restricting weeds to deplete nutrients (N, P and K) from the soil and finally fetched the highest DSR yield. • Zero-till DSR + residue + Sesbania brown manure (ZTDSR + R + SBM) enhanced rice grain yield. • Use of Pendimethalin (1000 g ai ha−1) as PRE. and POST chlorimuron + metsulfuron (4 g ai ha−1) is beneficial. • The combination of WM with ZTDSR + R + SBM was the best option for improving DSR yield. [ABSTRACT FROM AUTHOR]

A field experiment was conducted during rainy season of 2009 at the research farm of the Indian Agricultural Research Institute, New Delhi to evaluate the appropriate combination of pre-emergence and post-emergence herbicides in direct-seeded rice (Oryza sativa L.). All the weed control treatments brought significant increase in grain (25-52%) and straw yield (27-58%) as compared to season long crop weed competition. Cyhalofop-butyl residues in soil were found below detectable level indicating safety to soil microbial population and succeeding crop. It may be concluded that weeds can be managed during critical period of competition with the sequential application of pretilachlor (750 g/ha) as pre-emergence followed by post- emergence application of cyhalofop-butyl (60 g/ha) at 30 DAS in direct-seeded rice.

A field experiment was conducted during rainy season of 2010 at the research farm of the Indian Agricultural Research Institute, New Delhi to evaluate the performance of penoxsulam for weed management in direct-seeded and transplanted rice. The weed growth in terms of density and dry weight was relatively less in transplanted condition as compared to direct-seeded rice. Post-emergence application of penoxsulam @ 25 g/ha at 10 DAS/DAT was found more effective against weeds as compared to its application at 15 DAS/DAT. Herbicidal treatments provided a yield advantage of 66-73% over weedy check. Growth and yield attributes, grain and straw yield increased significantly with the penoxsulam at 25 g/ha applied at 10 DAS/DAT which was on par with its application at 15 DAS/DAT with the same dose. It may be concluded that weeds can be managed during critical period of competition with the application of penoxsulam at 25 g/ha at 10 DAS/DAT in both direct-seeded and transplanted rice cultures.

Field trials were conducted at Agricultural Research Farm, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi during kharif seasons of 2011 and 2012 to study the effect of crop establishment methods and weed management practices on weeds, growth and yield of direct-seeded rice. Results indicated that bed planting of dry-seeded rice suppressed dry matter accumulation of weeds-grasses, sedges and broad leaf weeds most effectively among crop establishment methods, and as a consequence this crop establishment method had markedly higher growth rates, higher growth and yield attributes. Among different weed management practices, integrated weed management practices, namely, pre-emergence spray of pendimethalin 1 kg/ha followed by brown manuring of dhaincha by 2,4-D 0.50 kg/ha at 25 days after sowing (DAS) and combination of pre-emergence spray of pendimethalin 1 kg/ha followed by early post-emergence spray of bispyribac 0.025 kg/ha followed by brown manuring of dhaincha by 2,4-D 0.50 kg/ha at 25 DAS significantly lowered dry matter of all weeds than other weed management practices, thus improved growth and its rate and yield attributes of direct-seeded rice. Though crop establishment methods did not significantly influence grain yield of direct-seeded rice, protein content in grain and its yield were markedly improved by bed and no-till methods than conventional method. Integration of pendithalin application with brown manuring of dhaincha and pendimethalin followed by bispyribac followed by brown manuring of dhaincha registered significantly higher grain yield, protein content in grain and its yield than remaining weed management practices. [ABSTRACT FROM AUTHOR]

Weeds are one of the key threats in sustaining the productivity of the rice-wheat cropping system in the Indo-Gangetic Plains. The development of sound integrated weed management technologies requires knowledge of mechanisms that influence weed flora composition and weed seedbank dynamics. A long-term study was initiated in 2015 at Patna, Bihar, India to evaluate the effect of seven tillage and crop establishment methods on weed density, weed seedbank composition, and crop productivity in rice-wheat-mungbean rotation. All the treatments included zero-till mungbean after wheat. Tillage and crop establishment methods had differential effects on weed and weed seedbank composition. In rice, zero-till direct-seeded rice recorded 62% lower emergence of Cyperus iria , 82–90% of Echinochloa colona, and 81–83% of total weeds compared to tilled systems, but the system of rice and wheat intensification favoured E. colona. In wheat, the system of wheat intensification favoured the Phalaris minor and Solanum nigrum. Zero-till rice and wheat reduced the seedbank of Trianthema portulacastrum by 95%, and total weed seedbank by 62% compared to the system of rice and wheat intensification. Nearly, 72% of C. iria seeds, 62% of grasses, and 64% of broad-leaved weeds were in 0–15 cm soil layer. Zero-till direct-seeded rice produced a 13% lower rice grain yield than conventional puddled transplanted rice. Compared to the system of wheat intensification, zero-till wheat under triple zero-till systems produced an 11.5% higher grain yield. Managing weed seedbank is a long-term endeavour. The present study revealed that tillage and crop establishment methods influence weed density and diversity. Under zero-till rice-wheat system, rice yield decreases marginally, but the system productivity maintains due to improvement in succeeding wheat yield. This system is also helpful in reducing the weed flora density and soil weed seedbank. Regular monitoring and management of emerging pests such as armyworm (Mythimna separata) are, however, required. The study suggests that the adoption of triple zero-tillage can be a viable option for reducing the weed density and weed seedbank concurrently increasing the system productivity of the rice-wheat-mungbean cropping system in eastern Indo-Gangetic Plains. • Effect of tillage and crop establishment on soil weed seedbank in rice-wheat-mung bean system is poorly explored. • Direct-seeded rice (DSR)-based conservation agriculture (CA) system reduced weed density and seedbank than conventional. • More than 60% weed seeds were placed in 0–15 cm soil depth. • Zero-till wheat after DSR produced higher yield than conventional till wheat after puddled transplant rice. • After five years, CA system favoured infestation of armyworm (Mythimna separata) in wheat. [ABSTRACT FROM AUTHOR]

A field experiment was conducted during rainy season of 2010-11 at the Research Farm of the Indian Agricultural Research Institute, New Delhi to study the efficiency of new low dose herbicide penoxsulam on growth and development of rice, their associated weeds and micro flora. The results of experiment revealed that penoxsulam 24 SC at 25 g/ha applied at 10 DAS/DAT significantly reduced the weed population, increased growth, yield (4.86 t/ha) and yield attributes of rice crop. Herbicidal treatments provided a yield advantage of 65.98 to 72.63% over weedy check. Herbicides exerted a significant detrimental effect on soil bacteria, fungi and actinomycetes. The counts of bacteria, fungus and actinomycetes recorded at 10 DAS/DAT revealed that soil microbes were more sensitive to penoxsulam 25 g/ha applied at 10 DAS/DAT and pre-emergence application of pretilachlor @ 750 g/ha as evident from significant reduction in their population, eventually microbial density started to recover slowly. [ABSTRACT FROM AUTHOR]

Abstract: Weed control is a primary concern in direct-seeded rice, particularly for herbicide-resistant weed species which stand to threaten the long-term sustainability of California rice systems. In a four-year field study we evaluated the potential for improved weed control using no-till stale seedbed practices in water-seeded (WS) and drill-seeded (DS) rice establishment systems. In addition, as the agronomic performance of alternative tillage and crop establishment methods is not well understood, we assessed the productivity of these systems and estimated economic optimum nitrogen (EON) rates based on yield response to nitrogen (N) trials. Establishment system treatments included: water-seeded conventional tillage (WS conventional), water-seeded conventional tillage stale seedbed (WS stale), water-seeded no-till stale seedbed (WS no-till stale), drill-seeded conventional tillage (DS conventional), and drill-seeded no-till stale seedbed (DS no-till stale). Compared to the WS conventional system, WS stale and WS no-till stale treatments significantly reduced sedge weed biomass by 59 and 95%, respectively. Although redstem (Ammannia spp.) was not controlled, alternative WS systems reduced grass weed biomass by more than 99% when present. Within DS systems, no-till stale seedbed practices significantly reduced watergrass (Echinochloa spp.) biomass by 75% in the first two years but did not improve watergrass control during the second half of the study. Grain yields were not different for conventional and alternative rice establishment systems each year when N was applied at 168kgNha−1 and weeds were fully controlled. However, yields were significantly lower for alternative establishment systems compared to the WS conventional system when no N fertilizer was applied, likely as a result of greater soil N losses. The response of grain yield to N rate was significantly different among systems and estimated EON rates indicated that WS stale and WS no-till stale systems required an increase of 30–35kgNha−1 to maximize yields and returns to N compared to the WS conventional system. Results from this experiment demonstrate that alternative tillage and crop establishment systems can lead to improved weed control while remaining viable from an agronomic and economic standpoint in California. Provided N rates are close to optimal and WS and DS establishment methods are selected to target weed species of concern, these findings suggest that no-till stale seedbed practices should be considered as a component of integrated weed management strategies in direct-seeded rice moving forward. [Copyright &y& Elsevier]

Abstract: Rice is one of the most important food crops in the world, and staple for more than half of the global population. Looming water crisis, water-intensive nature of rice cultivation and escalating labour costs drive the search for alternative management methods to increase water productivity in rice cultivation. Direct seeded rice (DSR) has received much attention because of its low-input demand. It involves sowing pre-germinated seed into a puddled soil surface (wet seeding), standing water (water seeding) or dry seeding into a prepared seedbed (dry seeding). In Europe, Australia and the United States, DSR is highly mechanised. The development of early-maturing varieties and improved nutrient management techniques along with increased availability of chemical weed control methods has encouraged many farmers in the Philippines, Malaysia, Thailand and India to switch from transplanted to DSR culture. This shift should substantially reduce crop water requirements, soil organic-matter turnover, nutrient relations, carbon sequestering, weed biota and greenhouse-gas emissions. Still, weed infestation can cause large yield losses in DSR. In addition, recent incidences of blast disease, crop lodging, impaired kernel quality and stagnant yields across the years are major challenges in this regard. In this review, we discuss the experiences, potential advantages and problems associated with DSR, and suggest likely future patterns of changes in rice cultivation. [Copyright &y& Elsevier]

Abstract: Weeds cause substantive yield losses in rainfed rice, particularly direct-seeded rice (DSR). Two field experiments were conducted in 2005 in north-east Thailand to examine the effects of cutting date and timing of fertilizer application on suppressed weed, growth and yield of DSR. Treatments consisted of two fertilizer applications to the main plots (top-dressing at the date of cutting and 15 days after cutting; DAC) and four cutting dates of the sub-plots. Rice and weed cutting was performed at 30, 45, 60 and 75 days after seeding (DAS), compared with an untreated control. Cutting resulted in a higher growth rate and improved grain yield of rice compared to the untreated control. Weed cutting at 60 DAS resulted in the greatest leaf area index, which contributed to the maximum number of tiller as well as maximum plant dry mass when observed at 30 DAC. Lower densities and dry weights of weeds at 30 DAC were observed when cutting was done 60 DAS, resulting in a higher grain yield than the other cutting dates. Timing of fertilizer application had no significant effect on the density and dry weight of grasses and broad-leaved weeds, but did have a significant affected on, resulting in the lowest density of sedges at 45 DAC was observed with fertilizer applied at cutting date. Rice grain yield was higher with top-dressing of fertilizer at 15 DAC than with fertilizer applied at cutting date. The cutting treatments resulted in higher net incomes than the untreated control. These results indicate that rice and weed cutting at an appropriate growth stage is an alternative method to chemical weed control for DSR in rainfed riceland. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

Rice grown in the Sacramento Valley of California is predominantly water seeded (WS), by direct-seeding rice into flooded basins. The effects of flooded rice monoculture and limited herbicides have led to difficult-to-control weed populations, and widespread local herbicide resistance. A novel "stale-drill" rice establishment method has been under investigation in California, to address these constraints. Two rice varieties with high seedling vigor ('M-206', 'M-209') were dry-drilled to 3 cm and 6 cm in 2018 and 2019, and fields were flush-irrigated to initiate weed germination prior to stand emergence. A postplant-burndown (PPB) application of glyphosate at 870 g a.e. ha-1 was applied 6-7 days after planting (DAP), at rice emergence, which controlled >50% of total seasonal weeds. Glyphosate PPB caused rice first-leaf dieback, but no other symptoms developed. Planting depth or cultivar did not affect date of emergence either year. Deeper seeding reduced M-206 and M-209 stands by 15.4% and 5.2%, respectively, in 2018, but not in 2019. Increased tillering compensated for stand reductions in 2018. Panicle yield components were largely unaffected by planting depth in 2018, however florets panicle-1 and filled grains panicle-1 were slightly greater for both cultivars at 6 cm. In 2019, M-209 suffered reductions in florets per panicle and grain filling at 6 cm planting depth. Grain yields were unaffected by planting depth in either study year. M-206 and M-209 grain yields were 10.2 T ha-1 and 12.2 T ha-1 respectively, in 2018, and 9.4 T ha-1 and 9.1 T ha-1 respectively, in 2019. Proper water management and scouting are essential to ensure that PPB treatments do not injure emerging rice to the extent that weak or reduced stands result. However, the present study serves as a promising proof-of-concept for the "stale-drill" method as an alternative stand establishment method in mechanized rice production. [ABSTRACT FROM AUTHOR]