Influence of Rice Residue Management Techniques and Weed Control Treatments on Soil Available Plant Nutrients in Rice-Wheat Cropping System

Rice-wheat is the predominant cropping system of fertile soils of Indian, Pakistan, Bangladesh and Nepal falling in the alluvial Indo-Gangetic Plains (IGP). Management of rice residues produced after the harvest of rice crop and before sowing of the next wheat crop is a big challenge in that area. Mostly farmers burn rice residues assuming it low profile fodder and of little use. Burning of rice residues deprives the fields from many plant nutrients as they are lost during burning along with environmental pollutions and other issues. A field study was conducted for two consecutive years at the experimental area of the Department of Agronomy, Punjab Agricultural University, Ludhiana (India) to assess the impact of different rice residue management techniques and weed control treatments in wheat on soil available plant nutrients in rice-wheat cropping system. The experiment was laid out in split plot design with three replications. In main plots, five rice residue management treatments viz., no rice residue, rice residue 5 t·ha-1 (surface), rice residue 6 t·ha-1 (surface), rice residue 7 t·ha-1 (surface) and rice residue 5 t·ha-1 (incorporation) were settled and in sub plots, four weed control treatments i.e. clodinafop 60 t·ha-1, sulfosulfuron 25 t·ha-1, mesosulfuron + iodosulfuron 12 t·ha-1 and control (unweeded) were arranged. Results of the study revealed that surface application as well as incorporation of rice residues improved the organic carbon and NPK status than no rice residues. Among the residue management practices, incorporation of rice residues 5 t·ha-1 significantly improved the soil organic carbon, available nitrogen, phosphorus and potassium than no rice residue treatment in the 0 - 15 soil layer during both the years. Same trend was observed for 15 - 30 cm soil layer but differences were less wide than 0 - 15 cm soil layer. Among the weed control treatments, organic carbon was not significantly influenced. Herbicide treated plots registered significantly higher available nitrogen, phosphorus and potassium than control (unweeded) treatment in the 0 - 15 cm soil layer during both the years.

Effect of Establishment Methods and Weed Management Practices on Some Growth Attributes of Rice

Studies were carried out for two years to evaluate the effect of methods of sowing and weed control practices on the productivity of transplanted and direct wet-seeded rice in Dera Ismail Khan, NWFP, Pakistan. The experiment was laid out in a randomized complete block design with a split plot arrangement. The planting techniques viz. transplanting and direct seeding were maintained in main plots while weed control practices included the use of granular herbicide Sunstar 15WG （ethoxy sulfuron）, Machete 60EC （butachlor）, conventional hand weeding, and the weedy check （control） were assigned to the sub-plots. Data were recorded on weed parameters like weed density and dry weed biomass 60 and 90 days after sowing （DAS）; agronomic parameters including plant population, number of panicles and paddy yield and physiological parameters like leaf area index and net assimilation rate 45 and 90 DAS. The planting methods and weed management significantly influenced most of the parameters studied. The data revealed that the paddy yield and its components were significantly higher in the transplanted method than that in direct-seeded method, while the weed density and biomass were lower in the transplanted plots than the direct-seeded plots. Among weed management tools, the maximum paddy yield was obtained in hand weeding, closely followed by herbicide application Machete 60EC during both cropping seasons.

Competitiveness of Winter Rice Varieties against Weed under Dry Direct Seeded Conditions

Aerobic rice or dry direct seeded rice is highly vulnerable to weeds because of lack of “head start” over weeds and standing water layer to suppress weeds. The risks of chemical control and the huge cost involvement in mechanical control demand an eco-friendly and cost-effective integrated weed management. Weed competitive rice cultivar may be considered as a viable tool for integrated weed management. In these circumstances, an experiment was designed to evaluate weed competitiveness of some selected winter rice varieties under aerobic soil conditions. The study was conducted during dry season (February to June) 2016 at the Agronomy Field Laboratory and Weed Management Laboratory, Bangladesh Agricultural University, Mymensingh. Fourteen rice varieties namely, BRRI dhan28, BRRI dhan29, BRRI dhan47, BRRI dhan50, BRRI dhan55, BRRI dhan58, BRRI dhan59, BRRI dhan67, Binadhan-5, Binadhan-6, Binadhan-8, Binadhan-10, BRRI hybrid dhan3 and Agrodhan-14 were grown under weedy and weed-free conditions. Plots with no rice were also maintained to observe the natural growth of weed in absence of rice. The experiment was conducted with split-plot design with three replications. Weeding regime was allocated in main plot and rice variety was allocated in sub-plot. Results showed that rice varieties varied widely in their yield performances and weed competitiveness. Among rice varieties, BRRI dhan59 allowed the minimum weed growth (19.2 g m-2) while Binadhan-5 allowed the maximum weed growth (62.8 g m-2). Grain yield ranged from 1.85 t ha-1 (BRRI dhan55) to 3.92 t ha-1 (Binadhan-5) under weed-free condition and between 0.41 t ha-1 (BRRI dhan55) and 2.06 t ha-1 (BRRI dhan59) under weedy condition. Weed inflicted relative yield loss ranged from 43.4% to 82.1% among the varieties. BRRI dhan59 allowed the least yield penalty (43.4%) while Binadhan-5 had the maximum yield penalty (82.1%) due to weed competition. Although Binadhan-5 is the most productive variety (3.92 t ha-1) for aerobic culture but its weed inflicted relative yield loss is higher (82.1%) than many other varieties with low yield potential. On the other hand, BRRI dhan59 appeared as the most weed competitive variety (only 43.4% relative yield loss) with productivity of 3.84 t ha-1. Therefore, weed competitive variety should be considered as a vital tool while designing integrated weed management system for aerobic rice.

Chemical Weeding in Dry Direct Seeding Fields of Single Cropping Middlelate Rice

Chemical weeding in dry direct seeding fields of single cropping middle-late rice was studied in Huida vegetable farm of Huizhou City in 2012. The main treatment was herbicide（ pretilachlor ＋ bensulfuron-methyl,Yangguo and butachlor）,and the sub-treatment was application method（ soil treatments,seedling treatment and integrated treatment）. The results showed that 80 g pretilachlor ＋ bensulfuron-methyl（ 36% pretilachlor ＋ 4% bensulfuron-methyl） diluted with 50 kg water could be sprayed or 200 g Yangguo（ 23. 9% butachlor ＋ 1. 1% bensulfuron-methyl） mixed with 15 kg sandy soil could be broadcasted per 667 m2 on the sowing day or the second day under moist condition of soil,which could effectively control weeds in dry direct seeding fields of single cropping middle-late rice.

Evaluation of Population Structure, Genetic Diversity and Origin of Northeast Asia Weedy Rice Based on Simple Sequence Repeat Markers

Weedy rice exerts a severe impact on rice production by competing for sunlight, water and nutrients. This study assayed the population structure, genetic diversity and origin of Northeast Asia weedy rice by using 48 simple sequence repeat markers. The results showed that weedy rice in Northeast Asia had a high genetic diversity, with Shannon＇s diversity index （I） of 0.748 and the heterozygosity （He） of 0.434. In each regional population, I value varied widely. The widest range of I （0.228-0.489） was observed in the weedy rice of Eastern China, which was larger than that of Northeast China and Korea （0.168-0.270）. The F-statistics of regional populations （Fis, Fit and Fst） also showed higher values in the weedy rice of Eastern China than those of Northeast China and Korea All weedy rice accessions were grouped into two clusters in the unweighted pair group method with arithmetic mean cluster analysis dendrogram, namely Eastern China branch and Northeastern China plus Korea branch. There was significant differentiation in genetic characteristics in weedy rice of northeastern and eastern Asia, especially in Eastern China.

Weed-Suppressing Effect and Mechanism of Allelopathic Rice Accessions

Two allelopathic rice accessions, PI312777 and Allelopathy1, significantly suppressedthe growth of associated weeds in the field. Moreover, their weed-suppressing effectswere correlated with the cultivation patterns. The weed-suppressing effects of throwingand transplanting were more effective than that of direct seeding. Furthermore, theamounts of allelochemicals (resorcinols, flavones and hydroxamic acids) produced andreleased from two allelopathic rice accessions were much higher than that from a non-allelopathic rice variety Hua-Jing-Xian1, and reached the maximum concentration at the6th leaf stage. Differences in the weed-suppressing effects of rice accessions appear toresult from the accessions producing and releasing different amounts of allelochemicalsin the field. Further research confirmed that in PI312777 plants, allelochemicals weresynthesized by the above-ground parts, and then secreted through the root tissues. Roottissues of PI312777 plants never produced the allelochemicals. Root exudates fromPI312777 could significantly inhibit the growth of E. crus-galli surrounding rice plantsin water culture. However, when activated carbon was added to the culture solution, whichcould absorb allelochemicals from root exudates, the growth of E. crus-galli was nolonger significantly inhibited. Weed-suppressing effects of rice accessions depended onallelopathy, cultivation patterns and other factors in rice fields, while allelopathywas one of important factors. Interestingly, the amounts of allelochemicals produced andreleased from allelopathic rice plants may be induced by the presence of E. crus-galli.This suggests that there is a possible chemical recognition between rice and E. crus-galli.

Prevention Effects of Pyrazosulfuron-ethyl·Quinclorac 50% WP on Stem and Leaf of Dry Direct Seeded Rice

[Objective] The aim was to explore the prevention effects of pyrazosul-furon-ethyl·quinclorac 50% WP on stem and leaf of dry direct seeded rice. [Method] Totaling 7 drug doses were set in the test and the effects were observed 5, 10, 15 and 30 d after drug application, with the remained weeds surveyed 15 and 30 d after drug application. [Result] The test showed pyrazosulfuron-ethyl·quinclorac 50%WP was safe to rice as treatment agent of stem and leaf, and rice yield increased dramatical y, with the growth rate in 2.1%-49.3%. After the drug application, the prevention effects on Echinochloa crusgal i, Ludwimlia prostrata, Monochoria vamli-nalis, and Zong grass were 92.2%, 96.6%, 93.5%, and 94.8%, and the effects on fresh weight were 94.8%, 97.1%, 93.3% and 94.9%, respectively. [Conclusion] Pyra-zosulfuron-ethyl·quinclorac 50% WP can be taken as treatment agents of stem and leaf of dry direct seeded rice.

Allelopathy:Potential Role to Achieve New Milestones in Rice Cultivation

Rice fields are ecosystems with many types of plants, microbes, invertebrates, birds and animals. The rice farming protects the biodiversity of the region and maintains the ecosystem for the benefit of environment. Some rice varieties release biocidal allelochemicals which might affect major weeds, microbial and pathogenic diversity around rice plants, even soil characteristics. A large number of compounds such as phenolic acids, fatty acids, indoles and terpenes have been identified in rice root exudates and decomposing rice residues, as putative allelochemicals which can interact with surrounding environment. Since these allelopathic interactions may be positive, they can be used as effective contributor for sustainable and eco-friendly agro-production system. Genetic modification of crop plants to improve their allelopathic properties and enhancement of desirable traits has been suggested. Development of crops with enhanced allelopathic traits by genetic modification should be done cautiously, keeping in view of the ecological risk assessment(non-toxic and safe for humans and ecosystem, crop productivity, ratio of benefit and cost, etc.).

Selection of Thickness of High Density Polyethylene Film for Mulching in Paddy Rice

In water deficit area, judicious use of water is essential for increasing area under crop production with limited water supply. Film Mulching has been advocated as an effective means for conserving soil moisture in rice production. The effects of high density polyethylene (HDPE) film on increasing rice production, controlling weeds and residue amount of plastic were studied under five treatments, including 5, 10, 15 and 20 μm thickness as well as bare cultivation (CK). The results indicated that the HDPE film mulching mode had significant effects on weed control, soil temperature, soil moisture, photosynthetic rate, seedling biomass, yield and residues of plastic film. Combined with economic effect, it showed that the HDPE film of 10 μm is the best option for rice production.

Impact of integrated package of agrotechniques on growth and yield of aerobic rice

A field experiment was conducted during Kharif, 2011-2012 and 2012-2013 at GKVK, Bengaluru, Karnataka to study the effect of integrated package of agrotechniques on growth and yield of aerobic rice. The predominant weed flora observed in the experimental field were, Eleusine indica, Digitaria marginata L., Dactyloctenium aegyptium L., Alternanthera sessilis, Mollugo distica L., Celosia argentia and Borreria hispida. Treatments receiving integrated weed management practices recorded significantly lower weed population and weed dry weight as compared to pre-emergence application of pyrazosulfuron ethyl alone. Application of RDF + FYM + Biofertilizers + FeSO4 +IWM practices (T8) recorded significantly higher growth, yield parameters and yield as compared to RDF + FYM + IWM practices and was being on par with RDF + FYM + Biofertilizers + IWM practices (T5).

除草剂不同时期应用对机直播稻田杂草的防除作用

为开发机直播水稻田高效安全的封闭除草剂,采用大田试验,比较了不同时期应用含有乙氧磺隆成分的除草剂对阔叶草和莎草科杂草的防除效果。结果发现,播种时同步喷施五氟·乙氧或混配乙氧磺隆与其他除草剂能够有效抑制机直播稻田阔叶草和莎草科杂草的萌发和生长,且对水稻出苗安全。机直播后10 d或15 d施用对阔叶草防效下降,但播种15 d后撒施0.65%五氟·乙氧控释颗粒剂97.5 g/hm^(2)对杂草防效较好,密度防效达到90%以上。表明采用五氟·乙氧或混配乙氧磺隆与其他除草剂防除机直播稻田阔叶草,越早施药效果越好。但如果因气候条件或其他因素影响错过施药窗口期时,撒施0.65%五氟·乙氧控释颗粒剂97.5 g/hm^(2)或喷施30%氰氟草酯112.5 g/hm^(2)+30%五氟·乙氧90 g/hm^(2)也可以防控绝大部分直播田杂草。

Physiological Age Status of Female Adults and Off-Season Survival of Rice Leaffolder Cnaphalocrocis medinalis in India

Rice leaffolder, Cnaphalocrocis medinalis, is one of the major foliage feeders found in the rice growing regions in India. When the crop was at maturity, numerous adults of rice leaffolder were found in the rice fields though the larval population gradually decreased, and no eggs were found on rice leaves. The population characteristics of C. medinalis were assessed based on the physiological age status of adults at different crop growth stages. Based on egg development within ovarioles, ovariole appearance number and colour of fat bodies, and characteristics of bursa copulatrix, physiological age status of the adults was described, which served as a basis for the determination of age composition. C. medinalis adults were found during the first week of August on rice plants, of which 44% were in Age 0 with immature ovaries, indicating immigrants. However, 28% adults each were at Ages 1-2 with developing ovaries, indicating local breeding population. The carryover and off-season survival of C. medinalis were also studied to determine the contribution of the alternative hosts in the population growth that helped in devising efficient management strategies. Rice was the most preferred host followed by Triticum aestivum, Echinochloa crusgulli and Brachiaria plantaginea. Various routes of the carryover of C. medinalis from season to season were discussed.

洁田稻稻田杂草防控及杂草稻种群耐药性研究

为探索咪唑啉酮类除草剂对洁田稻稻田常规杂草和杂草稻的防治效果及不同杂草稻种群对咪唑乙烟酸的耐药性,采用大田试验在不同时期喷施不同浓度的咪唑乙烟酸水剂防治田间不同杂草及室内盆栽试验鉴定杂草稻耐药性。结果表明:咪唑乙烟酸在水稻播后20 d施用,对田间杂草稻具有较好的防效,1 200 mL·hm^(-2)咪唑乙烟酸对田间杂草稻的防效达92.8%。过早施药对杂草稻防效普遍低于90%,过晚施药需加大剂量才能达到较好的防效。咪唑乙烟酸供试中、高浓度对稗草和千金子具有较好的防效,而对多花水苋和丁香蓼等阔叶杂草防效较差。耐药性鉴定结果表明,不同区域的杂草稻种子对咪唑乙烟酸较敏感,未产生明显的耐药性。

江西稻田杂草发生特点、危害损失与药剂防治研究

【目的】对江西稻田杂草的发生种类、危害损失及其药剂防治技术进行了研究,旨在为江西稻田杂草精准防控提供理论依据和实用技术。【方法】采用田间调查、回归分析及药剂防治试验等研究方法,系统分析了稻田杂草的种类、发生特点及其对水稻产量的影响,并评估了不同药剂的防治效果与经济阈值。【结果】江西稻田杂草种类丰富,主要有稗草、千金子、鸭舌草等,其中移栽稻田和水直播稻田杂草群落结构和出苗特征不同;杂草对水稻的产量影响显著,密度增加会导致产量损失,经济阈值根据不同杂草种类而异;通过药剂防治试验,确定了适合江西稻田的杂草防治药剂和施用技术,防效良好,增产效果显著。【结论】江西稻田杂草防治需要根据不同稻田类型和杂草种类选用合适的药剂及防治技术,合理控制杂草密度,以最大限度减少水稻产量损失,为稻田杂草的精准防控提供科学依据。

两种复配除草剂对直播稻田杂草的防除效果

【目的】杂草是制约直播水稻生产的关键因子,研究两种复配除草剂对直播稻田杂草的防除效果,为直播稻田杂草防除提供实用技术。【方法】2023年在上高县直播稻田采用茎叶喷雾法试验了两种复配除草剂对直播稻田杂草的防除效果。【结果】27.5%二氯•双草醚SC 247.50~330.00 g/hm^(2)处理后15 d对稗草、鸭舌草和异型莎草的总杂草株防效为89.32%~96.87%,药后30 d株防效和鲜重防效分别为87.83%~95.82%和89.30%~96.45%;30%苄嘧磺隆•丙草胺OD 360.00~540.00 g/hm^(2)处理后15 d株防效为93.62%~100.00%,药后30 d株防效和鲜重防效分别为92.46%~99.19%和94.09%~99.41%,且对水稻生长安全。【结论】27.5%二氯•双草醚SC、30%苄嘧磺隆•丙草胺OD这两种复配制剂适宜用于直播稻田杂草的防治。

基于ViT-改进YOLOv7的稻田杂草识别

为解决光线遮蔽、藻萍干扰以及稻叶尖形状相似等复杂环境导致稻田杂草识别效果不理想问题,该研究提出一种基于组合深度学习的杂草识别方法。引入MSRCP(multi-scale retinex with color preservation)对图像进行增强,以提高图像亮度及对比度;加入ViT分类网络去除干扰背景,以提高模型在复杂环境下对小目标杂草的识别性能。在YOLOv7模型中主干特征提取网络替换为GhostNet网络,并引入CA注意力机制,以增强主干特征提取网络对杂草特征提取能力及简化模型参数计算量。消融试验表明:改进后的YOLOv7模型平均精度均值为88.2%,较原YOLOv7模型提高了3.3个百分点,参数量减少10.43 M,计算量减少66.54×109次/s。识别前先经过MSRCP图像增强后,与原模型相比,改进YOLOv7模型的平均精度均值提高了2.6个百分点,光线遮蔽、藻萍干扰以及稻叶尖形状相似的复杂环境下平均精度均值分别提高5.3、3.6、3.1个百分点,加入ViT分类网络后,较原模型平均精度均值整体提升了4.4个百分点,光线遮蔽、藻萍干扰一级稻叶尖形状相似的复杂环境下的平均精度均值较原模型整体提升了6.2、6.1、5.7个百分点。ViT-改进YOLOv7模型的平均精度均值为92.6%,相比于YOLOv5s、YOLOXs、MobilenetV3-YOLOv7、YOLOv8和改进YOLOv7分别提高了11.6、10.1、5.0、4.2、4.4个百分点。研究结果可为稻田复杂环境的杂草精准识别提供支撑。

A Preliminary Study of the Key Technologies in Rice Seed Production

To study the production technology of rice seeds,with Lianjing 7 as test material,this paper explores the effects of the key rice seed production,processing and storage technologies( such as nitrogen fertilizer application and management,weeding mode in seed breeding field,temperature control of mechanical drying and water control on seed storage) on the quality of rice seeds. The results show that the optimal application proportion of tillering stage dressing and earing fertilizer is 8: 2,followed by 7 : 3; the best time of weeding is booting stage,with the highest purity; the effect of drying and germination rate is best when the temperature is controlled at 44℃ in mechanical drying process; the seed storage quality and storage costs can be guaranteed when the water content of rice seed is controlled at 18%.

轻简化栽培稻田杂草发生趋势与防控技术

随着水稻轻简化栽培技术的应用与推广,东北稻区、西北稻区、长江流域稻区和华南稻区等水稻主产区的杂草种群演替加快,稗草、千金子和马唐等恶性杂草频繁发生,杂草抗药性水平上升迅速。若杂草防控不及时、不彻底,极易对水稻生产构成严重威胁。为此,对水稻直播、机插和抛秧等轻简化栽培稻田杂草的草相特征、发展趋势和防除方法等进行了概述,以期为制定合理、高效的轻简化栽培稻田杂草综合防控技术、水稻用农药减量增效除草方案,延缓杂草抗药性产生与发展提供借鉴。

植保无人机喷施封闭除草剂对稻田杂草的防效研究

为探究植保无人机喷施除草剂对直播稻田杂草防效,采用50%丁草胺乳油、26%噁草酮悬浮剂、350 g/L异噁草松微囊悬浮剂、300 g/L丙草胺乳油4种封闭除草剂,在飞行高度2 m和3 m,用水量22.5、45.0 L/hm^(2)条件下设置不同处理,考察播前施药结合水层管理及播后干封对水稻安全性及对直播稻田不同种类杂草的防除效果。结果表明,26%噁草酮悬浮剂2个用水量处理的成苗率和苗高显著低于其余处理,播后30 d各处理水稻分蘖数均显著高于空白对照,各处理5株苗茎基宽与空白对照无差异。药后15 d,3种除草剂供试浓度下高用水量处理对稗草、千金子、多花水苋、异型莎草等杂草的防效均优于低用水量;播前水封与播后干封效果整体上差异不大。药后40 d,整体上各处理防效均降低,26%噁草酮悬浮剂、350 g/L异噁草松微囊悬浮剂在高用水量时对稗草的株数防效显著优于低用水量,3种药剂在高用水量时对千金子的株数防效均显著高于低用水量,鲜重防效与株数防效趋势基本一致。3种药剂不同飞防参数下对异型莎草和多花水苋的防效有差异,且效果较差。同一药剂在用水量45 L/hm^(2)和飞行高度3 m时对不同杂草的防效优于用水量22.5 L/hm^(2)和飞行高度2 m处理。不同除草剂对不同种类杂草的防效存在差异,高用水量播前施药结合水层管理对不同杂草的防效均优于播后干封处理。后期应适时进行茎叶处理,以提升施药对田间杂草的治理效果。

不同除草剂组配对旱地水稻杂草的防效

【目的】分析不同除草剂配施对旱地水稻农艺性状、产量和经济效益的影响,综合评估供试除草剂配施的杂草防控效果,以期为旱地稻田杂草的经济、高效防除提供科学依据。【方法】以滇型杂交粳稻滇禾优615为材料,进行播后苗前除草剂处理土壤和苗后除草剂处理茎叶的最佳组配筛选。【结果】不同除草剂组合对旱地水稻杂草的防效差异显著。采用播后苗前10%苄嘧磺隆可湿性粉剂(0.30 kg/hm^(2))+60%丁草胺水乳剂(1.80 L/hm^(2))处理土壤、苗后26%氰氟·氯氟吡乳油(0.53 L/hm^(2))+20%噁唑·氰氟乳油(0.90 L/hm^(2))处理茎叶的组配方案防效最佳,药后15和30 d的株数防效分别为92.00%和90.25%,30 d的鲜质量防效为95.75%;该组合对旱地水稻安全,且可节本增效。【结论】本研究筛选的药剂组配方案成本低、收益高、对杂草防除效果好,为旱地水稻种植选择高效安全的除草剂提供了依据。