Yield of Short Duration Drought Tolerant Transplant Aman Rice Varieties as Influenced by Integrated Nitrogen and Weed Management Practices

An experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh from December 2016 to May 2017 to investigate the effect of weeding regime on the performance of boro rice cultivars. The experiment comprised of two factors, Factor A- Rice cultivars: BRRI dhan28, BRRI dhan29, and BRRI dhan74, Factor B: Methods of weeding- no weeding, two hand weedings at 15 and 35 DATs, application of pre-emergence herbicide Commit, application of early post-emergence herbicide Pediplus, application of pre-emergence herbicide Commit followed by application of early post-emergence herbicide Pediplus, application of pre-emergence herbicide Commit followed by one hand weeding at 35 DAT, and application of early post-emergence herbicide Pediplus followed by one hand weeding at 35 DAT. The experiment was laid out in a split plot design assigning rice cultivars in the main plots and weed management practices in the sub-plots with three replications. Fourteen weed species infested the experimental field belonging to six families. Among the weed species, four were grasses, four were broad leaves and six were sedges. Cultivar exerted significant effect on weed density and dry weight. Both the highest weed density and dry weight were found in BRRI dhan28 and the lowest ones were observed in BRRI dhan29 rice cultivar. Weed density and weed dry weight were significantly influenced by weeding regime. The highest weed density and dry weight were observed in no weeding condition and application of pre-emergence herbicide Commit followed by one hand weeding at 35 DAT showed the best performance. BRRI dhan29 produced the highest grain and straw yields among the cultivars. Weed control had pronounced influence on yield of rice. The highest grain yield was obtained in application of pre-emergence herbicide Pretilachlor (Commit)followed by one hand weeding at 35 DAT and the lowest one was obtained in control (no weeding) treatment. From the results of the study it may be concluded that rice cultivar BRRI dhan29 with application of pre-emergence herbicide Commit followed by one hand weeding at 35 DAT might be the best treatment for controlling weed effectively as well as obtaining highest yield and highest economic return. J Bangladesh Agril Univ 17(3): 265–273, 2019

At Instructional Farm in Jaguli, a field experiment was carried out in the summer of 2022 and 2023 at Bidhan Chandra Krishi Viswavidyalaya Mohanpur, West Bengal. The experiment was laid out in split plot design with three main plot treatments (dates of sowing) and eight sub plot treatments (weed management practices) replicated thrice. Main plot treatments comprised of three dates of sowing i.e. D1: Sowing on February 21st, D2: Sowing on March 7th, and D3: Sowing on March 22nd. Sub plot treatments comprised of eight weed management practices i.e. W1. Pendimethalin @ 1 kg a.i. ha-1 [2 DAS (days after sowing)] + Hand weeding (30 DAS),W2:: Butachlor@ 1kga.i. ha-1(2 DAS)+Hand weeding(30 DAS),W3: Hand weeding(15DAS)+ Quizalofop ethyl @ 50 g a.i. ha-1 (30 DAS), W4: Pendimethalin @ 1 kg a.i.ha-1 (2 DAS) + Quizalofop ethyl @ 50 ga.i. ha-1 (30 DAS), W5: Butachlor @ 1 kg a.i.ha-1 (2 DAS) + Quizalofop ethyl @ 50 g a.i. ha-1 (30 DAS),W6: Hand weeding (15 DAS) + Hand weeding(30DAS),W7:Weedy check and W8:Weed free check. Sesame variety ‘Savitri’was chosen for the experiment. The weed density (Grass weed density, sedge weed density, broad leaved density and total weed density were significantly influenced by weed management practices only. Interactions between dates of sowing and weed management practices were found to be non-significant. Among the weed management practices, (W1) Pendimethalin @ 1 kg a.i. ha-1 (2 DAS) + Hand weeding 30 DAS observed significantly lower grass, weed, sedge weed, broad leaved weed and total weed density (7.94 m-2) were noticed. The highest total weed density (12.75 m-2) was observed in weedy check (W7).

The experiment was laid out in split plot design with three replications comprising sixteen treatment combinations. Treatments consisted of four weed management practices (W1: Pyrazosulfuron-ethyl at 25 g ha-1 at 3 DAS; W2: Pyrazosulfuron-ethyl at 25 g ha-1 at 3 DAS fb penoxsulam (1%) + cyhalofop-butyl (5%) 130 g ha-1 at 21 DAS ; W3: Pyrazosulfuron-ethyl at 25 g ha-1 at 3 DAS fb 1 HW at 35 DAS and W4: Hoeing and weeding at 25 and 45 DAS in main plot and four nitrogen management practices (N1: 100% Recommended dose of nitrogen through inorganic, N2: 50% RDN + 50% N through Farm Yard Manure (FYM), N3: 50% RDN+ 50% N through mustard cake, N4: 50% RDN+ 25 % N through FYM + 25% N through mustard cake) were taken in sub-plots. Among the different weed management practices, the lowest density and dry weight of all categories of weeds as well as total weed was recorded under hoeing and weeding twice and it was at par with pyrazosulfuron-ethyl at 25 g ha-1 PE fb one hand weeding. Among the nitrogen management practices, the lowest density and dry weight of all types weeds as well as total weed was recorded with 50% RDN+ 50% N through mustard cake at 60 days after sowing (DAS). Pyrazosulfuron-ethyl at 25 g ha-1 PE fb 1 HW recorded highest grain and straw yield along with high yield attributing characters like panicles per m2, grains per panicle, filled grains per panicle and panicle weight and it was at par with hoeing and weeding twice. Among the nitrogen management practices, application of 50% RDN+ 50% N through mustard cake recorded the maximum value of yield attributes and yield over others. Combined application of pyrazosulfuron-ethyl at 25 g ha-1 PE fb 1 hand weeding at 35 DAS along with 50% RDN+ 50% N through mustard cake recorded the maximum grain and straw yield over others. Thus, pyrazosulfuron-ethyl at 25 g ha-1 at 3 DAS fb 1 hand weeding (HW) at 35 DAS along with 50% RDN+ 50% N through mustard cake was found to be promising for effective weed management, higher productivity and profitability in direct seeded rice.

The Bangladesh Rice Research Institute (BRRI) has released more than 100 inbred rice varieties. Still, an old mega variety BRRI dhan28 dominates the farmers’ fields during the dry winter (Boro season: November–June) season. This variety is very susceptible to different diseases and insects, causing lower yield performance than its potential. To replace this variety, current on-farm research was planned to evaluate the newly developed four superior rice varieties: BRRI dhan58, BRRI dhan63, BRRI dhan67, and BRRI dhan74 during Boro season in 2017 and 2018. The objective was to create data and popularize new varieties among farmers all over the country. We conducted 15 on-farm trials with farmers’ active participation at Senbag, Fulgazi, and Mirsarai Upazila of Noakhali, Feni, and Chattogram districts, respectively, in Bangladesh. The results demonstrate that BRRI dhan74 produced the highest grain yield among the tested varieties, followed by BRRI dhan67, BRRI dhan63, and BRRI dhan58, while BRRI dhan28 produced the lowest. However, BRRI dhan67 obtained the highest preference scores from the farmers and extension personnel due to its medium and slender grains, shorter growth duration, resistance to lodging, less disease, and less insect invasion. Moreover, stability indices for yield revealed that BRRI dhan67 was the most stable, adaptive, and appropriate variety, followed by BRRI dhan74, across the locations. Farmers showed keen interest to grow BRRI dhan67 by themselves instead of BRRI dhan28 all over the study locations. The neighboring farmers also expressed their curiosity about cultivating BRRI dhan67 over BRRI dhan28 by collecting seeds from the participating farmers. Thus, BRRI dhan67 could be a perfect replacement for BRRI dhan28. However, conducting participatory varietal evaluation trials across the agroecological zones of the country is recommended to validate the results of this study.

Develoment of weed competitive crop cultivars is an attractive low-cost strategy of integrated weed management program that can reduce the heavy dependence of crop cultivation to chemical herbicides. Hence, to evaluate the weed competitiveness Bangladesh Rice Research Institute (BRRI) released selected monsoon rice varieties, a field experiment was conducted during July to December 2018 at the Agronomy Field Laboratory of Bangladesh Agricultural University. Thirty-three rice varieties were grown under season long weedy and weed-free conditions. Plots without rice plants were also maintained to investigate the natural growth of weed in absence of rice. The experiment was conducted following randomized complete block design with three replicates. The results showed that rice varieties varied widely in yielding ability and weed competitiveness. Among rice varieties, BRRI dhan31 allowed the minimum weed growth (32.5 g m-2) while BRRI dhan51 allowed the maximum weed growth (155.3 g m-2). Grain yield ranged between 3.6 t ha-1 (BRRI dhan49) and 7.5 t ha-1 (BR10) under weed-free condition and between 2.2 t ha-1 (BRRI dhan70) and 3.9 t ha-1 (BRRI dhan34) under weedy condition. Weed imposed relative yield loss ranged from 10.2 to 66.9% among the rice varieties. BRRI dhan34 allowed the least yield penalty (10.2%) while BRRI dhan70 had the maximum yield penalty (66.9%) due to competition with weeds. Although BR10 appear as the most productive variety (7.5 t ha-1) its weed imposed relative yield loss was higher (51.3%) than many other varieties with low yield potential. On the other hand, BRRI dhan34 appeared as the most weed competitive variety (only 10.2% relative yield loss) with productivity of 3.9 t ha-1. Considering the yield, BR10 was the best but for weed suppressive ability BRRI dhan34 performed well.

A field study was conducted at research field of Spices Research Sub-Centre (SRSC), Faridpur, Bangladesh to find out the efficacy of weed management practices on the growth, yield, quality and economics of onion with the variety BARI Piaz-6. Thirteen treatments such as: T1-control as check (no weeding), T2-weed free, T3-one hand weeding (HW) at 45 days after transplanting (DAT), T4-two HW at 25 and 45 DAT, T5-three HW at 25, 45 and 65 DAT, T6-pre-emergence (PE) spray of pendimethalin 33 EC @ 330g a.i/litre + one HW at 45 DAT, T7- PE spray of pendimethalin 33 EC @ 330g a.i/litre + two HW at 45 and 65 DAT, T8- post emergence (POE) spray of pendimethalin 33 EC @ 330g a.i/litre at 25 DAT + one HW at 65 DAT, T9- PE spray of oxyfluorfen 23.5 EC @ 235g a.i./litre + one HW at 45 DAT, T10- PE spray of oxyfluorfen 23.5 EC @ 235g a.i./litre + two HW at 45 & 65 DAT, T11- POE spray of oxyfluorfen 23.5 EC @ 235g a.i./litre at 25 DAT + one HW at 65 DAT, T12- PE spray of pendimethalin 33 EC @ 330g a.i/litre + POE spray of oxyfluorfen 23.5 EC @ 235g a.i./litre at 45 DAT + one HW at 65 DAT and T13- PE spray of oxyfluorfen 23.5 EC @ 235g a.i./litre + POE spray of pendimethalin 33 EC @ 330g a.i/litre at 45 DAT + one HW at 65 DAT were compared by randomized complete block design with three replications. The study revealed that the weed management treatments under the study significantly influenced all parameters except total soluble solid content of onion bulb. Weed density had reverse effect on growth, development and yield of onion. Among the weed’s infestation, Cyperus rotundus (55-60%), Echinochloa crusgalli (10-15%) and Chenopodium album (8-10%) were predominant. The highest weed density (137.25 weeds/m2) were recorded from the T1. The lowest weed density (15.24 weeds/m2) were observed from T13. The T3 had the least weed control efficacy (23.56%). The maximum fresh yield (19.49 t/ha) of onion bulb were obtained from T2 followed by T13 (19.31 t/ha). The highest benefit-cost ratio (2.19) was calculated from the T13 closely followed by T12 (2.18). From this study it was concluded that Pre-emergence application (PE) application of oxyflourfen or pendimethalin + post-emergence (POE) application of oxyflourfen or pendimethalin at 45 DAT (days after transplanting) + once HW (hand weeding) at 65 DAT and also PE of oxyflourfen or pendimethalin + twice HW at 45 & 65 DAT exhibited good performance to control weeds in onion field.

Pot experiments were conducted in net house during Boro 2002 and 2003 at Bangladesh Rice Research Institute (BRRI) to compare the growth and yield of hybrid and inbred rice varieties under controlled condition. Hybrid variety Sonarbangla-1 and BRRI hybrid dhan1 and inbred modern variety BRRI dhan29 were used in both the years. During Boro 2002, Sonarbangla-1 and BRRI hybrid dhan1 had higher plant height and tillers hill-1 compared to BRRI dhan29. The largest leaf area of 75cm2 hill-1 was recorded in BRRI hybrid dhan1 at 30 DAT but at 60 and 90 DAT, Sonarbangla-1 had the highest leaf area of 723 and 1406 cm2 hill-1, respectively. The highest shoot dry matter production was recorded in BRRI hybrid dhan1 at 30 DAT but in Sonarbangla-1 at 60 and 90 DAT. Rooting depth and root dry weight of Sonarbangla-1 were 15- 20% higher than those of BRRI hybrid dhan1 and BRRI dhan29. At harvest, the largest number of panicles hill-1 was observed in BRRI dhan29 followed by Sonarbangla-1. The number of grains panicle-1, 1000-grain weight and grain yield were higher in Sonarbangla-1 followed by BRRI dhan29. During Boro 2003, highest plant height, number of tillers hill-1, leaf area and shoot dry matter were recorded in BRRI hybrid dhan1 at all DAT, followed by Sonarbangla-1 in most cases. Rooting depth and root dry weight were the highest in Sonarbangla-1 followed by BRRI hybrid dhan1. At harvest, highest number of panicles hill-1 were observed in BRRI dhan29 and Sonarbangla-1 but BRRI hybrid dhan1 had the highest number of grains panicle-1. Sonarbangla-1 had the highest 1000-grain weight and grain yield.

Sustainable agriculture mostly relies on conservation tillage, crop residue retention and crop diversification. Weeds are major production hurdles in adoption of conservation agriculture (CA), therefore, weed management is important for sustainable crop yield. Designing efficient integrated weed management (IWM) practices under zero-tillage with crop residue (ZT+R) is helpful in getting optimum yield. A field experiment was carried out at research farm of ICAR-Directorate of Weed Research, Jabalpur (M.P.), India with eight treatment combinations, two crop establishment methods (conventional tillage and conservation tillage) in main plots and four weed management practices (weedy check, recommended herbicide, IWM, and herbicide rotation) in sub-plots were evaluated using a split plot design with three replications. The results indicated that the wheat sown under ZT+R led to significantly less weed density (105.9 no. m-2 in 2020-21 and 122.8 no. m-2 in 2022-23) and biomass (149.7 and 174.2 g m-2, respectively) hence, registered the highest weed control efficiency (WCE, 72.3% and 71.2%, respectively). Higher WCE helped in producing better wheat growth indices like plant height (106.3 and 101.1 cm, respectively), biomass (12.0 and 9.0 g plant-1, respectively) and no. of tillers (488.0 and 391.3 no. m-2, respectively) ultimately grain yield (4164 and 3814 kg ha-1, respectively) and straw yield (7265 and 6834 kg ha-1, respectively) compared with conventional tillage during both the years. Among the weed management practices, ready-mix application of clodinafop + metsulfuron at 60+4 g ha-1 (30-35 days after sowing, DAS) followed by (fb) hand weeding at 45 DAS increased growth indices like plant height (110.2 and 105.0 cm, respectively), plant biomass (14.9 and 12.1 g plant-1, respectively) and no. of tillers (547.2 and 436.7 no. m-2, respectively) ultimately grain yield (4708 and 4299 kg ha-1, respectively) and straw yield (7836 and 7610 kg ha-1, respectively), and WCE (97.4% and 96.8% respectively) with significantly less weed density (25.7 and 35.0 no. m-2, respectively) and biomass (13.6 and 19.9 g m-2, respectively) at 90 days after sowing. IWM also completely reduces the weed density and biomass over the other weed management practices during both the years. Therefore, wheat sown under ZT+R coupled with IWM was superior in terms of weed control, crop growth and yields.

Peanut (Arachis hypogaea L.) yield and financial return can be negatively affected by weeds and the combination of early leaf spot disease [ Passalora arachidicola (Hori) U. Braun] and late leaf spot disease [ Nothopassalora personata (Berk. & M.A. Curtis) U. Braun, C. Nakash., Videira & Crous] in Ghana. Research was conducted in southern Ghana to evaluate hand-weeding, herbicide applied preemergence (PRE) or herbicide applied postemergence (POST), a combination of PRE and POST herbicides, and PRE or POST herbicides supplemented with hand-weeding and disease management practices (i.e., no fungicide or a two sequential fungicide applications 45 and 60 days after planting). Although some differences in leaf spot severity were observed based on weed management, peanut pod yield and financial return based on yield and cost of pest management practices were affected by weed management and disease management practices individually but not the interaction of these treatment factors. The weed management practices with the highest financial return included a POST herbicide with or without hand weeding and a PRE herbicide followed by hand-weeding or a POST herbicide.

Weed is one of the major constraints for success of dry direct seeded rice (DDSR) technology. The productivity, weed density and weed dry weight of DDSR is influenced by weed management practices. A field experiment was done to evaluate tillage methods and weed management practices on weed dynamics and yield of DDSR using split plot design; each treatment replicated thrice. The treatment consisted of two tillage methods in the main plots, and eight weed management practices in the sub-plots. Gorakhnath-509 was the variety of rice used. Weed flora observed in the experiment comprised of 25 weed species, belonging to 12 families. Among them 12 were broadleaf weed, belonging to 10 families; 8 were grasses, belonging to Poaceae family, and the rest 5 were sedges, belonging to Cyperaceae family. Tillage methods did not influence weed density and weed dry weight in DDSR, but weed management practices reduced weed density and dry weight at all dates of observation compared to weedy check. All the weed management practices significantly improved the grain yield of DDSR in both tillage methods. Treatments with higher grain yield of DDSR were, use of pendimethalin followed by hand weeding (3,742 kg ha-1); pendimethalin followed by bispyribac-Na (3,552 kg ha-1), and pendimethalin followed by tank mixture application of bispyribac-Na and ethoxysulfuron(3,638 kg ha-1), but were statistically similar (p>0.05). Results thus supports the fact that application of popular pre-emergence herbicide- pendimethalin followed by manual weeding, or post-emergence herbicide, such as Bispyribac-Na, or tank mixture of post emergence herbicides bispyribac-Na and Ethoxysulfuron could be the most effective weed management practices in both tillage method of rice cultivation.

A field experiment was conducted during two consecutive kharif 2019 and 2020 on sandy loam soils of S.V. Agricultural College, Tirupati, Andhra Pradesh. The field experiment was laid out in a split-plot design with three replications. The treatments comprised of four nitrogen management practices viz., control (N1), recommended dose of fertilizer (N2), green seeker directed N application (N3) and soil test based fertilizer application (N4) assigned to main plots and nine weed management practices viz., unweeded check (W1), hand weeding twice at 15 and 30 DAS (W2), pre emergence application of atrazine 1.0 kg ha-1 fb post emergence application of topramezone 30 g ha-1 (W3), pre emergence application of atrazine 1.0 kg ha-1 fb post emergence application of tembotrione 120 g ha-1 (W4), application of parthenium water extract 15 l ha-1 twice at 15 and 30 DAS (W5), application of sunflower water extract 15 l ha-1 twice at 15 and 30 DAS (W6), pre emergence application of atrazine 1.0 kg ha-1 fb post emergence application of parthenium water extract 15 l ha-1 (W7), pre emergence application of atrazine 1.0 kg ha-1 fb post emergence application of sunflower water extract 15 l ha-1 (W8) and brown manuring (W9) allotted to subplots. Growth parameters of maize, yield attributes, and yield were higher with green seeker-directed N application (N3). Control (N1¬) recorded significantly lower values during both the years of study and in the pooled mean. With regard to weed management practices, significantly higher values were produced with hand weeding twice at 15 and 30 DAS (W2), which was however, in parity with pre-emergence application of atrazine 1.0 kg ha-1 fb post-emergence application of topramezone 30 g ha-1 (W3) and pre emergence application of atrazine 1.0 kg ha-1 fb post-emergence application of tembotrione 120 g ha-1 (W4). Lower values of growth parameters were recorded with an unweeded check (W1). Significant interaction between nitrogen and weed management practices was observed with dry matter production, cob length, kernel weight cob-1, kernel yield and stover yield. Higher and lower values were recorded with green seeker-directed N application along with hand weeding twice at 15 and 30 DAS (N3W2) and control coupled with an unweeded check (N1W1) respectively during both the years of study and in pooled mean.

Mechanical intervention in crop production is increasing rapidly in Bangladesh. Researchers are finding ways to manage weeds in rice field using suitable mechanical devices instead of conventional hand weeding. A study was conducted to evaluate the field performance of BRRI (Bangladesh Rice Research Institute) power weeder compared to BRRI weeder and hand weeding in the farmers’ field at Rashidpur in Mithapukur upazila under Rangpur district during boro season of 2014-15. Three treatments: T1 = BRRI weeder (BW), T2 = BRRI power weeder (BPW) and T3 = Hand weeding (HW) were used in the experiment. The experiment was carried out in a randomized complete block design (RCBD) and replicated in four farmers’ plots. Rice variety BRRI dhan28 was selected for the experiment. The effective field capacity of BW and BPW was found to be 0.06 and 0.09 ha hr-1, respectively. The weeding efficiency was the highest in HW (92%), followed by BPW (78%) and BW (73%). It was found that BW damaged the lowest number of plants (9%) compared to BPW (11%) during weeding operation, although the damaged plants recovered after a few days. BW and BPW reduced 74 and 85% of labor requirement in weeding operation compared to HW. The highest weeding cost was involved in HW (Tk. 4287 ha-1) compared to BW (Tk. 1103 ha-1) and BPW (Tk. 950ha-1). Weed control methods exerted insignificant effect on grain yield. BRRI power weeder and BRRI weeder reduced weeding cost, enhanced weed control and improved the labor efficiency without sacrificing grain yield. The highest BCR was obtained in BPW (1.22) followed by BW (1.16) and HW (1.11). BRRI power weeder and BRRI weeder appeared to be economic, easy and also environmentally safe weed control device in low land rice cultivation. The Agriculturists 2017; 15(1) 40-48

An experiment was conducted to examine the effect of weed management and plant nutrition practices on weed biomass, growth parameters and bulb yield of onion ( Allium cepa L.). Weed management practices included alone application of herbicides, viz. pendimethalin, oxyfluorfen and fluazipop-p-butyl, their combination with hand weeding, weed free and weedy check. The crop was fertilized with three levels viz., 75% RDF, RDF (100:50:50 NPK kg/ha) and 125% RDF. The results indicated that weed management and fertilizer levels had a significant ef- fect on weed population dynamics and onion bulb crop. The total weed density decreased significantly with appli- cation of pendimethalin 1 kg/ha or oxyfluorfen 0.24 kg/ha + one hand weeding at 40 days after transplanting (DAT) during both the seasons of investigation. Echinochloa ssp., Trianthema portulacastrum, Digera arvensis Forsk. Physalis minima L. and Cynodon dactylon (L.) Pers. were found as major weeds in the crop. Higher onion bulb yield (38.0 t/ha) was recorded with pendimethalin 1 kg/ha + one hand weeding at 40 DAT. The increase in yield was 83.7% compared to the yield obtain in weedy check. Increasing level of fertilizer applications increased the to- tal biomass of grassy and broad leaves weeds. Application of 125% RDF significantly improved bulb yield and in- crease in yield was 19.4 and 10.5 % over 75% RDF and RDF respectively. On the basis of interaction, combina- tion of pendimethalin 1 kg/ha fb 1 hand weeding at 40 DAT and 100 % RDF was most productive (39.8 t/ha) and profitable (Net return `2,69,422/ha and benefit: cost ratio 7.85).

Background: Weeds are one of the most important elements influencing crop productivity. Tillage practices have a significant effect on the weed seed bank and the appearance of weeds, both of which have a direct impact on farm productivity. Different tillage strategies based on ploughing depth, as well as weed control practices, change the dynamics of weed seeds in the soil. This research will aid in the development of integrated weed control methods by investigating the interaction between tillage and weed management practices. Methods: Field trials were carried out in two seasons, Summer and Kharif 2022, using a split-plot design with three tillage methods and four weed management practices. The treatments were replicated three times. Result: Among the different tillage treatments Mouldboard plough fb Cultivator fb Rotovator recorded the lowest weed density. With respect to weed management methods, pre- and post-emergence herbicide application and hand weeding at 20 and 40 DAS recorded the lower weed density. Interaction effects of tillage and weed management practices resulted in lower weed density in Mouldboard plough fb Cultivator fb Rotovator with herbicide application and Mouldboard plough fb Cultivator fb Rotovator with hand weeding. Highest weed density was recorded under Cultivator fb Rotovator in unweeded control. With respect to relative density, among the broad-leaved weeds (BLW) Trianthema portulacastrum and Dactyloctenium aegyptium in grasses dominated among the weed species in 30 and 60 DAS respectively. From the present study it was concluded that the Mouldboard plough fb Cultivator fb Rotovator with hand weeding twice or herbicide application reduces the weed emergence from the soil weed seed bank.

Weed management practices are crucial for controlling weeds as they reduce yield, increase the production cost as well as deteriorate the grain quality. So, an experiment was conducted at Monirampur, Jashore, Bangladesh during July 2020 to June 2021 to find out the appropriate weed management practices in boro rice. BRRI dhan29 was selected as planting material to see the effect of seven different weed management practices such as no weeding, pre-emergence, post-emergence, pre-emergence followed by (fb) hand weeding (HW) at 40 DAT, post-emergence fb HW at 40 DAT, pre-emergence fb post-emergence and two HW at 20 and 40 DAT following single factor randomized complete block design (RCBD) with three replications. The study revealed that Poaceae and Cyperaceae contributed more weeds among 15 different families. Monochoria vaginalis, Fimbristylis miliacea, Echinochloa crus-galli, Cyperus rotundus and Alternanthera sessilis were more abundant among 34 weed species. The highest weed density (98.22 m−2 ) and dry weight (51.36 g m−2 ) were found in no weeding condition but that of the lowest value (weed density: 9.93 m−2 and dry weight: 3.59 g m−2 ) was observed in pre-emergence fb one HW at 40 DAT. The highest grain yield (6.52 t ha-1 ), net income (91571 Tk ha-1 ) and B:C ratio (1.9) were recorded in pre-emergence fb HW at 40 DAT followed by pre-emergence fb post-emergence treatment. The lowest value of grain yield (3.29 t ha-1 ), net income (12290 TK ha-1 ) and B:C ratio (1.14) were found in no weeding treatment. As per results, it can be concluded that pre-emergence fb HW at 40 DAT has been revealed as the best weed management practice for BRRI dhan29.