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The experiment was conducted at the Agronomy Field Laboratory of Bangladesh Agricultural University during the period from July to December 2017 to evaluate the effect of barley crop residues on weed management and yield of transplant aman rice. The experiment consisted of three time of crop residue application viz. one week before transplanting, at the time of transplanting, at one week after transplanting and five doses of barley crop residues such as no crop residues, barley crop residues @ 0.5 t ha-1, barley crop residues @ 1.0 t ha-1, barley crop residues @ 1.5 t ha-1, and barley crop residues @ 2.0 t ha-1. The experiment was laid out in a split plot design with three replications. Weed population and weed dry weight were significantly affected by the dose and time of barley crop residues application. The minimum weed growth was noticed with the application of barley crop residues @ 2.0 t ha-1 at one week after transplanting and the maximum one was observed in no crop residues treatment at one week before transplanting. The highest values of percent weed inhibition was found with the application of barley crop residues @ 2.0 t ha-1 which were 48.13%, 41.39%, 39.71%, 39.88% and 38.73% for panikachu (Monochoria vaginalis), shama (Echinochloa crusgalli), chesra (Scirpus juncoides), amrul (Oxalis corniculata) and sabujnakful (Cyperus difformis), respectively. Rice grain yield and the yield contributing characters produced by the application of crop residues at one week before transplanting was the highest among different times of application and the highest reduction of rice grain yield was obtained in no crop residue treatment. The highest number of effective tillers hill-1, number of grains panicle-1, 1000-grain weight, rice grain and straw yields were observed when barley crop residues were applied @ 2.0 t ha-1 at one week before transplanting. Results of this study indicate that application of barley crop residues @ 2 t ha-1 at one week before transplanting showed the maximum suppression of weed growth. Therefore, barley crop residues might be used as an alternative tool for weed management in transplant aman rice. Progressive Agriculture 31 (2): 119-129, 2020

Herbicides are used successfully for weed control in rice fields for rapid effect, easier to application and low cost involvement in comparison to the traditional methods of hand weeding. Sulfentrazoneis a new pre-planting herbicide in Bangladesh. Field trials were conducted at Bangladesh Rice Research Institute (BRRI), Gazipur during Aman 2014 and Boro 2014-15 to evaluate the efficacy of sulfentrazone 48 SC on weed suppression and performance of transplanted rice. Treatments were Sulfentrazone 48 SC @ 150, 200 and 250 ml ha-1, pretilachlor 500 EC @ 1000 ml ha-1, weed free and unweeded control. Visual assessment indicated that this herbicide possesses high selectivity and not toxic to rice plants. The results revealed that the major weed flora associated with the transplanted rice was mainly comprised of two grasses, two sedges and four broadleaves in Aman 2014 and two grasses, two sedge and two broadleaves in Boro 2014-15. The most dominant weeds were Cyperus difformis, Echinochloa crus-galli, Scirpus maritimus and Monochoria vaginalis in both the growing seasons. Application of Sulfentrazone 48 SC @ 200 ml ha-1 was most effective to suppress weed density and dry masses in both the seasons resulting increased grain yield more than 50% as compared to unweeded control. Therefore, Sulfentrazone 48 SC @ 200 ml ha-1 should apply two or three days before plantingfor effectively control weeds in riceBangladesh Rice j. 2017, 21(1): 67-76

Experiment was carried out at the Agronomy field of Bangladesh Rice Research Institute, Gazipur, during the period from December 2014 to May 2015 to investigate the response of different levels of N and methods of weeding on weed abundance and grain yield of BRRI hybrid dhan3 under alternate wetting and drying (AWD) irrigation condition. The treatments consisted of five N levels viz.,0, 60, 120,180 and 240 kg N ha-1 and four different weed control methods viz., Pre-emergence herbicide followed by 1HW, Pre-emergence followed by post emergence herbicide, Weed free by 3 hand weedings and Unweeded (control). The experiment was laid out in factorial RCB design with three replication. Pre-emergence application of prefer 18WP (Bensulfuran Methyl + Acetachlor) and post emergence herbicide Dhaman 300wp (Bispyribac sodium 18% + Bensulfuran methyl 12%) followed by one hand weeding effectively control all weeds (78-93%). In the experimental field, sedges and grass weeds were highly dominant over treatments. Based on summed dominance ratio (SDR), the most dominant weed species could be arranged in the order of Echinochloa crus-galli > Scirpus juncoides > Cynodon dactylon > Cyperus difformis > Marselia minuta > Monochoria vaginalis. Interaction of nitrogen levels and weeding methods had significant response on yield and yield components of hybrid rice. The highest (7.61 t ha-1) grain yield was obtained from the combination @ 180 kg N ha-1 with weed free treatments. Comparable higher grain yield was obtained from the combination of pre emergence herbicide of bensulfuranm methyl + acetachlor) + one hand weeding with 180 kg N ha (7.48 t ha-1) and the combination of pre + post-emergence herbicide (Bispyribac sodium 18% + Bensulfuran methyl 12%) with 180 kg N ha-1 (7.56t ha-1). The estimated optimum dose of nitrogen for Pre EH, Post EH and 3HW (weed free) were 173, 189.1 and 189.4 kg N ha-1 respectively for BRRI hybrid dhan3 under AWD irrigation system.Bangladesh Agron. J. 2017, 20(1): 13-24

The genus Monochoria is represented in Sri Lanka by only two species, M. hastata and M. vaginalis . Of the two species M. vaginalis exhibits a high morphological diversity. A morphometric analysis was performed on the Sri Lankan members of the genus Monochoria to evaluate the morphological diversity exhibited by comparing 34 vegetative, anatomical and reproductive characters. Both cluster and principal coordinate analyses resulted in four clusters of which one corresponded to M. hastata , while M. vaginalis was divided into three phenetic groups indicating that the Sri Lankan M. vaginalis is a species complex involving more than one taxon. The length ratio of the lower spathe petiole to inflorescence stalk was identified as an informative character in delimiting the phenetic groups, a character that has not been considered before. Further, the occurrence of sub-palisade cavities that are filled with a red colored liquid in the leaves of two phenetic groups was a novel character for the genus as well as the family Pontederiaceae. Keywords: Monochoria vaginalis ; Morphological data; Sub-palisade cavities; Principal coordinate anaysis. Bangladesh J. Plant Taxon. 24 (1): 13–22, 2017 (June)

Field experiments were conducted at Bangladesh Rice Research Institute (BRRI), Gazipur in Aus, 2010 and BRRI Rangpur, during Boro 2011 to evaluate the performance of Acetochlor 50% EC for weed suppression, to find out an appropriate dose of the herbicide and its impacts on transplanted rice. Acetochlor 50%EC @ 200, 250 and 300 ml ha -1 were applied. Pretilachlor 50% EC @ 1L ha -1 , weed free and unweeded control was used for comparison. The most dominant weeds were Cyperus diffornis, Monochoria vaginalis and Echinochloa crus-galli in year 1 and Cyperus diffornis and Echinochloa crus-galli in year 2. Cyperus diffornis was at the higher rank of dominant in both years. Application of Acetochlor 50%EC @ 250 ml gave more than 80% weed control efficiency, lower number and dry weight of weeds which ultimately resulted in higher yield attributes and grain yield of transplanted rice that were comparable to the standard in both seasons. DOI: http://dx.doi.org/10.3329/jesnr.v4i2.10137 J. Environ. Sci. & Natural Resources, 4(2): 73-77, 2011