Application Of Metsulfuron-methyl Research Articles

Impact of Low-dose Herbicides on Weed Dynamics and Nutrient Removal by weeds in Transplanted Rice

The objective of this study is to find out the effect of low-dose herbicides on growth and yield in transplanted rice. A field experiment was conducted during the Kuruvai season (June – September 2023) at Experimental Farm, Department of Agronomy, Faculty of Agriculture, Annamalai University, Annamalai Nagar, Chidambaram, Tamil Nadu, India. The experiment was laid out in a randomized block design with nine treatments and three replications. The treatments consisted of T1 - unweeded control, T2 - Twice hand weeding @ 20 and 40 DAT, T3 - PE application of Pretilachlor 50% EC @ 0.75 kg ha-1 on 3 DAT alone, T4 - PE application of Pretilachlor 50% EC @ 0.75 kg ha-1 on 3 DAT alone + One hand weeding at 30 DAT, T5 - PE application of Metsulfuron-methyl 10% + Chlorimuron-ethyl 10% WP @ 20 g ha-1 on 3 DAT alone, T6 - PE application of Metsulfuron-methyl 10% + Chlorimuron-ethyl 10% WP @ 20 g ha-1 on 3 DAT + One hand weeding at 30 DAT, T7 - PoE application of Fenoxaprop-p-ethyl 6.9% EC @ 60 g ha-1 on 21 DAT alone, T8 - PE application of Pretilachlor 50% EC @ 0.75 kg ha-1 on 3 DAT + PoE application of Fenoxaprop-p-ethyl 6.9% EC @ 60 g ha-1 on 21 DAT, T9 - PE application of Metsulfuron-methyl 10% + Chlorimuron-ethyl 10% WP @ 20 g ha-1 on 3 DAT + PoE application of Fenoxaprop-p-ethyl 6.9% EC @ 60 g ha-1 on 21 DAT. Among these treatments, it is observed that the pre-emergence application of Metsulfuron-methyl 10% + Chlorimuron-ethyl 10% WP @ 20 g ha-1 on 3 DAT + Post-emergence application of Fenoxaprop-p-ethyl 6.9% EC @ 60 g ha-1 on 21 DAT (T9) had effectively decreased total weed count, weed dry matter production and nutrient removal by weeds. This led to an improvement in crop development and production.

Weed dynamics as influenced by different direct seeded establishment methods and new generation herbicidal combination in rice (Oryza sativaL.)

Field experiment was conducted at Periyanarkunam during Navarai 2021. The main treatments comprised three direct seeded rice establishment methods viz., dry, drum and manual wet seeded rice. The sub treatments are nine weed management practices and are made up with combination of herbicides with hand weeding viz., application of bensulfuron methyl 0.6% + pretilachlor 6% GR @ 10 kg ha-1 on 8 DAS (Days After Sowing) (PE), application of triafamone 20% + ethoxysulfuron 10% WG @ 200 g ha-1 on 12 DAS (EPoE), application of metsulfuron methyl 10% + chlorimuron ethyl 10% @ 20 g ha-1 on 25 DAS (PoE), twice hand weeding on 25 and 45 DAS and unweededcontrol. Among the main treatments drum seeded rice recorded the lowest weed population, dry matter production, the highest weed control efficiency and the highest grain yield which is on par with manual wet seeded rice. However, manual wet seeded rice led to higher cost of cultivation with lower benefit cost ratio. Hence, drum seeded rice is an economically feasible method of direct seeded rice establishment compared to others. Regarding the weed management practices evaluated application of bensulfuron methyl 0.6% + pretilachlor 6% GR @ 10 kg ha-1 on 8 DAS (PE) fb (followed by) application of metsulfuron methyl 10% + chlorimuron ethyl 10% @ 20 g ha-1 on 25 DAS (PoE) fb hand weeding on 45 DAS (S8) registered the similar trend. Hence, drum seeded rice coupled with S8 is an economically feasible method for effective control of weeds.

Bio-efficacy of metsulfuron methyl and carfentrazone ethyl against weed spectrum in wheat (Triticum aestivum L.)

A field experiment was conducted during the winter (rabi) season of 2016–17 and 2017–18 at the Chandra Shekhar Azad University of Agriculture and Technology Kanpur, Uttar Pradesh, to evaluate bio-efficacy and phytotoxicity of metsulfuron methyl 10% + carfentrazone ethyl 40% against weed flora in irrigated wheat crop (Triticum aestivum L). Major dominant weeds that infested the crop were lamb’s quarters (Chenopodium album L.), scarlet pimpernel (Anagallis arvensis L.) and white sweet clover (Melilotus albus Medik.). The lowest dry weight (g/m2) and weed-control efficacy (WCE) of test weed species were found in treatments T4 (metsulfuron methyl 10% + carfentrazone ethyl 40% @ 100 g/ha), T3 (metsulfuron methyl 10% + carfentrazone ethyl 40% @ 75 g/ha) and T2 (metsulfuron methane 10% + carfentrazone ethyl 40% @ 50 g/ha) respectively. Application of metsulfuron methyl 10% + carfentrazone ethyl 40% at all doses was found to be effective against all the 3 weeds and significantly increased the yield of the main crop. Application of weedicides did not show any phytotoxicity symptoms on the wheat crop in both the seasons and also on the succeeding crop of rice (Oryza sativa L.).

Efficacy of new generation herbicidal combination for weed management in direct seeded rice (Oryza sativa L.)

Weeds are the main yield limiting factor that can potentially reduce crop yields and is one of the main constraints in the larger scale implementation of direct seeded rice. Therefore, the present experiment was conducted at Periyanarkunam during Navarai 2021 to study the efficacy of new generation herbicidal combination for weed management in direct seeded rice. The experiment was laid out in split plot design replicated thrice with main plot treatments comprised of three direct seeded rice establishment methods viz., dry seeded, drum seeded and manual wet seeded rice. The sub-treatments were nine weed management practices with combination of herbicides with hand weeding viz., Pre-emergence application of bensulfuron methyl 0.6%+pretilachlor 6% GR @ 10 kg/ha on 8 DAS (Days after sowing), early post- emergence application of triafamone 20%+ethoxysulfuron 10% WG @ 200 g/ha on 12 DAS, post-emergence application of metsulfuron methyl 10%+chlorimuron ethyl 10% @ 20 g/ha on 25 DAS, twice hand weeding on 25 and 45 DAS and un-weeded check. Among the main treatments, drum seeded rice recorded lower weed population and dry matter production, higher weed control efficiency, weed control index, crop resistance index and herbicide efficiency index and higher grain yield which was at par with manual wet seeded rice. Regarding the weed management practices evaluated pre-emergence application of bensulfuron methyl 0.6%+pretilachlor 6% GR @ 10 kg/ha on 8 DAS fb (followed by) post-emergence application of metsulfuron methyl 10%+chlorimuron ethyl 10% @ 20 g/ha on 25 DAS fb hand weeding on 45 DAS (S8) registered lower weed population, dry matter and higher yield compared to unweeded check. Hence, drum seeded rice coupled with pre-emergence application on 8 DAS fb post-emergence application on 25 DAS fb hand weeding on 45 DAS (M2S8) is an economically feasible method for effective control of weeds.

Responses to defoliation and fertiliser, corm development and chemical control of onion grass (Romulea rosea) in the Mediterranean environment of southern Australia

AbstractBackgroundOnion grass (Romulea rosea) is a common weed that infests native and improved pastures in the Mediterranean environments of southern Australia. It is a very challenging weed to control due to its distinctive growth and survival mechanisms involving corms.MethodsThree glasshouse experiments were conducted in Australia to investigate the response of onion grass to defoliation and fertiliser application, the development and growth of onion grass corms and the chemical control of the weed in winter and spring.ResultsDefoliating consistently to 1 cm above ground reduced corm weight by 84% compared with the control. Medium or high fertiliser application did not increase herbage mass of onion grass compared with the nonfertilised treatment. The corm weight of onion grass declined from Weeks 1 to 8 after emergence, remained at 53–60 mg dry matter (DM) corm−1 from Weeks 8 to 19 and then declined on average to 37 mg DM corm−1 up to Week 26 after emergence. New corms started to develop at Week 6 after emergence. A small proportion of the onion grass plants (7.5%) developed multiple new corms (3–6 corms) from a single old corm. The most effective herbicide control was a winter application of metsulfuron methyl or imazamox as an alternative product to protect clover.ConclusionsThis study has identified the growth and development patterns of onion grass corms, how the plant responded to defoliation and fertiliser application and effective chemical control of this weed. These findings have significant practical implications for the improvement of onion grass‐infested pastures.

Metsulfuron-methyl soil persistence influence in corn grown in succession

The metsulfuron-methyl is a soil persistent herbicide and can affect the development and yield of sensitive crops grown in succession. The objective this study was evaluate the effect of the application of metsulfuron-methyl at different intervals before sowing on corn development and yield and determine a safe period between the application of the metsulfuron-methyl and corn sowing. The assay was conducted in the 2017/18 and 2018/19 seasons. The experimental design was of randomized blocks, with thirteen treatments and four replicates. The treatments were arranged in factorial scheme (2 × 6) + 1. The first factor consisted in doses of metsulfuron-methyl (1.98 and 3.96 g ha-1). The second factor in intervals between the application of the herbicide and corn sowing (0, 15, 30, 45, 60, and 75 days), plus a control with no herbicide application. The phytotoxicity, yield, and yield components of corn were assessed. The highest phytotoxicity occurred at 3.96 g ha-1, when the herbicide was applied on the day of sowing. Metsulfuron-methyl caused phytotoxicity and reduced corn yield. The safe interval between metsulfuron-methyl application and corn sowing was 15 and 30 days for the doses of 1.98 and 3.96 g ha-1, respectively.

Weed control for sustaining rice production under dry seeding systems in North-Western India

Identification and adoption of effective weed management practice play a fundamental role for a successful dry-seeded rice (DSR). This field experiment was designed to evaluate the impact of weed control options on weed management, productivity, nutrient uptake, and energetics in DSR. Echinochloa crus-galli (L.) Beauv. was the most dominant species followed by Leptochloa chinensis (L.) Nees. Among the weed control options, sequential applications of pendimethalin (1000 g a.i. ha−1) as pre-emergence and pre-mix combination of penoxsulam (1%) plus cyhalofop-butyl (5%) at 130 g a.i. ha−1 at 25 days after sowing (DAS) led to significant reduction in weed density (82.9%) and biomass (80.1%). This resulted in highest rice grain yield (3.92 t ha−1) and nutrient uptake, resulting in considerably higher energy productivity and lower specific energy. Brown manuring combined with application of metsulfuron methyl (10%) plus chlorimuron ethyl (10%) at 4 g a.i. ha−1 at 40 DAS was also effective in controlling weeds. Based on relative advantages of pendimethalin and penoxsulam plus cyhalofop-butyl in sequence over others, this may be recommended for weed control in DSR.

Toxicity by metsulfuron-methyl in the establishment of the soybean crop submitted to seed treatment

Different management strategies and products can be adopted for weed control and seed treatment. This study evaluated the effect of metsulfuron-methyl application on the establishment of soybean (Glycine max Merril. L) at two herbicide application times and in response to micronutrient and amino acid seed treatment. The soybean seeds, cultivar Nidera 5909, were submitted to the following treatments: control (without treatment); amino acid; micronutrient 1 (a product containing amino acids from seaweed, cobalt, and molybdenum) and micronutrient 2 (a product containing amino acids from seaweed). The sowing periods occurred 15 days after the herbicide application or immediately after its application. We evaluated the emergence of seedlings at seven and 14 days after sowing (DAS), and the dry matters of roots and shoots at 14 and 21 DAS. The metsulfuron-methyl affected the seedling emergence at seven days after the sowing in seed treated with micronutrient 1 immediately after the herbicide application. At 21 DAS, a reduction in the dry mass of seedling roots was observed, which sowing occurred immediately after the application of the herbicide. The application of metsulfuron-methyl at sowing may damage the establishment and performance of soybean seedlings. Therefore, it is important to carry out sowing respecting the period of carryover effects from the herbicide, in order to prevent phytotoxicity symptoms to the soybean crop.

Phytotoxic effect of herbicides on gladiolus and their effectiveness against weed flora associated with the crop

The present investigation was conducted during 2018-19 at Centre for Quality Planting Material, RDS Seed Farm CCSHAU, Hisar, Haryana. The experiment comprised of 16 treatments i.e. nine herbicidal treatments [viz. oxyfluorfen @ 500 g ha-1, pendimethalin @ 1000 g ha-1, butachlor @ 1000 g ha-1, carfentrazone @ 30 g ha-1 and metsulfuron-methyl @ 5 g ha-1 in combinations of pre and pre/post-emergence application at 50 DOP (days of planting) after the HW (hand weeding) or without HW], five mulch treatments (viz. mulching of black polyethylene sheet of 100 µ alone, and the paddy straw mulching @ 10 tonnes ha-1 in combinations with HW at 75 DOP or pre-emergence application of pendimethalin @ 1000, 1250 & 1500 g ha-1), and one treatment of hand weeding/hoeing (at 25, 50 & 75 DOP), and weedy check (control), laid out in simple randomized block design with three replications. Polypogon monspeliensis, Phalaris minor, Cyperus rotundus and Cynodon dactylon among monocots and Chenopodium murale, Convolvulus arvensis, Fumaria parviflora and Coronopus didymus in dicots were found dominant weeds in experimental field. Among the application of herbicides or mulch materials either alone or in combinations, black polyethylene mulch (T13) was found highly effective in controlling weeds followed by pendimethalin 1000 g fb HW + pendimethalin 1000 g (T12), straw mulch fb HW at 75 DOP (T14) and pendimethalin 1500 g/ha + straw mulch (T6). Amongst the herbicidal treatments, pendimethalin 1000 g fb HW + pendimethalin 1000 g (T12) was found comparatively more efficient in controlling weeds without any phytotoxic effect on crop. Interestingly, the applications of oxyfluorfen as a pre-emergence and metsulfuron-methyl as a post-emergence in different herbicidal combinations caused phytotoxicity in crop plants up to the level of growth check or one leaf burning, and the phytotoxic effect of metsulfuron-methyl was more than the oxyfluorfen. At 30 DOP the maximum level of phytotoxicity (1.70) was recorded with the pre-emergence application of oxyflurofen 500 g fb HW + oxyflurofen 500 g (T3), while at 60 DOP it was observed non-significant with most of the herbicidal applications, whereas at 90 DOP and 120 DOP, it was recorded highest (i.e. 2.73 and 2.97, respectively) with the application of oxyfluorfen 500 g fb metsulfuron-methyl 5 g (T2) and it was followed by post-emergence application of metsulfuron-methyl 5 g in combinations with pre-emergence application of other herbicides (T8 & T11). Overall, the application of mulch materials (either alone as a black polyethylene sheet of 100µ or paddy straw @ 10 tonnes ha-1 in the combination with HW or pendimethalin 1500 g ha-1) was found very effective with the aspect of weed control in gladiolus.

High bioremediation potential of strain Chenggangzhangella methanolivorans CHL1 for soil polluted with metsulfuron-methyl or tribenuron-methyl in a pot experiment.

Soil contamination caused by long-term application of metsulfuron-methyl and tribenuron-methyl has become an issue of increasing concern. In our previous study, strain Chenggangzhangella methanolivorans CHL1, capable of efficiently degrading sulfonylurea herbicides, was isolated. Here, the bioremediation potential of strain CHL1 was assessed for soil polluted with metsulfuron-methyl or tribenuron-methyl in a pot experiment. The growth parameters of waxy maize were measured on day 21 of the pot experiment. Additionally, the residues of metsulfuron-methyl and tribenuron-methyl in soils were analyzed, and the soil microbial community was investigated using a phospholipid fatty acids (PLFAs) method on days 1, 7, 14, and 21. The results indicated that strain CHL1 greatly accelerated the degradation of metsulfuron-methyl and tribenuron-methyl in soils. The degradation rates in the treatments inoculated with strain CHL1were all more than 91% after 7days, significantly higher than the 25-36% degradation measured in non-inoculated treatments. Furthermore, strain CHL1 reduced the negative effects of tribenuron-methyl and metsulfuron-methyl on waxy maize growth, especially the primary root length. Moreover, inoculation with strain CHL1 also reduced the effects of tribenuron-methyl and metsulfuron-methyl on soil microbial biomass, diversity, and community structure. The present study demonstrates that strain CHL1 has great potential application to remediate soil contaminated with metsulfuron-methyl or tribenuron-methyl.

Effect of herbicides on weed dynamics, efficiency and yield of linseed

The lowest weed density and weed dry matter was observed with hand weeding twice [(21 and 45 days aftersowing (DAS)]. Among herbicidal treatments, the lowest value was observed with isoproturon + metsulfuron-methyl (1 kg + 4 g/ha) as post-emergence application. The dry matter accumulation at 30 and 60 DAS was recorded significantly higher under hand weeding twice which was at par with the post-emergence application of isoproturon + metsulfuron-methyl (1 kg + 4 g/ha), metsulfuron-methyl (4 g/ha) post-emergence, isoproturon 1 kg/ha postemergence and pendimethalin (1 kg/ha) pre-emergence followed by post-emergence application of metsulfuronmethyl (4 g/ha).The seed yield was recorded significantly higher under treatment of hand weeding twice (at 21 and 45 DAS) which was statistically comparable to the post-emergence isoproturon + metsulfuron-methyl (1 kg + 4 g/ ha), metsulfuron-methyl (4 g/ha), pendimethalin (1 kg/ha) pre-emergence followed by metsulfuron-methyl (4 g/ha) postemergence and isoproturon (1 kg/ha) post-emergence. Among the herbicides applications, weed control efficiency at 90 DAS and at harvest was recorded maximum with the application of isoproturon + metsulfuron- methyl (1 kg + 4 g/ha) and minimum was noted with the application of imazethapyr (75 g/ha).

Interval between the application of metsulfuron-methyl and sowing soybean in different production environments

The persistence of herbicides in the soil is extremely important for controlling weeds during the critical period of weed interference, and for determining which substitute crops might be sown. The aim of this study was to evaluate the effect of metsulfuron-methyl when applied at different times in relation to sowing soybean, seeking to determine a safe interval between its application and sowing the legume under different conditions of soil and climate. Two experiments were conducted, one in the district of Campo Mourao in the state of Parana (PR) (2014/15 crop) and the other in Curitibanos in the state of Santa Catarina (SC) (2015/16 crop). Both experiments were carried out in a randomised block design with four replications. The treatments were arranged in a 2 x 6 + 1 factorial scheme, where factor A represented two doses of metsulfuron-methyl (1.98 and 3.96 g ha-1), and factor B six different intervals between applying the metsulfuron-methyl and sowing the soybean (0, 15, 30, 45, 60 and 75 days after application - DAA), in addition to a control without the application of herbicide, to serve as a standard for comparison. The following were evaluated: percentage phytotoxicity, plant height, stand, number of pods per plant, 100-grain weight and productivity. A difference was seen in the persistence of metsulfuron-methyl for the experiments in Campo Mourao PR, and Curitibanos SC, and was greater for Campo Mourao. The safe interval between applying the metsulfuron-methyl and sowing the soybean was 17 days for the experiment in Curitibanos and 40 days for Campo Mourao. Precipitation volume, pH and organic matter are the main factors to possibly have influenced this interval.

Weed management in dry direct-seeded rice: Assessing the impacts on weeds and crop

Weeds are the major biotic stress limiting productivity, profitability and sustainability of direct-seeded rice (DSR). Effective weed control determines the success of DSR. Therefore, a field study was undertaken to assess the impacts of potential pre-and post-emergence herbicides in sequence and integrated use of herbicides with other methods on weeds and DSR. Eleven weed control treatments comprising of six combinations of pre-and postemergence herbicides, two brown manuring, one herbicide with manual weeding, and two control (weed-free check and unweeded control) were evaluated in a randomized complete block design with three replications. Results showed that grassy weeds were most dominant, constituting 66.0- 91.8% of total weed dry weight across the treatments. Unit increase in weed density (per m2) and weed dry weight (g/m2) could reduce rice grain yield by 14.5 and 11 kg/ha, respectively. All weed control treatments impacted weed interference, crop growth and yield significantly. Sequential applications of pendimethalin (1.0 kg/ha) as pre-emergence and ready-mixture of penoxsulam + cyhalofop-butyl (130 g/ha) at 25 days after sowing (DAS) significantly reduced weed dry weight by 87.6% at harvest, and was superior to other treatments. This treatment increased rice grain yield (3.92 t/ha) by 378.9% over unweeded control, gross benefit: cost (2.30) by 31.4% over weed-free check, and gave highest overall impact index (1.27) with an economic threshold level of 9.0 weeds/m2, and found to be the best weed control option in DSR. Likewise, brown manuring followed by application of metsulfuron-methyl 10% + chlorimuron-ethyl 10% (20 g/ha Almix) at 40 DAS led to 80.3% reduction in weed dry weight, causing significant improvements in crop growth and grain yield (3.67 t/ha) with 30.3% higher gross benefit: cost over weed-free check, and could become a profitable alternative weed control option in DSR.

Properties of the enzyme acetolactate synthase in herbicide resistant canola

ABSTRACT Mutations in the gene that encodes the enzyme acetolactate synthase (ALS), conferring plant resistance to ALS inhibitor herbicides, can reduce or inhibit enzymatic function. The objective of this work was to determine the functionality and kinetic characteristics of the enzyme ALS and evaluate the action of the herbicides imazapic (imidazolinone) and metsulfuron-methyl (sulfonylurea) on the activity of the enzyme ALS in canola hybrid Hyola 571CL (imidazolinone resistant), compared to hybrids Hyola 555TT (triazine resistant) and Hyola 61 (conventional). The plants were grown in a greenhouse, and leaves were collected to perform ALS activity analysis. The concentration of pyruvate to provide initial velocity equal to half the maximum reaction rate (Km) and the maximum reaction rate (Vmax) was determined, as well as the enzyme’s activity in the presence of imazapic and metsulfuron-methyl inhibitors. There was no change in the Km and Vmax in the hybrid Hyola 571CL in relation to Hyola 61. The hybrid Hyola 555TT presented Vmax higher than the other hybrids. In the hybrid Hyola 571CL, the activity of ALS was reduced only by the application of metsulfuron-methyl, and the functionality of the enzyme did not change in relation to the other hybrids. The hybrid Hyola 571CL is resistant only to the imidazolinone group herbicide and this resistance does not cause adaptive cost in relation to the other hybrids.

Effectiveness of new herbicides in management of broadleaf weeds and sedges in transplanted rice

A study was planned to evaluate efectiveness of new pre-mix herbicide metsulfuron methyl+chlorimuron ethyl for management of sedges and broadleaf weeds in transplanted rice at research farm of Punjab Agricultural University, Ludhiana for three years. The treatments comprised of metsulfuron methyl+chlorimuron ethyl 3, 4 and 5g/ha, azimsulfuron 20g/ha and metsulfuron 4 g/ha as post emergence and unsprayed control, replicated four times. The results indicated that the density and biomass of sedges and broadleaf weeds was signifcantly less in metsulfuron methyl+chlorimuron ethyl 4 and 5g/ha than 3g/ha, azimsulfuron 20g/ha, metsulfuron 4g/ha and unsprayed control. Application of metsulfuron methyl+chlorimuron ethyl 4g/ha applied in rice recorded signifcantly highest average grain yield of 7.31t/ha. There was a negative linear relationship between weed biomass and grain yield (r=-24.08). Correlation matrix revealed that all the yield attributes showed higher correlation with metsulfuron methyl+chlorimuron ethyl 4g/ha. Post emergence application of metsulfuron methyl+chlorimuron ethyl at 4g/ha resulted in efective control of broadleaf weeds and sedges in transplanted rice.

Influence of weed management and nitrogen fertilization on weed dynamics, nutrient depletion by weeds, productivity and profitability of barley (Hordeum vulgare) in hot semi-arid region of western India

Field experimentation was conducted during rabi 2012-13 and 2013-14 to assess the performance of weed management practices and nitrogen (N) fertilization on weed dynamics, productivity and profitability of barley (Hordeum vulgare L.). Results indicated that hand–weeding at 25 and 50 days after sowing (DAS), and metsulfuron methyl @ 4 g/ha resulted in significant reduction in weed infestation and weed biomass production at different growth stages. The highest weed control efficiency (WCE) was recorded with 2 HWs' at 25 and 50 DAS followed by metsulfuron methyl @ 4 g/ha with lowest NPK depletion by weeds than other treatments. Two HWs' also remained superiormost w.r.t. grain (5.21 tonnes/ha) and straw (7.13 tonnes/ha) yields. Application of metsulfuron methyl also exhibited higher grain yield with minimum weed competition index (8.57%). Among N levels, application of 90 kg N/ha to barley resulted in highest weed count, weed intensity, weed infestation and their dry weight at all the stages as well as higher NPK concentrations in weeds and NPK depletion by weeds at harvest stage. Application of 90 kg N/ha also produced 20.8 and 20.6% more grain and straw yields over control (N0). Overall, metsulfuron methyl and N application at the rate of 90 kg/ha proved their superiority w.r.t. weed management, productivity and profitability in barley in hot semi-arid region of western India.

Herbicide combinations for weed management in transplanted rice

A field experiment was conducted during 2012–13, to study the effect of herbicides applied in mixture and sequence for managing complex weed flora in transplanted rice. Among the herbicides applied, bispyribac-Na applied in combination with almix as tank mixture recorded the least weed count, weed dry matter and highest WCE. Significantly higher yield attributes, viz. number of grains/panicle and grain yield were also recorded when bispyribac-Na and metsulfuron-methyl + chlorimuron-ethyl were applied as tank mixture. Pre-emergence application of pretilachlor fb post-emergence application of metsulfuron-methyl + chlorimuron-ethyl and hand weeding twice at 25 and 45 DAT were also equally effective. Application of pre-and post-emergence herbicide alone were found to be less effective in reducing weed density and weed dry matter.

Integrated Weed Management in Transplanted Rice (Oryza sativa)

A field experiment was conducted during the kharif season of 2010 and 2011 at the Regional Research Station, Kalimpong (1250 m a.s.l), to find out eff ective and suitable method of weed control in transplanted rice under mid hill conditions. The major weed found in control plot were Echinochloa crus-galli, Echinochloa colonum, Cynodon dactylon Cyperus rotundus, Cyperusiria, Cyperus difformis, Fimbristylis miliaceae, Ammania baccifera, Ludwigia parviflora. Pre-emergence application of metsulfuron methyl + chlorimuron ethyl supplemented with one hand weeding at 40 DAT, provided a broad - spectrum weed control and was significantly superior to rest all other integrated approach of weed control. The highest weedcontrol efficiency (91.4%) was also recorded under this treatment. The grain yield was highest with hand weeding thrice (6.61 t/ha) which was comparable with treatment of metsulfuron methyl + chlorimuron ethyl (0.005 kg/ha) supplemented with one hand weeding (6.47 t/ha). The highest benefit: cost ratio was with metsulfuron methyl + chlorimuron ethyl (0.005 kg/ha) supplemented with one hand weeding at 40 DAT (2.18) and was followed by pretilachlor (0.5 kg/ha) followed by one hand weeding (2.14). Metsulfuron methyl + chlorimuron ethyl (0.005 kg/ha) followed by one hand weeding at 40 DAT controlled weed population and gave yield a ributing traits and yield comparable to those of hand weeding thrice and proved more remunerative than other weed management practices.

Effect of Weed Management Practices on Growth and Yield of Rice (Oryza sativa L.) under Transplanted Lowland

A field experiment was conducted during kharif, 2010, to study the effect of weed management practices on weed control, growth and yield of rice (Oryza sativa L) under lowland conditions. The treatments consisted of pre-emergence application of butachlor and metsulfuron methyl along with post-emergence application of 2, 4-D EE or conoweeding at 20 DAT, which was compared to two hand weedings at 20 and 40 DAT and control. Among the herbicidal treatments, pre – emergence application of metsulfuron methyl at l 6 g ha -1 + post emergence spray of 2, 4-D EE at 500 g ha -1 recorded the least weed density (81.32 m -2 ), weed biomass (30.68 m-2 ) and maximum weed control efficiency (76.68%) in rice. Among the growth parameters of rice, maximum plant height (88.07 cm), plant dry weight (63.40 g), number of tillers plant -1 (22.1) and crop growth rate (0.951 g m -2 day -1 ) were recorded under the aforesaid treatment. Better yield attributes, higher grain yield (5.01 t ha -1 ), harvest index (39.10 %), net return ( 36235 ha -1 ) and benefit: cost ratio (2.02) of rice were recorded under the same treatment.

Effects of Metsulfuron-Methyl on the Microbial Population and Enzyme Activities in Wheat Rhizosphere Soil

The effects of metsulfuron-methyl, a sulfonylurea herbicide, on the wheat soil microorganisms were evaluated by the methods of microbial inoculation culture, and the activities of three enzymes were measured using the colorimetric method. The tolerant microorganisms that can resist 500 μ g·g−1 metsulfuron-methyl in the counting culture medium were studied specially. Metsulfuron-methyl distinctly inhibited the common aerobic heterotriphic bacteria, but the effects on common fungi and common actinomycete were not evident. In the meantime, the number of tolerant fungi increased greatly in the rhizosphere after the application of metsulfuron-methyl in contrast to the significant decrease of the amount of tolerant actinomycete. It indicates that fungi might turn into the dominant microbial type and actinomycete is the sensitive factor in the soil polluted by sulfonylurea residues. The population of aromatic compounds–decomposing bacteria, aerobic azotobacter, and nitrite bacteria all increased in the earlier period, but the aerobic azotobacter decreased rapidly in number 30 days later, and the amount of nitrite bacteria also showed a temporary decrease with time 15 days later. However, the denitrifying bacteria just began to increase significantly after the crops had grown for 50 days. The amount of sulfur-oxidizing bacteria gradually decreased with the growth of crops, and so were the sulfate-reducing bacteria after metsulfuron-methyl application. To all types of microorganisms, there were more microbes in rhizosphere samples than those in nonrhizosphere except aerobic azotobacter. It means the growth of wheat root system can stimulate the growth of most microorganisms. The activities of hydrogen peroxidase and polyphenol oxidase in soil samples after metsulfuron-methyl application were notably lower than those in the control, and the difference of the activities between the samples of rhizosphere and nonrhizosphere was evident. On the contrary, the activity of dehydrogenase was not inhibited by the application of metsulfuron-methyl, and the rhizosphere effect was not obvious either.