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An experiment was conducted to find out the effect of different weed control methods on growth, flowering and flower yield in African marigold (Tagetes erecta L.) cv. Pusa Narangi Gainda at the Department of Floriculture and Landscape Architecture, College of Agriculture, Indira Gandhi Agricultural University, Raipur, Chhattisgarh during the kharif season 2016-17. The experiment consisted of twelve treatments combination of different weed control methods. The results indicated that application of pendimethalin @ 1.0 kg/ha followed by one hand weeding at 30 DAT resulted in the maximum plant height (45.33 cm, 80.63 cm and 101.53 cm at 25,50 and 75 DAT, respectively), number of primary and secondary branches plant-1 (3.27, 6.87 and 10.67 primary branches and 8.60, 20.13 and 36.50 secondary branches at 25, 50 and 75 DAT, respectively), maximum plant spread (68.17 cm ), earliest 50 per cent flowering (47.00 days), significantly biggest flower (6.97 cm), maximum weight of flowers plant-1 (126.73 g.), flowers yield ha-1 (136.85 q). Similar treatment i.e. Pendimethalin 30% EC @ 1.0 kg ha-1 (PE) followed by one Hand Weeding at 30 DAT resulted the highest B:C ratio (3.98) followed by Pendimethalin 30% EC @ 1.0 kg ha-1 (PE) + Fenoxaprop - p-ethyl 9.3% EC @ 0.10 kg ha-1 at 30 DAT (PoE) with B: C Ratio (1:3.60) as compared to other treatments. The minimum values for these parameters were recorded in unweeded treatment.

Weeds are the major limiting factor for optimum soybean production in India. The herbicide mixture of fomesafen and quizalofop-ethyl provides effective control of a broad spectrum of weeds, but its fate in the tropical soybean ecosystem is unknown and also the risks involved to the consumer and the environment are still unexplored. Hence, a supervised field trial was conducted following the post-emergence application of fomesafen 12% + quizalofop-ethyl 3% in two consecutive seasons. The dissipation of fomesafen followed biphasic double first order in parallel kinetics, whereas quizalofop-ethyl dissipation followed first order kinetics. A significant difference in the persistence of fomesafen was observed due to seasonal variation of meteorological parameters. However, the variation was significant only in plant, but non-significant in soil, in case of quizalofop-ethyl. The overall shorter persistence of both fomesafen and quizalofop-ethyl was recorded in warmer climatic conditions of Season I than Season II. The results thus indicated that care must be taken during application of this herbicide mixture in cold climatic regions, since both the herbicides may exhibit higher stability. The absence of end-point residues at harvest concluded that the formulation is safe for application in tropical agroclimate. The low chronic dietary toxicity and low soil ecological toxicity indicated that the herbicide mixture will offer no threat against consumer health and soil ecosystem. However, there was a concern about the toxicity against soil algal population which needs to be reconfirmed by further studies.

Field experiment was conducted to find out the effect of pre-emergence(PE) and early post-emergence (EPoE) herbicides on weed control inirrigated blackgram at College of Agricultural Technology, Kullapuram- Theniduring 2015-2016. In this experiment, weed management practice of preemergenceapplication of Pendimethalin 30 EC 1.0 kg a.i. ha-1 at 3 daysafter sowing (DAS), early post-emergence application of Quizalofop ethyl@50 g a.i. ha-1 at 15 DAS, early post-emergence and Imazethapyr each @50 g a.i. ha-1 at 15 DAS and their combinations of Pendimethalin @ 1.0 kgha-1 at 3 DAS followed by either Quizalofop ethyl or Imazethapyr each @50 g a.i. ha-1 were tested against hand weeding twice at 20 and 40 DAS,weedy check and weed-free check as controls in randomized block designreplicated thrice. Among the different weed management practices, preemergenceapplication of Pendimethalin 1.0 kg a.i. ha-1 (3 DAS) followedby Imazethapyr @ 50g a.i. ha-1 as EPoE (15 DAS) recorded relatively lesserproportion of broad-leaved weeds (30.90 and 49.16%) and higher WeedControl Efficiency (WCE) of 91.27 at 60 DAS. Application of pendimethalin1.0 kg a.i. ha-1 PE (3 DAS) followed by Imazethapyr @ 50g a.i. ha-1 as EPoE(15 DAS) registered significantly taller plants (42.22 cm), higher dry matterproduction(2649 kg ha-1), more number of pods per plant (44.19), seedsper pod(5.57) and higher grain yield (1052 kg ha-1). Thus, pre-emergenceapplication of pendimethalin 1.0 kg a.i. ha-1 (3DAS) followed by Imazethapyr@ 50g a.i. ha-1 as EPoE (15DAS) recommended as effective and economicweed management practices on the basis of better weed control, crop growth,and yield of irrigated blackgram.

The enantioselective catabolism of the two enantiomers of the aryloxyphenoxypropionate (AOPP) herbicide, quizalofop-ethyl (QE), in environment by microorganisms is of great interest. In this study, Sphingobium sp. strain QE-1, capable of transforming both enantiomers of QE, was successfully isolated. A novel gene qeH, encoding an esterase capable of initially transforming (R)/(S)-QE to (R)/(S)-quizalofop acid [(R)/(S)-QA], was cloned. QeH showed the highest identity (36.9%) to the β-lactamase MT1414, and the purified QeH displayed optimal activity for (R)-QE at 40 °C and pH 7.0. QeH preferentially hydrolyzed (R)-QE than (S)-QE. Based on molecular docking analyses, the distance between the ligand molecule and the coordination atom was shorter when (R)-QE occupied the active sites as compared to that of (S)-QE, which resulted in a stronger ligand binding affinity for (R)-QE. Besides the two enantiomers of QE, QeH could also convert many other AOPP herbicides with different catalytic efficiency (clodinafop-propargyl > fenoxaprop-P-ethyl > fluazifop-P-butyl > cyhalofop-butyl). This study will enhance our understandings of the enantioselective catabolism of AOPP herbicides by microorganisms.

The experiment was conducted during Kharif season of 2006 at Junagadh (Gujarat) to study the weed dynamics and yield as influenced by various weed control practices with different fertility levels in soybean [ Glycine max (L.) Merril]. Results indicates that at 20 DAS the treatment W 1 (Pre-emergence pendimethalin @ 0.5 kg ha -1 + HW and IC at 30 DAS) recorded lowest number of monocots, dicots and sedges weeds next to W 5 (Weed free upto 60 DAS through hand weeding). Similarly at 40 and 60 DAS the treatment W 3 (Post-emergence imazethapyr @ 75 g ha -1 at 25 DAS + HW and IC at 45 DAS) also reported minimum number of weeds next to W 5 . The lowest dry weight of weeds was recorded under treatment W 5 followed by W 4 and W 3 . Application of 40:80:40 kg NPK ha -1 recorded significantly higher values of weed count and total dry weight of weeds and grain yield compared to other levels. The treatment W 4 (2 HW + 2 IC at 20 and 40 DAS) was found at par with treatment W 5 in respect of grain yield.

Italian ryegrass populations investigated in this study were harvested in an alfalfa-based cropping system. In that system, the agronomic practices and chemical weed management, based on the use of aryloxyphenoxy-propionates herbicides (i.e., quizalofop ethyl ester), were optimized to obtain a dual seed–forage production. Five of seven populations tested were confirmed resistant to quizalofop ethyl ester with resistance indexes ranging from 4.5 to >209. Both target- and nontarget-site resistance mechanisms were most likely involved. Three allelic variants were detected (Ile-1781–Leu, Trp-2027–Cys, and Ile-2041–Asn) in four resistant populations, whereas no known mutations were found in one resistant population. The herbicide treatment on Italian ryegrass plants at different phenological stages suggested that to control regrowth, it is necessary to use two to fives times the herbicide dose suitable for younger plants. This situation is encountered in fields when Italian ryegrass plants need to be controlled to maximize the alfalfa seed production, and it is comparable to using a sublethal herbicide dose, leading to the selection of herbicide-resistant biotypes. In such a situation, the cropping system is not sustainable, and integrated weed management should be implemented to deplete the soil weed seed bank and prevent new weed seed production.

選択性除草剤として,フェノキシプロピオン酸エステルあるいはピリジルオキシプロピオン酸エステルが知られている。著者らはフェノキシあるいはピリジルオキシに代わって縮合ヘテロ環を幅広く検討する中,キノキザリン類の中に細葉雑草の除草に卓効のある,有望な化合物群を見いだした。その中で,キザロホップェチル(コード No. NC-302 )は特に強い効力を持ち,茎葉処理型除草剤として企業化された。その工業化に際し,キノキザリン環部の合成は大きな課題の一つであったが,汎用な原料から合成できる簡単な方法を見いだした。また,キザロホヅプェチルは不斉炭素を持ち,光学異性体が存在するが,その有効成分は(R)-(+)体であり,ラセミ体にくらべて2倍の効果を持つ。(0)0(+)体の製造は,分割法ではなく,光学活性な原料を使いラセミ化させない方法で行っている。また,(R)-(+)体は,ラセミ体とは異なり結晶型が二つ存在する。この分測晶析法が発見され,(R)一(+)体の工業化が可能となった。本論文では,特に光学活性キザロホップエチルと,その重要な中間体である2-(4ヒドロキシフェノキシ)プロピオン酸エチルの製造法について,詳しく述べる。

Several derivatives of heterocyclic-oxy phenoxy propionic acid have been known as selective herbicides. During extensive investigations on this series with various condensed heterocyclic moieties, the quinoxalinyloxy phenoxy propionic acid derivatives were found to show an excellent herbicidal activity against grass weeds. Among them, ethyl 2- [4- (6-chloro-2-quinoxalinyloxy) phenoxy] propionate, (code No.NC-302, quizalofop ethyl) showed a potent herbicidal activity. It is commercialized as a novel post-emergence herbicide. In this paper, facile syntheses of substituted quinoxalines and quizalofop ethyl derivatives are described in detail.