Punia, S. S.Kumaresan, P.2021-12-132021-12-132019-10https://krishikosh.egranth.ac.in/handle/1/5810179138Green gram is grown under rainfed or irrigated conditions in wider rows, cultural and mechanical weed control practices could be rehearsed. Yet isn't constantly possible because of their high cost, non-accessibility of labour at right time, prevailing climatic conditions, long window of weed emergence in the growing season and persistent moisture amid rainy season is an issue which make it hard to expel within determined time when they cause most intense of damage to crop. Rather than blanket method, ―one soil-one crop-one dose‖ is the right approach to reduce the toxicity and residual effect as well prevent the herbicide resistant weeds. So, on considering this, the following entitled investigation, “Bio-efficacy of various herbicides in green gram, their dissipation behaviour and residual effect on succeeding mustard crop” has been carried out at Farm of Department of Agronomy, CCS HAU, Hisar. Residue analysis of soil conducted in laboratory study on dissipation behavior of imazethapyr+ pendimethalin (RM) and Iris (aciflourfen 16.5% + clodinafop 8% EC) RM in soil by GC-MS conducted in Residue Testing Laboratory of Department of Agronomy, CCS HAU, Hisar. Weed flora of the experimental field was dominated by Trianthema portulacastrum, Cyperus rotundus and other minor weeds. PRE application of pyroxasulfone alone at 127.5, 150 g ha-1 and tankmix (TM) combination of pyroxasulfone at 106 + 1000 g ha-1 provided good control of (90.7 and 88.3%) Cyperus rotundus up to 40 DAS. PoE application of Iris (aciflourfen 16.5% + clodinafop 8% EC) RM 245, 305 and 370 g ha-1 gave good control of Trianthema portulacastrum (94.8, 48.6, 92.5, and 83.2%) up to 40 DAS. At 20 and 40 DAS imazethapyr + pendimethalin (RM) at 1000 g ha-1 applied at PRE application provided maximum control of weeds which was at par with two hoeings employed at 20 & 40 DAS gave excellent control of complex weed flora and increased seed and biological yield of green gram significantly over weedy check during both the years. PoE use of imazethapyr 70 g ha-1, imazethapyr fb quizalofop 70+60 g ha-1 and PRE application of imazethapyr + imazamox (RM) at 70 g ha-1 exhibited 18-23 % control of weeds with slight crop suppression which mitigated within 10-15 days after spray resulting maximum crop growth and seed yield. As the dose of of imazethapyr 70 g ha-1, imazethapyr fb quizalofop 70+60 g ha-1 and PRE application of imazethapyr + imazamox (RM) at 70 g ha-1 and its combination applied in green gram as PRE and PoE increased from 52.8 to 82.8 and 56.5 to78.8 %, phytotoxicity on mustard increased singnificantly. Plant population, growth parameters viz. emergence, number of leaves, plant height, seed yield and biological yield also reduced significantly, during both the years. Residue analysis of experimental field soil by GC-MS-tandem mass spectrometry equipped with capillary column revealed that percent recoveries at fortification level 0.003 and 0.006 μg/g in soils were 81.3 to 88.7 per cent depicting validity of methods used for present studies. Dissipation followed a first order kinetics with a half-life of aciflourfen and clodinafop was 7.7 and 7.0 days when applied as 3-4 leaf stage, PRE application of imazethapyr + pendimethalin (RM) at 1000 g/ha. The imazethapyr residues on 0 day were observed to be 0.017 μg/g. The residues dissipate to 17.6, 59 and 70% on 3, 15 and 30 DAA with half -life period of 9.2 days following first order dissipation kinetics. The initial deposit of pendimethalin residues on 0 day were 2.65 μg/g. About 44% dissipation of residues was observed within 10 DAA and about 100% dissipation of residues was observed on 60 DAA. Half-life of imazethapyr+ pendimethalin (RM) at 1000 g ha-1 and Iris (aciflourfen 16.5% + clodinafop 8% EC) RM as 370 g ha-1 was in order of PRE > PoE.EnglishThesis