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M. Sc. Dissertations

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Subject: Plant Physiology × End date: 2009 × Start date: 2009 ×
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    ThesisItemOpen Access
    Evaluation of some herbicides for management of resistant littleseed canarygrass (Phalaris minor retz.)
    (CCSHAU, 2009) P. Bhasker; Dhawan, Rupa
    Littleseed canarygrass (Phalaris minor Retz.) is a major weed in wheat fields, and has developed resistance to the commonly used herbicide isoproturon. Some reports of evolution of cross resistance against fenoxaprop-p-ethyl have also appeared. This study explores the potential use of fenoxaprop-p-ethyl, clodinafop, pinoxaden and ready mix formulation of sulfosulfuron plus metsulfuron (‘Total’), as post-emergence herbicides to control resistant littleseed canarygrass in wheat(Triticum aestivum L.) and investigate the mechanism of evolution of cross resistance to fenoxaprop in P.minor. Greenhouse studies were carried out to determine the phytotoxicity of these herbicides in relation to percent mortality, plant height, fresh plant biomass, dry plant biomass, chlorophyll and carotenoid content and leaf membrane injury on littleseed canarygrass and wheat. These experiments were conducted in green house unit, Department of Agronomy, CCS HAU, Hisar (India). Resistant biotypes of Phalaris minor were collected from different locations of Haryana during 2007-08. Seven biotypes of P.minor from HAU-Hisar, Uchana, Ambala, Nangla, Chanarthal-1, Chanarthal-2 and Chanarthal-3, were raised along with wheat (PBW- 343) in pots. Herbicides (0-240 g ha-1 fenoxaprop, 0-60 g ha-1 clodinafop, 0-120 g ha-1 pinoxaden, 0-80 g ha-1 ‘Total’) were sprayed 35 DAS. Application of fenoxaprop 120 g ha-1, clodinafop 60 g ha-1, pinoxaden 60 g ha-1, provided control of biotypes from HAU-Hisar, Uchana, Ambala and Nangla but not from Chanarthal. However, application of pinoxaden 120 g ha-1 and ready mix formulation of sulfosulfuron plus metsulfuron 80 g ha-1 provided complete control of all biotypes of P.minor. Same situation was observed in laboratory experiments. Of the 7 biotypes studied, these were classified as sensitive (HAU-Hisar and Ambala), partially resistant (Uchana and Nangla) and resistant types (Chanarthal-1, Chanarthal-2 and Chanarthal-3). Dose response curves of decline in fresh weight against herbicide doze provided good indication of the resistance in various biotypes. GR50 values of the populations tested against fenoxaprop were in the range of 80 - >240 g ha-1, against clodinafop 30->60 g ha-1, against pinoxaden 10-120 g ha-1 and against ‘Total’ was 20 - > 80 g ha-1. This is supported by pigment retention tests and ion efflux tests. Pigment retention (chl-a, chl-b and carotenoid) was lesser in susceptible biotypes and more in resistant biotypes after herbicide spray. Ion efflux was also more in susceptible biotypes as compared to resistant biotypes. Experiment on mechanism of evolution of resistance to fenoxaprop is indicative of the fact that there is lesser involvement of detoxification mechanism pointing towards target site alteration.