ABSTRACT
Title of thesis	:	Management of Herbicide Resistant Biotypes of Phalaris minor in Wheat Growing Sub-tropics of Jammu	
Name of the Student	:	Deepak Kumar	
Registration No.	:	J-18-D-328-A	
Major subject	:	Agronomy	
Name and designation of Major Advisor 	:	Dr. Anil Kumar
Chief Scientist (Agronomy) & Head
FSR, Centre	
Degree to be awarded  	:	Ph.D. (Agronomy)	
Year of Award of degree	:	2022	
Name of University 	:	Sher-e-Kashmir University of Agricultural Sciences and Technology Jammu, UT of J&K 	
ABSTRACT
The present study entitled “Management of Herbicide Resistant Biotypes of Phalaris minor in Wheat Growing Sub-tropics of Jammu” was conducted at the Research Farm, Division of Agronomy, Faculty of Agriculture, SKUAST- J, Chatha during Rabi season of 2019-20 and 2020-21. The soil of the experimental site was sandy clay loam in texture, slightly alkaline in reaction, low in organic carbon and available nitrogen but medium in phosphorus and potassium. The pot experiment-I for identification of resistant biotypes at recommended herbicidal applications was laid out in completely randomized design with six treatments and four replications for twenty-five P. minor biotypes. The P. minor biotypes were evaluated against five recommended herbicides (isoproturon, sulfosulfuron, pinoxaden, clodinafop and fenoxaprop) with their graded doses (0, 1/4X, 1/2X, X (Recommended dose), 2X and 4X) i.e. isoproturon (0, 187.50, 375, 750, 1500 and 3000 g/ha.), sulfosulfuron (0, 6.25, 12.5, 25, 50 and 100 g/ha.), clodinafop (0, 15, 30, 60, 120 and 240 g/ha.), fenoxaprop  (0, 25, 50, 100, 200 and 400 g/ha.) and pinoxaden (0, 10, 20, 40, 80, 160 g/ha.), respectively where total 3000 pots were used. Sunderbani, Rajouri biotype (33.413”N, 74.284”E, 580 m) was taken as susceptible. The field experiment II for management of resistant biotypes of P. minor in crop- weed association with alternative herbicidal options was laid out in randomized block design with eleven treatments and three replications for each three identified resistant P. minor biotypes. The treatments consisted of pre-emergence application of pendimethalin (1000 g/ha), pendimethalin + pyroxasulfone (910 g + 75 g/ha), pendimethalin + metribuzin (1000 g + 150 g/ha), post-emergence application of metribuzin + clodinafop (210 g + 60 g/ha), pinoxaden (40 g/ha), fenoxaprop  (100 g/ha), clodinafop (60 g/ha), sulfosulfuron (25 g/ha), isoproturon (750 g/ha) along with weed free and weedy check for comparison. The recommended dose of NPK was applied in wheat crop through inorganic sources of nutrients viz. Urea, DAP and MOP as per the package of practices.
In pot experiment –I, three P. minor biotypes were found resistant to different herbicides. One biotype of P. minor collected from Karnal Kothi, Suchetgarh, Jammu was found resistant to electron transport in PS-II inhibitor isoproturon. Secondly, biotype of P. minor collected from Bera, R.S. Pura, Jammu was found to be resistant to electron transport in PS-II inhibitor isoproturon, ALS inhibitor sulfosulfuron and ACCase inhibitors clodinafop and fenoxaprop. Also, the biotype of P. minor collected from Sangyal, R.S. Pura, Jammu was found resistant to electron transport in PS-II inhibitor isoproturon, ALS inhibitor sulfosulfuron and ACCase inhibitors clodinafop, fenoxaprop and pinoxaden. The development of resistance among these three P. minor biotypes were also confirmed by the higher GR50 (g/ha) values and resistant index compared with susceptible biotype (Sunderbani, Rajouri) during both the year of experimentation. Resistant P. minor were recorded numerically higher plant height, number of tillers, spike length, spike width, leaf blade length, leaf blade width and test weight compared to susceptible biotype of P. minor during both the year. Seed colour was observed dark brown in susceptible and resistant biotypes during both the years of experimentation.
In field experiment-II, among the herbicidal weed management treatments against isoproturon resistant P. minor (B-14: Karnal Kothi, Suchetgarh, Jammu) , the lowest P. minor density, biomass and weed index along with highest weed control efficiency, grain and straw yield, number of effective tillers, net return and B:C ratio were recorded in sulfosulfuron (25 g/ha) which was statistically at par with clodinafop (60 g/ha), fenoxaprop (100 g/ha), pinoxaden (40 g/ha) and metribuzin + clodinafop (210 g + 60 g/ha) in wheat crop. The biotype (B-18: Bera, R.S. Pura, Jammu) isoproturon, sulfosulfuron, clodinafop and fenoxaprop resistant P. minor was effectively checked by the application of pinoxaden (40 g/ha) with lowest P. minor density, biomass and weed index recorded highest weed control efficiency, grain and straw yield, number of effective tillers, net return and B:C ratio which was statistically at par with metribuzin + clodinafop (210 g + 60 g/ha) in wheat crop. Whereas, against the biotype (B-19: Sangyal, R.S. Pura, Jammu) isoproturon, sulfosulfuron, clodinafop, fenoxaprop and pinoxaden resistant P. minor, the application of metribuzin + clodinafop (210 g + 60 g/ha) with lowest P. minor density, biomass and weed index recorded highest weed control efficiency, grain and straw yield, number of effective tillers, net return and B:C ratio than other herbicides in wheat crop.
Based on two years investigation it was concluded that three resistant P. minor biotypes were identified out of twenty-five biotypes collected from farmers’ fields against different modes and mechanism of herbicides. P. minor biotype collected from Karnal Kothi, Suchetgarh, Jammu was found resistant to electron transport in PS-II inhibitor isoproturon. The P. minor biotype collected from Bera, R.S. Pura, Jammu was found to be resistant to electron transport in PS-II inhibitor isoproturon, ALS inhibitor sulfosulfuron and ACCase inhibitors clodinafop and fenoxaprop. Whereas, P. minor biotype collected from Sangyal, R.S. Pura, Jammu was found resistant to electron transport in PS-II inhibitor isoproturon, ALS inhibitor sulfosulfuron and ACCase inhibitors clodinafop, fenoxaprop and pinoxaden. Morphologically resistant biotypes were found higher in plant height, number of tillers, spike length, spike width, leaf blade length, leaf blade width and test weight compared to susceptible biotype of P. minor although, seed colour was observed dark brown in susceptible and resistant biotypes. The selection pressure exerted by continuous use of herbicides in wheat might have led to the development of herbicide resistance in P. minor. This necessitated the evaluation of new chemicals with different modes of action for management of P. minor in wheat. Application of sulfosulfuron (25 g/ha), clodinafop (60 g/ha), fenoxaprop (100 g/ha), pinoxaden (40 g/ha) and metribuzin + clodinafop (210 g + 60 g/ha) was found to be a good option for management of isoproturon resistant P. minor, application of pinoxaden (40 g/ha) and metribuzin + clodinafop (210 g + 60 g/ha) was promising option for management of isoproturon, sulfosulfuron, clodinafop and fenoxaprop resistant P. minor and application of metribuzin + clodinafop (210 g + 60 g/ha) was good alternative for management of isoproturon, sulfosulfuron, clodinafop, fenoxaprop and pinoxaden resistant P. minor in wheat crop. These promising herbicidal management options in respect of three location specific diverse biotypes can be safely recommended to target farmers on the premise that the germplasm doesn’t spread further over larger pockets of wheat growing areas. 

Key words: Herbicide resistance, bioassay, P. minor and wheat.

Signature of Major Advisor					Signature of the Student