Induction of resistance in potato against phytophthora infestans (mont.) De bary
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Date
2009
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Punjab Agricultural University, Ludhiana
Abstract
Late blight of potato caused by Phytophthora infestans is a serious disease of potato and is generally managed by the application of fungicides. Induced resistance in plants offers viable alternative to fungicidal control of diseases. Attempt was made to induce resistance in potato against P. infestans through application of inducer chemicals and bioagents. Seven inducer chemicals viz. salicylic acid, benzothiodiazol, fosetyl-Al, calcium chloride, ethylene, hydrogen peroxide and potassium phosphate along with bio-agents Pseudomonas fluorescens, Trichoderma viride and Trichoderma harzianum at different doses were used for inducing resistance in potato cvs. Kufri Chanramukhi and Kufri Badshah against late blight. The treatments included tuber treatment, foliar application and both tuber treatment and foliar application. Maximum resistance was induced by salicylic acid and benzothiadiazol @ 50 and 100 µg/ml, respectively, when tuber treatment was combined with foliar application. Under field conditions, maximum control of the disease was obtained in treatment with salicylic acid @100µg/ml followed by benzothiadiazol @100µg/ml. Treatment with fosetyl-Al was next in inducing resistance where considerable resistance was induced at 500 and 1000 µg/ml. Other treatments were found less effective. The bio-agents used in the present study failed to induce much resistance as evident from higher disease severity in these treatments. All treatments with inducers stimulated phenolics and enzymatic activities. The highest activity was obtained in plants treated with salicylic acid and benzothiodiazol @50 and 100 µg/ml, respectively. The inducers used also increased chitinase, peroxidase and phenylalanine ammonia lyase activity as compared with untreated control plants. The observation indicated that induced resistance in potato plants is promising for commercial application as a new approach for controlling late blight of potato.
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