Induced resistance in potato against black scurf caused by Rhizoctonia solani Kühn through inorganic chemicals as inducer

Abstract

Black scurf caused by Rhizoctonia solani is an important disease of potato worldwide, and can cause significant reduction in the economic value of potato. The management of the disease can be done through conventional methods viz., biological, chemical and cultivation of resistant variety. However, resistance against pathogen is not a permanent solution and fungicidal is not ecofriendly and economical. But new approach of plant disease management through induce resistance has drawn a great attention for ecofriendly management in near future. Therefore, present investigation for induce defense by certain inorganic chemicals like Salicylic acid, DPHP, Hydrogen peroxide, Indole acetic acid, calcium chloride, Fecl3 Boric acid, Thiophanate methyl and Azoxystrobin as inducer at 0.25 g L-1 were assessed during the course of present investigation and mechanism of defense response in term of soluble protein, total phenol and defense enzyme viz., peroxidase, poly phenol oxidase, phenylalanine ammonia lyase, a biochemical mechanism of defense response were also ascertained. Tuber treatment with inducing agent provide good protection against black scurf disease caused by R. solani and also stimulate the germination of tuber. Growth promoting effects of the inducers were also perceived. Foliar spray with the inducers before pathogen inoculation, protected the plant against infection resulting great reduction in disease incidence and percent disease index. The minimum mean disease incidence (29.16 %) and per cent disease index (08.63 %) were recorded in salicylic acid treated plant against 70.93 % disease incidence and 40.46 % per cent disease index in case of control after harvesting. The treatment with inorganic chemicals as inducer prior to challenge inoculation sensitized the plant to produce increased levels of soluble newlineprotein. The maximum increase of soluble protein was found in salicylic acid treated leaves (35.58 and 35.63 mg/gm) at 11 days of pathogen inoculation. A highest content of phenol, which is an indicator