Abiotic resistance inducers for management of bacterial wilt in tomato (Solanum lycopersicum L.)

The disease incidence of bacterial wilt of tomato, caused by Ralstonia solanacearum (Smith), ranged from 10.00 to 70.45 per cent in major tomato growing districts of Himachal Pradesh, India. In order to develop eco-friendly management strategies against the bacterial wilt disease, induction of resistance in pathogen-challenged tomato plants through abiotic resistance-inducers viz., salicyclic acid, inorganic and organic salts were evaluated. Seedling dip method of application of abiotic resistance-inducers was more effective in reducing wilt disease incidence than foliar spray application. Potassium chloride and oxalic acid at 300 and 200 mM concentration were most effective in managing the disease and increasing plant weight and plant height with maximum disease control of 70.27 and 56.76 per cent, respectively while sodium salicylate at 10 mM was least effective. Total phenol content and activity of enzymes viz., phenyl alanine lyase, polyphenol oxidase and peroxidase was measured in tomato plants treated with abiotic resistance-inducers at 0, 1, 2, 3, 5, 7 and 10 days after challenge-inoculation with bacterial pathogen. Total phenol content progressively increased in all the treatments upto 7(th) day after the spray of abiotic inducers of resistance and thereafter it declined. Maximum increase was observed in potassium chloride sprayed leaves (94 mu g/g tissue) followed by oxalic acid (92 mu g/g tissue). While, polyphenol oxidase, peroxidase and phenyl alanine lyase activity was found to be at the peak immediately after 24 h of elicitation and was found maximum in potassium chloride treated leaves and minimum in sodium salicylate treated leaves.