Effect of GA3 on the Phytotoxicity of Aldicarb and Carbofuran on Seedling Growth in Capsicum frutescens var. California Wonder and Rate of Root Knot Nematode Infestation

The present investigation dealt with the effect of the two granular systemic nematicides aldicarb and carbofuran, individually and in combination with 100 mg · 1^-1 GA₃, on plant growth and root knot formation in C. frutescens var. California Wonder. Both nematicides and GA₃ were applied as a seed-dip treatment. GA₃ increased seed germination and seedling growth. All concentrations (2 to 20 g a.i. · 1^-1) of aldicarb and carbofuran, when applied independently, reduced seed germination and length of epicotyl and hypocotyl. However, application of these nematicides in combination with 100 mg · 1^-1 GA₃ showed antagonistic behaviour. All the treated seedlings were inoculated with 1000 nematode larvae of Meloidogyne incognita. Vegetative parameters of the plant were studied 15 days after transplantation. A combination of GA₃ (100 mg · 1^-1) with different concentrations of nematicides showed a synergistic effect on treated plants. Root knot index in plants treated with nematicides was found to be reduced with increasing concentrations of both nematicides. Maximum reduction in root knot index was observed at highest dose (20 g a.i. · 1^-1) of both nematicides, when applied in combination with 100 mg · 1^-1 GA₃. Proteolytic activities were decreased in plants treated with both aldicarb and carbofuran. Supplementation of the nematicides with GA₃ resulted in an increase in enzyme activities of the treated plants. Toxic residues increased with increasing concentration of both nematicides, whereas it was reduced at highest concentration of both nematicides when applied in combination with GA₃.