Estimation of biochemical factors responsible for resistance to root and collar rot (Macrophomina phaseolina (Tassi) Goid.) in okra

Abstract

Twenty okra genotypes were screened for their resistance to root and collar rot incited by Macrophomina phaseolina in the experimental fields of Department of Plant Pathology, B. A. College of Agriculture, Anand Agricultural University. Based on their disease reaction, they were grouped into four categories i.e., resistant, moderately resistant, susceptible and highly susceptible. The biochemical analysis of the resistant and susceptible genotypes revealed that the total soluble sugar, reducing sugar and non reducing sugar decreased following inoculation by the pathogen. The decrease in total soluble sugar, reducing sugar and non reducing sugar were 21.54, 21.73 and 21.42 per cent in resistant variety, whereas in highly susceptible variety it was 6.06, 6.10 and 3.03 per cent, respectively. The total phenol content, soluble protein and peroxidase activity increased on inoculation with the pathogen. In the resistant variety, the increase in phenol content, soluble protein and peroxidase activity was 23.4, 32.56 and 63.86 per cent whereas in moderately resistant variety this was 19.85, 21.63 and 55.29 per cent, respectively. Susceptible and highly susceptible genotypes had low to moderate increase in the three parameters. The experimental results confirmed the importance of these biochemical factors in imparting the host resistance to root and collar rot.