Biochemical Factors Associated with Resistance to Spotted Pod Borer, Maruca vitrata (Fabricius) in Green Gram

Background: Legume pod borer or spotted pod borer, Maruca vitrata is one of the serious insect pest to the green gram, which causes damage mainly at the reproductive phase of the crop growth. The larvae of spotted pod borer are known to cause damage by webbing the leaves, bud, flower and pods together and feed from inside on them. Due to its webbing nature, it is very difficult to enter inside by natural enemies and chemicals cannot directly reach inside webbing. Host plant resistance to insect pests is an economically and ecologically preferred alternative as compared to other pest management tactics, particularly the synthetic pesticides. The present investigation was undertaken to examine the role of certain bio-chemical constituents of the immature pods of green gram in the expression of damage by the spotted pod borer. Methods: The experiments on screening were conducted during the kharif 2014 and 2015 at the Agricultural Research Farm, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, (U.P.) to define the occurrence of M. vitrata on 20 promising varieties/genotypes of green gram. Pods were collected at the immature stage from different varieties/genotypes and biochemical constituents such as total soluble sugar, total chlorophyll, protein were estimated. Result: The maximum protein content was found in genotype IPM 306-6 (36.17 mg/g) and minimum in genotype PM-5 (20.53 mg/g). Highest total sugar content was reported from genotype ML 1256 (16.71 mg/g) and lowest total sugar content was recorded in PM-5 (10.94 mg/g).The phenol content in genotype PM-5 (9.00 mg/g) was significantly higher than others whereas, the minimum phenol content was reported in IPM 306-6 (5.14 mg/g). The higher amount of total chlorophyll content found in genotype IPM 306-6 (3.22 mg/g) and lowest in PM-5 (1.85 mg/g). The significant and positive correlation was observed between M. vitrata larval population, pod damage and protein (r=0.954** and r=0.952**, respectively) and total sugar content (r=0.986** and r=0.986**, respectively) and total chlorophyll content (r=0.994** and r=0.993**, respectively) in immature pods, while, the significant and negative correlation was found between phenol (r= -0.916** and r= -0.919**, respectively).