Screening certain mung bean varieties against thrips (Thysanoptera: Thripidae) and exploration of resistance sources

Plant biophysical and biochemical properties play important roles to explore the resistance sources against thrips. In this study, we investigated the effect of trichomes and biochemical contents of 11 mung bean (Vigna radiata L.) varieties to search for the most resistant varieties against the incidence and damage of two thrips species, Megalurothrips usitatus and Thrips palmi. Resistance was quantified by examining the incidence of the thrips on different plant parts regarding the trichomes and biochemical content of the varieties. Further, the extent of damage by the thrips species and the effects on yield of the selected varieties were examined. All the 11 mung bean varieties were attacked by both the thrips during vegetative and flowering stage, however, lowest incidence occurred in BARI Mung-7 followed by BARI Mung-8 and BU Mug 2. The lower incidence was associated with higher trichomes and biochemicals content of the same varieties, as thrips population showed significant negative relationships with trichome density, moisture, chlorophyll((a+b),) potassium, and phenol content. Although several biochemicals had negative effects, the increasing total soluble sugar content in leaves increased the incidence of both M. usitatus and T. palmi. There was no variation in phosphorous content in the leaves of the 11 varieties. Significant variations were detected in damaging the flower bud, flower infestation, and shedding by thrips which affected the yield of mung bean. Negative responses of thrips to the increasing trichomes, moisture, chlorophyll, phenol, and potassium in mung bean suggest the significance of these properties to develop resistant varieties against thrips.