Role of morphological factors of pigeonpea in imparting resistance to spotted pod borer, Maruca vitrata Geyer (Lepidoptera: Crambidae)

Abstract

Morphological characters of eleven test genotypes of pigeonpea, such as growth habit, pubescence of pods and leaves, pod angle and pod wall thickness were studied in order to work out the relationship of these traits vis-à-vis resistance/susceptibility to Maruca vitrata. It was observed that genotype AL 1747 possessed significantly
highest trichome density on leaves and pods (177.33 and 43.33 trichomes/4.6cm2, respectively), whereas MN 1 possessed lowest trichome density (47.33 and 7.66 trichomes/4.6cm2, respectively). Trichome length on leaves and pods was significantly highest in AL 1747 (66.26 and 180.83?m, respectively) and lowest in MN 1 (33.53 and 43.25?m, respectively). Genotype AL 1747 recorded significantly highest pod angle (65o), whereas MN 1 recorded lowest pod angle (18.66o). There was significant negative correlation between trichome density on leaves and pods with larval weight gain (r = -0.71 and -0.69, respectively) as well as with per cent pod damage ( r = -0.75 and -0.75, respectively) and between trichome length on leaves and pods with larval weight gain (r = -0.81 and -0.81, respectively) as well as with per cent pod damage (r = -0.87 and -0.87, respectively). Pod angle was found to be significantly negatively correlated with both larval weight gain and per cent pod damage. Thus, early maturing pigeonpea genotypes with indeterminate growth habit, higher leaf and pod pubescence with wider pod angles should be preferred for breeding M. vitrata tolerant lines.