Screening of blackgram varieties and role of biophysical characters on damage potential of spotted pod borer, Maruca vitrata fabricius

Spotted pod borer, Maruca vitrata is one of the most serious lepidopteran pests in pulses which occurs from seedling to pod formation stage. The occurrence of M. vitrata depends upon various biophysical and biochemical characters of host plants. Plant characters viz., plant height, number of branches, number of pods per cluster, pod length, pod width, angle between pods, number of seeds per pod, seed size, trichome density and trichome length in pods were studied to observe the association of different morphological traits with resistance or susceptibility to M. vitrata in nine blackgram varieties. Among the tested nine varieties, CO 5 and MDU 1 were considered susceptible having highest pod damage per cent of 14.38 and 13.70, respectively while VBN (Bg) 5 and VBN 6 have lowest pod damage per cent of 5.79 and 6.15, respectively. It was observed that highly susceptible variety CO 5 has less number of trichomes (2.13/mm²) and trichome length (3.95 mm) while the resistant variety VBN 6 has dense trichomes (4.13/mm²) and trichome length (5.01 mm) which is considered to be the main factor to confer resistance in plants.