Phenotyping Diversity Population of Black Pepper for Phytophthora Resistance

A population of 57 genotypes representing diversity germplasm of black pepper was phenotyped for Phytophthora resistance following leaf, stem and root inoculation methods with a virulent isolate of Phytophthora capsici (IISR 05–06) isolated from black pepper. The black pepper genotypes showed varying reaction upon inoculation with P. capsici. The Disease Severity Index (DSI) of diversity population due to leaf infection ranged from 31.25 to 100% whereas due to stem infection ranged from 25 to 93.75%. Area under disease progression curve (AUDPC) analysis coupled with hierarchical clustering grouped the diversity population into four classes based on leaf and shoot lesions. Ten and six genotypes were grouped along with P. colubrinum, a distant Phytophthora resistant species, forming the first class on AUDPC analysis based on disease incidence on leaf and shoot respectively. Acc. No. 1324, 1231, 1386 1605, HP 780 and HP 1372 were the six common genotypes ranked along with P. colubrinum on AUDPC analysis of leaf and shoot lesion progression. Among the fifty seven genotypes only a single genotype (Acc. No. 1324) survived till 100 dai upon root inoculation but was found to exhibit an average of 50% root rotting.