Principal component analysis for quantitative traits and powdery mildew resistance in pea (Pisum sativum L.)

Powdery mildew (PM) caused by Erysiph episi is an important fungal disease of pea. Resistance to PM is known to be governed by two independent recessive genes e1 and er2 in cultivated peas and by a dominant gene Er3 in wild peas (Pisum fulvum L.). Identification of new resistance sources and introgression of these gene(s) into varietal development is one of the most effective methods to control the disease. In the present study, 50 pea genotypes comprising vegetable and field peas were screened in the field during crop seasons 2012–13 and 2013–14 for seven quantitative characters including, days to 50% flowering, days to pod formation, plant height (cm), number of pods per plant, number of seeds per pod, 100-seed weight (g) and disease severity (%). Estimates of correlation coefficients indicated highly significant but negative associations between AUDPC with days to flowering (r =-0.448, p < 0.001) and 100-seed weight (r =-0.622, p < 0.001). Days to pod formation was significantly associated with days to 50% flowering (r = 0.79, p< 0.0001). Multivariate and regression analysis found, 100-seed weight and days to 50% flowering were the most reliable traits for selection of resistant genotypes. Some potent Indian PM resistant vegetable (VRPMR-9, VRPMR-10, VRPMR-11 and Arka Ajeet) and field (HUDP-5, JP-4, PMR-45 II and VRP343) pea genotypes have been identified in the present study, that would be used in PM resistance breeding programs.