Identification and biochemical characterization of resistance against downy mildew in pumpkin

Downy mildew, a foliar disease caused by Pseudoperonospora cubensis is an emerging disease of cucurbits. (Cucurbita moschata L.) is an important vegetable crops grown in north India. The present research investigated the screening of thirty three germplasm of pumpkin accessions as well as the potential role of four antioxidant enzymes in imparting resistance against P. cubensis during the cropping season 2016 and 2017. Plants were inoculated at optimum level of sporangial suspension (4.0 × 10⁴ sporangia per ml) to create downy mildew and per cent disease index was worked out. Out of thirty three accessions, thirteen were resistant and rest were moderately resistant, moderately susceptible, susceptible and highly susceptible. Significant mean maximum disease severity was observed in accession Bn 364 and minimum in accession P-111. Antioxidant enzyme activity was estimated spectrophotometrically from the leaf samples collected at 7, 14 and 21 days after inoculation. Results indicated an increase in enzyme activity during 7 days and decrease during 14 and 21 days of post inoculation. Pumpkin accession Punjab Samrat showed maximum enzyme activity, whereas Bn-364 showed the least.