Identification and Characterization of resistance against downy mildew in Pumpkin (Cucurbita moschata L.) and Snapmelon (Cucumis melo L. var. momordica )
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Date
2017
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Punjab Agricultural University, Ludhiana
Abstract
Pseudoperonospora cubensis [(Berk and Curtis) Rostovez] an obligate parasite causing downy mildew of snapmelon and pumpkin, that can survive and reproduce on living host tissue resulting in significant yield losses. Fourty six and thirty three accessions of snapmelon and pumpkin were screened against P. cubensis in year 2015-2016 and 2016-2017 cropping season respectively. Plants were inoculated at optimum level of sporangial suspension (4.0 x 104 sporangia per ml) to create downy mildew. Out of fourty six accessions of snapmelon, three were resistant having incidence in the range of 20-30 per cent and rest were moderately resistant, moderately susceptible, susceptible and highly susceptible. However, in case of pumpkin, thirteen accessions were resistant having incidence in the range of 3-6 per cent and rest were moderately resistant, moderately susceptible, susceptible and highly susceptible. Significant mean maximum disease index was observed in snapmelon accession SM 2013-7 and minimum in accession MC 2013-4. Similarly, in case of pumpkin, mean maximum disease index was observed in accession BN 364 and minimum in accession P-111. Antioxidant enzymes activity was estimated spectrophotometrically from the leaf samples. The data pertaining to the activity of antioxidant enzymes revealed significant differences among the accessions showing different reaction against P. cubensis. Higher activity of antioxidant enzymes were observed in resistant followed by moderately resistant accessions whereas; activity gradually declined among susceptible and highly susceptible accessions of snapmelon and pumpkin. Negative correlation was obtained between antioxidant enzyme activity and disease development suggesting possible involvement of these enzymes in imparting disease resistance against downy mildew in sanpmelon and pumpkin. Improving the genetic resistance of snapmelon and pumpkin to downy mildew through introgressive breeding could be an effective way to control this disease. The narrow genetic base of modern snapmelon and pumpkin accessions and a few sources of resistance make downy mildew resistance an important objective in snapmelon and pumpkin breeding programs. Therefore, the identification of new sources of resistance is desirable.
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