Morphological characterization and floral biology of parental lines of pumpkin cv. Pusa Hybrid 1

Morphological characterization and floral biology of parental lines of pumpkin cv. Pusa Hybrid 1 were studied during summer seasons of 2008 and 2009 at Seed Production Unit Farm, IARI, New Delhi. The parental lines were evaluated for 40 phenotypic characters (3 plant, 2 stem, 3 tendril, 7 leaf, 4 flower, 19 fruit and 2 seed), following NBPGR descriptor list at vegetative, flowering and fruit maturity stages. Parental lines showed considerable variation in early plant vigour, plant growth habit, petiole length, leaf size, leaf blotches and number of primary branches, node number at which first female flower appears, days to 50% flowering, sex ratio, fruit colour, fruit shape, blossomend shape, ridges on fruit, rind thickness, fruit weight, length, breadth, flesh thickness and 100-seed weight. Flower anthesis began between 3.00 and 4.00 AM with peak reaching between 5.00 and 6.00 AM in both parental lines. The flower closure was initiated at 8.00 AM and finally closed between 11.00 and 12.00 noon in both the male and female flowers. The flowers remained open for 3 h 30 min in male and female parents. However, there was a period of overlapping in flower anthesis of both sexes, which coincides with the peak of pollen viability and pollinator activity. Pollen viability was about 97.64–98.55% in freshly-opened flowers but decreased to 74.73% after 48 h and crashed to 23.40% after 96 h of its storage under ambient conditions. Pollens-giains stored under refrigerated conditions (4°°C temperature and RH-40%) maintained 63% viability after 96 h of storage. Stigma receptivity, measured by fruit set percentage, was noted from 12 h before anthesis, highest being at the time of anthesis.