An Analysis of Pollen Parameters, Fruit Set and Fruit Development During Attempts on Intergeneric Hybridization of Papaya (Carica papaya L.)

Research was conducted at the University Orchard, Horticultural College and Research Institute, to investigate the extent of pollen production, pollen fertility, fruit set, fruit growth and seed set as well as seedling vigour when two wild relatives of papaya (Vasconcellea cauliflora and Vasconcellea candamarcensis) are involved in the hybridization programme as male parents with three papaya cultivars (CO 7, TNAU Papaya CO 8 and Pusa Nanha) as female parents. Among the two wild relatives, V. candamarcensis was more polleniferous but with significantly lesser pollen viability and germination than V. cauliflora. Among the six intergeneric crosses, although the fruit set ranged from 60.00% to 93.33% the fruit retention till harvest was only 30.77 per cent to 35.71 per cent. The study also revealed metaxenic influence of wild parent on the growth of the fruits derived after crossing. Seed set was observed only with CO 7 as female parent but the seed size and weight, germination and seedling vigour recorded by intergeneric crosses of CO 7 with Vasconcellea were found to be low. The implications of the observations are discussed in relevance to employing the wild relatives for improvement of papaya.