Exploitation of diploids in Indian banana breeding programmes.

Banana is a recalcitrant crop for improvement due to inherent plant-based constraints like polyploidy, parthenocarpy and male and/or female sterility. Success of banana breeding depends mainly on the use of natural diploids and/or developing superior synthetic diploids. India has nurtured the development of a number of wild and parthenocarpic diploids harbouring resistant gene sources for a number of biotic and abiotic factors. Present study on 15 diploids includes nine parthenocarpic and six wild diploid accessions of which ten are indigenous and five are exotic introductions. They have been evaluated for various traits like resistance to nematodes, weevils and borers, Fusarium wilt, leaf spot complex and reaction to drought. Based on their usefulness of traits, diploids were included in the breeding programme either directly or through development of synthetic diploids. This paper reports on the results of evaluation of these 15 diploids for their fertility status, breeding behaviour and compatibility status with other diploid and triploid parents. The paper also provides baseline information on factors affecting seed set, like temperature and relative humidity, extent of seed set in 79 diploid cross combinations, percent of good seeds with viable embryos, germination time (10-432 days), germination success (0-92%) and regeneration capacity (2.5-98.3%). This baseline information will be useful in selecting parents for future breeding programmes with better success in seed yield. The poor germination and regeneration of hybrid seeds into plantlets reiterates the need for standardized techniques for embryo rescue for better success in improvement of banana through classical breeding