ISHS Acta Horticulturae 57: I International Symposium on Tropical and Subtropical Fruits
BREEDING AND DISEASE PROBLEMS IN SOME TROPICAL AND SUBTROPICAL FRUITS WITH EMPHASIS ON PAPAYA |
| Author: | Henry Y. Nakasone |
| Abstract:
Tree crop improvement by conventional breeding methods is difficult because of the long life cycle, and further complicated in plants that produce apomictic embryos or seedless fruits such as the banana, mango, and pineapple. Breeding banana cultivars with fruit characteristics of the 'Gros Michel' with resistance to the Panama Wilt disease resulted in obtaining disease resistance but not all the fruit and bunch characteristics of the 'Gros Michel'. In mangos, selections from open pollinated progenies from monoembryonic cultivars have provided many desirable cultivars. Pineapple breeding has contributed significantly to the knowledge of cytology and genetics but not to the list of new cultivars. Improvements have been accomplished by roguing and selecting among millions of plants. The avocado, macadamia and guava have been improved by selecting desirable types from large open pollinated seedling populations. Avocado hybrids with cold hardiness have been obtained by natural cross pollinations in heterogeneous plantings in Florida. Current guava breeding studies are directed towards the development of tolerance or resistance to the red-banded thrips. Passion fruit breeding studies have shown that the flavicarpa (yellow passion fruit) carries a dominant resistant gene for a wilting disease and Passiflora edulis (purple passion fruit) is susceptible. Vines showing high tolerance to the Brown spot disease have also been identified in Hawaii. Breeding for disease resistance is the major objective in papaya. Breeding lines with field tolerance to the Phytophthora root rot have been identified. Results obtained from Phytophthora fruit rot inoculations have not been consistant. Search for resistance to the Papaya Mosaic Virus (PMV) among cultivars and lines of Carica papaya has not been successful. Several Carica species are reported to be resistant to the papaya virus but crosses between these species and papaya have not been obtained due to strong cross incompatibility. | |
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