ISHS Acta Horticulturae 465: IV International Peach Symposium
BREEDING FOR MULTIRESISTANCE IN PEACH TREE |
| Authors: | J. Kervella, T. Pascal, F. Pfeiffer, E. Dirlewanger |
| Keywords: | early selection, powdery mildew, peach green aphid, plum pox virus |
| Abstract:
Sources of resistance to peach pests and diseases are often found in wild related species, such as Prunus davidiana, P. kansuensis, P. mira. When using such sources in a breeding programme, the challenge is to reach as early as possible an acceptable agronomic level, while preserving most of the resistance characteristics of the donor parents. Short cycles of selection and crossing must be used to optimise genetic gain per time unit. Two-year and four-year breeding cycles have been experimented. Two-year breeding cycles have been successfully used for the breeding of powdery mildew resistance. An early evaluation on seedlings in the greenhouse and in the nursery allows to select hybrids with the main genetic factor of resistance, before flowering. A new cycle may be started after two years by pollinating a recurrent cultivar with the selected hybrids. Four-year cycles were designed to select simultaneously for resistance to powdery mildew, peach green aphid and plum pox virus and for fruit quality. Vegetative propagation by herbaceous grafting provided 6 to 8 plants from each seedling in the spring following the cross. One plant from each seedling was planted outdoors. Most of them flowered after two years. Three plants from each seedling were used for the screening of resistance to plum pox virus. The remaining plants were scored for resistance to powdery mildew and peach green aphid. Four years after the initial cross, the selection both for resistance characteristics and agronomic features will be completed. Intercrossing between hybrids with complementary resistance factors and acceptable agronomic levels should allow to accumulate resistance factors while preserving the agronomic level. The respective interest of both types of procedures is discussed, according to the desired genetic gain. These two types of procedures may be combined in a breeding programme. | |
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