A SURVEY OF SELF-INCOMPATIBILITY IN HIGHBUSH BLUEBERRY (VACCINIUM CORYMBOSUM L.)

Self and cross pollination studies were conducted with 5 cultivars of V. corymbosum L. Pollen viability, growth of the pollen tubes to ovary and percentage of fruit set were examined. Pollen viability, indicated by stainability, fluctuates from 66% to 97% depending on the cultivar. Self and cross pollinated pollen tubes grow similarly through the style to ovary while differences have been observed among cultivars. Pollen tubes need more than 20 hours to cover the length of the style. They do not enter the ovary immediately but fertilization occurs at least 6 days after pollination.

Generally a higher percentage of fruit set is obtained with cross pollination.

There is a range of variation in the levels of self-incompatibility depending on cultivar: 'Berkeley' is the most self-compatible and 'Goldtraube 53' the most self-incompatible. Cultivar genetic potential, evaluated with the X² test of independence, shows a higher mother effect. There was no parthenocarpic fruit set.