AN ABSTRACT OF THE THESIS OF Guiwen Cheng for the degree of Doctor of Philosophy in Horticulture presented on Au,gust 23. 1991 Title: Changes in Developing Strawberry Fruit: I. Cell Division and

Size and color are important visual quantity attributes of the fruit of strawberry (Fmgaria x ananassa Duch.). Strawberry cultivars produce fruit of a characteristic size and color, the later being the result of accumulation of particular anthocyanins. This research sought to determine the basis for genotypic differences in fruit size and to monitoring changes in the amount of anthocyanins and related phenols, and the activity of associated enzymes during strawberry fruit development. Fruit size (weight and volume), number cells per fruit, and mean cell size were determined throughout the development of secondary fruit of the day-neutral strawberry cultivars Tillikum, Tristar, and Selva. Fruit size among the cultivars showed a four fold range and resulted from differences in the number of cells per fruit. The number of cells per mature fruit was 0.72, 1.96, and 2.94 x 106 for `Tillikum', `Tristar', and `Selva', respectively. The relative difference in cell number among cultivars was established by anthesis. In all cultivars, mean size of fruit cells was similar (z 6 x 106 µm3 at maturity) and cell division continued for about 12 days after anthesis