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A relationship between ovary size at anthesis and final fruit diameter of 12 tomato (Lycopersicon esculentum Mill.) cultivars with a range of fruit sizes, shapes, and maturation rates was determined. 'Fireball', 'Michigan/Ohio Hybrid', and 'New Yorker' produced nonfasciated, spherical fruits of intermediate maturation rate and showed a significantly higher correlation between ovary diameter at anthesis and final fruit diameter than 'Small Fry', 'Roma VF', 'Early Cascade', 'Campbell 1327', or 'Ponderosa'. A linear regression of final fruit diameter at maturity on ovary diameter at anthesis of the cultivars was highly significant (r 2 = 0.92**; y = 22.5X - 0.3). Continuous root application of 0.01 BA to seedlings of 'Fireball' significantly de- layed anthesis. A single foliar application of 0.37 mM NOA to 'Fireball' plants at the appearance of the first inflorescence significantly increased ovary diameter on the first inflorescence, but decreased ovary diameter on the second inflorescence. Treatment with NOA altered final fruit shape but not final fruit diameter. Single foliar applications of 0.1 mM GA stimulated stem and peduncle elongation but did not affect fruit size. Chemical names used: s-naphthoxyacetic acid (NOA), N 6 -benzylaminopurine (BA), gibberellic acid, (GA). Fruit size in plants is not usually corre- lated with the size of the entire plant, but it is related to the size of the meristem. A pos- itive relationship has been demonstrated be- tween tomato ovary size at anthesis and final fruit size (Houghtaling, 1935). Early ovarian growth is mainly a result of cell division; thereafter, fruit growth is influenced primar- ily by cell expansion (Geelen et al., 1987; Bohner and Bangerth, 1988). Many mor- phological and environmental factors influ- ence tomato fruit growth, including fruit shape, maturation rate, and the application of plant growth regulators. Genetically inherited traits for shape in- fluence the direction of cell division (MacArthur and Butler, 1938). Genes for elongated fruit tend to decrease fruit size, whereas those for flatness tend to increase fruit size. In addition, traits for maturation rate affect final fruit size. Tomato cultivars characterized by a relatively long cell di- vision stage or fast rate of cell division generally produce relatively large fruits (MacArthur and Butler, 1938). Cytokinins have been shown to stimulate |
