UBC Theses and Dissertations
Studies on the effects of genotype and relatively cool temperatures on rough fruit production by tomato (Lycopersicon esculentum, Mill.) Yankson, Mary Figyina
Tomato fruits which are misshapen or rough are frequently a problem in the field crop, and sometimes in the greenhouse crop. This horticultural problem has been attributed to the exposure of seedling plants to relatively cool temperatures (below 15°C), but lack of knowledge about conditions causing rough fruit resulted in experiments to explore the influence of genotype and relatively cool temperatures on the production of rough fruit. A field study was carried out at the University of British Columbia in 1975 using 3 cultivars (Bonny Best, Fireball and Immur Prior Beta [IPB]) and 2 reciprocal hybrids of Bonny Best and IPB. In that season, there was a substantial quantity of rough fruit, and there were highly significant differences among genotypes. Controlled environment studies were used in 3 greenhouse experiments. In the first, tomato seedlings of 6 cultivars (Bonny Best, Cold Set, Early Red Chief, Fireball, IPB and Vendor) were chilled for either 3 or 7 nights to 10° ± 1°C at each of 4 different ages ranging from 3.5 to 6.5 weeks after seeding. Control plants were kept at 19° ± 1°C. None of the cultivars in any treatment produced enough rough fruit to be of any horticultural concern, but there were some highly significant differences (1% level) among the cultivars for the number of rough fruits produced. The second experiment employed more severe chilling conditions. Seedlings from 4 age groups ranging from 3 to 6 weeks were chilled for 2 weeks using a night temperature low of 4.4°C and a day high of 12.8°C. Four cultivars (Cold Set, Fireball, IPB and Vendor) were used, and although there were significant differences (5% level), the numbers of rough fruit did not match the horticultural problem. The third controlled environment experiment employed a regime of hourly changes in temperature to range from a night low of 4.4 °C and a day high of 21.1 °C, using only 2 cultivars (IPB and Vendor). Control plants were kept at 20.0UC/23.9°C. The plants were transferred to controlled environment chambers 35 days after seeding, and kept in the contrasting temperature regimes until fruit matured. Although the IPB had a significantly greater number of rough fruit than Vendor, the magnitude of the numbers of rough fruit were too small to be of practical importance. Apparently, the rough fruit problem is not caused by the simple matter of exposure to chilling temperatures, and it is supposed that an interaction, possibly a very complex one, may be the cause of this type of misshapen fruit.