UBC Theses and Dissertations
Some effects of temperature on flower production, compatibility relations and pollen development in certain lines of the tomato (Lycopersicon esculentum. Mill.) Guccione, Gioacchino Maria
The development of tomato varieties is desired for commercial production in agricultural areas having relatively low spring temperatures, and/or short growing seasons. These varieties would need the character of being able to set fruit under the unfavorable conditions of temperatures below 65 F. the English variety. Puck, has the characteristic of setting fruit at low temperatures, but is otherwise unsuitable for profitable tomato production. To identify the mechanism of this desirable character in Puck, and mode of inheritance of the character, experiments were carried out to study flower production, pollen compatibility relationships, and the production, development and germination of pollen. Experiments were carried out at two temperature levels in greenhouses to observe effects on flower and fruit development. These plant responses were studied in a relatively cool greenhouse kept at 55°- 65° F. and in another house kept at 65 - 75°P. range which is considered optimum for tomato production. The plants used were Puck and Bonny Best varieties and their reciprocal F1 hybrids. Blower production was significantly increased by lower temperatures, and the increases on Puck and the hybrids were larger than on Bonny Best. Fruit setting was reduced by low temperatures, suggesting reduction of self-compatibility in the hybrids as well as in Bonny Best, the latter having a high percentage of parthenocarpic fruits. The number of days between pollination and maturity of fruits was found to be in versely related to the number of seed formed in the fruits. Low temperatures, probably interacting with low light intensities and short photoperiods, appeared to reduce markedly the viability of pollen on all lines, as shown by viability tests on the pollen with the acetocarmine staining procedure and with germination tests in vitro. These experiments revealed an unexpected variability in pollen germination, which was possibly due to the effects of temperature on microsporogenesis. Percentages of normal meioses were only slightly affected, but there was evidence that a minimum temperature is required for the completion of meiosis, and that such minima were different for different meiotic stages. Rates of pollen deterioration following dehiscence of the anthers were found to be different in different varieties. Puck had a higher number of flowers produced at low temperatures showed no reduction of self-compatibility, and had a consistent seed set; therefore, this variety is to be considered a possible source of germ plasm in the breeding of tomatoes tolerant of cool temperatures.
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