Some effects of cool temperatures on flower production, fruit set and growth of four tomato varieties and their Fl hybrids.

It is desirable to develop tomato varieties which have the character of being able to set fruit at relatively cool temperature between 10°C to 15.5°C for commercial production in Canada. The tomato varieties Puck, Bonny Best, Immur, Prior Beta, Cold Set and some of their reciprocal Fl hybrids were grown both in greenhouses and in growth chambers under two different temperature levels, experiments were carried out to study fruit, set and the effects of self and cross-pollination on fruit development in four varieties and the Fl hybrids of PxBB, BBxP, IPBxBB, BBxIPB, CSxBB, and BBxCS. Under both cool and warm temperatures, the percentage of fruit set and also size of fruit were increased when cross-pollination was used in contrast to self-pollination. Under cool temperature, all Fl hybrid lines had a higher percentage of fruit set than their two parents, but in warm temperature the Fl hybrid lines had a intermediate percentage between those of the two parents. Under both temperature regimes there were distinct differences among lines in the time intervals for different component stages in the life cycle. Cool temperatures increased lengths of these intervals, but relative difference in lengths of interval was clearly evident. Among the ten lines, IPB was notably the earliest variety to ripe first fruit. In the first component interval from seeding to flower opening, IPB was the earliest and Bonny Best the latest; however, for the two succeeding intervals, namely flowering to fruit set and fruit set to ripening, IPB did not have the shortest intervals or most rapid growth. In fact Puck variety was better than IPB for the second component interval, and in the third interval, (BBxIPB) Fl and the reciprocal cross were the earliest. This sort of variability suggests recombination to put the earliest component stages together to synthesize a very early line.Land and Food Systems, Faculty ofGraduat