The effect of night temperature upon the vegetative and reproductive developments in lycopersicon esculentum

The tomato is one of the most sensitive plants, and yet one of the most tolerant and one of the most readily influenced by its environment. It thrives under a wide range of conditions, but the crop is not well adapted to regions where monthly mean temperatures are 80° F or higher. The influence of temperature during the period preceding fruiting of tomatoes has been studied for some time. Various observations suggested that low temperature following establishment in the field might be responsible for rough fruits, poor fruit-set of the first clusters, poor pollination and other common low temperature effects. With the work of Went, Wittwer and others it seemed that some of these effects might not, in fact, occur but that other effects did take place. Low temperature during seedling stage, provided it did not fall below 50° F seemed to encourage the development of flowers, and did not diminish fruit set. With these bits of information, it seemed desirable to study the effect of low night temperature, beginning at 45° F, after the plants were set in the field. From the information which was at hand it became the object of this experiment to study the fruiting behavior of tomatoes through the flowering, fruit-setting and fruit development of the first three clusters. If the idea that lower temperatures at night encourages more flowering and do not discourage fruit setting, could be extended to clusters beyond the first, perhaps a means of increasing total crop productions would be available. For field tomatoes a choice of location having a long growing season with relatively cool nights might have special value.