Physiological Genetic studies of Photoperiodic Responses in Beans (Phaseolus vulgaris L.)

Although the practical grower has always known well that temperature and sunshine are important factors affecting the growth of his crops, the importance of the length of day, technically known as the photoperiod, as a major external factor affecting the plants in their growth and development was discovered by Garner and Allard in 1920. Since then, numerous investigations have been conducted and plants have been classified with respect to their responses to relative length of day and night as short-day plants, long-day plants, and day-neutral plants. Day-neutral plants are those which disregard relative length of day and night and in which flowering is controlled by other factors such as age of the plant, number of nodes, and previous history of cold treatment.