The photoperiod phenomenon is the response of vegetable crop growth and development (flower bud differentiation, twitching and flowering) to the relative length of day and night. Daily light hours are related to plant development and yield formation. Vegetable crops can be divided into long-term, short-day and medium-light vegetables according to the requirements of growth and flowering and sunshine length.
1, long-term vegetables: longer sunshine (generally 12 ~ 14 hours or more), to promote plant flowering, short days to prolong flowering or not flowering. It is a long-term vegetable with cabbage, cabbage, mustard, radish, carrot, celery, spinach, lettuce, broad beans, peas, green onions, onions, etc.
2, short-term vegetables: shorter sunshine (generally less than 12 to 14 hours) to promote plant flowering, do not bloom or prolong flowering under long days of sunshine. The short-term vegetables include cowpea, lentils, leeks, loofah, spinach, fungus and late-maturing soybeans.
3, medium-light vegetables: can bloom under longer or shorter sunshine conditions. Among the medium-light vegetables are: cucumber, tomato, kidney bean, and early-maturing soybean. Such vegetables do not require strict illumination time, and as long as the temperature is appropriate, the results can be flowered in spring or autumn.
The length of light is related to the formation of some vegetables. For example, the formation of potato tubers requires shorter sunshine, and the formation of bulbs by onions and garlic requires long sunshine.