There are many reasons for the big and small years, such as climate influence, such as warm winter and spring floods, which are one of the reasons for the big and small years, as well as genetic and physiological reasons, but the main reason is that the nutrition adjustment of litchi trees is not suitable and the fertilization management measures are not in place.
For example, litchi consumes a lot of nutrients after high yield. If sufficient nutrients are not supplemented, new fruiting mother branches cannot be formed, or because the new shoots are pulled out too late and the tissues are too tender, and the new shoots have not accumulated enough nutrients to supply the nutrients needed for flower bud differentiation, the next year will not blossom and bear fruit, and become a small year. In small years, there are few fruits and relatively more nutrition, which is easy to produce a large number of fruiting mother branches. Under suitable conditions, the flower buds are well differentiated, and a large number of flowers and fruits will be produced in the second year, which will become a big year.
After the New Year, if the management of litchi orchards is not strengthened, a new year will be formed. This annual cycle is caused by the imbalance of nutrition, growth and fruit of litchi trees.
In litchi tree nutrition, carbohydrates and nitrogen are the premise of flower bud differentiation, and they are important nutrients and energy. Starch accumulation plays an important role in flower bud development. When the ratio of carbon to nitrogen is large, it is beneficial to flower bud differentiation and flowering. On the other hand, when the ratio of carbon to nitrogen is low, it is not conducive to flower bud differentiation, autumn shoots can not bloom, or flowering spikes appear.
According to the research results of Peng Jian (2004) on glutinous rice paste, Guiwei, Feizixiao, Heiye and Hu Aizhi, the contents of starch and total sugar in leaves of each variety in early years were significantly lower than that in the same period of the new year, and the lack of carbohydrates in autumn leaves, too high nitrogen content and too low carbon-nitrogen ratio would affect the reproductive growth of trees in the following year. In the flower bud differentiation stage and fruit setting stage, the nitrate nitrogen content in older leaves is higher than that of younger trees, but lower than that of younger trees at flowering stage. The contents of phosphorus and potassium in the leaves of older trees are basically high, and it is easy to crack fruits, such as glutinous rice paste and cinnamon. The calcium content of older leaves is lower, while the calcium content of younger leaves is higher. It is necessary to promote the growth of fruiting branches, mature on time, store enough carbohydrates and improve the flowering rate of autumn shoots.