Causes and Control measures of Castanea mollissima canopy

Chinese chestnut is one of the important economic forest tree species in China. There are about 700000 hectares of Chinese chestnut in China, with an annual output of about 1.5 billion kg, with an average yield of 270Mel 300kg per hectare and about 2kg per plant. In addition to the long-term use of seed reproduction and extensive management, the canopy of Castanea mollissima is one of the important reasons for its low yield. Therefore, preventing or reducing the empty canopy of Chinese chestnut is one of the important problems to be solved to improve the yield of Chinese chestnut.

Causes of Castanea mollissima canopy

The pollination and fertilization of ① Chinese chestnut is poor at flowering stage.

② is malnourished. Lack of boron and available phosphorus in soil will cause Castanea mollissima canopy.

The influence of other factors in ③. First, varieties, different varieties, different numbers of male and female inflorescences, different nutrients consumed, the rate of empty tent is also different. Second, in the year of drought, watering enough water or enough Rain Water in the flowering period, fruit filling period and freezing period of chestnut can not only make the chestnut grow vigorously, but also reduce the rate of empty tent obviously. Third, light is poor, water, nutrients and oxygen in the soil are in short supply, chestnut trees can not carry out normal photosynthesis, resulting in short shoots, yellow leaves, poor results, and the rate of empty canopy is also greatly increased. The fourth is the wind, in the flowering period of Chinese chestnut, if the wind speed is too high, the empty tent rate of Chinese chestnut increases; if the wind speed is too small, even no wind, the empty tent rate of Chinese chestnut also increases. The most suitable wind force in the flowering period of Chinese chestnut is generally 3mur4, and there is a great difference between the open area and the non-open area.

Prevention and treatment of Castanea mollissima canopy

① selected excellent varieties of Chinese chestnut with high seed setting rate. In the production of Chinese chestnut, through years of investigation and analysis, the excellent varieties with low empty tent rate are: Jiaoza, Qingza, the End of Heat Hong, Dahongpao, nine species, Maobanhong and so on.

The best tree structure was cultivated by ②. From the young tree stage to the early fruiting stage, the natural spindle shape is better, which can increase the early yield and economic income. in the early stage of full fruit, the tree should be thinned properly and pruned reasonably to cultivate the trunk tree, which can make more effective use of the space and increase the wind and light conditions of the tree, so as to reduce the empty canopy rate and increase the yield.

③ allocates pollination trees reasonably. The rate of empty canopy of Chinese chestnut could be significantly reduced by pollination assisted by the mixture of multi-variety pollen. It is generally believed that the number of pollination trees should be mainly planted in 1x3 of variety trees.

④ can reduce the nutrient consumption of trees by thinning male and canopy properly. When the male inflorescence was 15 cm long, the male inflorescence was removed, and only 3 branches were left in the mixed inflorescence. The abortion rate of the mixed inflorescence was significantly lower than that of the control. Generally, the female-to-male ratio is kept above 1RU 149, which not only does not affect the normal pollination of chestnut trees, but also greatly reduces the unnecessary nutrient consumption of chestnut trees.

⑤ strengthens the management of fertilizer and water to keep the tree growing healthily. Fertilization should be paid attention to in the appropriate period of topdressing and irrigation, especially in the flower primordial stage and pollination stage of Chinese chestnut: 3 kg of urea or 2 kg of nitrogen and phosphorus compound fertilizer can be applied to adult trees and irrigated after application. For the mountain areas without irrigation conditions, the method of making plates under the tree canopy and shallow trenches outside the plate is used in the rainy season to intercept and store Rain Water, and green manure can be applied inside the trenches to improve soil fertility. Nitrogen is the main topdressing in the early stage, and nitrogen, phosphorus and potassium should be combined in the later stage.

⑥ foliar spraying boron, phosphorus and other nutrient solution. Spraying 0.15% 0.25% boron fertilizer at flowering stage can reduce the rate of empty tent by 23% 32%, and the effect of mixing with urea and potassium dihydrogen phosphate at full flowering stage is the best. The key periods for the most effective control of Castanea mollissima canopy are ovule formation (late May) and double fertilization (late June). At the beginning of the differentiation period of chestnut female flowers, spraying 0.3%-0.5% potassium dihydrogen phosphate or 0.3% superphosphate + 0.3% urea solution twice combined with boron spraying, phosphorus spraying and urea spraying at flowering stage can not only prevent the canopy of chestnut fruit, but also promote the increase of female flowers of Chinese chestnut.