Studies On The Relationship Between The Fruit Quality And The Microclimate In Apple Tree Canopies

The relationship between the dynamic distribution of the microclimate (including radiation, temperature and relative humidity) in tree canopy and the types of branches and leaves as well as the fruit quality was studied by using 12-year Red Fuji apple orchard trained as Standard open center shape. The results were as follows(l)The sum of branches per 666.7m2 was 65,000 and the proportion of the long branches, middle branch and spur was 12:14:74. The average annual light transmittance through tree canopy was about 0.45~0.55. The sections where the relative solar radiation intensity were more than 30% account for 80% of the tree volume. The distribution of the fruits was relatively symmetrical, and the percentage of high quality fruit was more than 80%.(2) The temperature difference was obvious within different seasons and in different positions of the canopy. The general trend was that the temperature increased gradually from the bottom to the top, and from the inner to the outer of the canopy. In May and June, the maximum temperature difference was about 0.3~0.8℃ between the top and the bottom of the canopy, and between the outer and inner of the canopy. The temperature difference was about 0.5~2.5℃ during the middle period of fruit growing, and was 0.5~1.5℃ during the fruit maturing period.(3) The relative humidity within the canopy varied obviously. It was higher in the bottom and inner than in the top and outer in the canopy. The difference of relative humidity within different part of the canopy was higher in the period of fruit expansion than in the period of canopy formation and fruit harvest.(4) The regression equations were developed between the microclimate factors of the tree canopy and the quantity of the leaf and branch and the fruit quality through multivariate statistical analysis. The mathematic model was built to predict the relative solar radiation intensity distribution, temperature and the relative humidity inside the canopy through the quantity and distribution of the leaves and branches in the canopy, an optimal scheme could be made between the microclimate of canopy and fruit quality, and furthermore, a comprehensive combination was made among the distribution and the quantity of the branches and leaf area with the tree canopy microclimate and fruit quality through this study.(5) The quality of fruit had strong and positive correlation with the relative radiation intensity within the canopy. The best range of relative radiation intensity for single fruit weight is within 30—90%, in which the best value was 46%; for rigidity of fruit, the best value was 70%; for content of solubility substance and the ratio of the content of solubility substance to acid, 60~...