Light Interception Rate and Canopy Structure Optimization of Korla Fragrant Pear
[Objective]This study investigated the canopy structure of five tree shapes of Korla fragrant pears,analyzed the differences in light distribution within different tree shapes,established a daily change model of light interception,calculated the light interception rate,clarified the regulation methods and target parameters of the canopy structure,to provide a reference basis for cultivating high-light-efficiency tree shapes.[Method]Korla fragrant pear trees with different shapes were chosen as the test materials,the canopy structural parameters and photosynthetic-effective-radiation(PAR)passing through different tree shapes were measured.Based on a quadrant approach,a three-dimensional space was constructed,the light distribution maps were drawn,an evaluation index system of light interception was established,and the light interception amount and light interception rate were calculated.Through correlation analysis and principal component analysis,the main canopy structure and regulation methods that affect light interception were identified.[Result](1)The ground diameter and average branch diameter of large cylindrical-shaped trees were larger,with main branches with imbalanced branch-to-trunk ratios.The number of branches and branch diameter through the canopy of the cylindrical-shaped trees were more uniform.The number of branches,total length of branches,and average branch length of the narrow cylindrical-shaped trees were significantly lower than those of the cylindrical-shaped trees.The height of trees with the short cylindrical-shaped trees was significantly lower and other parameters were similar to the narrow cylindrical-shaped trees.The ground diameter,average branch length,average branch diameter,average branch angle,and average distance of branches of slender-spindle-shaped trees were significantly lower than those of cylindrical-shaped trees,but the proportion of short branches was significantly larger.(2)The distance from the trunk and height were the main factors which affected the canopy light interception(LI),and the average light interception(ALI)at a distance of 100 cm from the trunk increased significantly,reached 572 μmol·m-2·s-1,which was approximately twice that of the inner chamber.The lighting conditions below 220 cm were poor.The south,north,southeast,and southwest sides were high-light areas,while the west,east,northeast,and northwest sides were low-light areas.The daily variation in ALI can be roughly divided into five periods.(3)As the tree shape became narrower and shorter,the ALI significantly increased in the inner chamber,in each or partial layer,in all or partial directions,and in partial periods.(4)The single-day cumulative light interception(CLI)of slender-spindle-shaped trees was 22.2 mol·m-2,the group CLI was 3 712 mol/667 m2,and the light interception rate(LIR)was 35.6％,which was significantly higher than that of other tree shapes.The proportion of low-light area(PLL)was 50.9％,which was significantly lower than that of other tree shapes.(5)Five canopy structural parameters were significantly positively correlated with the LIR while fifteen canopy structural parameters were significantly negatively correlated.[Conclusion]The proportion of short branches is the most important parameter affecting the light interception in Korla fragrant pear trees,while the length of branches is the most important parameter affecting the proportion of low-light area.Control the tree height and canopy width can improve the light interception rate and the uniformity of light distribution.The slender-spindle-shaped canopy has a more uniform light distribution and the highest light interception rate.It can maintain a larger number of branches and a larger proportion of short branches with reduced average branch length to improve the lighting level of the canopy.
Pyrus sinkiangensis Yutree shapelight distributionlight interceptionproportion of low light area
万方数据
维普
