Evaluation On Three Kinds Of Tree Shape Structures Of Korla Fragrant Pear

The experimental materials of this study were evacuation shape, open center shape and level trellis shape of Korla fragrant pear, and the canopy microclimate, photosynthesis and fluorescence characteristics, variation of sap flow velocity and its relationships with meteorological factors, yield and fruit quality of three tree shapes were analyzed. The main results were as follows:?1? The upper part canopy photosynthetically active radiation and temperature of the three tree shapes in Korla fragrant pear were both higher than the lower part's, while the lower part relative humidity was higher than the upper part's. The daily photosynthetically active radiation of level trellis shape was the highest, and the daily temperature of open center shape was the highest, and the daily relative humidity of evacuation shape was the highest. In addition, the photosynthetic active radiation, the temperature and the relative humidity of each tree shape were changed with the change of leaf crown and season.?2? The daily variation of net photosynthetic rate, intercellular CO₂ concentration and transpiration rate of the three tree shapes all presented “double peaks” curves, and photosynthetic ability of level trellis shape was the best. The CO₂ response curves of the three tree shapes were in line with the trend of light response curves, and the level trellis shape had the best adaptability to light environment, while the evacuation shape could adapt to a higher CO₂ concentration environment.?3? Under the stress of high temperature and strong light intensity, the three tree shapes showed different degree of light inhibition. Among them, the open center shape suffered stronger light inhibition, but the evacuation shape suffered lower light inhibition, meanwhile, the level trellis shape could resist to stronger light, higher temperature and lower air humidity environment.?4? During growing season, the sap flow velocity of the three tree shapes showed an obvious trend of high in daytime but low in nighttime under different weather, and that in sunny and cloudy days presented “single peak” curve; while the sap flow velocity in overcast days mostly presented “multiple peaks” curve, which was lower than that in sunny and cloudy days. The sap flow velocity was especially highest in July; it was also different among tree shapes. The sap flow velocity and sap flow flux of evacuation tree shape was the highest, and that of level trellis tree shape took second place. In addition, the sap flow velocity was closely related to meteorological factors, and it was most affected by light intensity.?5? The fruit yield and quality of level trellis shape and open center shape were all better than that of evacuation shape. Among three tree shapes, the high grade fruit rate and leaving calyx rate of level trellis shape was the highest, and that of open center shape took second place, while the convex calyx of evacuation shape was the highest. The level trellis shape was convenient for management, less artificial investment, but higher material input in the first year. The sap flow flux of open center shape was the lowest, so it needed less theoretical water costs. The yield of level trellis shape and open center shape had little difference, but the output value of level trellis shape was higher than that of open center shape. Comprehensive consideration, the level trellis shape had higher yield and quality, convenient management and higher output value in later year, so the most reasonable tree shape of Korla fragrant pear was level trellis shape.