Effects Of Different Tree Shapes On Canopy Structure,Photosynthetic Characteristics And Fruit Quality Of Pear

As one of the main cultivated fruit trees in Northwest China,pear plays an important role in the development of agricultural economy.With the increasing importance of improving the quality and efficiency of pear trees,various new tree shapes have appeared in production.In order to accurately study the canopy structure,photosynthetic efficiency,yield and fruit quality of different tree shapes of pear,the existing tree shapes of 4-year-old ‘Dangshansuli’,‘Changba’,‘Yuluxiang’,‘Zaosu’ and ‘Huangguan’ in the pear orchard test station were taken as the research objects.The branch amount,branch composition,canopy characteristics,light distribution,photosynthetic characteristics,fruit yield and quality of different tree shapes were measured and compared.The main results are as follows :1.The number of short branches of Y-shaped,inverted umbrella-shaped and multi-trunkshaped of ‘Dangshansuli’ pear was higher than that of cylindrical.The overall flowering rate of Y-shaped and inverted umbrella is higher;the proportion of short branches of Y-shaped and cylindrical trees was higher,and the proportion of short branches of multi-trunk trees was the lowest.The flowering rate of short branches in Y shape was higher than that of the other three tree shapes.The proportion of inverted umbrella-shaped short branches and the overall flowering of ‘Yuluxiang’ were better than those of cylindrical;the proportion of short branches and flowering of ‘Zaosu’ pear and ‘Huangguan’ Y-shaped trees were better than those of cylindrical trees.2.The density of Y-shaped and inverted umbrella-shaped leaves of ‘Dangshansuli’ pear was less than that of shape of cylinder and multi-trunk leaves,and the sky visibility was greater than that of shape of cylinder and multi-trunk leaves.The Y-shaped blade density of ‘Changba’was the smallest,the sky visibility was the largest,the shape of cylinder blade density was the largest,the sky visibility was the smallest,and the inverted umbrella and multi-trunk were centered;the inverted umbrella leaf density of ‘Yuluxiang’ was small,and the sky visibility was large,but the difference with the shape of cylinder shape was not significant.The density of Y-shaped leaves of ‘Zaosu’ and ‘Huangguan’ was smaller than that of shape of cylinder leaves,and the sky visibility was significantly higher than that of shape of cylinder leaves.3.The PPFD of different tree canopy parts of ‘Dangshansuli’ pear showed upper layer >middle layer > lower layer,and the overall PPFD of Y-shaped and inverted umbrella canopy was significantly higher than that of the other two tree shapes.The proportion of high-quality light areas in the Y-shaped canopy was the highest,the multi-trunk shape was the lowest,and the inverted umbrella and cylindrical shapes were centered;the overall PPFD of the ‘Changba’Y-shaped is the highest,and the cylindrical overall PPFD is the lowest.The Y-shaped highquality light area in the canopy is higher,the cylindrical and multi-stem shape is lower,and the inverted umbrella shape is in the middle;the PPFD and overall illumination of the inverted umbrella canopy of ‘Yuluxiang’ were better than those of the cylindrical canopy.The PPFD and overall illumination of Y-shaped canopy of ‘Zaosu’ pear and ‘Huangguan’ pear were better than those of cylindrical canopy.4.The overall Pn,Tr and Gs of different tree canopy of ‘Dangshansuli’ pear showed Yshaped > inverted umbrella > cylindrical > multi-trunk,while the order of Ci was opposite.The overall Pn,Tr and Gs of the Y-shaped and inverted umbrella-shaped canopy of ‘Changba’were significantly larger than those of the other two tree shapes,and Ci was smaller than the other two tree shapes.The Pn,Tr,Gs and Ci of ‘Yuluxiang’ inverted umbrella shape were higher than those of the cylindrical shape.The overall Pn,Tr and Gs of ‘Zaosu’ pear and‘Huangguan’ Y-shaped were higher than those of cylindrical,and Ci was less than cylindrical.The photosynthetic efficiency of different tree shapes in the direction is: southeast > northwest.5.The yield per plant and fruit quality of ‘Dangshansuli’ pear and ‘Changba’ pear with Y shape were the highest.Cylindrical and multi-stem shape had low yield and poor fruit quality,and inverted umbrella shape was in the middle.Compared with the cylindrical shape,the inverted umbrella shape of ‘Yuluxiang’ had lower single fruit weight,but higher overall quality,color and flavor.The Y-shaped and cylindrical yields of ‘Zaosu’ pear and ’Huangguan ’pear were concentrated in the middle layer.The single fruit weight of ‘Zaosu’ pear was lower than that of cylindrical shape,but the solid content and solid-acid ratio were higher than those of cylindrical shape.The overall quality of ‘Huangguan’ Y-shaped fruit was higher than that of cylindrical fruit.6.After principal component analysis of the original determination indexes of different tree shapes of each variety,it can be concluded that the order of the advantages and disadvantages of each tree shape of Dangshansuli pear is : Y shape > inverted umbrella shape >cylinder shape > multi-trunk shape;‘Changba’ is Y-shaped > inverted umbrella > shape of cylinder = multi-trunk;‘Yuluxiang’ is inverted umbrella > shape of cylinder;‘Zaosu’ is Yshaped > shape of cylinder;the ‘Huangguan’ is Y-shaped > shape of cylinder.