Effects of tree shapes on growth, yield and quality of peach

LIU Li;LI Qiulia;GAO Dengtao;WEI Zhifeng;SHI Caiyun;WANG Zhiqiang;LIU Junwei;Zhengzhou Fruit Research Institute,the Chinese Academy of Agricultural Sciences;

Peach;;Zhongyou 20;;Different tree shapes;;Tree structure;;Fruit quality;;Principal component analysis

【Objective】Although peach industry in China has made great progress, yield and fruit quality improvement remains the focus of fruit research. In order to fully realize the production potential of new varieties, we examined the effects of tree shape on fruit yield and quality of Zhongyou 20 peach,hoping to select the most suitable tree shape for peach production.【Methods】The experiment was carried out in a peach orchard in Yandianzhuang village, Qiaobei Township, Yuanyang City, Henan Province. The trees were 3-year-old, and the experimental plots covered an area of 0.6 hectares. It was planted in north-south rows. The whole orchard was under unified routine soil, fertilizer and water management. Five tree shapes, including Y-shape(Y), trunk shape(Trunk), three main branch open center shape, four main branch open center shape and V-shape(V) were selected for the study. Light intensity was investigated during the canopy formation period in summer; fruit quality was investigated during fruit ripening period, and tree structure was investigated before winter pruning after defoliation. In the middle stage of canopy formation(July), light intensity at different heights(0.5 m, 1.0 m, 1.5 m, 2.0 m and 2.5 m above the ground) in the same direction of tree crown was measured at 8:00, 11:00, 14:00 and 17:00 with a TSE-1332 digital illuminance meter on sunny days for 3 times at 10-day intervals. The average valued of the results of the 4 time points within a day of the 3 measurements was taken as the light intensity value at different heights during the canopy formation period. The tree crowns with different shapes were divided into four parts: lower layer(<0.8 m above the ground), middle lower layer(0.8-1.6 m above the ground), middle upper layer(1.6-2.4 m above the ground) and upper layer(>2.4 m above the ground). Fruit quality indexes such as fruit weight, fruit hardness, soluble solid content, titratable acid content, vertical and horizontal diameters and fruit color were measured, and tree productivity and yield per 1/15 hectare were investigated. Fruit weight was obtained with an electronic balance. The vertical, horizontal and lateral diameters of the fruit were measured with a vernier caliper, and fruit shape index was calculated. In the winter of 2020(early December), the number of branches was recorded. Trunk height and diameter, tree height, north-south crown width, east-west crown width, number of main branches, main branch diameter, number of different types of branches of the whole peach tree were investigated, and the proportions of branch types was calculated. The branch types included long branches, which were above 30.0 cm in length, middle branches, which were 15.0-30.0 cm in length,and short branches, which were shorten than 15.0 cm. Stem height was the distance from the ground surface to the base of the main branch measured with a tape measure. Stem diameter was the diameter of the trunk 10 cm above the ground. Tree height was the distance from the ground surface to the highest point of the crown measured with a benchmark and tape ruler. Crown width, also known as branch spread, was the diameter of the crown in the east-west or north-south directions. The diameter of main branch was measured at 5 cm from the base of main branch with a vernier caliper.【Results】The results showed that there were significant differences in light intensity and fruit quality among different parts of the same tree, which followed a pattern of upper > middle > lower, and there was no significant difference at the same position in different trees. The unit area yield in different tree shapes followed a pattern of Trunk > V > Y > three main branch open center > four main branch open center. The more main branches, the thicker the trunk diameter, the higher the tree height, and the larger the crown width. The total number of trunk shape per plant was the least, and the four main branches are the most, but the Vshaped branches per 666.7 m~2 was the most, followed by the trunk shape. Although the total number of branches per plant was high, the number of branches per unit area was not. The branch number in Yshaped tree was between the main branch and the three main branches. The proportion of long branches was in the order of Trunk > V > Y > three main branch open center > four main branch open center, and the proportion of medium and short branches showed an opposite pattern to that of the long branches.13 indexes were selected for principal component analysis. The results showed that the score order of the five tree shapes was V> four main branch open center shape> three main branch open center shape>Y and trunk shape.【Conclusion】The V-shaped trees have the highest comprehensive score, with higher tree yield and branches per unit area and better quality performance, and is thus suitable for standardized cultivation.