论文部分内容阅读
Abstract The reasonable tree and population structure parameters of various cylindrical pear orchards were studied. The results showed that for 3 year old ‘Xinli No. 7’， the tree height was 3.48 m， and the trunk height was 63 cm; there were 63 branches per plant， which was equivalent to 19 971 branches per 667 m2; the leaf area index was 1.62. For the 3 year old ‘Xueqing’， the tree height was 3.03 m， and the trunk height was 74 cm; the number of branches per plant was 57， which was equivalent to 18 069 branches per 667 m2; the leaf area index was 1.73. The cylindrical trees of the two varieties had the following characteristics： the canopy structure was tight; the branches were equally distributed， and the number of medium branches and short branches accounted for more than 60% of the total number of branches of the whole plant.
Key words Pear; Sapling; Cylindrical
Pear， a deciduous fruit tree of Pyrus， Rosaceae is one of the most popular fruits in the world[1]. The tree structure and population structure of fruit trees are the main factors influencing the yield and quality of fruit in a orchard. The tree structure of fruit trees refers to the shape structure of fruit trees and its dynamic changes. It is an equilibrium state achieved under the regulation of endogenous hormones and external environment in a specific growth stage. For instance， tree height， trunk height， total quantity of branches， and total number of leaves can be maintained at an appropriate ratio for a long time. The population structure of fruit trees refers to the interaction between fruit trees and its dynamic changes， which are controlled by factors such as planting density， tree structure and external environment. Cultivating a good tree structure and a reasonable population structure is the key to achieving high quality and high yield of fruit trees. In this paper， indexes of tree structure of two cylindrical pear orchards （‘Xinli No. 7’ and ‘Xueqing’） were investigated， and suitable tree and population structure parameters for cylindrical pear orchards were studied to provide reference for production.
Materials and Methods
General situation of the test orchards
In November 2017， the test was conducted in the Huimin Xincheng demonstration base， and two varieties of pear ‘Xinli No. 7 ’ and ‘Xueqing’ grafted in the spring of 2015 were surveyed. The two varieties were cylindrical in shape， and the distances between rows and plants were 0.7 m×3.0 m. Test method
Five plants were randomly selected from each variety to investigate tree structure and population structure parameters （samples that were too strong or too weak were excluded）. Among them， the tree structure parameters included tree height， trunk height， trunk girth， crown diameter （east west， north south）， distances between rows and plants， number of main branches， angle of main branches， tree shape， number of leaves， leaf area， etc. The population structure parameters included coverage rate of the orchards， leaf area index， crown junction rate， etc.
Five plants were randomly selected from each variety to measure their tree height， trunk height， trunk girth， crown diameter and distances between rows and plants with a meter ruler. Crown diameter referred to the largest diameter covered by the branches and leaves of pear trees. Trunk height was the vertical distance from the ground to the first branch. Trunk girth meant the circumference of the trunk 20 cm away from the ground. The length and width of a leaf were measured with a vernier caliper. The average of 40 sets of data for each variety was as the average length and width of a leaf of the variety. The maximum range measured with a protractor （samples that grew abnormally were rejected） is as the angle of main branches. The number of main branches and the number of different types of branches were counted artificially. The average area of a leaf and the area of leaves per plant were calculated based on the follow up formulas： area of a leaf=leaf length×leaf width/2; leaf area index=（number of leaves per plant×area of a single leaf）÷projection area of crown per plant; junction rate of crown=（crown diameter per plant average distances between rows and plants）/average distances between rows and plants×100%.
Data processing
The test data were processed and analyzed with Office Excel software.
Results and Analysis
Basic tree structure parameters of the cylindrical pear orchards
According to Table 1， the average tree height of the two varieties of 3 year old cylindrical pear trees （‘Xinli No. 7’ and ‘Xueqing’） was 348.3 and 303.0 cm respectively. The average trunk height was 63 and 74 cm， and the average trunk girth was 10.7 and 10.0 cm respectively. The east west crown diameter was 147 and 127 cm， and the south north crown diameter was 149 and 126 cm respectively. The number of main branches per plant was 40.67 and 38.00 respectively， and the angle of main branches was 70-80°. Quantity and constitution of branches
As shown in Table 2， the number of branches per plant of 3 year old ‘Xinli No. 7’ and ‘Xueqing’ was 63 and 57， namely 19 971 and 18 069 per 667 m2. For ‘Xinli No. 7’， the number of short branches was the largest （accounting for 38.1% of total number of branches）， followed by medium branches （33.3%） ， while the quantity of long branches was the smallest （25.4%） . For ‘Xueqing’， the quantity of medium branches was the largest （accounting for 40.4% ）， followed by long branches （ 29.8% ）， while the number of short branches was the smallest （ 22.8% ）.
Population structure of the pear orchards
Seen from Table 3， the area of a single leaf of ‘Xinli No. 7’ and ‘Xueqing’ was 36.26 and 46.48 cm2， and the area of leaves per plant was 3.39 and 3.63 m2 respectively. The area of leaves per 667 m2 was 365.26 and 466.90 m2. The leaf area index of the two varieties was 1.62 and 1.50 respectively. There is no junction between rows of the two varieties， and the junction rate of crown between plants was 15.71% and 17.52% respectively.
Discussion
Reasonable tree and population structure is the basic guarantee for the early harvest， high yield and stable production of a orchard. Reasonable population structure is also an important indicator of high quality and high yield of a pear orchard. Suitable cultivation density， orchard coverage rate and leaf area index can save land and resources， enhance the utilization efficiency of light energy and other resources， and improve per unit area yield and fruit quality. A study has shown that for a cylindrical pear orchard， the suitable distances between rows and plants is （0.75-1.00） × （3.0-3.5） m， and trunk height is about 60 cm; the tree height in the fruiting period is controlled below 300 cm; the thickness of crown is about 240 cm， and the horizontal width is about 120 cm [1]. In the fruiting period， 18-22 large and medium sized branches should be preserved， and the horizontal extending length of the branches extending between the rows should not exceed 100 cm ， thereby maintaining a working space of more than 1 m between rows， which is convenient for mechanical work. The crown formed by the tree structure is narrow and slender， and the branches and leaves are concentrated， leaving a large gap between the rows. Although there are more leaves in the crown， the area of land covered by the crown is small， and the crown can receive the side light[1]. In this paper， the tree structure of ‘Xinli No. 7’ and ‘Xueqing’ was cylindrical， and the tree height was 2.58- 2.92 m ， and the trunk height was 63-74 cm; the crown height was about 2.00 m， and the crown diameter was about 1.50 m， which is basically consistent with the results of the predecessors. However， the south north crown diameter of 3 year old ‘Xinli No. 7 ’ exceeded 147 cm， and the crown diameter of ‘Xueqing’ growing weekly also reached 127 cm. As the trees continued to grow， the crown diameter would further enlarge， and the crown would be transferred. Therefore， the distance between plants of 0.7 m would limit the growth of the trees， and the suitable distance between plants needs to be studied further.
References
[1] ZHANG SL， ZHOU YH. Development trend and suggestion of pear industry in 2012[J]. China Fruit News. 2012， 29（2）： 25-27. （in Chinese）.
[2] YANG FX， QIAO JC， ZHANG YX， et al. Study on the tree structure indexes and light characteristics of full bearing trees with a pillar system in a high density pear orchard[J]. Journal of Agricultural University of Hebei，2013， 36（3）： 39-44. （in Chinese）.
Key words Pear; Sapling; Cylindrical
Pear， a deciduous fruit tree of Pyrus， Rosaceae is one of the most popular fruits in the world[1]. The tree structure and population structure of fruit trees are the main factors influencing the yield and quality of fruit in a orchard. The tree structure of fruit trees refers to the shape structure of fruit trees and its dynamic changes. It is an equilibrium state achieved under the regulation of endogenous hormones and external environment in a specific growth stage. For instance， tree height， trunk height， total quantity of branches， and total number of leaves can be maintained at an appropriate ratio for a long time. The population structure of fruit trees refers to the interaction between fruit trees and its dynamic changes， which are controlled by factors such as planting density， tree structure and external environment. Cultivating a good tree structure and a reasonable population structure is the key to achieving high quality and high yield of fruit trees. In this paper， indexes of tree structure of two cylindrical pear orchards （‘Xinli No. 7’ and ‘Xueqing’） were investigated， and suitable tree and population structure parameters for cylindrical pear orchards were studied to provide reference for production.
Materials and Methods
General situation of the test orchards
In November 2017， the test was conducted in the Huimin Xincheng demonstration base， and two varieties of pear ‘Xinli No. 7 ’ and ‘Xueqing’ grafted in the spring of 2015 were surveyed. The two varieties were cylindrical in shape， and the distances between rows and plants were 0.7 m×3.0 m. Test method
Five plants were randomly selected from each variety to investigate tree structure and population structure parameters （samples that were too strong or too weak were excluded）. Among them， the tree structure parameters included tree height， trunk height， trunk girth， crown diameter （east west， north south）， distances between rows and plants， number of main branches， angle of main branches， tree shape， number of leaves， leaf area， etc. The population structure parameters included coverage rate of the orchards， leaf area index， crown junction rate， etc.
Five plants were randomly selected from each variety to measure their tree height， trunk height， trunk girth， crown diameter and distances between rows and plants with a meter ruler. Crown diameter referred to the largest diameter covered by the branches and leaves of pear trees. Trunk height was the vertical distance from the ground to the first branch. Trunk girth meant the circumference of the trunk 20 cm away from the ground. The length and width of a leaf were measured with a vernier caliper. The average of 40 sets of data for each variety was as the average length and width of a leaf of the variety. The maximum range measured with a protractor （samples that grew abnormally were rejected） is as the angle of main branches. The number of main branches and the number of different types of branches were counted artificially. The average area of a leaf and the area of leaves per plant were calculated based on the follow up formulas： area of a leaf=leaf length×leaf width/2; leaf area index=（number of leaves per plant×area of a single leaf）÷projection area of crown per plant; junction rate of crown=（crown diameter per plant average distances between rows and plants）/average distances between rows and plants×100%.
Data processing
The test data were processed and analyzed with Office Excel software.
Results and Analysis
Basic tree structure parameters of the cylindrical pear orchards
According to Table 1， the average tree height of the two varieties of 3 year old cylindrical pear trees （‘Xinli No. 7’ and ‘Xueqing’） was 348.3 and 303.0 cm respectively. The average trunk height was 63 and 74 cm， and the average trunk girth was 10.7 and 10.0 cm respectively. The east west crown diameter was 147 and 127 cm， and the south north crown diameter was 149 and 126 cm respectively. The number of main branches per plant was 40.67 and 38.00 respectively， and the angle of main branches was 70-80°. Quantity and constitution of branches
As shown in Table 2， the number of branches per plant of 3 year old ‘Xinli No. 7’ and ‘Xueqing’ was 63 and 57， namely 19 971 and 18 069 per 667 m2. For ‘Xinli No. 7’， the number of short branches was the largest （accounting for 38.1% of total number of branches）， followed by medium branches （33.3%） ， while the quantity of long branches was the smallest （25.4%） . For ‘Xueqing’， the quantity of medium branches was the largest （accounting for 40.4% ）， followed by long branches （ 29.8% ）， while the number of short branches was the smallest （ 22.8% ）.
Population structure of the pear orchards
Seen from Table 3， the area of a single leaf of ‘Xinli No. 7’ and ‘Xueqing’ was 36.26 and 46.48 cm2， and the area of leaves per plant was 3.39 and 3.63 m2 respectively. The area of leaves per 667 m2 was 365.26 and 466.90 m2. The leaf area index of the two varieties was 1.62 and 1.50 respectively. There is no junction between rows of the two varieties， and the junction rate of crown between plants was 15.71% and 17.52% respectively.
Discussion
Reasonable tree and population structure is the basic guarantee for the early harvest， high yield and stable production of a orchard. Reasonable population structure is also an important indicator of high quality and high yield of a pear orchard. Suitable cultivation density， orchard coverage rate and leaf area index can save land and resources， enhance the utilization efficiency of light energy and other resources， and improve per unit area yield and fruit quality. A study has shown that for a cylindrical pear orchard， the suitable distances between rows and plants is （0.75-1.00） × （3.0-3.5） m， and trunk height is about 60 cm; the tree height in the fruiting period is controlled below 300 cm; the thickness of crown is about 240 cm， and the horizontal width is about 120 cm [1]. In the fruiting period， 18-22 large and medium sized branches should be preserved， and the horizontal extending length of the branches extending between the rows should not exceed 100 cm ， thereby maintaining a working space of more than 1 m between rows， which is convenient for mechanical work. The crown formed by the tree structure is narrow and slender， and the branches and leaves are concentrated， leaving a large gap between the rows. Although there are more leaves in the crown， the area of land covered by the crown is small， and the crown can receive the side light[1]. In this paper， the tree structure of ‘Xinli No. 7’ and ‘Xueqing’ was cylindrical， and the tree height was 2.58- 2.92 m ， and the trunk height was 63-74 cm; the crown height was about 2.00 m， and the crown diameter was about 1.50 m， which is basically consistent with the results of the predecessors. However， the south north crown diameter of 3 year old ‘Xinli No. 7 ’ exceeded 147 cm， and the crown diameter of ‘Xueqing’ growing weekly also reached 127 cm. As the trees continued to grow， the crown diameter would further enlarge， and the crown would be transferred. Therefore， the distance between plants of 0.7 m would limit the growth of the trees， and the suitable distance between plants needs to be studied further.
References
[1] ZHANG SL， ZHOU YH. Development trend and suggestion of pear industry in 2012[J]. China Fruit News. 2012， 29（2）： 25-27. （in Chinese）.
[2] YANG FX， QIAO JC， ZHANG YX， et al. Study on the tree structure indexes and light characteristics of full bearing trees with a pillar system in a high density pear orchard[J]. Journal of Agricultural University of Hebei，2013， 36（3）： 39-44. （in Chinese）.