A method for identifying the effectiveness of transpiration water consumption of fruit trees

Abstract

This invention discloses a method for identifying the effectiveness of water consumption through transpiration in fruit trees, belonging to the technical fields of agricultural water conservation and fruit tree cultivation. This invention first completes the grading and classification of branches, and then stabilizes representative branches... 13 C30 isotope labeling experiments were used to obtain basic data on assimilate transport and distribution. Combined with source-sink theory and a three-dimensional function-structure model of plants, the contribution of different branches to fruit growth was calculated, thereby classifying the transpiration water use efficiency level and ultimately guiding fruit tree pruning and water management. This invention solves the problem in existing technologies where the spatial heterogeneity of the canopy is ignored, leading to difficulties in defining redundant growth. It can significantly reduce ineffective and inefficient transpiration water use, improve water use efficiency, and simultaneously improve the canopy light environment, enhancing fruit quality and uniformity. It is suitable for water-saving cultivation management in various orchards.

Description

Technical Field

[0001] This invention relates to the fields of agricultural water conservation and fruit tree cultivation technology, and in particular to a method for identifying the effectiveness of water consumption by fruit tree transpiration. Background Technology

[0002] Current mainstream research on water management in fruit trees generally treats the canopy as homogeneous, assuming it to be a uniform underlying surface. Water consumption, growth, and fruit yield and quality are often measured by overall average values. This method ignores the spatial heterogeneity of micrometeorological factors such as branch and leaf distribution and light environment within the canopy. This makes it difficult to precisely distinguish redundant growth and extravagant transpiration from overall growth and total water consumption, limiting the in-depth exploration of water-saving potential and failing to explain the differences in fruit size at different locations on the tree. Even with integrated water and fertilizer precision irrigation technology, the fruit size of each tree remains inconsistent, making it difficult to achieve uniform fruit size, color, and taste across the entire tree that meet the standards for high-quality fruit. The goal of precise water control over fruit tree water consumption and yield has not yet been achieved.

[0003] The complex canopy structure of fruit trees, with different types of branches and leaves intertwining and creating light shading, leads to uneven radiation distribution. Radiation is a direct driver of physiological activities such as photosynthesis and transpiration; therefore, the intensity of transpiration and photosynthesis varies significantly across different parts of the canopy depending on the intensity of received radiation. Spatial differences in transpiration intensity further cause changes in microclimate conditions such as temperature and humidity within the canopy, which in turn affect physiological activities. Simultaneously, differences in photosynthetic intensity within the canopy result in varying amounts of assimilates produced by leaves, directly impacting the total amount of carbohydrates transported to the fruit. Furthermore, controlled by factors such as assimilate transport resistance and distance, assimilates produced by leaves with strong photosynthetic capacity may not be efficiently transported to the fruit, ultimately leading to spatial variations in fruit size.

[0004] The core objective of water management measures such as irrigation in arid and semi-arid regions is to prioritize water use to support economic yield (fruit) growth rather than vegetative growth (branches and leaves). Current technologies lack sufficient understanding of the mechanisms linking canopy spatial structure with water consumption and fruit formation, leading to significant uncertainty in water management decisions and hindering the healthy and sustainable development of orchards. Therefore, based on quantitative analysis of canopy spatial structure and combined with the principle of water balance between vegetative and reproductive growth in fruit trees, accurately identifying the effectiveness of water consumption by branches and leaves and defining redundant growth areas is crucial for achieving water-saving pruning and precise water management. Summary of the Invention

[0005] The purpose of this invention is to address the problem in existing technologies that neglect the heterogeneity of canopy space, making it difficult to accurately distinguish between effective, inefficient, and ineffective transpiration water-consuming branches and leaves, resulting in a difficulty in balancing water conservation and stable yield in orchards and uneven fruit quality. This invention provides a method for identifying the effectiveness of fruit tree transpiration water consumption, which accurately defines redundant growth parts by quantifying the contribution of different branches and leaves to fruit yield, and guides water-saving pruning and irrigation management.

[0006] To achieve the above objectives, the present invention provides the following solution: A method for identifying the effectiveness of water consumption through transpiration in fruit trees includes the following steps: First, the branches of the fruit trees are classified into levels: the trunk is classified as level 0, the large lateral branches on the trunk are classified as level 1 branches, and the forks on level 1 branches are classified as level 2 branches; then, the current year's branches are classified according to their function and growth characteristics. Select representative branches for stabilization 13 C isotope labeling assay to detect C in fruits from different levels of branches 13 C abundance was used to preliminarily identify the contribution of leaves at different locations to fruit growth. A source-sink relationship-based assimilate transport and distribution model was constructed. The model parameters were calibrated using isotope test results, and the contribution of different branches of the whole tree to fruit growth was calculated. The effectiveness of water consumption by branches and leaves can be judged based on the contribution of branches to fruit growth.

[0007] Furthermore, the current year's branches are divided into long vegetative branches, medium-long vegetative branches, short vegetative branches, short fruit-bearing branches, and secondary fruit-bearing shoots. According to the growth year and branching order, the tree body is divided into old roots, new roots, trunk, old branches, new branches, and fruit.

[0008] Furthermore, the method for selecting representative branches is as follows: Based on tree height, the first-order branches are divided into three layers: upper, middle, and lower. One first-order branch is randomly selected from each layer, and three current-year branches of each type are randomly selected from each selected first-order branch for isotope labeling.

[0009] Furthermore, the assimilate transport allocation model includes assimilate generation calculation, assimilate demand calculation, and assimilate transport flow calculation, which is implemented using a three-dimensional functional-structural model such as GroIMP or Qualitree.

[0010] Furthermore, the formula for calculating the amount of assimilate generated is as follows: in, For new branches Assimilate production per hour L i Indicates branches ileaf area; Indicates branches Intercepted photosynthetically active radiation; Indicates respiratory rate; Indicates the maximum photosynthetic intensity; This represents the initial slope value of the light response curve; This is the unit conversion factor.

[0011] Furthermore, the formula for calculating the assimilate requirement is as follows: in, Indicates the proportion of carbon in structural biomass; This represents the respiration coefficient used to maintain growth. Indicates branches Initial relative growth rate; This represents the ratio of the current branch-to-root ratio to the equilibrium branch-to-root ratio; This represents the daily accumulated temperature increase. For the weight of the branches and trunk; The formula represents the decreasing function of a branch's carbon demand as its biomass accumulates. in, The maximum dry weight of a certain type of branch. The carbon requirement of the branches decreases as a function of accumulated temperature, and the calculation formula is: in, For a certain type of branch The effective accumulated temperature required to stop growth For effective accumulated temperature, when it is less than hour, The value is 0.

[0012] Furthermore, the formula for calculating the assimilate transport flow rate is as follows: in, For new branches The amount of assimilates remaining after satisfying its own needs; for Organ reservoir strength; For new branches arrive Source-sink distance of organs; Source-sink distance adjustment factor; This represents the total number of organs.

[0013] The present invention discloses the following technical effects: This invention solves the problems of high cost and significant damage associated with whole-tree isotope labeling by combining representative branch isotope experiments with model calculations. Furthermore, pruning redundant branches and leaves can better balance vegetative and reproductive growth, improve the canopy light environment, reduce spatial differences in fruit size, promote fruit coloring and sugar accumulation, and increase the rate of high-quality fruit. It is suitable for fruit trees of different varieties, ages, and cultivation methods and can be widely applied to water and canopy management in various orchards. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] like Figure 1 As shown in the figure, this invention provides a method for identifying the effectiveness of water consumption through transpiration in fruit trees, comprising the following steps: The tree trunk is classified as level 0, large lateral branches on the trunk as level 1 branches, forks on level 1 branches as level 2 branches, and so on. Carbon isotope labeling is performed by dividing level 1 branches into three layers (upper, middle, and lower) based on tree height, with one level 1 branch randomly selected from each layer for labeling. From each selected level 1 branch, three current-year shoots of each type are randomly selected (in young fruit trees, current-year shoots often correspond to level 2 branches, while in middle-aged trees they correspond to level 3 branches or even higher) for isotope labeling. Current-year shoot types are categorized as long vegetative shoots, medium-long vegetative shoots, short vegetative shoots, short fruit-bearing branches, and secondary fruit-bearing shoots, etc., with adjustments made based on the branching characteristics of different fruit trees. Select representative branches for stabilization 13 C isotope labeling assay to detect C in fruits from different levels of branches 13C abundance was used to preliminarily identify the contribution of leaves at different locations to fruit growth. A source-sink relationship-based assimilate transport and distribution model was constructed. The model parameters were calibrated using isotope test results, and the contribution of different branches of the whole tree to fruit growth was calculated. The effectiveness of water consumption by branches and leaves can be judged based on the contribution of branches to fruit growth.

[0019] Leaves consume a large amount of water through transpiration in exchange for photosynthetic products, supporting tree growth and biomass accumulation. According to the source-sink theory, photosynthetic products from leaves are distributed among different organs; if more are transported to the fruit, it is beneficial for increasing yield. The dense foliage within the canopy is connected by different types of branches. Due to factors such as transport resistance and distance, the assimilates produced by leaves with strong photosynthetic capacity may not be efficiently transported to the fruit. Although these branches and leaves consume a large amount of water, their contribution to fruit yield is minimal, and they can be defined as ineffective or inefficient water consumption. Based on this idea, we conduct a method to determine the effectiveness of water consumption by branches and leaves in the fruit canopy: based on the transport efficiency and distribution ratio of photosynthetic assimilates to fruits on branches at different levels, we determine the contribution of branches and leaves of different spatial locations and types to fruit biomass accumulation, and classify the effectiveness level of branches and leaves. This level corresponds one-to-one with the water consumption effectiveness level, that is: the assimilates are transported to the branches and leaves with high efficiency and large proportion to the fruit, which makes a significant contribution to the yield, and its transpiration water consumption is effective water consumption; otherwise, it is ineffective or inefficient water consumption (the corresponding branch and leaf growth is defined as redundant growth), that is, luxury transpiration.

[0020] Ineffective and low-efficiency foliage assimilates contribute little to fruit formation, but are accompanied by transpiration water consumption. They can be used as an important part of pruning regulation. Pruning them has little impact on tree yield, but can significantly reduce ineffective and low-efficiency transpiration water consumption, thus serving the purpose of saving irrigation and optimizing water use.

[0021] The assimilate transportation allocation model includes the calculation of assimilate generation, the calculation of assimilate demand, and the calculation of assimilate transportation flow. The formula for calculating the assimilate generation is: in, For new branches Assimilate production per hour (gC h) -1 ), The leaf area (m²) of branch i 2 ); Indicates branches Photosynthetically active radiation intercepted (μmol Photon m⁻² s⁻¹); Respiration rate (μmol CO2·m -2 ·s -1 ); This represents the maximum photosynthetic intensity (μmol CO2·m).-2 ·s -1 ); This represents the initial slope value of the light response curve (μmol CO2·μmol photon). -1 ); The unit conversion factor is 0.00432 (g·C·s·h). -1 μmol CO2 -1 ).

[0022] Furthermore, the formula for calculating the assimilate requirement is as follows: The formula for calculating the assimilate requirement is: in, Indicates the first Tianzhi Daily carbon requirement for growth (gC·d) -1 ); Indicates the proportion of carbon in structural biomass (gC⁻¹·gDM⁻¹). The respiration coefficient (gC⁻¹·gDM⁻¹) represents the respiration coefficient used to maintain growth. Indicates branches Initial relative growth rate (gC·d⁻¹); This represents the ratio of the current branch-to-root ratio to the equilibrium branch-to-root ratio; This represents the daily temperature increment (°C·d). Branch dry weight (gDM); This represents a function that indicates the decreasing carbon demand of branches as their biomass accumulates, with values ​​ranging from 0 to 1. The calculation formula is as follows: in, The maximum dry weight (gDM) of a certain type of branch. The function representing the decrease in carbon demand of branches with accumulated temperature, taking values ​​from 0 to 1, is calculated as follows: in, For a certain type of branch Effective accumulated temperature (°C·d) required to stop growth. For effective accumulated temperature (°C·d), when it is less than hour, The value is 0.

[0023] Furthermore, the formula for calculating the assimilate transport flow rate is as follows: in, For new branches Flow direction The carbon content ratio; For new branches The amount of assimilate remaining after satisfying its own needs (gC); for Organ reservoir strength (gC); For new branches arrive Source-sink distance of organs (mm); Source-sink distance adjustment factor; This represents the total number of organs.

[0024] Based on the isotope test results and the above formula, the values ​​of relevant function parameters for different types of one-year-old branches were determined. Then, the assimilate transport and distribution calculations were carried out using three-dimensional functional-structure models such as GroIMP or Qualitree to obtain the contribution of different types of branches to fruit growth, and thus determine the water consumption effectiveness of branches and leaves of different types and locations.

[0025] Technical Effects: While ineffective and low-efficiency photosynthetic compounds in branches and leaves contribute little to fruit formation, they are accompanied by transpiration water loss. Pruning these branches has minimal impact on overall tree yield but significantly reduces ineffective and low-efficiency transpiration water loss, thus contributing to optimized water resource utilization. In irrigated orchards, it reduces irrigation volume; in rainfed orchards, it promotes soil water retention and prevents water-related ecological problems such as soil desiccation. Furthermore, pruning redundant branches and leaves better balances vegetative and reproductive growth, improves the canopy light environment, reduces spatial differences in fruit size, aids in fruit coloring and sugar accumulation, and increases the rate of high-quality fruit.

[0026] Example 1: The application was implemented in an apple orchard located in Luochuan County, Yan'an City, Shaanxi Province, in the Loess Plateau region. The orchard was planted in 2012, covering an area of ​​2 mu (approximately 0.33 hectares), with a plant spacing of 2×4 m. The variety is Yanchang Red Fuji. Through conventional pruning, the tree height was controlled to 3 m, and the tree shape was a tall spindle shape. The orchard has long been under rainfed conditions, with no additional irrigation during the growing season.

[0027] The trunk is divided into level 0, the large lateral branches are level 1 branches, the level 1 branches branch into level 2 branches, and the current year's branches are mainly level 2 branches, which are divided into 5 categories: long vegetative branches, medium long vegetative branches, short vegetative branches, short fruit spur branches, and secondary fruit spur shoots.

[0028] The first-order branches were divided into three layers (upper, middle, and lower) according to tree height. One first-order branch was randomly selected from each layer, and three current-year shoots of each type were selected from each first-order branch and marked. The target branches were placed in a transparent PVC sealed chamber and aeration was introduced. 13A 99% CO2 concentration of labeled gas was used to ensure sufficient photosynthesis in the branches and leaves. Fruits from different levels of branches were collected, and stable isotope ratio mass spectrometry was used to determine the fruit composition. 13 C abundance. The results showed that if the length of the branch connection path (the length of the assimilate transport path from the base of the branch to the nearest fruit) between the current year's long or medium vegetative branches and the fruit exceeds 60 cm, then the contribution to fruit growth is small and it is classified as a low-efficiency water-consuming branch; while the short branches and secondary branches of the fruit spur are both high-efficiency water-consuming branches.

[0029] Based on this standard, pruning was carried out in 2024. By June, branch growth had stabilized, and branch types could be clearly identified. After routine fruit thinning, branches with a connection length exceeding 60cm between the current year's long and medium-sized vegetative branches and the fruit were pruned. Yield was measured after harvest on October 30th of that year. Compared with the control plot (separated only by a road, with all other management methods consistent except for pruning), the yield difference was small and did not reach a significant level (pruning: 4978 kg / mu, control: 5237 kg / mu, equivalent to a yield decrease of only 1.75 kg per tree). However, the transpiration water consumption during the tree's growing season (May-October), measured using the heat ratio method, was significantly reduced. After pruning, the transpiration water consumption was 193.74 mm, while the control was as high as 275.39 mm, which translates to a 35.11% increase in water use efficiency after pruning. After the experiment, the soil moisture content in the 0-1 m soil layer of the pruned plot was 23.59%, significantly higher than that of the control plot (19.36%). This indicates that summer pruning of rain-fed apple orchards based on the water consumption effectiveness assessment results can significantly improve orchard moisture conditions, prevent the aggravation of soil drying problems in the area, and basically ensure no yield reduction, making it a highly efficient measure in terms of both economy and ecology.

[0030] Example 2: The application was also implemented in an apple orchard in the Loess Plateau region, located in Mizhi County, Yulin City, Shaanxi Province. Planted in 2015, the orchard covers an area of ​​3 mu (approximately 0.2 hectares), with a plant spacing of 2×4 m. The variety is Qin Cui. Through conventional pruning, the tree height was controlled at 2.5 m, and the tree shape was a high spindle shape. Because this area is located in a relatively arid section of the Loess Plateau, the orchard uses a deficit irrigation model. Under normal circumstances, irrigation is controlled at 60%-75% of field capacity, with an average annual irrigation water consumption of 135 m³ / mu (approximately 15.3 hectares). 3 .

[0031] The branch grading method is the same as in Example 1. The current year's branches are mainly third-level branches, and the classification criteria are consistent with those in Example 1.

[0032] The isotope labeling method was the same as in Example 1, and the model parameters were calibrated and calculated. In 2022, carbon isotope labeling experiments and model calculations were conducted. The results showed that if the length of the branch connection path between the current year's long or medium vegetative branches and the fruit exceeded 70 cm, the contribution to fruit growth was relatively small, and they were classified as low-efficiency water-consuming branches; while short branches and secondary branches of fruit spurs were classified as high-efficiency water-consuming branches.

[0033] Based on this standard, pruning was carried out in 2023. By June, branch growth had stabilized, and branch types could be clearly identified. After fruit thinning, branches with a connection length exceeding 70 cm between the current year's long and medium-sized vegetative branches and the fruit were pruned. Furthermore, based on the 2022 trial results, it was initially estimated that branches meeting the pruning standards accounted for approximately 20% of the total canopy foliage; therefore, irrigation volume was reduced accordingly. The control irrigation volume was set at 135 m³. 3 Irrigation was carried out in eight sessions based on rainfall. The irrigation volume for pruning was set at 100 m³. 3 The pruning was carried out concurrently with the control group, with irrigation reduced proportionally. Yields were measured after harvest on October 30th of the same year. The yield difference between the pruning and control plots (without this pruning) was small and did not reach a statistically significant level (pruning: 3518 kg / mu, control: 3677 kg / mu). However, transpiration water consumption during the tree's growing season (May-October), measured using a heat diffusion probe, was significantly reduced. After pruning, transpiration water consumption was 174.69 mm, while the control was as high as 232.43 mm, representing a 27.30% increase in water use efficiency. After the experiment, the soil moisture content in the 0-1 m soil layer was 15.33%, with little difference from the control plot's 14.97%, indicating no deterioration of soil moisture conditions. This demonstrates that summer pruning of apple orchards guided by water consumption efficiency assessment results can effectively ensure no yield reduction and no decrease in soil moisture conditions, while effectively saving irrigation water, thus representing a highly efficient measure both economically and ecologically.

[0034] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0035] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for identifying the effectiveness of water consumption through transpiration in fruit trees, characterized in that, Includes the following steps: First, the fruit trees are graded, with the trunk classified as grade 0, the large lateral branches on the trunk as grade 1 branches, and the forks on grade 1 branches as grade 2 branches; then, the current year's branches are classified according to their function and growth characteristics. Select representative branches for stabilization 13 C isotope labeling assay to detect C in fruits from different levels of branches 13 C abundance was used to preliminarily identify the contribution of leaves at different locations to fruit growth. A source-sink relationship-based assimilate transport and allocation model was constructed. The model parameters were calibrated using isotope experimental results, and the contribution of different branches to fruit growth was calculated. The effectiveness of water consumption by branches and leaves can be judged based on the contribution of branches to fruit growth.

2. The method for identifying the effectiveness of water consumption through transpiration in fruit trees according to claim 1, characterized in that, The current year's branches are divided into long vegetative branches, medium-long vegetative branches, short vegetative branches, short fruit-bearing branches, and secondary fruit-bearing shoots. According to the growth year and branching order, the tree body is divided into old roots, new roots, trunk, old branches, new branches, and fruit.

3. The method for identifying the effectiveness of water consumption through transpiration in fruit trees according to claim 1, characterized in that, The method for selecting representative branches is as follows: Based on tree height, the first-order branches are divided into three layers: upper, middle, and lower. One first-order branch is randomly selected from each layer, and three current-year branches of each type are randomly selected from each selected first-order branch for isotope labeling.

4. The method for identifying the effectiveness of water consumption through transpiration in fruit trees according to claim 1, characterized in that, The assimilate transport allocation model includes the calculation of the total assimilate generation, the calculation of the assimilate demand, and the calculation of the assimilate transport flow, which is implemented using GroIMP or Qualitree three-dimensional functional-structural models.

5. The method for identifying the effectiveness of water consumption through transpiration in fruit trees according to claim 4, characterized in that, The formula for calculating the amount of assimilate generated is: in, For new branches Assimilate production per hour L i Indicates branches i leaf area; Indicates branches Intercepted photosynthetically active radiation; Indicates respiratory rate; Indicates the maximum photosynthetic intensity; This represents the initial slope value of the light response curve; This is the unit conversion factor.

6. The method for identifying the effectiveness of water consumption through transpiration in fruit trees according to claim 4, characterized in that, The formula for calculating the assimilate requirement is: in, Indicates the proportion of carbon in structural biomass; This represents the respiration coefficient used to maintain growth. Indicates branches Initial relative growth rate; This represents the ratio of the current branch-to-root ratio to the equilibrium branch-to-root ratio; This represents the daily accumulated temperature increase; For the weight of the branches and trunk; The formula represents the decreasing function of a branch's carbon demand as its biomass accumulates. in, The maximum dry weight of a certain type of branch. The carbon requirement of the branches decreases as a function of accumulated temperature, and the calculation formula is: in, For a certain type of branch The effective accumulated temperature required to stop growth For effective accumulated temperature, when it is less than hour, The value is 0.

7. The method for identifying the effectiveness of fruit tree transpiration water consumption according to claim 4, characterized in that, The formula for calculating the assimilate transport flow rate is: in, For new branches The amount of assimilates remaining after satisfying its own needs; for Organ reservoir strength; For new branches arrive Source-sink distance of organs; Source-sink distance adjustment factor; This represents the total number of organs.

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