A method for preventing and treating citrus fruit cracking by pruning and shaping

Abstract

The application provides a shaping pruning method for preventing and treating citrus fruit cracking, belongs to the field of citrus cultivation, and the citrus variety is Ganneng. The method is characterized in that: through high top shaping pruning, 5-8 length 60-80 cm long branches at the top of the tree crown are reserved, and one-year-old high-quality fruiting branch fruiting sites with a diameter of greater than or equal to 0.4 cm are selected, and the annual renewal mechanism of the long branches is combined to significantly reduce the fruit cracking rate. The application does not need to apply exogenous hormones or special fertilizer and water management, is simple and easy to operate, has low cost, wide applicability, and has a good popularization and application prospect.

Description

Technical Field

[0001] This invention relates to the field of fruit tree cultivation, specifically to a method for shaping and pruning citrus fruits to prevent cracking. Background Technology

[0002] 'Ganping' is a new citrus variety bred by crossing 'Xizhixiang' with Ponkan oranges. It has excellent quality and superior taste and is a late-maturing citrus variety. However, its disadvantage is that the fruit cracking rate under conventional cultivation techniques can reach 40%-80%, or even as high as 90%, causing many fruit farmers to suffer huge losses.

[0003] Currently, the main technical solutions for preventing fruit cracking in citrus trees involve applying gibberellin, potassium or boron fertilizers, and using mulch around the tree base to conserve soil moisture. In natural open-field cultivation, natural rainfall is uncontrollable, and relying solely on it cannot achieve a balanced supply and retention of soil moisture. Currently, soil moisture conservation is primarily achieved through greenhouse cultivation, which provides rain protection and water control. However, greenhouse equipment requires significant investment and is costly. Furthermore, there is a lack of comprehensive planting and management experience in open-field cultivation. Control measures are mainly implemented through spraying hormones, potassium and calcium micronutrient fertilizers, and various pesticides, which can only keep the cracking rate below 50%. The causes of citrus fruit cracking are complex. Soil nutrient and environmental conditions vary significantly across citrus-growing areas, and the cultivation and management skills of citrus growers also differ, making current control methods difficult to apply universally.

[0004] In general, the existing technology has the following drawbacks: (1) Dependence on exogenous hormones and improper use of concentrations can easily lead to a decline in fruit quality; (2) The investment cost of facility greenhouses is high, and their promotion is difficult; (3) The fruit cracking rate remains high under open-field cultivation; (4) The technical threshold is high and the acceptance rate of ordinary farmers is low.

[0005] In conclusion, there is an urgent need to propose a simple, practical, easy-to-learn, low-cost, and widely applicable solution for preventing citrus fruit cracking. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a pruning method for preventing citrus fruit cracking. This method primarily reduces the cracking rate of the Ganping citrus variety through pruning techniques. The pruning technique is simple and eliminates the need for fertilization, hormone spraying, and mulching, saving materials and reducing labor intensity. It is a cultivation technique that reduces fertilizer and pesticide use, saving costs and increasing efficiency.

[0007] The basic concept of the technical solution adopted in this invention is as follows: A method for shaping and pruning citrus fruits to prevent cracking, wherein the citrus variety is Ganping, includes the following steps: (1) High-top shaping pruning: In spring, prune the Ganping citrus, retain 5 to 8 vigorous branches with a length of 60 to 80 cm at the top of the canopy, remove the buds and new shoots on them, and distribute them evenly at the top to form a high-top canopy; (2) Selection and thinning of high-quality fruiting branches: In the early stage of fruit development, only one-year-old fruiting branches with a diameter ≥0.4cm are retained to set fruit, and the rest of the fruit are removed directly; (3) Renewal of vigorous shoots: After fruiting, remove the vigorous shoots and cultivate new vigorous shoots in the following year according to step (1), and repeat the cycle.

[0008] As an example, the vigorous shoots in step (1) are formed from the spring shoots of the current year.

[0009] As an example, the pruning time in step (1) is in early March.

[0010] As an example, the method is applicable to Ganping citrus trees grown in the open air or in greenhouses.

[0011] As an example, in step (1), five vigorous shoots with a length of ≥60cm at the top of the canopy are retained.

[0012] As an example, the length of the vigorous shoots is 60-80 cm.

[0013] As an example, the diameter of the one-year-old fruiting branch is ≥0.4cm.

[0014] As an example, the method also includes conventional fertilizer and water management measures.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. The method of the present invention, by using only shaping and pruning techniques combined with the selection of high-quality fruiting branches, significantly reduces the fruit cracking rate from the conventional 40%~80% to about 10%.

[0016] 2. The method of this invention does not rely on exogenous hormones; it achieves fruit cracking prevention solely through pruning, thus avoiding a decline in fruit quality. No additional facilities or special fertilizers are required, resulting in low cost.

[0017] 3. The method of the present invention is simple to operate, easy to learn and master, and easy for ordinary farmers to master.

[0018] 4. The method of the present invention has wide applicability and is suitable for both open-air and greenhouse cultivation modes. Attached Figure Description

[0019] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of the present invention and do not constitute a limitation on the technical solutions of the present invention.

[0020] Figure 1 This is a schematic diagram of the tall-topped tree structure of the 'Ganping' citrus variety.

[0021] Mark 1 in the diagram - let the top vigorous shoots grow long. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0023] Based on a comprehensive analysis of multiple dimensions of relevant indicators, including hormone tissue differences, transcriptomics, and physiological and biochemical analysis of Ganping plants in the early stage, and combined with current prevention and control measures for citrus fruit cracking, this invention found that the commonly used dwarfing and shaping pruning method for citrus is not suitable for varieties such as Ganping, and is an important cause of fruit cracking.

[0024] Bound by traditional concepts, conventional fruit tree shaping and pruning techniques, including those for citrus, generally do not retain vigorous shoots, believing that they disrupt tree shape, affect light penetration, and have no positive effects. However, this invention has found that vigorous shoots play an irreplaceable role in the synthesis and transport of endogenous hormones and are a key factor in controlling fruit cracking rates. Conventional methods such as fertilizer and water management and exogenous hormones can only achieve half the desired results.

[0025] This invention significantly reduces the fruit cracking rate by improving traditional pruning methods and selecting high-quality fruiting branches, resulting in remarkable effects.

[0026] Example 1 In early March, in a citrus orchard in Xiangshan County, Ningbo City, Zhejiang Province, 8-year-old 'Ganping' citrus trees, grown under both greenhouse and open-field cultivation methods and free from pests and diseases, with healthy growth and moderate vigor, were selected for spring pruning. Ground-level branches at the bottom of the canopy were pruned, as were overly dense branches, to increase light intensity within the canopy and improve the tree's photosynthetic efficiency.

[0027] Then, the following different processing methods are used respectively: Treatment A: In a greenhouse environment, the Ganping citrus plants are generally pruned to a dwarfing shape, but five upright, vigorous shoots of 60-80cm in length are left at the top of the canopy for extended growth. Figure 1 As shown, it continues to maintain its apical dominance without any pruning.

[0028] Selection and thinning of high-quality fruiting branches: In the early stage of fruit development, before the peak period of fruit cracking, high-quality fruiting branches are generally determined at the end of May. Only one-year-old fruiting branches with a diameter ≥0.4cm are retained to set fruit, and fruiting branches with insufficient diameter are not retained to directly thin the fruit, so as to ensure that the tree's nutrients are concentrated on the high-quality fruiting branches to set fruit. Treatment B: Based on Treatment A above, three upright, vigorous shoots are reserved at the top of the canopy of the Ganping citrus trees under greenhouse cultivation. These shoots are then allowed to grow freely without any pruning. For the selection of high-quality fruiting branches, only one-year-old fruiting branches with a diameter ≥0.4cm are retained for fruit setting. Fruiting branches with a diameter less than 0.4cm are not allowed to bear fruit and are directly thinned. Treatment C: Select root-controlled container seedlings of *Gynostemma pentaphyllum* grown in open-field cultivation and perform pruning treatment, using the same method as Treatment A; Treatment D: Select container seedlings of *Gynostemma pentaphyllum* grown in an open-field environment. Use conventional dwarfing and shaping pruning methods, leaving no vigorous shoots at the top and outer edges of the canopy. Starting from June 15th, spray the canopy with 10 mg / kg gibberellin every 20 days for three consecutive applications. The pesticide should be prepared and used immediately, and agricultural organosilicon surfactants should be added before use. Treatment E: Based on Treatment A above, nine upright vigorous shoots are reserved at the top of the canopy of Ganping citrus trees under greenhouse cultivation conditions, and these shoots are allowed to grow freely without any pruning. For the selection of high-quality fruiting branches, only one-year-old fruiting branches with a diameter ≥0.4cm are retained for fruit setting; fruiting branches with a diameter less than 0.4cm are not allowed to bear fruit and are directly thinned. Treatment F: Based on the above treatment A, five upright vigorous shoots with a length of 60-80cm were reserved at the top of the canopy of the Ganping citrus plant under the greenhouse cultivation environment. These shoots were left to grow freely without any pruning or selection of high-quality fruiting branches. Blank control treatment: In the open-air environment (root-controlled container seedlings), conventional shaping and pruning methods were used. No upright vigorous branches were left in the canopy, and no high-quality fruiting branches were selected. Only deformed and diseased fruits were thinned.

[0029] During the later stages of the peak fruit cracking period in Ganping (generally at the end of October), the fruit cracking rate was statistically analyzed, and the ratio of the total number of cracked fruits to the total number of fruits on each tree was calculated. Fruit cracking rate / % = number of cracked fruits / total number of fruits × 100.

[0030] The results are shown in Table 1 below.

[0031] Table 1. Analysis of fruit cracking rate and fruit quality of citrus variety 'Ganping' The above data analysis shows that: To reduce the fruit cracking rate of the 'Ganping' citrus variety, five vigorous shoots longer than 60cm should be retained at the top of the canopy during pruning to create a high-top tree shape. Retaining too many vigorous shoots (as in treatment E) will disrupt the overall light penetration of the canopy, resulting in poor ventilation and light transmission, which will affect fruit set and fruit quality. Retaining too few vigorous shoots (as in treatment B) will not play a role in balancing the distribution of hormones in the tree and will not significantly alleviate the problem of fruit cracking.

[0032] Meanwhile, long-term field observations revealed that if high-quality fruiting branches are not selected (e.g., treatment F), weak fruiting branches are prone to fruit cracking; if only excessively thick (diameter > 0.8 cm) fruiting branches are retained, yield will decrease significantly. However, since the 'Ganping' variety actually has relatively few one-year-old fruiting branches that can reach this diameter threshold (diameter > 0.8 cm), setting an excessively high diameter threshold is inappropriate.

[0033] Therefore, in addition to the high-top shaping and pruning method described in this invention, it is also necessary to properly select high-quality fruiting branches. Only by combining the two can the excellent effect of this invention be achieved.

[0034] Example 2 In early March, spring pruning was carried out on 9-year-old 'Ganping' citrus trees of the variety grown in greenhouses in Yinzhou District, Ningbo City, Zhejiang Province. These trees were free from pests and diseases, exhibited healthy growth, and had moderate vigor. The pruning involved removing ground-level branches and overly dense branches to increase light intensity within the canopy and improve photosynthetic efficiency. The following specific treatment methods were then applied: Treatment A: Generally, a dwarfing pruning method is adopted, but five upright, vigorous shoots (60-80cm in length) are retained at the top of the canopy. These are left to grow long, with buds and new shoots removed to maintain apical dominance. Figure 1 As shown, no trimming is done.

[0035] Selection and thinning of high-quality fruiting branches: In the early stage of fruit development, before the peak period of fruit cracking, high-quality fruiting branches are generally determined at the end of May. Only one-year-old fruiting branches with a diameter ≥0.4cm are retained for fruit setting. Fruiting branches with insufficient diameter are not retained for fruit setting and are thinned directly to ensure that the tree's nutrients are concentrated on supplying high-quality fruiting branches for fruit setting. Treatment B: Based on Treatment A above, the selection of high-quality fruiting branches will only retain fruiting branches with a diameter of 0.30cm or less. Control treatment: The conventional dwarfing and shaping pruning method was adopted, that is, no upright and vigorous branches were retained in the tree crown, and no high-quality fruiting branches were selected. Only deformed and diseased fruits were thinned.

[0036] During the later stages of the peak fruit cracking period in Ganping (generally at the end of October), the fruit cracking rate was statistically analyzed, and the ratio of the total number of cracked fruits to the total number of fruits on each tree was calculated. Fruit cracking rate / % = number of cracked fruits / total number of fruits × 100.

[0037] The results are shown in Table 2 below.

[0038] Table 2. Fruit cracking rate of citrus variety 'Ganping' The above data analysis shows that: Long-term field observations revealed a close correlation between the fruit cracking rate and the diameter of the fruiting branches in the 'Ganping' citrus variety. Even when thinner one-year-old fruiting branches were retained for fruit setting (Treatment B), the fruit cracking rate remained high. This was mainly due to the weaker competitive growth of these branches, poor growth vigor, and inadequate vegetative growth. Furthermore, the fruit cracking rate was even higher if the improved high-top pruning method was not used (Control group).

[0039] Therefore, the key technology of this invention is to use ≥0.4cm as a threshold for selecting high-quality one-year-old fruiting branches, which, together with other characteristics, effectively reduces the fruit cracking rate.

[0040] Example 3 In early March, at the 'Ganping' citrus planting base in Bishan District, Chongqing, 9-year-old 'Ganping' citrus trees grown under greenhouse conditions—those free from pests and diseases, with healthy growth and moderate vigor—were selected for spring pruning. Overly dense branches were thinned to increase light intensity within the canopy and improve photosynthetic efficiency. Five upright, vigorous shoots were retained at the top of the canopy, and three horizontal treatments were implemented according to different length ranges: Treatment group: The dwarfing and shaping pruning method is generally adopted, but 5 spring shoots with upright vigorous growth at the top of the canopy are reserved, with a length of 60-80cm. The long-term treatment is adopted, and the buds and new shoots on them are removed to maintain their apical dominance.

[0041] Selection and thinning of high-quality fruiting branches: In the early stage of fruit development, before the peak period of fruit cracking, high-quality fruiting branches are generally determined at the end of May. Only one-year-old fruiting branches with a diameter ≥0.4cm are retained for fruit setting. Fruiting branches with insufficient diameter are not retained for fruit setting and are thinned directly to ensure that the tree's nutrients are concentrated on supplying high-quality fruiting branches for fruit setting. Control group: The conventional dwarfing and shaping pruning method was adopted, that is, no upright and vigorous branches were retained in the tree crown, and no high-quality fruiting branches were selected. Only deformed and diseased fruits were thinned.

[0042] During the later stages of the peak fruit cracking period in Ganping (generally at the end of October), the fruit cracking rate was statistically analyzed, and the ratio of the total number of cracked fruits to the total number of fruits on each tree was calculated. Fruit cracking rate / % = number of cracked fruits / total number of fruits × 100.

[0043] The results are shown in Table 3 below.

[0044] Table 3. Statistics on fruit cracking rate of citrus variety 'Ganping' The above data analysis shows that: Under the aforementioned regional environmental conditions, the citrus variety 'Ganping', which adopts the high-top pruning method, also effectively reduced the fruit cracking rate, while the fruit cracking rate under the traditional management method was as high as 70%. This shows that the local microclimate conditions did not affect the excellent effect of the pruning method used in this invention in reducing the fruit cracking rate.

[0045] Example 4 In early March, spring pruning was carried out on 8-year-old 'Ganping' citrus trees grown under greenhouse cultivation in Xiangshan County, Ningbo City, Zhejiang Province. These trees were free from pests and diseases, exhibited healthy growth, and had moderate vigor. Ground-level branches at the bottom of the canopy were pruned, as were overly dense branches, to increase light intensity within the canopy and improve photosynthetic efficiency. Five upright, vigorous shoots were retained at the top of the canopy, and three horizontal treatments were applied according to different length ranges: Treatment A: Generally adopt the dwarfing and shaping pruning method, but leave 5 spring shoots upright vigorous branches at the top of the canopy, with the length of the vigorous branches ≤40 cm; adopt the long-release treatment, remove the buds and new shoots on them, and continue to maintain their apical dominance.

[0046] Selection and thinning of high-quality fruiting branches: In the early stage of fruit development, before the peak period of fruit cracking, high-quality fruiting branches are generally determined at the end of May. Only one-year-old fruiting branches with a diameter ≥0.4cm are retained for fruit setting. Fruiting branches with insufficient diameter are not retained for fruit setting and are thinned directly to ensure that the tree's nutrients are concentrated on supplying high-quality fruiting branches for fruit setting. Treatment B: Leave vigorous shoots with a length of 40-60 cm, and manage them in the same way as treatment A; Treatment C: Leave vigorous shoots with a length of 60-80 cm, and manage them in the same way as treatment A; Control group: The conventional dwarfing and shaping pruning method was adopted, that is, no upright and vigorous branches were retained in the tree crown, and no high-quality fruiting branches were selected. Only deformed and diseased fruits were thinned.

[0047] During the later stages of the peak fruit cracking period in Ganping (generally at the end of October), the fruit cracking rate was statistically analyzed, and the ratio of the total number of cracked fruits to the total number of fruits on each tree was calculated. Fruit cracking rate / % = number of cracked fruits / total number of fruits × 100.

[0048] The results are shown in Table 3 below.

[0049] Table 4. Statistics on fruit cracking rate of citrus variety 'Ganping' The above data analysis shows that: A close correlation exists between the length of vigorous shoots retained and the fruit cracking rate in the 'Ganping' citrus variety using the high-top pruning method. If the length of the vigorous shoots retained is ≤40 cm (Treatment A), the fruit cracking rate is still as high as 25%, mainly due to insufficient endogenous hormone synthesis in the branches and poor vegetative growth caused by weak apical dominance. Furthermore, if the length of the vigorous shoots retained is 40-60 cm (Treatment B), although the fruit cracking rate is better than the conventional treatment and Treatment A, it is still slightly higher than Treatment C.

[0050] Therefore, the present invention is more suitable for retaining vigorous shoots with a length of 60-80 cm, which can reduce the fruit cracking rate to a lower level.

[0051] While the embodiments disclosed in this invention are as described above, the content is merely for the purpose of facilitating understanding of the invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and changes to the form and details of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection of this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A method for shaping and pruning citrus fruits to prevent cracking, characterized in that, The citrus variety is Ganping, and the process includes the following steps: (1) High-top shaping pruning: In spring, prune the Ganping citrus, retain 5 vigorous branches with a length of 60-80cm at the top of the canopy, remove the buds and new shoots on them, and distribute them evenly at the top to form a high-top canopy; (2) Selection and thinning of high-quality fruiting branches: In the early stage of fruit development, only one-year-old fruiting branches with a diameter ≥0.4cm are retained to set fruit, and the rest of the fruit are removed directly; (3) Renewal of vigorous shoots: After fruiting, remove the vigorous shoots and cultivate new vigorous shoots in the following year according to step (1), and repeat the cycle.

2. The pruning and shaping method for preventing citrus fruit cracking as described in claim 1, characterized in that, The vigorous shoots in step (1) are formed from the spring shoots of the current year.

3. The pruning and shaping method for preventing citrus fruit cracking as described in claim 1, characterized in that, The pruning time in step (1) is in early March.

4. The pruning and shaping method for preventing citrus fruit cracking as described in claim 1, characterized in that, The method is applicable to Ganping citrus trees grown in the open air or in greenhouses.

5. The pruning and shaping method for preventing citrus fruit cracking as described in claim 1, characterized in that, The method also includes conventional fertilizer and water management measures.

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