Efficient prevention and control method for citrus juice sac granulation and application thereof

Abstract

The invention belongs to the technical field of fruit tree cultivation management and postharvest preservation, and particularly relates to an efficient prevention and control method for citrus juice sac granulation and application thereof. In order to reduce the citrus juice sac granulation rate and improve the fruit quality and yield, the invention discloses a prevention and control method for citrus fruit juice sac granulation, namely, gibberellin or / and brassinolide are / is sprayed to the whole citrus tree exogenous source in the specific development stage, and conventional orchard cultivation management measures are adopted after the gibberellin or / and brassinolide are / is sprayed. Experiments show that both gibberellin and brassinolide can effectively inhibit citrus juice sac granulation and improve the fruit quality and yield, and the combined application of gibberellin and brassinolide has a significant synergistic effect. The method adopts a whole-plant spraying mode, is convenient and fast to operate, can be mixed with a leaf fertilizer for spraying, is high in practicability, is easy to popularize and apply in a large scale, and has important significance on quality improvement and yield increase in the citrus industry.

Description

Technical Field

[0001] This invention belongs to the field of fruit tree cultivation management and post-harvest preservation technology, specifically involving a highly efficient method for controlling citrus juice cell granulation and its application. Background Technology

[0002] Citrus fruits, especially pomelos, are highly susceptible to granulation of juice vesicles during ripening and post-harvest storage. This phenomenon is characterized by juice vesicle dehydration and hardening, cell wall corking, and irregular swelling of the pulp tissue, ultimately leading to reduced juice content, bland taste, and significantly lower commercial value. Granulation is particularly prevalent in pomelos such as Guanxi honey pomelo and red-fleshed honey pomelo, as well as some loose-skinned citrus fruits, with incidence rates reaching 30%-90% in extreme years, becoming a key bottleneck restricting the high-quality development of the industry. Existing research indicates a close relationship between granulation and factors such as disordered cell wall metabolism, abnormal lignin accumulation, and imbalances in water and nutrient transport during fruit senescence.

[0003] Currently, the control of citrus juice sac granulation in production mainly relies on cultivation management measures. This includes adjusting nitrogen fertilizer application, increasing the application of mineral elements such as potassium, calcium, and zinc (e.g., a combination of sugar alcohol calcium and sugar alcohol zinc), and adopting scientific water management measures to delay senescence and reduce the granulation index. Citrus flowering often occurs in the rainy season in southern regions, making flower and fruit retention difficult. The fruit load on the tree is easily affected by the annual weather conditions, resulting in alternate bearing. Trees with low fruit loads tend to have rapid fruit enlargement later on, easily forming large, rough-skinned fruits, which in turn induces juice sac granulation. Conventional cultivation management measures can only reduce the incidence of granulation to a certain extent under normal fruit load conditions; when the fruit load is severely insufficient, the control effect is significantly reduced. Therefore, the need for developing new technologies for the control of citrus juice sac granulation is extremely urgent, especially in the special circumstances of low citrus yields. Summary of the Invention

[0004] To overcome the shortcomings of the existing technology, this invention provides a method for controlling granulation of citrus fruit juice vesicles. This method involves exogenously spraying gibberellin and / or brassinolide at specific developmental stages, thereby reducing the granulation rate and improving fruit quality and yield. Furthermore, this invention employs a whole-plant spraying method, which is convenient and quick, and can be sprayed together with foliar fertilizers, making it highly operable and easy to promote and apply on a large scale.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of this invention provides the application of gibberellin and / or brassinolide in controlling juice cell granulation in citrus fruits or improving the quality of citrus fruits.

[0006] This invention has shown through experiments that both gibberellin and brassinolide can effectively inhibit citrus juice cell granulation, and their combined application has a significant synergistic effect. Furthermore, treatment with gibberellin and / or brassinolide significantly increases the TSS (total solids content) and Vc (vitamin c) content of the fruit, resulting in a significant improvement in fruit quality.

[0007] A second aspect of the present invention also provides a medicament for preventing granulation of citrus fruit juice sacs, the medicament comprising gibberellin and / or brassinolide.

[0008] Preferably, the agent further includes excipients acceptable in the pesticide field.

[0009] More preferably, the excipients acceptable in the pesticide field include solvents, emulsifiers, dispersants, wetting agents, fillers, and stabilizers. Solvents aid dissolution, emulsifiers promote compatibility, dispersants prevent agglomeration, wetting agents aid adhesion, fillers increase volume, and stabilizers preserve efficacy.

[0010] The third aspect of this invention also provides a method for preventing granulation of citrus fruit juice sacs, specifically: during the later stage of citrus fruit enlargement, exogenous gibberellin and / or brassinolide are sprayed onto the entire citrus tree, and conventional orchard cultivation and management measures are adopted after spraying.

[0011] Preferably, the later stage of citrus fruit enlargement is 30 to 50 days before harvest.

[0012] Preferably, the citrus varieties include white-fleshed pomelo, red-fleshed pomelo, and Asumi mandarin orange.

[0013] Preferably, the effective concentration of gibberellin is 5–40 mg / L, and the effective concentration of brassinolide is 1–4 mg / L.

[0014] Preferably, when gibberellin and brassinolide are sprayed simultaneously, brassinolide is sprayed first, and gibberellin is sprayed 15 to 40 days later.

[0015] Preferably, spraying should be carried out during suitable weather times, avoiding the hot midday hours (before 10 a.m. and after 4 p.m.) and rainy weather.

[0016] Compared with the prior art, the beneficial effects of the present invention are: To reduce the granulation rate of citrus juice sacs and improve fruit quality and yield, this invention discloses a method for controlling granulation of citrus juice sacs. This involves exogenously spraying the entire citrus tree with gibberellin and / or brassinolide at specific developmental stages, followed by conventional orchard cultivation and management practices. Experiments show that both gibberellin and brassinolide effectively inhibit granulation of citrus juice sacs, improving fruit quality and yield, and their combined application exhibits a significant synergistic effect. This invention uses a whole-tree spraying method, which is convenient and quick to operate, can be mixed with foliar fertilizers, is highly practical, and is easy to promote and apply on a large scale, making it of great significance for improving the quality and yield of the citrus industry. Detailed Implementation

[0017] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0018] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0019] Example 1: (1) Experimental method: On the morning of August 1, 2024 (when the weather was good, avoiding the hot midday hours), in a 5-year-old white-fleshed pomelo orchard in Meixian County, Meizhou City, Guangdong Province, during the late stage of citrus fruit enlargement (about 30-50 days before harvest), gibberellin at concentrations of 5, 10, 20, and 40 mg / L or brassinolide at concentrations of 1, 2, 3, and 4 mg / L (water as the solvent) was sprayed evenly onto the entire tree until it was thoroughly wetted. Five trees were sprayed with each concentration. A control group was sprayed with plain water. Due to heavy rainfall that spring, the orchard had poor flower and fruit retention, with only 3-5 fruits per tree, compared to over 30 fruits per tree in normal years. At the time of spraying, the average weight of the fruit in the orchard had already reached over 3 jin (approximately 1.5 catties), far exceeding the normal average weight of a single fruit in previous years (approximately 2.5-3.5 jin (approximately 1.75-1.75 catties) at maturity.

[0020] Harvested on September 2, 2024, the fruits were transported to a laboratory in Guangzhou and stored at room temperature. Fifteen fruits were collected from each treatment. The fruits were opened at 10, 20, and 60 days post-harvest to check for granulation. On the 10th day after opening, the soluble solids (TSS) content of each treatment fruit was determined according to standard NY / T 2637-2014, and the vitamin C (Vc) content was determined according to standard GB 5009.86-2016. The granulation grading standard for individual fruits and the method for calculating the granulation index were based on the literature “Zhang J, Wang M, Cheng F, et al. Identification of microRNAs correlated with citrus granulation based on bioinformatics and molecular biology analysis[J]. Postharvest Biology and Technology, 2016, 118: 59-67”. The specific grading is as follows: Grade 0 is 0% granulation; Grade 1 is <10% granulation; Grade 2 is 10%–25% granulation; Grade 3 is 25%–50% granulation; and Grade 4 is 50% or higher granulation. The granulation index is calculated as follows: Granulation Index (%) = [∑(granulation grade × number of fruits in the corresponding grade)] / (highest granulation grade × total number of fruits) × 100%.

[0021] (2) Experimental results: As shown in Table 1, treatment with 10 mg / L and 20 mg / L gibberellin significantly extended the storage period of white-fleshed pomelos. By day 20 post-harvest, the control group had almost completely granulated, but the 10 mg / L and 20 mg / L gibberellin-treated groups had not yet granulated. This indicates that 10 mg / L and 20 mg / L gibberellin treatment can effectively inhibit granulation of white-fleshed pomelos, and the solids content and vitamin C content of the treated groups were much higher than those of the control group, indicating that the fruit quality of pomelos was significantly improved after gibberellin treatment.

[0022] As shown in Table 2, compared with the control group, all experimental groups treated with 1–4 mg / L brassinolide effectively inhibited the granulation process of white-fleshed pomelos and significantly prolonged their storage shelf life, with the 3 mg / L and 4 mg / L treatment groups showing the best efficacy. By day 20 post-harvest, the control group had almost completely granulated, while the granulation rate of the 3 mg / L and 4 mg / L brassinolide treatment groups was 8.33%. By day 60, the granulation rates of the 3 mg / L and 4 mg / L brassinolide treatment groups were 16.67% and 8.33%, respectively. This indicates that treatment with 3 mg / L and 4 mg / L brassinolide can effectively inhibit the granulation of white-fleshed pomelos, and the solids content and vitamin C content of the treatment groups were much higher than those of the control group, indicating that the fruit quality of pomelos was significantly improved after treatment with brassinolide.

[0023] Table 1. Effects of gibberellin on the control of granulation and quality of white-fleshed pomelo fruit Table 2. Effects of brassinolide on the control of granulation and quality of white-fleshed pomelo fruit Example 2 (1) Experimental method: On the morning of August 10, 2025 (when the weather was good, avoiding the midday heat), in a 4-year-old red-fleshed pomelo orchard in Meixian County, Meizhou City, Guangdong Province, gibberellin at concentrations of 5, 10, 20, and 40 mg / L or brassinolide at concentrations of 1, 2, 3, and 4 mg / L was sprayed evenly on the entire tree during the late stage of citrus fruit enlargement (about 30-50 days before harvest). Five trees were sprayed with each concentration. A control group was sprayed with water. The orchard had poor flower and fruit retention; most pomelo trees bore only 3-6 fruits, compared to over 30 fruits per tree in normal years. Trees bearing more than 6 fruits were discarded. At the time of spraying, most fruits in the orchard weighed over 3 jin (approximately 1.5 catties), far exceeding the normal weight of a single fruit in previous years (approximately 2.5-3.5 jin).

[0024] Harvested on September 20, 2025, the grapefruits were transported to a laboratory in Guangzhou and stored at room temperature after harvesting. Fifteen fruits were collected from each treatment. The grapefruits were opened at 10, 20, and 30 days post-harvest to check the granulation status. On day 10, the soluble solids (TSS) content of each treatment fruit was determined according to standard NY / T2637-2014, and the vitamin C (Vc) content was determined according to standard GB 5009.86-2016. The granulation grading standard for individual fruits and the method for calculating the granulation index were based on the literature “Zhang J, Wang M, Cheng F, et al. Identification of microRNAs correlated with citrus granulation based on bioinformatics and molecular biology analysis[J]. Postharvest Biology and Technology, 2016, 118: 59-67”. The specific grading is as follows: Grade 0 is 0% granulation; Grade 1 is <10% granulation; Grade 2 is 10%–25% granulation; Grade 3 is 25%–50% granulation; and Grade 4 is 50% or higher granulation. The granulation index is calculated as follows: Granulation Index (%) = [∑(granulation grade × number of fruits in the corresponding grade)] / (highest granulation grade × total number of fruits) × 100%.

[0025] (2) Experimental results: As shown in Table 3, compared with the control group, all experimental groups treated with 5–40 mg / L gibberellin effectively inhibited granulation of red-fleshed pomelos. Among them, the 10 mg / L and 20 mg / L gibberellin treatment groups showed the best effects, significantly extending the storage period of red-fleshed pomelos. By day 20 post-harvest, the granulation index of the control group reached 75%, but at this time, the 10 mg / L and 20 mg / L gibberellin treatment groups were still not granulated or had a low granulation index (8.33%). This indicates that treatment with 10 mg / L and 20 mg / L gibberellin effectively inhibited granulation of red-fleshed pomelos, and the total solids content (TSS) and vitamin C content of the treatment groups were much higher than those of the control group, indicating that the fruit quality of pomelos was significantly improved after gibberellin treatment.

[0026] As shown in Table 4, compared with the control, all experimental groups treated with 1–4 mg / L brassinolide effectively inhibited granulation of red-fleshed pomelos and significantly prolonged their storage period, with the 3 mg / L and 4 mg / L treatment groups showing the best efficacy. By day 20 post-harvest, the granulation rate of the control group reached 75%, while the granulation rates of the 3 mg / L and 4 mg / L brassinolide treatment groups were both 8.33%. By day 60, the granulation rate of the control group reached 83.33%, while the granulation rates of the 3 mg / L and 4 mg / L brassinolide treatment groups were 16.77% and 8.33%, respectively. This indicates that treatment with 3 mg / L and 4 mg / L brassinolide effectively inhibited granulation of red-fleshed pomelos, and the solids content and vitamin C content of the treated groups were significantly higher than those of the control group, indicating that brassinolide treatment significantly improved the fruit quality of pomelos.

[0027] Table 3. Effects of gibberellin on the control of granulation and quality of red-fleshed pomelo fruit Table 4. Effects of brassinolide on the control of granulation and quality of red-fleshed pomelo fruit Example 3 (1) Experimental method: On the morning of August 1, 2025 (when the weather was good, avoiding the hot midday hours), in a 5-year-old red-fleshed pomelo orchard in Meixian County, Meizhou City, Guangdong Province, brassinolide at a concentration of 4 mg / L was sprayed evenly by misting during the late stage of citrus fruit enlargement (about 30-50 days before harvest). The entire tree was sprayed until it was thoroughly wetted, and a total of 10 trees were treated. At the same time, on August 20, gibberellin at a concentration of 20 mg / L was sprayed evenly on the 10 pomelo trees that had been sprayed with brassinolide, with water spraying serving as a control.

[0028] Harvested on September 20, 2025, the grapefruits were transported to a Guangzhou laboratory for room temperature storage after harvesting. Three fruits were harvested from each tree, for a total of 30 fruits. The grapefruits were opened at 10, 20, and 30 days post-harvest to check the granulation status. On day 10, the soluble solids (TSS) content of each treated fruit was determined according to standard NY / T 2637-2014, and the vitamin C (Vc) content was determined according to standard GB 5009.86-2016. The granulation grading standard for individual fruits and the method for calculating the granulation index were based on the literature "Zhang J, Wang M, Cheng F, et al. Identification of microRNAs correlated with citrus granulation based on bioinformatics and molecular biology analysis[J]. Postharvest Biology and Technology, 2016, 118: 59-67". The specific grading is as follows: Grade 0 is 0% granulation; Grade 1 is <10% granulation; Grade 2 is 10%–25% granulation; Grade 3 is 25%–50% granulation; and Grade 4 is 50% or higher granulation. The granulation index is calculated as follows: Granulation Index (%) = [∑(granulation grade × number of fruits in the corresponding grade)] / (highest granulation grade × total number of fruits) × 100%.

[0029] (2) Experimental results: As shown in Table 5, compared with the control group, the experimental group treated with a combination of gibberellin and brassinolide showed a significant inhibitory effect on the granulation of pomelo juice cells. Moreover, the degree of granulation of red-fleshed pomelo was significantly reduced compared with the single-agent treatment group. This indicates that both gibberellin and brassinolide have the effect of inhibiting the granulation of pomelo juice cells, and the combined application has a significant synergistic effect.

[0030] Table 5. Effects of combined use of gibberellin and brassinolide on the control of granulation and quality of red-fleshed pomelo fruit. Example 4 (1) Experimental method: On the morning of October 20, 2024, in a 5-year-old Shimizu mandarin orchard cultivated in the experimental greenhouse of the Fruit Tree Research Institute of the Guangdong Academy of Agricultural Sciences in Guangzhou, Guangdong Province, gibberellin at concentrations of 2.5, 5, 10, and 20 mg / L or brassinolide at concentrations of 0.5, 1, 1.5, and 2 mg / L was sprayed evenly on the entire plant until it was wet. Five plants were sprayed with each concentration. Spraying with water was used as a control.

[0031] Fruits were harvested on November 30, December 10, and December 20, 2024. After harvesting, the fruits were sent to the laboratory, the peels were removed, and the granulation of the fruits was examined directly without storage. The fruits were stored at room temperature, with 10 fruits collected for each treatment. The fruits harvested on November 30 were used as test samples. The soluble solids (TSS) content of each treatment fruit was determined according to standard NY / T 2637-2014, and the vitamin C (Vc) content was determined according to standard GB 5009.86-2016. The granulation grading standard and granulation index calculation method for individual fruits were based on the literature "Zhang J, Wang M, Cheng F, et al. Identification of microRNAs correlated with citrus granulation based on bioinformatics and molecular biology analysis[J]. Postharvest Biology and Technology, 2016, 118: 59-67". The specific grading is as follows: Grade 0 is 0% granulation; Grade 1 is <10% granulation; Grade 2 is 10%–25% granulation; Grade 3 is 25%–50% granulation; and Grade 4 is 50% or higher granulation. The granulation index is calculated as follows: Granulation Index (%) = [∑(granulation grade × number of fruits in the corresponding grade)] / (highest granulation grade × total number of fruits) × 100%.

[0032] (2) Experimental results: As shown in Table 6, treatment with 5 mg / L and 10 mg / L gibberellin significantly prolonged the fruiting period of *Ashita no Miko* on the tree, extending it to as late as December 20th. At this point, the granulation index of the control group reached 100%, while the granulation index of the 5 mg / L and 10 mg / L gibberellin-treated groups remained at a low level (5 mg / L: 7.5%; 10 mg / L: 5%). This indicates that treatment with 5 mg / L and 10 mg / L gibberellin effectively inhibited granulation of *Ashita no Miko*, prolonging its fruiting period on the tree. Furthermore, the solids content and vitamin C content of the treated groups were significantly higher than those of the control group, demonstrating that gibberellin treatment significantly improved the fruit quality of *Ashita no Miko*.

[0033] As shown in Table 7, treatment with brassinolide at concentrations of 0.5–2 mg / L significantly prolonged the fruit-bearing period of *Emperor's Birthday* on the tree, extending it to as late as December 20th. At this point, the granulation index of the control group reached 100%, while the granulation index of the 1.5 mg / L and 2 mg / L brassinolide treatment groups remained at a lower level (1.5 mg / L: 12.5%; 2 mg / L: 5%). This indicates that treatment with 1.5 mg / L and 2 mg / L brassinolide effectively inhibited granulation of *Emperor's Birthday*, prolonging its fruit-bearing period on the tree. Furthermore, the solids content and vitamin C content of the treatment groups were significantly higher than those of the control group, demonstrating that the fruit quality of *Emperor's Birthday* was significantly improved after treatment with brassinolide.

[0034] Table 6. Effects of gibberellin on the control of granulation and quality of citrus fruit. Table 7. Effects of brassinolide on the control of granulation and quality of Akita mandarin orange fruit Example 5 On the morning of October 10, 2024, in a 5-year-old Tomorrow Mandarin orchard cultivated in a net greenhouse in Guangzhou, Guangdong Province, brassinolide at a concentration of 2 mg / L was sprayed evenly by spraying during the late stage of fruit enlargement (about 30-50 days before harvest). Then, on November 5, the same batch of plants were sprayed with gibberellin at a concentration of 5 mg / L. All plants were sprayed until they were wet. A total of 10 trees were treated, and water spraying was used as a control.

[0035] Fruits were harvested on December 5, 15, and 25, 2024, and January 5 of the following year. After harvesting, the fruits were sent to the laboratory to have their peels removed and to examine the granulation. Ten fruits were collected for each treatment each time. The fruits harvested on December 15 were used as test samples. The soluble solids (TSS) content of each treatment fruit was determined according to standard NY / T 2637-2014, and the vitamin C (Vc) content was determined according to standard GB 5009.86-2016. The granulation grading standard and granulation index calculation method for individual fruits were based on the literature "Zhang J, Wang M, Cheng F, et al. Identification of microRNAs correlated with citrus granulation based on bioinformatics and molecular biology analysis[J]. Postharvest Biology and Technology, 2016, 118:59-67". The specific grading is as follows: Grade 0 is 0% granulation; Grade 1 is <10% granulation; Grade 2 is 10%–25% granulation; Grade 3 is 25%–50% granulation; and Grade 4 is 50% or higher granulation. The granulation index is calculated as follows: Granulation Index (%) = [∑(granulation grade × number of fruits in the corresponding grade)] / (highest granulation grade × total number of fruits) × 100%.

[0036] (2) Experimental results: As shown in Table 8, the combined treatment with brassinolide and gibberellin significantly prolonged the fruit-bearing period of *Eriocaulon buergerianum* (a type of jujube). By December 25th, the granulation index of the control group had reached 100%, while the granulation index of the treated group was only 2.50%. By January 5th of the following year, the granulation rate of the treated group remained at a low level of 2.50%. This indicates that the combined application of brassinolide and gibberellin can effectively inhibit granulation of *Eriocaulon buergerianum*, prolong its fruit-bearing period, and exhibits a good synergistic effect.

[0037] Table 8. Effects of brassinolide combined with gibberellin on the control of granulation and quality of Akita mandarin orange fruit. The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. Application of gibberellin and / or brassinolide in controlling granulation of citrus fruit juice sacs or improving the quality of citrus fruit.

2. An agent for preventing granulation of citrus fruit juice vesicles, characterized in that, The agents include gibberellin and / or brassinolide.

3. The agent for preventing granulation of citrus fruit juice vesicles according to claim 2, characterized in that, The agent also includes excipients acceptable in the pesticide field.

4. The agent for preventing granulation of citrus fruit juice vesicles according to claim 3, characterized in that, The excipients acceptable in the pesticide field include solvents, emulsifiers, dispersants, wetting agents, fillers, and stabilizers.

5. A method for preventing granulation of citrus fruit juice vesicles, characterized in that, During the later stages of citrus fruit enlargement, apply exogenous gibberellin and / or brassinolide to the entire citrus tree. After spraying, follow conventional orchard cultivation and management practices.

6. The method for preventing granulation of citrus fruit juice vesicles according to claim 5, characterized in that, The later stage of citrus fruit enlargement is 30 to 50 days before harvest.

7. The method for preventing granulation of citrus fruit juice vesicles according to claim 5, characterized in that, The varieties of citrus mentioned include white-fleshed pomelo, red-fleshed pomelo, and Asumi mandarin orange.

8. A method for preventing granulation of citrus fruit juice vesicles according to claim 5, characterized in that, The effective concentration of gibberellin is 5–40 mg / L, and the effective concentration of brassinolide is 1–4 mg / L.

9. A method for preventing granulation of citrus fruit juice vesicles according to claim 5, characterized in that, When spraying both gibberellin and brassinolide, spray brassinolide first, and then spray gibberellin 15 to 40 days later.

10. A method for preventing granulation of citrus fruit juice vesicles according to claim 5, characterized in that, Choose a suitable time of day for spraying, avoiding the hottest part of the day and rainy weather.

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