Method for preventing and controlling black heart disease of pineapple

Abstract

The present application belongs to the technical field of fruit tree cultivation and plant growth regulator, and particularly relates to a method for preventing and controlling black heart disease of pineapple. The present application uses a sugar substance aqueous solution or a combination of a sugar substance and a stachyose aqueous solution to spray and / or soak the pineapple, and the sugar substance is selected from at least one of sucrose, maltose and raffinose, so as to prevent and control the black heart disease of the pineapple. Experimental results show that the use of sucrose, maltose or raffinose alone or in combination can significantly reduce the incidence and disease index of the black heart disease of the pineapple, and the sugar solution obtained by the combination of sucrose, maltose, raffinose and stachyose has the best prevention and control effect. Further endogenous hormone detection shows that the above-mentioned sugar solution can regulate the level of endogenous hormones in the pineapple pulp, which indicates that it plays a prevention and control role by regulating the hormone balance of the fruit. The present application provides a new solution for preventing and controlling the black heart disease of the pineapple, and can effectively reduce the loss caused by the black heart disease of the pineapple.

Description

Technical Field

[0001] This invention belongs to the technical field of fruit tree cultivation and plant growth regulators. More specifically, it relates to a method for controlling black heart disease in pineapples. Background Technology

[0002] Pineapple( Ananas comosus (L.) Merr.) is a perennial herbaceous fruit tree belonging to the genus *L.* of the family Bromeliaceae, and is a characteristic tropical economic crop widely cultivated in southern my country. However, pineapples are susceptible to internal browning (IB) after harvest. The disease initially manifests as translucent, water-soaked spots in the core tissue, which gradually expand to browning of the fruit axis and flesh, eventually leading to the fruit losing its commercial value. Unlike common post-harvest oxidative browning or fungal diseases such as heart rot caused by pathogens, which exhibit obvious external symptoms like softening at the fruit base, water-soaked rot, surface mold, or off-odors, pineapple black heart disease originates inside the fruit, making it highly insidious: the fruit appears intact, with normal peel color, no softening, rotting, or off-odors, and retains the characteristic aroma of pineapple. It is difficult to judge the severity of the disease externally using the naked eye or conventional non-destructive testing methods; often, severe internal browning is only discovered after processing or cutting open the fruit for fresh consumption. This characteristic of "perfect appearance but rotten inside" makes it difficult to remove pineapple fruits during storage, transportation, and sales, which has a significant impact on the pineapple industry.

[0003] The exact causes of pineapple black heart disease are not fully understood, but the academic community generally agrees that its main causes are low temperature and exogenous gibberellin (GA3) (He Roujing, Deng Xiaoguo. Research progress and prospects of pineapple black heart disease control methods [J]. Agriculture and Technology, 2025, 45(20).). Low temperature is the primary environmental factor inducing black heart disease. Studies have shown that whether it occurs in the field before harvest or during post-harvest storage, exposure of the fruit to an environment below 22 ℃ can induce black heart disease, and the lower the temperature and the longer the duration, the more severe the disease. Below this temperature, the metabolic balance of the fruit is disrupted, membrane lipid peroxidation is aggravated, and ultimately black heart disease is triggered. Exogenous GA3 is another important independent inducing factor. In production, GA3 is widely used to promote flowering and fruit development in pineapples and is a key agronomic measure to ensure yield. However, studies have confirmed that exogenous GA3 treatment can independently induce black heart disease in summer-harvested pineapples even without low-temperature stress. The mechanism may involve independent mechanisms such as interfering with the balance of endogenous hormones in the fruit and activating the phenylpropane metabolic pathway, thereby triggering black heart disease.

[0004] Extensive research has been conducted to control pineapple black heart disease. Physical control methods include low-temperature waxing storage, heat treatment, and controlled atmosphere storage. However, these methods generally suffer from complex operation, unstable effectiveness, or high costs, making them difficult to meet the actual needs of the industry. Therefore, chemical control has gradually become a major research direction. Chinese patent application CN103070223A discloses a method for controlling pineapple black heart disease using abscisic acid (ABA). However, this technology still has shortcomings in practical application: while it can inhibit the disease, it causes severe wilting of the pineapple crown buds. Since the vitality of the crown buds is a key indicator of fruit freshness, wilted crown buds directly sacrifice the product's appearance and marketability. Even if the internal quality is preserved, its market value will still be significantly reduced.

[0005] Therefore, developing a simple, safe, and effective method for controlling black heart disease in pineapples is of great significance to the development of the pineapple planting industry. Summary of the Invention

[0006] This invention addresses the problem of the lack of safe and effective methods for preventing and controlling black heart disease in pineapples in the existing technology, and aims to provide a method for preventing and controlling black heart disease in pineapples.

[0007] A second objective of this invention is to provide the application of sugars or a combination of sugars and stachyose in the preparation of agents for preventing and controlling black heart disease in pineapples.

[0008] The above-mentioned objective of this invention is achieved through the following technical solution: This invention provides a method for preventing black heart disease in pineapples, which involves spraying and / or soaking pineapples with an aqueous solution of sugars or an aqueous solution of a combination of sugars and stachyose. The concentration of the aqueous solution of the carbohydrate, or the aqueous solution of a combination of carbohydrate and stachyose, is 50-300 mmol·L. -1 ; The sugar is selected from at least one of sucrose, maltose, and raffinose.

[0009] The sucrose, maltose, raffinose, and stachyose selected in this invention are all food-grade raw materials with clear national or industry standards as a basis for safety. They are naturally derived and highly safe. Applying these sugars to the prevention and treatment of pineapple black heart disease poses no risk of residue, is safe and reliable for human health, and meets the requirements of green environmental protection.

[0010] This invention has found that sucrose, maltose, or raffinose, applied alone before or after harvest (either by spraying or soaking), can significantly reduce the incidence and severity of pineapple black heart disease. However, fructose (one of the monosaccharides of sucrose) treatment has the opposite effect, exacerbating the disease. Chitosan (a coating agent with antibacterial and preservative properties) and stachyose (an oligosaccharide, similar to sucrose, maltose, or raffinose) treatments alone are not effective in controlling pineapple black heart disease. These results indicate that different sugars have significantly different regulatory effects on black heart disease, and these differences are not directly related to their nutrient supply or preservative / antibacterial effects. Further hormone testing showed that effective sugar treatment can significantly alter the endogenous hormone levels in pineapple pulp, suggesting that it does not control the disease through simple nutrient supply or preservation, but rather acts as a plant growth regulator, differentially regulating the endogenous hormone network of the fruit through chemical means, thereby exerting plant growth regulatory activity and controlling pineapple black heart disease. This invention provides a novel technical solution for the control of pineapple black heart disease.

[0011] Preferably, the concentration of the aqueous solution of the carbohydrate, or the aqueous solution of a combination of carbohydrate and stachyose, is 100-300 mmol·L. -1 .

[0012] Preferably, the carbohydrate is composed of sucrose and maltose, with a mass ratio of sucrose to maltose of 1:(0.5~3).

[0013] More preferably, the carbohydrate is composed of sucrose and maltose, with a mass ratio of sucrose to maltose of 1:(0.5~1.5).

[0014] Preferably, the carbohydrate is composed of sucrose, maltose and raffinose, and the mass ratio of sucrose, maltose and raffinose is 1.5:(0.2~1):(0.5~3).

[0015] More preferably, the carbohydrate is composed of sucrose, maltose and raffinose, and the mass ratio of sucrose, maltose and raffinose is 1.5:(0.2~0.8):(0.5~1.5).

[0016] Preferably, the mass ratio of the carbohydrate to stachyose is 3:(0.5~3).

[0017] More preferably, the mass ratio of the carbohydrate to stachyose is 3:(0.5~1.5).

[0018] As a preferred embodiment, the pineapple is sprayed and / or soaked with a sucrose aqueous solution or a maltose aqueous solution, wherein the concentration of the sucrose aqueous solution or the maltose aqueous solution is 50~300 mmol·L⁻¹. -1 More preferably, 100~300 mmol·L-1 .

[0019] In a preferred embodiment, the pineapple is sprayed and / or soaked using an aqueous solution of sucrose and maltose, wherein the concentration of the aqueous solution of sucrose and maltose is 50-300 mmol·L⁻¹. -1 The mass ratio of sucrose to maltose is 1:(0.5~3); more preferably, the concentration of the aqueous solution of sucrose and maltose is 100~300 mmol·L. -1 The mass ratio of sucrose to maltose is 1:(0.5~1.5).

[0020] As a preferred embodiment, pineapples are sprayed and / or soaked with an aqueous solution of sucrose, maltose, raffinose, and stachyose, wherein the aqueous solution of sucrose, maltose, raffinose, and stachyose is 50–300 mmol·L⁻¹. -1 The mass ratio of sucrose, maltose, and raffinose is 1.5:(0.2~1):(0.5~3), and the mass ratio of the total mass of sucrose, maltose, and raffinose to the mass of stachyose is 3:(0.5~3); more preferably, the concentration of the aqueous solution of sucrose, maltose, raffinose, and stachyose is 100~300 mmol·L. -1 The mass ratio of sucrose, maltose and raffinose is 1.5:(0.2~0.8):(0.5~1.5), and the mass ratio of the total mass of sucrose, maltose and raffinose to the mass of stachyose is 3:(0.5~1.5).

[0021] Preferably, the spraying treatment is performed 12-72 hours before harvest and / or 12-72 hours after harvest; Preferably, the soaking treatment time is 12 to 72 hours after harvesting.

[0022] Preferably, the spraying involves spraying an aqueous solution of sugars, or an aqueous solution of a combination of sugars and stachyose, onto the surface of the pineapple fruit and the crown bud.

[0023] More preferably, the soaking time is 10-15 minutes.

[0024] Preferably, the pineapple is in its green-ripe stage. At this time, the fruit is plump, the bloom has fallen off, the suture of about 1 / 4 of the fruit at the base shows a slight pale yellow, the peel is mainly green, and the flesh begins to change from white to light yellow.

[0025] Furthermore, the present invention does not limit the source of the sugar or stachyose.

[0026] Preferably, the pineapple variety is Bali.

[0027] The present invention also provides the application of sugars or a combination of sugars and stachyose in the preparation of agents for preventing and controlling black heart disease in pineapples, wherein the sugars are selected from at least one of sucrose, maltose, and raffinose; The formulation is an aqueous solution of the sugar substance, or an aqueous solution of the sugar substance and stachyose, with a concentration of 50-300 mmol·L⁻¹. -1 .

[0028] Preferably, the carbohydrate is composed of sucrose and maltose, with a mass ratio of sucrose to maltose of 1:(0.5~3); more preferably, it is 1:(0.5~1.5).

[0029] Preferably, the carbohydrate is composed of sucrose, maltose, and raffinose, and the mass ratio of sucrose, maltose, and raffinose is 1.5:(0.2~0.8):(0.5~1.5). Preferably, the mass ratio of the carbohydrate to stachyose is 3:(0.5~3); more preferably, it is 3:(0.5~1.5).

[0030] The present invention has the following beneficial effects: This invention utilizes an aqueous solution prepared from at least one of sucrose, maltose, and raffinose, or a mixture thereof with stachyose, for spraying and / or soaking treatment of pineapples to effectively control pineapple black heart disease. Experiments have shown that treatment with sucrose, maltose, or raffinose alone or in combination significantly reduces the incidence and severity index of pineapple black heart disease, with the sugar solution obtained from the combination of sucrose, maltose, raffinose, and stachyose exhibiting the best control effect. Endogenous hormone analysis shows that the above sugar solution treatment can regulate the level of endogenous hormones in pineapple pulp, suggesting that it exerts its control effect by regulating the hormonal balance of the fruit. The method provided by this invention offers a novel solution for the control of pineapple black heart disease, effectively reducing losses caused by this disease. Attached Figure Description

[0031] Figure 1 The figure shows the effect of preharvest sucrose solution spraying on the control of black heart disease in pineapples. Figure 1 In the figure, A represents the bar chart showing the change in the incidence of black heart disease in pineapples over time; Figure 1 B in the figure represents the bar chart showing the change of the pineapple black heart disease severity index over time.

[0032] Figure 2 The images show the effects of postharvest sucrose and fructose immersion treatments on the control of postharvest black heart disease in pineapples. Figure 2 A in the diagram represents the appearance of black heart disease in pineapples during storage; Figure 2 B in the figure represents the bar chart showing the change in the incidence of black heart disease in pineapples over time. Figure 2C in the figure represents the bar chart showing the change of the pineapple black heart disease severity index over time.

[0033] Figure 3 The diagram shows the effect of spraying pre-harvest sucrose aqueous solution and sucrose and maltose compound aqueous solution on the control of post-harvest black heart disease in pineapples.

[0034] Figure 4 A comparative graph showing the effects of post-harvest soaking in different compound sugar solutions on the control of black heart disease in pineapples.

[0035] Figure 5 The graph shows the effects of postharvest soaking in sucrose and fructose solutions on the levels of endogenous hormones in pineapple. Figure 5 In the diagram, A represents the content of abscisic acid (ABA). Figure 5 B in the figure represents the content of abscisic acid glucoside (ABA-GE); Figure 5 The C in the figure represents the content of indole-3-carboxaldehyde (ICAld); Figure 5 D in the text stands for gibberellin A. 19 (GA) 19 Content chart; Figure 5 The figure shows the content of 12-oxophytic dienoic acid (OPDA) in the graph. Figure 5 F in the figure represents the content of salicylic acid (SA); Figure 5 G in the figure represents the content of jasmonic acid (JA); Figure 5 The H in the figure represents the content of jasmonic acid analogues (JA-like). Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0037] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0038] The sources of the carbohydrates used in this invention are as follows: Sucrose: Purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., product number S112228; Maltose: Purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., product number M104815; Raffinose: Purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., product number R413236; Stachyose: Purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., product number S353428; Fructose: Purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., product number F108331; Chitosan: Purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., product number C1516213; In this invention, the incidence and disease index of black heart disease in pineapples were observed using the following methods: During pineapple storage, the pineapple fruit was periodically cut along its longitudinal central axis, and photographs were taken of the cross-sections. Image analysis software (ImageJ 1.8.0) was used to determine the percentage of the cross-section area affected by black heart disease. Based on the percentage of black heart disease area, the severity of black heart disease in the pineapple flesh was classified into 5 levels, from 0 to 5. Level 0: Area with black heart disease <5%; Level 1: Black heart disease covers an area ≥5% and <25% of the surface area; Level 2: Black heart disease covers an area ≥25% and <50%; Level 3: Black heart disease covers an area ≥50% and <75%; Level 4: Black heart disease covers an area ≥75% and <100%; Level 5: 100% of the surface area is blackened (entirely blackened). Black heart disease incidence rate = number of fruits with black heart disease / total number of fruits; Disease index = Σ(level × number of fruits of the corresponding level) / total number of fruits.

[0039] The incidence rate method uses only a binary judgment based on whether the fruit shows signs of black heart disease, merely distinguishing between the presence or absence of the disease and failing to quantify the severity of black heart disease. The disease severity index, on the other hand, uses a graded weighting system to consider both the incidence and severity of black heart disease, exhibiting higher resolution and stability, and more objectively measuring the control effectiveness of each treatment. Therefore, this invention uses the disease severity index as the primary evaluation indicator.

[0040] According to the above grading standards, the disease index is equal to the weighted average of the black heart disease grades of each fruit in the tested fruit population. Specifically, a disease index of 3.0 corresponds to an average black heart disease grade of exactly 3 for the population, meaning the black heart disease area accounts for ≥50% and <75% of the total longitudinal section area. A disease index below 3.0 indicates an average black heart disease grade below 3, meaning the black heart disease area does not exceed 50% of the total longitudinal section area in a statistically average sense; conversely, a disease index above 3.0 indicates an average black heart disease grade above 3. Similarly, a disease index of 2.0 corresponds to an average black heart disease grade of exactly 2, meaning the black heart disease area accounts for ≥25% and <50% of the total longitudinal section area. A disease index below 2.0 indicates an average black heart disease grade below 2, meaning the black heart disease area does not exceed 25% of the total longitudinal section area; conversely, a disease index above 2.0 indicates an average black heart disease grade above 2. In summary, the lower the disease index, the lower the average black heart disease grade of the tested fruit population, and the milder the disease severity.

[0041] The pineapple variety used in this invention is "Bali" ( Ananas comosus (L.) Merr. cv. Comte de Paris), grown in Zhanjiang City, Guangdong Province, is harvested at 7-8 maturity (green ripening stage, at which time the fruit is plump, the bloom has fallen off, the suture of about 1 / 4 of the fruit at the base of the fruit shows a slight pale yellow, the skin color is mainly green, and the flesh begins to change from white to light yellow).

[0042] In this invention, each treatment group has 3 replicates, each replicate has 100 fruits, for a total of 300 fruits.

[0043] Example 1: Effect of pre-harvest sucrose spraying on the control of black heart disease in pineapples In this embodiment, sucrose was used as the active ingredient and sprayed onto pineapple fruits in the field before harvest to evaluate its control effect on pineapple black heart disease.

[0044] Forty-eight hours prior to harvest, at 7:00 AM, pineapple fruits in the field were sprayed with a solution. The treatment group received a spray concentration of 300 mmol·L⁻¹. -1 The amount of sucrose solution sprayed should be such that the surface of the pineapple fruit and the crown buds are evenly covered with the sucrose solution (the surface is moist, the same below), and it is called "sucrose treatment group A".

[0045] After harvesting, the pineapples were packaged in polyethylene (PE) bags and stored in a warehouse at 20°C. Samples were taken periodically starting from day 0 of storage, and the incidence and severity index of black heart disease were recorded according to the aforementioned grading standards. The observation period was 15 days, with observations every 3 days.

[0046] Example 2: Effect of postharvest sucrose spraying on the control of black heart disease in pineapples In this embodiment, sucrose was used as the active ingredient and sprayed onto pineapple fruits after harvest to evaluate its effect on the control of pineapple black heart disease.

[0047] Apply at a concentration of 50 mmol·L⁻¹ 12 hours after pineapple harvest. -1 A sucrose aqueous solution was sprayed onto pineapple fruits. The amount of sucrose solution was sprayed until the surface of the pineapple fruits and the crown buds were evenly covered with the sucrose solution. This was designated as "sucrose treatment group B".

[0048] After drying, the samples were packaged in polyethylene (PE) bags and stored in a warehouse at 20°C. Samples were taken periodically starting from day 0 of storage, and the incidence and severity index of black heart disease were recorded according to the aforementioned grading standards. The observation period was 15 days, with observations every 3 days.

[0049] Example 3: Effect of postharvest maltose spraying on the control of black heart disease in pineapples The difference from Example 2 is that 50 mmol·L⁻¹ was used. -1Maltose aqueous solution replaces 50 mmol·L -1 A sucrose aqueous solution was sprayed on the treatment, with other conditions and steps remaining unchanged, and this group was designated as the "maltose treatment group".

[0050] Example 4: Effect of postharvest raffinose spraying on the control of black heart disease in pineapples The difference from Example 2 is that 50 mmol·L⁻¹ was used. -1 50 mmol·L⁻¹ raffinose aqueous solution replaced -1 A sucrose aqueous solution was sprayed on the treatment, with other conditions and steps remaining unchanged, and this group was designated as the "raffinose treatment group".

[0051] Example 5: Effect of postharvest sucrose soaking treatment on the control of black heart disease in pineapples In this embodiment, sucrose was used as the active ingredient. After harvesting, pineapple fruits were soaked in the solution to evaluate its effect on the control of pineapple black heart disease.

[0052] Apply at a concentration of 100 mmol·L⁻¹ for 48 hours after pineapple harvest. -1 Pineapple fruits were soaked in a sucrose aqueous solution for 10 minutes, and this treatment was designated as "sucrose treatment group C".

[0053] After drying, the samples were packaged in polyethylene (PE) bags and stored in a warehouse at 15°C. Starting from day 0 of storage, the incidence and severity index of black heart disease were recorded according to the aforementioned grading standards, and the observation period lasted for 18 days, with observations every 6 days.

[0054] Example 6: Effect of pre-harvest sucrose and maltose compound spray treatment on the control of black heart disease in pineapples. In this embodiment, a combination of sucrose and maltose was used as the active ingredient. The mixture was sprayed onto pineapple fruits in the field before harvest to evaluate its effect on the control of pineapple black heart disease.

[0055] 24 hours before harvest, at 5 PM, use a solution containing 100 mmol·L⁻¹ -1 Sucrose and 100 mmol·L -1 A compound aqueous solution of maltose (i.e., the mass ratio of sucrose, maltose and water in the compound aqueous solution is 1:1:29) was sprayed onto pineapple fruits in the field. The amount of spraying was determined by evenly covering the surface of the pineapple fruit and the crown with the sugar solution, and it was recorded as "sucrose and maltose compound aqueous solution treatment group".

[0056] After harvesting the pineapples, they were packaged in polyethylene (PE) bags and stored in a warehouse at 11 ℃. Starting from day 0 of storage, samples were taken periodically, and the incidence and severity index of black heart disease were recorded according to the aforementioned grading standards. The observation period was 30 days, with observations every 6 days.

[0057] Example 7: Effect of pre-harvest sucrose spraying on the control of black heart disease in pineapples The difference from Example 6 is that 200 mmol·L⁻¹ was used. -1 The substitute for sucrose aqueous solution contains 100 mmol·L -1 Sucrose and 100 mmol·L -1 A maltose-based aqueous solution was sprayed on the affected area, with all other conditions and steps remaining unchanged. This treatment was designated as "sucrose treatment group D".

[0058] Example 8: Effect of postharvest soaking treatment with a compound of sucrose, maltose, raffinose, and stachyose on the control of black heart disease in pineapples. In this embodiment, a compound of sucrose, maltose, raffinose, and stachyose was used as the active ingredient. After harvesting, the pineapple fruit was soaked in the solution to evaluate its effect on the control of pineapple black heart disease.

[0059] The formula for the compound sugar solution is as follows: 1.5 parts by mass of sucrose, 0.5 parts by mass of maltose, 1 part by mass of raffinose, and 1 part by mass of stachyose, added to 96 parts by mass of water (i.e., the concentration of sucrose in the compound sugar solution is 45.6 mmol / L, the concentration of maltose in the compound sugar solution is 15.2 mmol / L, the concentration of raffinose in the compound sugar solution is 20.6 mmol / L, and the concentration of stachyose in the compound sugar solution is 15.6 mmol / L), and thoroughly dissolved and mixed.

[0060] Twenty-four hours after pineapple harvest, the fruits were soaked in the above sugar solution for 15 minutes, and this group was designated as “Compound Sugar Solution A Treatment Group”.

[0061] After drying, the samples were packaged in polyethylene (PE) bags and stored in a warehouse at 11 ℃. Samples were taken periodically starting from day 0 of storage, and the incidence and severity index of black heart disease were recorded according to the aforementioned grading standards. The observation period was 25 days, with observations every 6 days.

[0062] Comparative Example 1: The effect of pre-harvest water spraying on the control of black heart disease in pineapples. The difference from Example 1 is that an equal amount of water was used instead of sucrose solution, while other conditions and steps remained the same. This was designated as "blank control group A".

[0063] Comparative Example 2: The effect of postharvest stachyose spraying on the control of black heart disease in pineapples. The difference from Example 2 is that 50 mmol·L⁻¹ was used. -1 Stachyose aqueous solution replaces 50 mmol·L -1 A sucrose aqueous solution was sprayed on the treatment, with other conditions and steps remaining unchanged, and this group was designated as the "stachyose treatment group".

[0064] Comparative Example 3: Effect of post-harvest sugar spraying on the control of black heart disease in pineapples The difference from Example 2 is that 50 mmol·L⁻¹ was used. -1 Fructose aqueous solution replaces 50 mmol·L -1 A sucrose aqueous solution was sprayed on the affected area, with all other conditions and steps remaining unchanged. This group was designated as "fructose treatment group A".

[0065] Comparative Example 4: The effect of postharvest chitosan spraying on the control of black heart disease in pineapples. 2% (w / v) chitosan is a recognized effective coating concentration for chitosan, therefore this concentration was selected for this comparative example.

[0066] The difference from Example 2 is that a 2% w / v chitosan dispersion was used instead of 50 mmol·L⁻¹. -1 A sucrose aqueous solution was sprayed on the chitosan treatment group, with other conditions and steps remaining unchanged.

[0067] Comparative Example 5: The effect of postharvest water spraying on the control of black heart disease in pineapples. The difference from Example 2 is that an equal mass of clean water was used instead of sucrose aqueous solution for spraying treatment, while other conditions and steps remained unchanged. This was designated as "blank control group B".

[0068] Comparative Example 6: Effect of post-harvest fructose soaking treatment on the control of black heart disease in pineapples The difference from Example 5 is that 100 mmol·L⁻¹ was used. -1 Fructose aqueous solution replaces 100 mmol·L -1 The fructose group was soaked in a sucrose aqueous solution, with other conditions and steps remaining unchanged. This group was designated as "Fructose Treatment Group B".

[0069] Comparative Example 7: The effect of postharvest water soaking treatment on the control of black heart disease in pineapples. The difference from Example 5 is that water was used instead of 100 mmol·L⁻¹ -1 The sucrose aqueous solution was used for soaking treatment, with other conditions and steps remaining unchanged, and this was recorded as "blank control group C".

[0070] Comparative Example 8: The effect of pre-harvest water spraying on the control of black heart disease in pineapples. The difference from Example 6 is that an equal mass of pure water was used instead of the solution containing 100 mmol·L⁻¹. -1 Sucrose and 100 mmol·L -1 A maltose-based aqueous solution was sprayed on the sample, with all other conditions and steps remaining unchanged. This treatment was designated as "blank control group D".

[0071] Comparative Example 9: The effect of postharvest soaking treatment with a combination of chitosan, maltose, raffinose, and stachyose on the control of black heart disease in pineapples. The difference from Example 8 is that the sucrose in the compound sugar solution A formula is replaced with an equal mass of chitosan, while other conditions and steps remain unchanged. This is referred to as "compound sugar dispersion treatment group B".

[0072] Comparative Example 10: The effect of post-harvest water soaking treatment on the control of black heart disease in pineapples. The difference from Example 8 is that water was used instead of compound sugar solution A for soaking treatment, while other conditions and steps remained the same, and this was designated as "blank control group E".

[0073] Results Statistics 1: Comparison of the prevention and control effects of Example 1 and Comparative Example 1 The experimental results of pre-harvest spraying treatment in Example 1 and Comparative Example 1 were summarized and compared.

[0074] Experimental results are as follows Figure 1 As shown in Table 1, compared with the blank control group, the pre-harvest sucrose aqueous solution spraying treatment significantly reduced the incidence and disease index of black heart disease in pineapples during storage.

[0075] Table 1. Results of black heart disease in pineapples on day 15 of storage.

[0076] Note: Different letters indicate significant differences between different treatments (p≤0.05).

[0077] Depend on Figure 1 As shown in Figure A, regarding the incidence rate, on day 9 of storage, the proportion of pineapples with black heart disease in the blank control group A reached 30%, while the pineapples in the sucrose treatment group A showed no disease, with an incidence rate of 0%, achieving a 100% control rate for black heart disease. By day 12 of storage, the proportion of pineapples with black heart disease in the blank control group A reached 66.0%, while the proportion in the sucrose treatment group A was only 30%, a decrease of 36%. By day 15 of storage, the proportion of pineapples with black heart disease in the blank control group A reached 94.0%, while the proportion in the sucrose treatment group A was 66.0%, a decrease of 28%. From Table 1 and Figure 1As shown in Figure B, regarding the disease index, on day 15 of storage, the disease index of the sucrose treatment group A (2.8) was significantly lower than that of the blank control group A (4.0). Throughout the storage period, the disease index of the sucrose treatment group A was kept below 3.0. According to the grading standard, a disease index of 3.0 corresponds to an average grade 3 (black heart disease area ≥50% and <75%). The average black heart disease grade of the sucrose treatment group A was suppressed to below grade 3, meaning the average black heart area was less than 50%. Compared with the blank control group, this prevented the complete loss of commercial value of the fruit due to large-scale black heart necrosis (black heart area >50%).

[0078] In conclusion, pre-harvest sucrose spraying can effectively control pineapple black heart disease.

[0079] Results 2: Comparison of the prevention and control effects of Examples 2-4 and Comparative Examples 2-5 The experimental results of postharvest spraying treatment in Examples 2 to 4 and Comparative Examples 2 to 5 were summarized and compared.

[0080] The experimental results are shown in Table 2.

[0081] Table 2. Results of black heart disease in pineapples on day 15 of storage.

[0082] Note: Different letters indicate significant differences between different treatments (p≤0.05).

[0083] As shown in Table 2, there are significant differences in the control effects of different sugar solution spraying treatments on pineapple black heart disease.

[0084] Regarding the incidence rate, on day 15 of storage, the proportion of pineapples with black heart disease in the blank control group B (incidence rate of black heart disease) reached 92%; the proportion in the chitosan treatment group was 88%; the proportion in the stachyose treatment group was 80%; and the proportion in the fructose treatment group A was even as high as 100%, significantly higher than that in the blank control group B. In contrast, the proportion of pineapples with black heart disease in the sucrose treatment group B was 64%, the proportion in the maltose treatment group was 68%, and the proportion in the raffinose treatment group was 70%.

[0085] Regarding the disease index, the variation pattern of the disease index was consistent with the incidence rate. The disease index of sucrose treatment group B was 1.9; the disease index of maltose treatment group was 2.1; and the disease index of raffinose treatment group was 2.6, all significantly lower than the disease index of blank control group B (4.2), chitosan treatment group (4.0), stachyose treatment group (3.3), and fructose treatment group A (4.4). Throughout the storage period, the disease index of sucrose treatment group B, maltose treatment group, and raffinose treatment group was consistently controlled below 3.0. According to the grading standard, a disease index of 3.0 corresponds to an average grade 3 (black heart disease area ≥50% and <75%), indicating that the average black heart disease grade of the above treatment groups was suppressed to below grade 3, that is, the average black heart area was less than 50%, thus avoiding the complete loss of commercial value of the fruit due to large-scale black heart necrosis.

[0086] In summary, sucrose, maltose, and raffinose, when applied individually, can significantly reduce the incidence of black heart disease in pineapples, with sucrose and maltose showing the best effects. Fructose treatment, on the other hand, exacerbates the disease, while chitosan or stachyose treatments have limited effect on controlling black heart disease.

[0087] Results Statistics 3: Comparison of the prevention and control effects of Example 5, Comparative Example 6, and Comparative Example 7 The experimental results of post-harvest soaking treatment in Example 5, Comparative Example 6, and Comparative Example 7 were summarized and compared.

[0088] Experimental results are as follows Figure 2 As shown in Table 3, postharvest sucrose aqueous solution soaking treatment significantly reduced the incidence and disease index of black heart disease in pineapples during storage, while fructose treatment showed the opposite promoting effect.

[0089] Table 3. Incidence of black heart disease in pineapples on days 12 and 18 of storage.

[0090] Note: Different letters indicate significant differences between different treatments (p≤0.05).

[0091] As shown in Table 3, regarding the incidence rate, on day 12 of storage, the proportion of pineapples with black heart disease in the blank control group C was 78%, the proportion in the sucrose treatment group C was only 62%, and the proportion in the fructose treatment group B was 90%. By day 18 of storage, the proportion of pineapples with black heart disease in all three groups reached 100%. Regarding the disease index, on day 12 of storage, the black heart disease disease index of the blank control group C was 1.1, that of the sucrose treatment group C was 0.9, and that of the fructose treatment group B was 1.6. On day 18 of storage, although the incidence rate in all three groups reached 100%, the black heart disease disease index of the sucrose treatment group C was 1.9, significantly lower than that of the blank control group C (2.9) and the fructose treatment group B (3.0). This indicates that although black heart disease had occurred in all three groups by day 18 of storage, the sucrose treatment group C significantly reduced the severity of the disease. According to the grading standard, a disease index of 2.0 corresponds to an average grade 2 (black heart disease area ≥25% and <50%), indicating that the average black heart disease grade in the sucrose treatment group C was suppressed to below grade 2, meaning the average black heart area was less than 25%, thus preventing the fruit from completely losing its commercial value due to large-scale black heart necrosis.

[0092] In addition, by Figure 2 It is evident that the pineapple crown buds in sucrose treatment group C remained bright green, indicating that sucrose treatment had no negative impact on the appearance of the fruit while achieving the desired control effect.

[0093] In conclusion, sucrose soaking treatment can significantly control pineapple black heart disease, while fructose treatment exacerbates the disease.

[0094] Results Statistical Analysis 4: Comparison of the prevention and control effects of Examples 6, 7 and Comparative Example 8 The experimental results of pre-harvest spraying treatment in Examples 6, 7 and 8 were summarized and compared.

[0095] Experimental results are as follows Figure 3 And as shown in Table 4.

[0096] Table 4. Results of black heart disease incidence in pineapples on day 30 of storage.

[0097] Note: Different letters indicate significant differences between different treatments (p≤0.05).

[0098] As shown in Table 4, compared with the blank control group D, the pre-harvest sucrose spraying treatment and the pre-harvest spraying treatment with a mixture of sucrose and maltose reduced the incidence and disease index of black heart disease in pineapples during storage.

[0099] Regarding the incidence of black heart disease: On day 30 of storage, the proportion of pineapples with black heart disease in the blank control group D reached 100% (incidence rate of black heart disease); while the proportion of pineapples with black heart disease in the sucrose treatment group D was 80% (incidence rate of black heart disease), a decrease of 20%; and the proportion of pineapples with black heart disease in the sucrose and maltose compound treatment group was only 66% (incidence rate of black heart disease), a decrease of 34%; Regarding the black heart disease disease index: on day 30 of storage, the disease index of the blank control group D was 4.0, the disease index of the sucrose treatment group D was 2.8, and the disease index of the sucrose and maltose compound treatment group was 1.7. According to the grading standard, a disease index of 3.0 corresponds to an average grade 3 (black heart disease area ≥50% and <75%), and 2.0 corresponds to an average grade 2 (black heart disease area ≥25% and <50%). The disease index (2.8) of the sucrose treatment group D was lower than 3.0, indicating that its average black heart disease grade was suppressed to below grade 3, that is, the average black heart area was less than 50%; while the disease index (1.7) of the sucrose and maltose compound treatment group was even lower than 2.0, indicating that its average black heart disease grade was suppressed to below grade 2, that is, the average black heart area was less than 25%, thus avoiding the complete loss of commercial value of the fruit due to large-scale black heart necrosis. The above results indicate that the combined treatment of sucrose and maltose has a better control effect on black heart disease than the single sucrose treatment.

[0100] In addition, by Figure 3 It is evident that the pineapple crown buds in sucrose treatment group D and the sucrose and maltose compound treatment group remained fresh green, indicating that sucrose treatment had no negative impact on the appearance of the fruit while exerting its control effect.

[0101] In conclusion, both pre-harvest sucrose spraying and sucrose and maltose combined spraying can effectively control pineapple black heart disease.

[0102] Results Statistics 5: Comparison of the prevention and control effects of Example 8, Comparative Example 9, and Comparative Example 10 The experimental results of Example 8, Comparative Example 9, and Comparative Example 10 were summarized and compared.

[0103] Experimental results are as follows Figure 4 As shown in Table 5.

[0104] Table 5. Results of black heart disease incidence in pineapples on day 25 of storage.

[0105] Note: Different letters indicate significant differences between different treatments (p≤0.05).

[0106] As shown in Table 5, there are significant differences in the control effects of different compound sugar solutions on black heart disease in pineapples after harvest.

[0107] Regarding the incidence of black heart disease: On day 15 of storage, the proportion of pineapples with black heart disease in the blank control group E reached 60%, the proportion of pineapples with black heart disease in the compound sugar dispersion treatment group B also reached 40%, and the proportion of pineapples with black heart disease in the compound sugar solution A treatment group was only 10%, with the incidence rate decreasing by 50% compared to the blank control group E; On day 25 of storage, the incidence rate in the blank control group E reached 100%, the incidence rate in the compound sugar dispersion treatment group B was 86%, and the incidence rate in the compound sugar solution A treatment group was only 64%, with the incidence rate decreasing by 36% compared to the blank control group E.

[0108] Regarding the black heart disease severity index: on day 25 of storage, the severity index of the blank control group E was 4.3, the severity index of the compound sugar dispersion treatment group B was 3.0, and the severity index of the compound sugar solution treatment group A was 1.6. According to the grading standard, a severity index of 3.0 corresponds to an average grade 3 (black heart disease area ≥50% and <75%), and 2.0 corresponds to an average grade 2 (black heart disease area ≥25% and <50%). The severity index of the compound sugar solution treatment group A (1.6) is lower than 2.0, meaning that the average black heart area is less than 25%, thus avoiding the complete loss of commercial value of the fruit due to large-scale black heart necrosis.

[0109] In addition, by Figure 4 It is evident that the pineapple crown buds in the compound sugar solution A treatment group remained bright green, indicating that it had no negative impact on the appearance of the fruit while exerting a control effect.

[0110] The above results indicate that the compound solution of sucrose, maltose, raffinose, and stachyose has a synergistic effect and can effectively control pineapple black heart disease. However, when sucrose is replaced with chitosan, the control effect is significantly reduced and the overall control effect is poor, indicating that sucrose plays a key role in this compound system.

[0111] Experiment 1: Regulation of endogenous plant hormone levels in pineapple pulp by exogenous sugar treatment This experiment explores the mechanism of exogenous sugar treatment in preventing black heart disease in pineapples from the perspective of endogenous hormone regulation, and analyzes its regulatory effect on the fruit's hormone metabolism network.

[0112] 1. Experimental Methods Experimental samples: Fruit samples from Example 5 (sucrose treatment group C) and Comparative Example 6 (fructose treatment group B) stored for 12 days were taken, with fruit samples from Comparative Example 7 (blank control group C) as controls.

[0113] Determination of abscisic acid (ABA), abscisic acid glucose ester (ABA-GE), indole-3-carboxaldehyde (ICAld), and gibberellin A in the sample 19 (GA) 19The content of eight hormones, including 12-oxophytic dienoic acid (OPDA), salicylic acid (SA), jasmonic acid (JA), and jasmonic acid analogues (JA-like).

[0114] 2. Experimental Results Experimental results are as follows Figure 5 And as shown in Table 6.

[0115] Table 6. Effects of different sugar solution soaking treatments on the endogenous hormone content of pineapple (ng / g)

[0116] Note: "*" indicates a significant difference between the treatment group and the control group (p≤0.05); "**" indicates an extremely significant difference (p≤0.01).

[0117] Compared with the blank control group C, the pineapples in the fructose-treated group B showed significantly increased levels of ABA, ABA-GE, and ICA1d (p≤0.05), extremely significantly increased levels of OPDA and SA (p≤0.01), and significantly increased levels of JA (p≤0.05), while GA... 19 There were no significant changes compared to JA-like; Pineapple in sucrose treatment group C, GA 19 The contents of JA and JA-like were significantly or extremely significantly decreased (p≤0.05 or p≤0.01), while OPDA and SA were extremely significantly increased (p≤0.01), and ABA, ABA-GE, and ICA1d showed no significant changes. The aforementioned hormonal changes correlated consistently with the severity of black heart disease: fructose treatment exacerbated the disease, while sucrose treatment alleviated it. This result indicates that different sugars can influence the occurrence and development of black heart disease by differentially regulating the endogenous hormone levels in pineapple pulp.

[0118] The above results indicate that sugars such as sucrose, maltose, and raffinose do not simply provide nutrition, but rather act as signaling molecules for plant growth regulation. They differentially regulate the hormone metabolism network through chemical means, thereby controlling black heart disease, a physiological disorder.

[0119] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for controlling black heart disease in pineapples, characterized in that, Pineapples can be sprayed and / or soaked with an aqueous solution of sugars or a combination of sugars and stachyose. The concentration of the aqueous solution of the carbohydrate, or the aqueous solution of a combination of carbohydrate and stachyose, is 50-300 mmol·L. -1 ; The sugar is selected from at least one of sucrose, maltose, and raffinose.

2. The method as described in claim 1, characterized in that, The aqueous solution of the carbohydrate, or the aqueous solution of a combination of carbohydrate and stachyose, satisfies at least one of the following conditions: (1) The sugars are composed of sucrose and maltose, and the mass ratio of sucrose to maltose is 1:(0.5~3). (2) The sugars are composed of sucrose, maltose and raffinose, and the mass ratio of sucrose, maltose and raffinose is 1.5:(0.2~1):(0.5~3). (3) The mass ratio of the sugars to stachyose is 3: (0.5~3).

3. The method as described in claim 1, characterized in that, The spraying treatment is to be applied 12 to 72 hours before harvest and / or 12 to 72 hours after harvest.

4. The method as described in claim 1, characterized in that, The soaking treatment time is 12 to 72 hours after harvesting.

5. The method as described in claim 1, characterized in that, The spraying involves applying an aqueous solution of sugars, or an aqueous solution of a combination of sugars and stachyose, to the surface of the pineapple fruit and its crown buds.

6. The method as described in claim 1, characterized in that, The soaking time is 10-15 minutes.

7. The method as described in claim 1, characterized in that, The pineapple is in its green-ripe stage.

8. The method as described in claim 1, characterized in that, The pineapple variety mentioned is Bali.

9. The application of sugars or a combination of sugars and stachyose in the preparation of agents for controlling black heart disease in pineapples, characterized in that, The sugar is selected from at least one of sucrose, maltose, and raffinose; The formulation is an aqueous solution of the sugar substance, or an aqueous solution of the combination of the sugar substance and stachyose, with a concentration of 50-300 mmol·L. -1 .

10. The application as described in claim 9, characterized in that, The sugar substance or the combination of sugar substance and stachyose must satisfy at least one of the following conditions: (1) The sugars are composed of sucrose and maltose, and the mass ratio of sucrose to maltose is 1:(0.5~3). (2) The sugars are composed of sucrose, maltose and raffinose, and the mass ratio of sucrose, maltose and raffinose is 1.5:(0.2~1):(0.5~3). (3) The mass ratio of the sugars to stachyose is 3: (0.5~3).

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