Method for breaking dormancy of winter buds of kiwi fruits and promoting germination

Abstract

The invention belongs to the technical field of plant biology, and particularly relates to a method for breaking dormancy of winter buds of kiwi fruits and promoting germination. The method comprises the following steps: S1, collecting annual kiwi fruit bearing branches meeting a preset cold demand condition after the field air temperature is lower than 7 DEG C for continuous 3 days; s2, carrying out surface disinfection treatment on the collected fruiting branches; s3, smearing or spraying a dormancy breaking agent on bud points on the fruiting branches treated in the step S2; and S4, placing the base parts of the bearing branches treated in the step S3 under a water culture condition, and culturing under the conditions that the temperature is 20-25 DEG C and the light-dark period is 12 hours until winter buds germinate. According to the method for breaking dormancy of winter buds of kiwi fruits and promoting germination, the period is remarkably shortened; according to the method disclosed by the invention, branch collection meeting partial cold demand is combined with efficient dormancy breaking agent treatment, and an optimal dormancy breaking starting condition is created.

Description

Technical Field

[0001] This invention belongs to the field of plant biotechnology, and in particular relates to a method for breaking the dormancy of winter buds in kiwifruit and promoting germination. Background Technology

[0002] kiwi( Actinidia Kiwifruit (spp.) is an important temperate deciduous fruit tree with a significant dormancy characteristic. During winter, kiwifruit winter buds enter a deep dormancy state. This dormancy is an adaptation of the plant to unfavorable environments, but it also becomes a significant limiting factor for greenhouse cultivation, early market entry, and genetic breeding research. To achieve early and uniform bud sprouting, physical or chemical methods are often used in production to break dormancy.

[0003] Currently, the most commonly used physical method is the low-temperature accumulation method, which involves natural overwintering or artificial cold storage to meet the chilling requirement of the buds. However, this method is time-consuming. For example, the 'Guichang' kiwifruit variety requires a long period of accumulated low temperatures under natural conditions to effectively break dormancy, which seriously affects the advance and flexibility of production. Chemical dormancy-breaking methods mainly rely on dormancy-breaking agents such as cyanamide (HC) and gibberellin (GA). However, in existing technologies, the application of chemical dormancy-breaking agents is often rather crude, lacking synergistic optimization with the specific chilling requirement of the variety, precise timing of treatment, and supporting management measures. This leads to unstable dormancy-breaking effects, low or uneven germination rates, and may even cause phytotoxicity.

[0004] Therefore, developing an efficient, stable, and controllable method for breaking the dormancy of kiwifruit winter buds, which will significantly shorten the dormancy period, is of great significance for promoting the intensive and facility-based development of the kiwifruit industry and accelerating the breeding process. Summary of the Invention

[0005] The main objective of this invention is to provide a method for breaking the dormancy of winter buds in kiwifruit and promoting germination, thereby overcoming the shortcomings of the prior art.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes: According to a first aspect of the present invention, a method for breaking the dormancy of winter buds of kiwifruit and promoting germination is provided, comprising the following steps: S1. After the field temperature is below 7°C for three consecutive days, collect one-year-old kiwifruit fruiting branches that meet the predetermined chilling requirements; S2. Perform surface disinfection treatment on the collected result branches; S3. Apply or spray a dormancy-breaking agent to the buds on the resulting branches after step S2 treatment; S4. Place the base of the resulting branch after step S3 in a hydroponic environment and cultivate it at 20℃-25℃ with a light-dark cycle of 12 hours until the winter buds sprout.

[0007] Furthermore, in step S1, meeting the predetermined cooling requirement means that the field temperature is below 7°C for three consecutive days, followed by a month of data collection.

[0008] Furthermore, the predetermined cooling demand is estimated using the Utah model, with a cumulative cooling demand of 300 cooling units.

[0009] Furthermore, in step S1, the length of the one-year-old kiwifruit fruiting branch is 50-60 cm, and each branch has 6-8 plump buds.

[0010] Furthermore, in step S2, the disinfection process involves soaking the branches in a carbendazim solution diluted 400-600 times for 8-12 minutes, then rinsing them with ultrapure water and air-drying them.

[0011] Furthermore, the carbendazim solution is diluted 500 times and the soaking time is 10 minutes.

[0012] Furthermore, in step S3, the somnolence-disrupting agent is a cyanamide solution or a 5-ALA (5-aminolevulinic acid) solution.

[0013] Furthermore, the dilution factor of the cyanamide solution is 10-20 times.

[0014] Furthermore, the dilution factor of the cyanamide solution is 20 times.

[0015] According to a second aspect of the present invention, the method of breaking the dormancy of winter buds of kiwifruit and promoting germination as described above is provided for use in early forcing cultivation or breeding experiments.

[0016] Compared with the prior art, the advantages of the present invention include: This invention provides a method for breaking the dormancy of winter buds in kiwifruit and promoting germination, significantly shortening the cycle: This method combines the collection of branches that meet a partial chilling requirement (approximately 300 U) with treatment with a highly effective dormancy-breaking agent, creating optimal conditions for initiating dormancy breaking. Compared to waiting for the natural chilling requirement to be fully met, or simply relying on longer periods of low-temperature treatment, this method allows germination to begin approximately 14 days after branch collection. The total cycle from branch collection to germination is as short as approximately 26.5 days, 14 days shorter than the natural process and nearly 20 days shorter than the fastest method using only low-temperature treatment. By precisely defining the chilling requirement collection point and using a specific concentration of the dormancy-breaking agent, this method achieves repeatable and stable dormancy-breaking effects. Examples show that treatment with 20-fold diluted cyanamide achieves a germination rate of 47.37%, with concentrated germination time. In contrast, the water control or low-dose treatment results in delayed germination, low germination rates, or uneven germination. Furthermore, the method of this invention has clear steps and well-defined parameters, making it easy to standardize and apply in production and research. After collecting branches that have accumulated low temperatures in the field, indoor treatment is carried out, avoiding complete reliance on uncontrollable natural climate or expensive long-term cold storage equipment, providing a flexible and efficient solution for facility cultivation and laboratory research. Attached Figure Description

[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 These are germination images of different processing groups at each stage in a typical embodiment of the present invention; Figure 2 This is the final germination image of each processing group in a typical embodiment of the present invention; Figure 3 This is the germination rate of different treatment groups at each stage in a typical embodiment of the present invention; Figure 4 This is the final germination rate of each treatment group in a typical embodiment of the present invention; Figure 5 This refers to the germination rate achieved by low-temperature treatment in a typical embodiment of the present invention. Detailed Implementation

[0018] In view of the shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate this technical solution, its implementation process, and its principles.

[0019] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0020] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials used in the following embodiments are commercially available.

[0021] This invention provides a method for breaking the dormancy of winter buds in kiwifruit and promoting germination, comprising the following steps: S1. After the field temperature has been below 7°C for three consecutive days, one-year-old kiwifruit fruiting branches meeting the predetermined chilling requirement are collected. Meeting the predetermined chilling requirement means that the collection takes place one month after the field temperature has been below 7°C for three consecutive days. The predetermined chilling requirement is estimated using the Utah model, with a cumulative chilling requirement of 300 chill units. The one-year-old kiwifruit fruiting branches are 50-60 cm long, and each branch has 6-8 plump buds.

[0022] S2. Perform surface disinfection on the collected fruit branches; the disinfection process is as follows: soak the branches in a carbendazim solution diluted 400-600 times for 8-12 minutes, then rinse them thoroughly with ultrapure water and air dry. The carbendazim solution is diluted 500 times, and the soaking time is 10 minutes.

[0023] S3. Apply or spray a dormancy-breaking agent to the buds on the resulting branches treated in step S2; the dormancy-breaking agent is a cyanamide solution or a 5-ALA (5-aminolevulinic acid) solution. The dilution factor of the cyanamide solution is 10-20 times. Preferably, the dilution factor of the cyanamide solution is 20 times.

[0024] S4. Place the base of the resulting branch after step S3 in a hydroponic environment and cultivate it at 20℃-25℃ with a light-dark cycle of 12 hours until the winter buds sprout.

[0025] In addition, the present invention also provides the use of the method for breaking the dormancy of winter buds of kiwifruit and promoting germination as described in any one of the claims in early forcing cultivation or breeding experiments.

[0026] To better understand the technical solution of the present invention, the following detailed discussion is provided in conjunction with specific embodiments.

[0027] Example 1: Comparison of the effects of the method of the present invention with that of water control Materials Preparation: In the Guiyang area, one-year-old fruiting branches of the 'Guichang' kiwifruit variety were collected one month after the field temperature remained below 7°C for three consecutive days (mid-December). At this time, according to the Utah model, the branch buds had accumulated approximately 300 U of chilling requirement (equivalent to 12.5 days of continuous treatment at 4°C). The selected branches were 50-60 cm in length and had 6-8 plump buds.

[0028] Disinfection treatment: Soak the branches in a 500-fold diluted carbendazim solution for 10 minutes to sterilize the surface, then rinse them three times with ultrapure water and place them in a clean and ventilated place to dry.

[0029] Treatment with hypnotic agents: Experimental group (HC1): Prepare a 20-fold dilution of cyanamide for bud growth. Carefully apply the solution to each plump bud on each branch using a soft brush.

[0030] Control group (CK): Apply an equal amount of water to each bud point using a soft brush.

[0031] Each treatment group had 12 branches, totaling 85 buds.

[0032] Hydroponic cultivation: Insert the base of the treated cuttings into a container filled with a hydroponic nutrient solution diluted 500 times. Place all cuttings in an artificial climate chamber and set the conditions as follows: temperature 20℃-25℃, light / dark cycle of 12 hours of light / 12 hours of darkness.

[0033] Observation and statistics: Observe the changes in bud morphology daily, record the time points of bud break (bud scales cracking and revealing green) and bud emergence (true leaves emerging), and calculate the final budding rate.

[0034] result: like Figure 1 and Figure 3 As shown, in the HC1 group, germination began on day 14, with a final germination rate of 47.37%.

[0035] Group CK: It took 21 days for germination to begin and 28 days for germination to begin, with a final germination rate of 52.5%.

[0036] Analysis: Although the final germination rate of the CK group was slightly higher, its germination initiation time was 14 days later than that of the HC1 group. Looking at the total experimental period, the HC1 group (approximately 26.5 days: 12.5 days of low-temperature equivalent period + 14 days of hydroponics) was a full 14 days shorter than the CK group (40.5 days: 12.5 days of low-temperature equivalent period + 28 days of hydroponics). This indicates that, based on the partial chilling requirement (300 U) set in this invention, applying a 20-fold diluted cyanamide can significantly advance and concentrate the germination initiation time, which is crucial for securing agricultural opportunities or obtaining early experimental materials.

[0037] Example 2: Comparison of treatment effects of different concentrations of cyanamide like Figure 2 and Figure 4 As shown, based on the same materials and disinfection methods as in Example 1, different concentration treatment groups were added: HC2 group: treated with a 10-fold dilution of cyanamide.

[0038] ALA2 group: treated with a 1000-fold dilution of "Kimchon-Aki" (the main active ingredient is 5-ALA, 5-aminolevulinic acid).

[0039] The treatment and cultivation methods are the same as in Example 1.

[0040] result: HC2 group: Germination occurred, with a germination rate of 21.42%, but the effect was inferior to that of HC1 group.

[0041] Group ALA2: Germination began on the 21st day, with a germination rate of 11.32%.

[0042] Conclusion: Under the conditions set by this invention, cyanamide-based somnolence-disrupting agents are more effective; for cyanamide, a 20-fold dilution (HC1) is a better choice than a 10-fold dilution (HC2).

[0043] Comparative example: Simple low-temperature treatment To compare the advantages of the "chemical sedation agent-assisted" method of this invention, a purely physical low-temperature treatment scheme was proposed: Materials: Fruiting branches of the same 'Guichang' kiwifruit variety were collected when the field temperature was below 7℃ for three consecutive days.

[0044] Treatment: No chemical dormancy-breaking agents were used; the branches were directly placed in a 4°C artificial climate chamber for continuous low-temperature treatment. Three treatment durations were set: 12.5 days (300 U), 25.0 days (600 U), and 37.5 days (900 U).

[0045] Cultivation: After each treatment period, the branches were removed, the base was inserted into clean water, and placed in the same greenhouse conditions as in Example 1 (20℃-25℃, light-dark cycle 12h) for hydroponics. The budding situation was recorded weekly.

[0046] The results are as follows Figure 5 As shown: 37.5-day treatment group: Germination began on the 14th day after hydroponics, with a final germination rate of 41.00%. Total cycle: 37.5 days + 14 days = 51.5 days.

[0047] 25.0-day treatment group: Germination began on the 21st day after hydroponics, with a final germination rate of 33.27%. Total cycle: 25.0 days + 21 days = 46 days.

[0048] 12.5-day treatment group: Germination only began on the 28th day after hydroponics, with a germination rate of only 9.78%. Total cycle: 12.5 days + 28 days = 40.5 days.

[0049] Comparative analysis: While simple low-temperature treatment can eventually break dormancy, it has significant drawbacks: ① To achieve good germination results (e.g., germination rate >30%), a longer low-temperature accumulation time (≥25 days) is required; ② Even with a sufficiently long low-temperature treatment time (37.5 days), the total cycle of "low-temperature treatment + hydroponics" (51.5 days) is much longer than the method of this invention (26.5 days); ③ With the same amount of low-temperature accumulation (300 U, i.e., 12.5 days of treatment), the germination time and germination rate of simple low-temperature treatment (40.5 days, 9.78%) are both far inferior to the method of this invention combined with 20 times the amount of cyanamide treatment (26.5 days, 47.37%). This fully demonstrates the superiority of the technical solution of this invention, which combines "partial low-temperature accumulation" with "efficient chemical dormancy breaking".

[0050] Application example: Application in breeding experiments Using the method described in Example 1 (HC1 group), 'Guichang' kiwifruit branches were treated to obtain new shoots that sprouted at the end of December. These materials were immediately used to: extract high-quality total RNA and perform real-time quantitative PCR (qRT-PCR) analysis of genes related to winter dormancy, successfully obtaining gene expression data that would normally be available in March of the following year. Young stem segments were also used as explants for the preparation of genetic transformation recipient materials, advancing the seasonally limited operational window in conventional breeding by more than two months.

[0051] The above descriptions are merely some embodiments of the present invention. It should be noted that those skilled in the art can make other modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A method for breaking the dormancy of winter buds in kiwifruit and promoting germination, characterized in that, Includes the following steps: S1. After the field temperature is below 7°C for three consecutive days, collect one-year-old kiwifruit fruiting branches that meet the predetermined chilling requirements; S2. Perform surface disinfection treatment on the collected result branches; S3. Apply or spray a dormancy-breaking agent to the buds on the resulting branches after step S2 treatment; S4. Place the base of the resulting branch after step S3 in a hydroponic environment and cultivate it at 20℃-25℃ with a light-dark cycle of 12 hours until the winter buds sprout.

2. The method according to claim 1, characterized in that, In step S1, meeting the predetermined cooling requirement means that the field temperature is below 7°C for three consecutive days, followed by a month of data collection.

3. The method according to claim 2, characterized in that, The predetermined cooling demand was estimated using the Utah model, with a cumulative cooling demand of 300 refrigeration units.

4. The method according to claim 1, characterized in that, In step S1, the length of the one-year-old kiwifruit fruiting branch is 50-60 cm, and each branch has 6-8 plump buds.

5. The method according to claim 1, characterized in that, In step S2, the disinfection process is as follows: soak the branches in a carbendazim solution diluted 400-600 times for 8-12 minutes, then rinse them with ultrapure water and air dry.

6. The method according to claim 5, characterized in that, The carbendazim solution was diluted 500 times and the soaking time was 10 minutes.

7. The method according to claim 1, characterized in that, In step S3, the sedative is a cyanamide solution or a 5-ALA solution.

8. The method according to claim 7, characterized in that, The dilution factor of the cyanamide solution is 10-20 times.

9. The method according to claim 8, characterized in that, The cyanamide solution was diluted 20 times.

10. The use of the method for breaking the dormancy of winter buds of kiwifruit and promoting germination as described in any one of claims 1-9 in early forcing cultivation or breeding trials.

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