Rubber tree rootstock seedling juvenile phase maintaining and rapid vegetative propagation method

Abstract

The invention discloses a rubber tree rootstock seedling juvenile phase maintaining and rapid asexual propagation method which comprises the following steps: S1, preparation of juvenile phase seedling rootstock seedlings: after rootstock seeds are sown and grow to at least two leaf canes, cutting wood can be collected; s2, cutting slips of the seedling rootstock seedlings are sheared, when the diameter of the seedling rootstock seedlings is smaller than 0.5 cm, at least one leaf is reserved on the rootstock seedlings, and when the diameter of the seedling rootstock seedlings is larger than or equal to 0.5 cm, no leaf is reserved on the rootstock seedlings; after the branches are sheared, when the newly-grown branches grow at least one canopy, the next round of cutting wood can be collected, and the branches are repeatedly taken for cuttage for multiple times; s3, treating the cutting slips; s4, cutting rooting and seedling formation; s5, transplanting and managing; s6, reusing the Gn-generation seedlings; and S7, utilizing the Gn-generation cutting seedlings. According to the method, the juvenile phase of the rootstock seedlings can be guaranteed, the rootstock seedlings can be rapidly propagated, and dependence of the rootstock seedlings of rubber trees on rubber seeds is greatly reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of plant propagation, and particularly relates to a method for maintaining the juvenile stage and rapid asexual propagation of rubber tree rootstock seedlings. Background Art

[0002] The natural rubber produced by rubber trees ( Hevea brasiliensis ) has good quality and high yield, so it is the main source of natural rubber. At present, the commercial planting materials of rubber trees are mainly propagated by grafting. The rootstocks of rubber grafted trees are derived from the seedlings of certain specific rubber tree varieties. In the conventional production of rubber grafted seedlings, one seedling rootstock can obtain one grafted seedling, and the breeding of rubber grafted seedlings is restricted by the seedling rootstock. The reasons are as follows: (1) The planting areas of rubber tree varieties that produce seeds (such as GT1 and RRIM600 varieties) are decreasing year by year, and the available rootstock seeds are getting fewer and fewer; (2) If the rubber trees encounter diseases or continuous stormy weather during the flowering and fruiting seasons, the seed production will be severely reduced or even no seeds will be harvested; (3) The recalcitrant rubber seeds are not resistant to storage, and the seed vigor rapidly decreases with the extension of time; (4) The rubber rootstock seeds are produced and utilized only once a year to provide seedling rootstocks for the production of grafted seedlings in the next year. If the supply of rubber tree rootstock seeds is insufficient or even the seeds are completely lost in the current year, no rubber tree grafted seedlings can be produced in the next year due to the lack of rootstock seedlings. Therefore, the current production of rubber tree rootstock seedlings extremely depends on rubber tree seeds, which affects the sustainable production of rubber tree seedlings. There is an urgent need in production for an asexual propagation method for rubber tree rootstock seedlings to minimize the dependence on rubber tree rootstock seeds.

[0003] Cutting is the main propagation method for horticultural and forestry crops, and rubber tree rootstock seedlings can be propagated by cutting. Chinese Patent CN108651024B discloses a method for cutting seedlings of rubber trees in the field, and the steps include the establishment of a seedling bed, the preparation and treatment of a seedling substrate, the preparation and treatment of cuttings, cutting, and post-management. The cuttings of rubber tree varieties used in this technical method are in the physiological maturity stage. The plants propagated do not have the juvenile stage traits, and the adventitious roots grown do not have obvious main roots, and the lodging resistance is poor. They are not suitable for cultivation in places with wind damage and are not suitable as rootstocks either. The number of cuttings obtained by this technical method is small and the propagation coefficient is low, so the breeding efficiency is very low.

[0004] It should be noted that the information disclosed in the above background art section is only used to strengthen the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to those of ordinary skill in the art. Summary of the Invention

[0005] The object of the present invention is to provide a method for maintaining the juvenile stage and rapid asexual propagation of rubber tree rootstock seedlings, which solves the problems of few cuttings and low propagation coefficient in the existing methods, can ensure the juvenile stage of the rootstock seedlings and rapidly propagate the rootstock seedlings, and greatly reduces the dependence of rubber tree rootstock seedlings on rubber seeds.

[0006] To achieve the above object, the present invention provides a method for maintaining the juvenile stage and rapid asexual propagation of rubber tree rootstock seedlings, which method comprises the following steps: S1. Preparation of juvenile stage seedling rootstock: After the rootstock seeds are sown and grow to at least 2 leaf clusters, cutting slips can be collected. S2. Cutting slips from the seedling rootstock: Cut branches from the seedling rootstock for use as cuttings. When the diameter of the seedling rootstock is less than 0.5 cm, at least 1 leaf should be retained on the rootstock seedling. When the diameter of the seedling rootstock is greater than or equal to 0.5 cm, the leaves of the rootstock seedling do not need to be retained. After cutting the branches from the seedling rootstock, when the newly sprouted branches grow to 1 - 2 leaf clusters, the next round of cutting slips can be collected, and the process of taking branches for cutting can be repeated several times. After cutting the slips from the seedling rootstock and its propagated cuttings, the height of the remaining stub should not exceed 50 cm to ensure that the branches sprouted from the rootstock stub all maintain the juvenile stage. The growth time of the branches collected from the seedling rootstock and its propagated seedlings is 2 - 8 months. Branches that have grown for more than 8 months must be cut off and discarded, and are not suitable for collecting cuttings. Branches less than 8 months old can maintain the juvenile stage characteristics of the branches. Plant age is one of the main factors affecting the success of cutting. The juvenile stage rubber tree seedlings have a higher cutting rooting rate and can develop a main root. Therefore, maintaining the juvenile stage state of the rootstock seedlings is the key to the success of cutting propagation in the cutting propagation process of rubber tree rootstock seedlings.

[0007] S3. Cutting slip treatment: Cut cuttings from the cut branches. Cut the collected cutting slips into cuttings with a length of 2 - 4 cm. Each cutting contains one petiole with 1 - 3 leaves on the petiole. The cut cuttings are immediately immersed in a shaking aqueous solution containing ethanol and potassium permanganate. S4. Cutting and rooting into seedlings: Insert the cuttings into a seedling tray or seedbed, and carry out routine management of shading and watering until the cuttings take root and sprout new buds. S5. Transplanting and management: After the roots grow at the base of the cuttings and the branches sprouted from the axillary buds enter the stable phenological period, transplant the cuttings to the nursery or nursery bags to cultivate Gn - generation cuttings, where n is an integer greater than or equal to 1. S6. Re - utilization of Gn - generation seedlings: When the Gn - generation seedlings grow more than 2 leaf clusters, they can be used as mother plants to cut cutting slips, and repeat steps S2 - S5 to obtain Gn + 1 - generation cuttings. S7. Utilization of Gn - generation cuttings: When the diameter of the Gn - or Gn + 1 - generation cuttings grows to reach the grafting standard, they are used as rootstock seedlings for grafting rubber varieties.

[0008] Preferably, in step S3, the aqueous solution containing ethanol and potassium permanganate contains 3-5% ethanol and 0.2-0.4% potassium permanganate. The latex at the incision is washed away by the aqueous solution containing ethanol and potassium permanganate. At the same time, potassium permanganate can disinfect, and ethanol can prevent browning of the incision.

[0009] More preferably, in step S3, the aqueous solution containing ethanol and potassium permanganate contains 2% ethanol and 0.2% potassium permanganate.

[0010] Preferably, in step S3, for the shaking, the rotation speed of the solution is 60-80 revolutions per minute.

[0011] More preferably, for the shaking, a stirrer or a vibrator or a shaker is used to rotate the solution.

[0012] The method for maintaining the juvenile stage and rapid asexual propagation of rubber tree rootstock seedlings of the present invention solves the problems of few cuttings and low propagation coefficient obtained by the existing methods, and has the following advantages: (1) By restricting the stubble height and branch growth time of the seedling rootstock and its propagated offspring seedlings, the present invention ensures that the cuttings taken therefrom remain in the juvenile stage, and ensures that the obtained cuttings have juvenile traits; (2) In the method of the present invention, the seedling rootstock can be continuously cut for 3-4 times of cuttings every year. Each cutting is only 2-4 cm long. A large number of G1 generation seedlings can be propagated every year. Similarly, the propagation coefficients of the G1, G2, G3 generations and the like of the propagated seedlings are also the same. Therefore, the seedling proliferation coefficient of the present invention is much greater than other current propagation technologies; (3) In the method of the present invention, since the branches of the seedlings are continuously pruned and the long-term growth of the branches is restricted, the space occupied by the growth of the seedlings is small, the planting density is high, and the proliferation coefficient is further increased, and the propagation efficiency is improved; (4) In the method of the present invention, the seedling rootstock is planted once and can be continuously used for many years, significantly reducing the dependence on rootstock seeds; (5) In the cutting process of the present invention, no growth hormone treatment is required. The present invention finds that the rooting rate of cuttings in the juvenile stage is not significantly improved after being treated with growth hormone. Although the present invention does not use growth hormone treatment, the rooting rate is also very good by using the method of the present invention. The method of the present invention can reduce the working steps and shorten the treatment time, and reduce the cost. Description of the Drawings

[0013] Figure 1 This is a photo of the seedling after taking the cuttings for the present invention.

[0014] Figure 2 This is Photo 1 of the cuttings rooting and growing in the substrate of the seedling tray for the present invention.

[0015] Figure 3 This is the second photo of the cuttings of the present invention taking root and growing in the substrate of the seedling tray.

[0016] Figure 4 This is the first photo of the cuttings with roots of the present invention.

[0017] Figure 5 This is the second photo of the cuttings with roots of the present invention. Detailed implementation mode

[0018] Next, the technical solutions in the embodiments of the present invention will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0019] It should be noted that: for those not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For the instruments not specified by the manufacturer, they are all conventional products that can be purchased commercially. For the raw materials and reagents not specified by the manufacturer, they are all commercially available products or can be prepared by known methods.

[0020] In the present invention, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents and concentrations, are only for the sake of simplicity and convenience. Accordingly, the description of the numerical range or percentage range should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0021] The features mentioned in the present invention can be combined arbitrarily, as long as there is no contradiction in the combination of these features. All possible combinations should be considered as the scope described in this specification. Each feature disclosed in the specification can be replaced by any alternative feature that can provide the same, equivalent or similar purpose. Therefore, unless otherwise specified, the disclosed features are only general examples of equivalent or similar features.

[0022] Example 1 A method for maintaining the juvenile stage and rapid asexual propagation of rubber tree rootstock seedlings includes the following steps: S1. Preparation of juvenile stage seedling rootstock: After the seeds of rubber tree variety GT1 are sown and grow to 3 leaf whorls, the cutting strips can be collected. S2. Cutting the cutting strips from the seedling rootstock: When the diameter of the mother plant of the seedling rootstock is less than 0.5 cm, cut the branches above the first leaf whorl as cuttings, and keep 1 leaf whorl on the mother plant of the seedling rootstock to enable the mother plant of the seedling rootstock to continue to sprout new branches; after the newly sprouted branches of the mother plant of the seedling rootstock grow to 3 leaf whorls, the next round of cutting strips can be collected, and continue to cut the new branches as cutting strips, and keep 1-2 leaves on the mother plant. Repeat this process many times to obtain branches for cutting. S3. Cutting slip treatment: Cut cuttings from the cut branches. Each cutting has a stem segment length of 3 cm and contains 1 small leaf. The cut cuttings are immediately placed in an aqueous solution containing 2% ethanol and 0.2% potassium permanganate. Stir the aqueous solution with a stirrer at a speed of 60 revolutions per minute. The purpose is to wash away the latex at the cutting incision to prevent the latex from solidifying into rubber blocks at the incision, which may hinder the absorption and transportation of substances. S4. Cuttage and rooting into seedlings: Insert the cuttings into a seedling tray or seedbed, and conduct routine management of shading and watering until the cuttings take root and new buds grow. S5. Transplanting and management: After the cuttings grow roots at the base and the branches germinated from axillary buds enter the phenological stable period, transplant the cuttage seedlings to a nursery or a seedling bag to obtain G1 generation cuttage seedlings.

[0023] In addition, the G1 generation cuttage seedlings can be reused. When the G1 generation cuttage seedlings grow to a diameter meeting the grafting standard, they are used as rootstock seedlings for grafting rubber varieties.

[0024] See Figures 1 to 5 , which are the photos of the seedling plants after taking the cuttings, the cuttings taking root and growing in the substrate of the seedling tray, and the rooted cuttings of the present invention.

[0025] Example 2 A method for maintaining the juvenile stage and rapid asexual propagation of rubber tree rootstock seedlings includes the following steps: S1. Preparation of juvenile stage seedlings: Take cuttings with the G1 generation cuttage seedlings obtained in Example 1 as the mother plants. After the G1 generation cuttage seedlings grow for 6 - 7 months, if the diameter of the branches of the seedlings reaches > 0.5 cm and the number of leaf clusters has exceeded 2, cuttings can be collected at this time. S2. Cutting of cutting slips: Cut the branches at 45 cm above the ground of the seedlings as cutting slips; when the branches regrown from the G1 generation cuttage seedling mother plants grow to 2 - 3 leaf clusters, cut the cutting slips again in the above - mentioned method. The diameter of the G1 mother plant in step S1 has been > 0.5 cm. For the regrown branches, only the number of leaf clusters of the new branches needs to be judged, and the diameter of the new branches does not need to be considered. S3. Cutting slip treatment: Cut cuttings from the cut branches. Each cutting has a stem segment length of 4 cm and contains 2 small leaves. The cut cuttings are immediately placed in an aqueous solution containing 2% ethanol and 0.2% potassium permanganate. Stir the aqueous solution with a stirrer at a speed of 60 revolutions per minute. S4. Cuttage and rooting into seedlings: Insert the cuttings into a seedling tray or seedbed, and conduct routine management of shading and watering until the cuttings take root and new buds grow. S5. Transplanting and management: When the cuttings grow roots and the germinated new buds enter the phenological stable period, transplant the cuttage seedlings to a nursery or a seedling bag to obtain G2 generation cuttage seedlings.

[0026] In addition, the G2 generation of seedlings can be reused. When the cuttings of the G2 generation grow to a diameter that meets the grafting standard, they can be used as rootstock seedlings for grafting rubber varieties.

[0027] Example 3 A method for maintaining the juvenile stage and rapid asexual propagation of rubber tree rootstock seedlings includes the following steps: S1. Preparation of juvenile stage seedling rootstock: The rubber tree seedlings grow for 8 months. At this time, the diameter is already greater than 0.5 cm and the number of leaf whorls is more than 4, so cuttings can be collected. S2. Cutting of cuttings from the seedling rootstock: Cut the branches at 40 cm above the ground of the seedlings to make cuttings. S3. Treatment of cuttings: Cut cuttings from the cut branches. The stem segment length of each cutting is 3 cm and it contains 1 small leaf. The cut cuttings are immediately put into an aqueous solution containing 4% ethanol and 0.3% potassium permanganate, and the aqueous solution is stirred with a stirrer at a speed of 70 revolutions per minute. S4. Rooting and seedling formation by cutting: Insert the cuttings into a seedling tray or a seedling bed, and conduct routine management of shading and watering until the cuttings take root and new buds grow. S5. Transplanting and management: When the cuttings grow roots and the germinated new buds enter the phenological stable period, transplant the cuttings to the nursery or nursery bags to cultivate the G1 generation of cuttings.

[0028] In addition, the G1 generation of seedlings can be reused. When the cuttings of the G1 generation grow to a diameter that meets the grafting standard, they can be used as rootstock seedlings for grafting rubber varieties.

[0029] Example 4 A method for maintaining the juvenile stage and rapid asexual propagation of rubber tree rootstock seedlings includes the following steps: S1. Preparation of juvenile stage seedlings: Take cuttings with the G2 generation of cuttings obtained in Example 2 as the mother plant. After the G2 generation of cuttings grow for a period of time, cut the cuttings. S2. Cutting of cuttings: If the diameter of the seedlings is less than 0.5 cm, when cutting the branches, leave 2 leaves on the stubble seedlings. S3. Treatment of cuttings: Take cuttings from the cut branches. The stem segment length of each cutting is 4 cm and it contains 1 small leaf. The cut cuttings are immediately put into an aqueous solution containing 4% ethanol and 0.3% potassium permanganate, and the aqueous solution is stirred with a stirrer at a speed of 70 revolutions per minute. S4. Rooting and seedling formation by cutting: Insert the cuttings into a seedling tray or a seedling bed, and conduct routine management of shading and watering until the cuttings take root and new buds grow. S5. Transplanting and management: When the cuttings grow roots and the germinated new buds enter the phenological stable period, transplant the cuttings to the nursery or nursery bags to cultivate the G3 generation of cuttings.

[0030] In addition, the G3 generation of nursery stock can be reused. When the cutting seedlings of the G3 generation grow to a diameter that meets the grafting standard, they are used as rootstock seedlings for grafting rubber varieties.

[0031] Comparative example The conventional rootstock seedlings for rubber trees are seedling rootstocks, which grow from the germination of rubber tree seeds. This is used as the comparative example. The rubber tree rootstock seeds are sown and germinated, and then transplanted into nursery bags. When the seedling rootstocks grow for about 1 year and reach the grafting standard, rubber varieties are grafted.

[0032] The breeding efficiency within one year of the examples was statistically analyzed. 20 plants were counted for each example. The number of cuttings that could be taken from each plant in 1 year was calculated, and the rooting rate of the cuttings was calculated. The average value was taken and rounded to an integer. In the comparative example, each germinated seed finally grew into one rootstock seedling. Table 1 shows the results of the examples and the comparative example.

[0033] Table 1 shows the grafting results of the examples and the comparative example of the present invention The results show that the present invention can achieve the reproduction of 15 - 18 cutting seedlings from 1 seedling rootstock within 1 year, with a propagation coefficient of more than 15. Moreover, the cutting seedlings propagated from the seedling rootstocks can maintain the characteristics of the juvenile stage, and the rooting rate is basically the same as that of the seedling.

[0034] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present invention. After those skilled in the art have read the above content, various modifications and substitutions of the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims

1. A method for maintaining the juvenile stage and rapid asexual propagation of rubber tree rootstock seedlings, characterized in that, The method comprises the following steps: S1. Preparation of juvenile seedling rootstocks: After the rootstock seeds are sown and grow to at least two leaf whorls, cutting slips can be collected; S2. Cutting of slips: Cut branches from the juvenile seedling rootstocks as slips. When the diameter of the juvenile seedling rootstock is less than 0.5 cm, at least one leaf or more should be retained on the rootstock seedling. When the diameter of the juvenile seedling rootstock is greater than or equal to 0.5 cm, the leaves of the rootstock seedling do not need to be retained. After cutting the branches from the juvenile seedling rootstock, when the newly sprouted branches grow to at least one leaf whorl, the next round of cutting slips can be collected, and the process of taking branches for cutting can be repeated several times. After cutting the slips from the juvenile seedling rootstock and its propagated cuttings, the height of the remaining stubble piles does not exceed 50 cm. The growth time of the branches collected from the juvenile seedling rootstock and its propagated seedlings is 2 - 8 months; S3. Treatment of slips: Cut slips from the cut branches. Cut the collected cutting slips into cuttings with a length of 2 - 4 cm. Each cutting contains one petiole with 1 - 3 leaves on the petiole. The cut cuttings are immediately immersed in a shaking aqueous solution containing ethanol and potassium permanganate; S4. Rooting and seedling formation by cutting: Insert the cuttings into a seedling tray or a seedbed, and carry out conventional management such as shading and watering until the cuttings take root and sprout new buds; S5. Transplanting and management: After the roots grow at the base of the cuttings and the branches sprouted from the axillary buds enter the stable phenological period, transplant the cuttings to a nursery or a seedling bag to cultivate Gn - generation cuttings, where n is an integer greater than or equal to 1; S6. Re - utilization of Gn - generation seedlings: When the Gn - generation seedlings grow more than two leaf whorls, they can be used as mother plants to cut cutting slips, and repeat steps S2 - S5 to obtain Gn + 1 - generation cuttings; S7. Utilization of Gn - generation cuttings: When the Gn - or Gn + 1 - generation cuttings grow to reach the grafting standard in diameter, use them as rootstock seedlings for grafting rubber varieties.

2. The method for maintaining the juvenile stage and rapid asexual propagation of rubber tree rootstock seedlings according to claim 1, characterized in that, In step S3, in the aqueous solution containing ethanol and potassium permanganate, the aqueous solution contains 3 - 5% ethanol and 0.2 - 0.4% potassium permanganate.

3. The method for maintaining the juvenile stage and rapid asexual propagation of rubber tree rootstock seedlings according to claim 2, characterized in that, In step S3, in the aqueous solution containing ethanol and potassium permanganate, the aqueous solution contains 2% ethanol and 0.2% potassium permanganate.

4. The method for maintaining the juvenile stage and rapid asexual propagation of rubber tree rootstock seedlings according to claim 1, characterized in that, In step S3, for the said shaking, the rotation speed of the solution swirling is 60 - 80 revolutions per minute.

5. The method for maintaining the juvenile stage and rapid asexual propagation of rubber tree rootstock seedlings according to claim 4, characterized in that, For the said shaking, use a stirrer or a vibrator or a shaker to make the solution swirl.

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