Method for shortening rubber tree breeding age limit

Abstract

The invention provides a systematic breeding method for shortening the breeding age limit of a rubber tree, and solves the technical problems that the breeding time of the rubber tree is too long and the breeding and development of a new variety of the rubber tree are not facilitated in the prior art. The method comprises the following steps: S1, screening excellent single plants; s2, rejuvenating in the field, and expanding propagation; s3, character identification; s4, field planting verification; s5, according to the step S3 and the step S4, varieties with high disease resistance, cold resistance, drought resistance, fast-growing property, high gelatin yield and excellent growth adaptability can be screened out. According to the systematic breeding method capable of effectively shortening the breeding age limit of the rubber tree, the breeding time of a new variety of the rubber tree can be shortened from 30 years to 15 years or less, the breeding time limit of the new variety is greatly shortened, and the systematic breeding method has great significance on breeding of the rubber tree.

Description

Technical Field

[0001] The invention relates to the field of rubber tree breeding, and in particular to a method for shortening the breeding period of rubber trees. Background Art

[0002] Natural rubber (NR) is an important global strategic material and industrial raw material. Its production mainly depends on the rubber tree (Hevea brasiliensis Muell.-Arg.), a tree species native to the Amazon River Basin in Brazil and later introduced to tropical regions around the world. The development of rubber tree breeding technology is of great significance to improving the yield, quality and sustainable development of natural rubber. The traditional rubber tree breeding cycle is long, generally taking about 30 years. This process includes multiple stages such as "sexual hybridization, progeny selection, and asexual selection". Due to the special production cycle and complicated measurement procedures of rubber trees, scientific researchers often need to spend a lot of time and resources to complete the breeding of a new variety. At the same time, the long breeding cycle of traditional rubber tree breeding limits the rapid promotion and application of new rubber tree varieties, especially in response to climate change and changes in market demand.

[0003] For a long time, the main challenges faced by rubber tree breeding include long breeding cycles, low efficiency, and the contradiction between high yield and resistance. In addition, rubber tree breeding materials are mostly derived from a narrow genetic background, which limits the mining and utilization of excellent gene resources and makes breeding bottlenecks increasingly prominent. In order to break through this bottleneck, researchers have been exploring new breeding technologies and methods in order to shorten the breeding cycle, improve breeding efficiency, and cultivate new rubber tree varieties with higher yields and multiple resistance.

[0004] In recent years, early identification techniques such as molecular marker-assisted selection and physiological index determination can be used to predict the stress resistance and yield of rubber trees. However, these early prediction methods have the problem of low accuracy. To obtain high-resistance and high-yield varieties in production practice, it is still necessary to undergo multi-year variety system comparison tests and regional tests, and the breeding cycle reaches more than 30 years. Therefore, developing a new method that can effectively shorten the rubber tree breeding period is of great practical significance for improving rubber tree breeding efficiency and success rate.

[0005] The applicant has found that the prior art has at least the following technical problems:

[0006] 1. In the prior art, the rubber tree breeding time is too long, and the efficiency is low, which is unfavorable for the development and utilization of new varieties of rubber trees;

[0007] 2. The existing technology has low breeding efficiency, resulting in a single variety, which cannot meet the planting needs of diverse planting environments.

[0008] 3. In the existing technology, the breeding time of rubber trees is as long as 30 years, and the characterization and promotion of new varieties are slow, which hinders production and utilization. Summary of the invention

[0009] The object of the present invention is to provide a method for shortening the rubber tree breeding age, to solve the existing breeding technology of rubber tree, what adopt is traditional hybrid breeding, this process approximately needs at least 30 years, because the breeding time is too long, is unfavorable for the breeding and development technical problem of rubber tree new variety.Many technical effects that the preferred technical scheme in many technical schemes provided by the present invention can produce are described in detail below.

[0010] To achieve the above object, the present invention provides the following technical solutions:

[0011] A method for shortening the breeding period of rubber trees provided by the present invention comprises the following steps:

[0012] S1 Selection of high-quality individual plants: In the first year, from April to October, select high-quality individual plants from the rubber tapping population for more than 5 years and collect scions;

[0013] First, select the seedling trees with high rubber production; at the same time, the excellent individual trees must also have at least two of the following target traits: resistance to powdery mildew, cold resistance, drought resistance, fast growth, and straight and smooth trunks;

[0014] The scions of excellent individual plants were collected and screened according to the following conditions: stem thickness of more than 8mm, length of more than 8cm, with terminal buds, facing the sun, and full buds;

[0015] S2 Field rejuvenation and expanded reproduction

[0016] S21 Grafting: Graft the scions collected in S1 onto 1-3 year old rootstocks by branch grafting or bud grafting; untie the scions after leaf buds emerge and the joints heal, and establish a clone system;

[0017] S22 budding propagation: In the second year, from July to September, when the scion grows 3-4 leaves and is 60-100cm high, use the axillary buds on the S21 scion to carry out budding propagation to expand the number of plants; after the budding survives, saw the anvil in the same year to make the buds germinate to form grafted plants, and remove the axillary buds and scale buds within 15cm of the stem base when the first leaf is stable;

[0018] S23 Promote rooting: In the third year, from February to June, bend the main stem to promote the germination of the adventitious buds at the base into upright plants; when the first leaf is stable, remove the axillary buds and scale buds within 15 cm below the stem, tie the stem with thick wire at the lower 5-10 cm, cut the stem at multiple locations within 3 cm above the binding position, apply naphthaleneacetic acid solution, and then cover the soil to 10 cm above the wound site to promote the production of adventitious roots in the stem;

[0019] S24 Obtaining buds that can be grafted: In the fourth year, from April to June, check the growth of adventitious roots, bend the stems of plants with adventitious roots, and pay attention to removing buds to promote the germination of adventitious buds near the adventitious roots, so that they grow into stems with good uprightness and fast growth; if the stems have multiple buds with excellent traits, obtain buds that can be grafted;

[0020] S3 Trait Identification

[0021] Using the clones obtained after the second year of expanded propagation as materials, conducting seedling field drought stress experiments and seedling field low temperature stress experiments, as well as evaluating the rubber yield at the seedling stage, comprehensively screening out high-yield and high-resistance clones; this step is performed simultaneously with step S23 and step S24;

[0022] S4. Field Planting Verification

[0023] S41: Propagation of excellent clones: Based on the high-yield and high-resistance excellent clones selected in S3, the young buds of the same clone obtained in S24 are selected accordingly, and the young buds are budded and propagated in the fifth year to obtain young excellent clone seedlings;

[0024] S42 Field planting verification in multiple locations in potential promotion areas

[0025] During the fifth year of propagation, a systematic measurement point was selected in the breeding field. Multiple plots were selected from sunny or shady slopes, upper slopes, middle slopes or slope feet at an altitude of 100-1200m in the potential promotion area as verification points. The young and excellent clones propagated in S41 were planned to be planted. Two replicates were set for each clone, and 30 plants were planted in each replicate. A control variety was set at each test point.

[0026] S43 Seedling planting and management

[0027] In the sixth year, from May to August, seedlings were planted at various points selected in S42. After planting, the seedlings needed to be watered thoroughly, leaf buds and buds of seedlings were promptly removed, pests and diseases were observed at any time, and pesticides were sprayed at appropriate times.

[0028] From the 7th to the 14th year, routine cultivation and management of seedlings at each site are carried out in accordance with the "NY / T 221-2016 Rubber Tree Cultivation Technical Regulations". The annual growth of the trees is measured in mid-to-late December each year. The measurement standard is the stem circumference 1.3m above the ground, and the data is recorded. When the statistics reach the 11th year of breeding, the tree growth analysis is carried out, and plants with stem circumference ≥50cm are selected for tapping in the next year.

[0029] S44 Powdery Mildew Resistance Verification

[0030] From the 7th to the 14th year, the powdery mildew resistance of the participating asexual lines at each site was observed in accordance with the "NY / T 1089-2015 Technical Procedure for Monitoring and Forecasting of Powdery Mildew of Rubber Trees", and the repeatability was evaluated compared with the disease resistance identified in S3.

[0031] S45 Rubber production measurement and evaluation

[0032] In the 12th year, rubber tapping was carried out from September to January of the following year, based on the climate and stability of the rubber leaves at each location. The dry rubber yield of each plant was recorded. After the tapping was completed, the average rubber yield per plant of the clones and the yield stability between plants within the clones were analyzed.

[0033] In the 13th to 15th year, based on the growth, rubber yield, and stress resistance of the plants at each verification point, combined with the corresponding traits of the plants at the systematic measurement points in the breeding site in step S42, the repeatability of the superior traits and the acceptability of the inferior traits are evaluated to determine the superior clones and their suitable planting areas;

[0034] S46 DUS test

[0035] Simultaneously, in the 13th to 15th year, the excellent clones selected in step S45 are subjected to DUS testing in accordance with the requirements of "NY / T 2749-2015 Guidelines for Specificity, Consistency and Stability Testing of New Plant Varieties - Rubber Tree";

[0036] In the 14th to 15th year, based on the comprehensive evaluation results of stress resistance, rubber yield and small-area adaptability in steps S3 and S4, small-scale production promotion planting is carried out in suitable areas;

[0037] S5. According to step S3 and step S4, new varieties of rubber trees with excellent stress resistance, rubber yield and growth adaptability can be screened out.

[0038] Furthermore, in step S23, the mass percentage concentration of the naphthylacetic acid solution is 3%-4%.

[0039] Furthermore, in step S23, the mass percentage concentration of the naphthylacetic acid solution is 3.5%.

[0040] Furthermore, in step S3, the seedling field drought stress experiment is specifically as follows: the plants obtained after the second year of expanded reproduction are transplanted into flower pots, trenches are dug in the field, the flower pots are placed in the trenches, bricks are placed underneath to isolate water absorption, and a shading net is covered on the top to ensure that only drought stress is applied but not affected by the temperature difference between day and night. After the stress is applied, tissue water content (PWD), protective enzymes (SOD, POD), malondialdehyde (MDA), soluble protein (SP) and recovery capacity index are measured in time gradients, the drought resistance and drought tolerance of each clone are analyzed, and the availability in production is comprehensively evaluated;

[0041] Simultaneously, the spatial distribution characteristics of chlorophyll at different leaf positions of seedlings without drought stress were evaluated, and the SPAD values ​​and leaf color changes at different developmental stages of leaves were determined;

[0042] Synchronously, the anatomical structures of the middle and upper parts of the middle leaflets of mature leaves of normally growing seedlings were measured, including leaf thickness, upper epidermis thickness, palisade tissue thickness, spongy tissue thickness, lower epidermis thickness, vein thickness, and leaf compactness.

[0043] Furthermore, in step S3, the seedling field low temperature stress experiment is specifically as follows: using the plants obtained after the second year of expansion and propagation as materials, controlling the low temperature constant temperature stress at 3°C ​​in an incubator, collecting leaf samples every 2 days to measure the relative conductivity, restoring to normal temperature for 1 day after 8 days of stress, and measuring the relative conductivity again;

[0044] Simultaneously, temperature gradient measurement was carried out: healthy branches of the current year were selected, and the second green branch with leaf canopy from the top was collected, and subjected to in vitro low-temperature stress; the temperature was lowered at a rate of 4°C per hour, and four temperature gradients of 4°C (CK), 0°C, -2°C, and -5°C were set, and constant temperature stress was applied for 12 hours, and then the temperature was raised to room temperature at a rate of 4°C per hour, and the relative conductivity of the branch bark was measured.

[0045] Furthermore, in step S4, the control variety set is a variety that is productively planted locally at the planting site.

[0046] Based on the above technical solution, the embodiments of the present invention can at least produce the following technical effects:

[0047] (1) The systematic breeding method provided by the present invention can effectively shorten the rubber tree breeding period, and can shorten the rubber tree breeding process from 30 years to within 15 years, greatly shortening the breeding period of new varieties and improving the breeding efficiency, which is of great significance to rubber tree breeding.

[0048] (2) The systematic breeding method provided by the present invention can effectively shorten the breeding period of rubber trees. While greatly shortening the breeding period, it can screen out new rubber tree varieties with excellent stress resistance, yield and growth adaptability. Therefore, the rubber tree breeding method of the present invention also has the advantage of excellent breeding effect.

[0049] (3) The systematic breeding method provided by the present invention can effectively shorten the rubber tree breeding period. Since multiple plots with different altitudes and slopes are selected as test points, new rubber tree varieties suitable for planting in multiple planting sites with different altitudes and slopes can be obtained. Therefore, the rubber tree breeding efficiency is improved, the rubber tree variety diversity is increased, and the planting needs of environmental diversity can be met. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0051] Figure 1 This is a diagram of a field drought stress test in the embodiment;

[0052] Figure 2 is a schematic diagram of the anatomical structure of a leaf in an embodiment;

[0053] Figure 3 It is the entire breeding technology roadmap in the embodiment;

[0054] Figure 4 It is a thumbnail of the seedling treatment and growth conditions during the entire breeding cycle in the embodiment;

[0055] Figure 5 This is the rubber production of the juvenile propagation clones in the example (the 7-year-old Yunyan 314 is actually the 13th year of breeding);

[0056] Figure 6 This is the rubber production of the juvenile propagation clones in the example (9-year-old Yunyan 272, actually the 15th year of breeding);

[0057] Figure 7 It is a stable morphological diagram of the young leaf canopy of Yunyan 272 in January 2018 in the embodiment;

[0058] Figure 8 This is a diagram of the stable shape of the large leaf canopy of Yunyan 272 in February 2022 in the embodiment. DETAILED DESCRIPTION

[0059] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0060] In the following Example 1, the following were carried out: drought resistance evaluation, drought resistance evaluation (physiological indicators), cold resistance evaluation (anatomical structure), cold resistance evaluation (seedlings) and yield evaluation (ex vivo young stems); Yunyan 77-4 was used as a control, and Yunyan 272, Yunyan 314 and Yunyan 617 were the names of new rubber tree varieties in the cultivation process.

[0061] Embodiment 1:

[0062] The present invention provides a method for shortening the breeding period of rubber trees, comprising the following steps:

[0063] S1 Excellent single plant screening:

[0064] In the first year (2009), from April to October, we selected high-quality seedlings from rubber plantations in Jinghong, Menghai, Dehong, Hekou, Pu'er and Wenshan rubber plantations in Yunnan Province, and collected scions;

[0065] The selection of high-quality individual plants takes high rubber yield as the first goal. At the same time, the high-quality individual plants must also have at least two of the following target traits: resistance to powdery mildew, cold resistance, drought resistance, fast growth, and straight and smooth trunks;

[0066] The selected excellent scions are screened according to the following conditions: stem thickness of more than 8mm, length of more than 8cm, with terminal buds, facing the sun, and full buds;

[0067] S2 Field rejuvenation and expanded reproduction

[0068] S21 Grafting: The scions collected in S1 are grafted onto two-year-old rootstocks using the branch grafting method and the bud grafting method; after the leaf buds emerge and the interface heals, the grafts are untied in the same year to establish a clone system;

[0069] S22 budding propagation: In the second year (2010), from July to September, when the scion grows 3-4 leaves and is 60-100cm high, use the axillary buds on the S21 scion to carry out budding propagation to expand the number of plants; after the budding survives, saw the anvil in the same year to make the buds germinate to form grafted plants. When the first leaf is stable, use a sharp knife to remove the axillary buds and scale buds within 15cm of the stem base;

[0070] S23 Promote rooting: In the third year (2011), from February to June, bend the main stem to promote the germination of the adventitious buds at the base into upright plants; when the first leaf is stable, use a sharp knife to remove the axillary buds and scale buds within 15 cm below the stem, tie the stem with thick wire at the lower 5-10 cm, make multiple cuts on the stem within 3 cm above the binding position, apply 3.5% naphthaleneacetic acid solution on the cuts, and then cover the soil to 10 cm above the wound to promote the production of adventitious roots in the stem;

[0071] S24 Obtaining buds that can be grafted: In the fourth year (2012), from April to June, check the growth of adventitious roots, bend the stems of plants with adventitious roots, and pay attention to removing buds to promote the germination of adventitious buds near the adventitious roots, so that they can grow into stems with good uprightness and fast growth; if the stems have multiple buds with excellent traits, then use bud grafting to expand reproduction and obtain buds that can be grafted;

[0072] S3 Trait Identification

[0073] Using the clones obtained after the second year of expanded propagation (step S22) as materials, conduct seedling field drought stress experiments and seedling field low temperature stress experiments, as well as evaluate the rubber yield at the seedling stage, and comprehensively screen out high-yield and high-resistance clones; this step is carried out simultaneously with steps S23 and S24;

[0074] S31 seedling field drought stress experiment ( Figure 1 Specifically:

[0075] The plants obtained after the second year of expanded reproduction were transplanted into pots with a diameter of 40 cm and a depth of 60 cm. A ditch was dug in the field, and the pots were placed in the ditch. Bricks were placed underneath to isolate water absorption, and a shading net was covered on the top to ensure that they were only subjected to drought stress and not affected by the temperature difference between day and night. After the stress was implemented, the tissue water content (PWD), protective enzymes (SOD, POD), malondialdehyde (MDA), soluble protein (SP), and recovery capacity were measured at different time length gradients to analyze the drought resistance and tolerance of each clone, and to comprehensively evaluate their availability in production.

[0076] Synchronously, the spatial distribution characteristics of chlorophyll at different leaf positions of seedlings without drought stress were studied, and the SPAD values ​​and leaf color changes at different developmental stages of leaves were determined;

[0077] Specific experimental implementation steps and results: Drought stress treatment was carried out by natural drying method. Yunyan 77-4 was used as the control, and Yunyan 272, Yunyan 314 and Yunyan 617 were evaluated for drought resistance. Soil drought stress was carried out in late May 2011. After being fully watered for 3 consecutive days, no more watering was done and the plants were allowed to dry naturally. During the stress period, the temperature and humidity in the nursery were kept consistent with the surrounding soil environment and the interference of natural precipitation was prevented. Leaf samples were taken at 0 (CK), 5 and 10 days after water was cut off for the determination of various physiological indicators. Five plants with basically the same growth were selected from each asexual line for mixed leaf samples. The leaf samples were quickly frozen in liquid nitrogen in cryopreservation tubes and brought back to the laboratory for the determination of various physiological indicators. The results are shown in Table 1.

[0078] Table 1 Results of physiological indexes of rubber tree clones under drought stress

[0079]

[0080] The results in Table 1 show that during drought stress, with the extension of water cut-off time, the SOD / POD content of Yunyan 272 and Yunyan 314 first increased and then decreased, the MDA content showed an upward trend, and the SP content first increased and then decreased. When the stress reached 5 days, the values ​​of SOD, POD, and SP reached the maximum, and the SP content of Yunyan 272 increased the most, followed by Yunyan 314. Comprehensively considering various indicators, Yunyan 272 had the strongest drought resistance among the tested varieties.

[0081] At the same time, the anatomical structures of the middle and upper parts of the middle leaflets of mature leaves of normally growing seedlings were measured, including leaf thickness, upper epidermis thickness, palisade tissue thickness, spongy tissue thickness, lower epidermis thickness, vein thickness, and leaf compactness. Figure 2 And as shown in Table 2.

[0082] Table 2 Multiple comparisons of leaf anatomical structure indices of the rubber tree clones tested

[0083]

[0084] Note: The data in Table 2 are the average values ​​of 54 groups of data for each indicator. Different uppercase and lowercase letters after the same row of data indicate extremely significant differences (P<0.01) and significant differences (P<0.05), respectively.

[0085] Table 3 Membership function evaluation of leaf anatomical structure of rubber tree clones

[0086]

[0087] The results in Tables 2 and 3 showed that there were significant differences in the anatomical structures of different clones. Principal component analysis was performed, and finally 7 indicators representing drought resistance were screened out, including upper epidermis thickness, lower epidermis thickness, palisade tissue thickness, spongy tissue thickness, palisade-sea ratio, leaf density and leaf thickness; the results of drought resistance evaluation using the membership function analysis method showed (Table 3) that the drought resistance of the four clones, from strong to weak, was Yunyan 617> Yunyan 272> Yunyan 77-4> Yunyan 314.

[0088] The specific experiment of low temperature stress on S32 seedlings in the field is as follows:

[0089] The plants obtained after expanded reproduction in the second year were used as materials. The plants were placed in an incubator to control the low-temperature constant temperature stress at 3°C. Leaf samples were collected every 2 days to measure the relative conductivity. After 8 days of stress, the plants were restored to normal temperature for 1 day and the relative conductivity was measured again.

[0090] Specific experimental implementation steps and results: Seedlings were used as materials, and a constant temperature stress of 3°C was controlled in an incubator. Leaf samples were collected every 2 days to measure relative conductivity. After 8 days of stress, the temperature was restored to normal for 1 day and the conductivity was measured again. The measured data are shown in Table 4.

[0091] Table 4 Relative conductivity of the rubber tree clone seedlings after low temperature stress (unit / %)

[0092]

[0093] The results in Table 4 show that Yunyan 272 and Yunyan 77-4 were basically unharmed after 4 days of stress. After 6 and 8 days of stress, Yunyan 77-4 was obviously harmed, but Yunyan 272 and Yunyan 617 were slightly harmed. After 1 day of recovery, the measured data were not much different from those after 8 days of stress. This shows that Yunyan 272 has more obvious low temperature tolerance and recovery ability.

[0094] Specific experimental implementation steps and results: Temperature gradient measurement was carried out. Healthy branches of the current year were selected. Green branches were collected from the second leaf canopy from the top as materials. In vitro low temperature stress was applied. The temperature was lowered at a rate of 4°C per hour. Four temperature gradients of 4°C (CK), 0°C, -2°C, and -5°C were set. The temperature was kept constant for 12 hours. The temperature was then raised to room temperature at a rate of 4°C per hour and the relative conductivity of the branch bark was measured. The results are shown in Table 5.

[0095] Table 5 Relative conductivity of young stems of rubber tree clones after in vitro low temperature stress (unit / %)

[0096]

[0097] The results in Table 5 show that among the four clones tested, Yunyan 272 is the most cold-resistant, Yunyan 314 is slightly stronger than Yunyan 77-4 (CK), and Yunyan 617 ranks second.

[0098] S4. Field Planting Verification

[0099] S41 excellent clone propagation:

[0100] Based on the clones with strong stress resistance screened in S3, the young buds of the corresponding clones obtained in S24 were selected, and the young buds were budded and propagated in the fifth year (2013) to obtain young and excellent clones;

[0101] S42 Multi-point and multi-area field planting verification

[0102] In the fifth year (2013), a systematic measurement point was established in Jinghong City, Yunnan Province, and plots with different altitudes and slopes were selected in Gengma County, Lincang City, Hekou County, Honghe Prefecture, and Ruili City, Dehong Prefecture, to plan and plant the excellent clones propagated in S41; a control material was set at each test point, and the control variety was Yunyan 77-4;

[0103] S43 Seedling planting and management

[0104] In the sixth year (2014), from May to August, seedlings were planted at each test site selected in S42. After planting, the seedlings needed to be watered thoroughly, leaf buds and buds from seedlings were promptly removed, pests and diseases were observed at any time, and pesticides were sprayed at appropriate times.

[0105] From the 7th to the 14th year (2015 to 2022, which is the 1st to 8th year of the clone planting experiment), rubber tree planting management is carried out in accordance with the "NY / T 221-2016 Rubber Tree Cultivation Technical Regulations"; the annual growth of the tree is measured in mid-to-late December each year, and the measurement standard is the stem circumference 1.3m above the ground, and the data is recorded; when the statistics reach the 11th year (the 5th year of planting at each site), the tree growth analysis can be carried out, and the germplasm with a stem circumference ≥50cm can be selected for tapping in the next year; after 11 years, the stem circumference will continue to be measured, because different varieties have different growth rates, and this indicator is one of the indicators for evaluating fast growth;

[0106] S44 Powdery mildew identification and multi-point verification

[0107] From the 7th to the 14th year, from February to March every year, the powdery mildew resistance of the clones planted at each verification point was observed in accordance with the "NY / T 1089-2015 Technical Regulations for the Detection and Forecasting of Powdery Mildew on Rubber Trees", and the powdery mildew resistance was divided into several types, such as "anti-invasion, anti-expansion, damage tolerance, and disease avoidance". And according to the powdery mildew grading standards in the "NY / T 1089-2015 Technical Regulations for the Detection and Forecasting of Powdery Mildew on Rubber Trees", it was divided into six levels: 0, 1, 3, 5, 7, and 9.

[0108] After a 10-year investigation of the clones of Yunyan 774 (control), Yunyan 272, Yunyan 314 and Yunyan 617, it was found that the leaves of Yunyan 272 and Yunyan 314 were early in growth. In general, the leaves of large trees are stable in February, while those of young trees are stable in January. Figure 3 ), according to the powdery mildew grading standards in "NY / T 1089-2015 Technical Regulations for Rubber Tree Powdery Mildew Monitoring and Reporting", it is identified as:

[0109] Yunyan 272 is at level 0-1, not resistant to invasion, resistant to expansion, resistant to damage, able to avoid disease, and easy to recover;

[0110] Yunyan 314 performs at level 1-3, is not resistant to invasion, is not resistant to expansion, is slightly resistant to damage, can avoid disease, and is easy to recover.

[0111] Yunyan 617 and Yunyan 77-4 perform similarly, at levels 3-5. They are not resistant to invasion or expansion, are slightly resistant to damage, are slightly disease-resistant, and are slightly easier to recover.

[0112] S45 Rubber production measurement and evaluation

[0113] In the 12th year (2020), rubber tapping was carried out from September to January of the following year based on the climate environment and the stability of the rubber leaves of each test site, and the dry rubber yield of each plant and each tap was recorded. After tapping was completed, the inter-plant variation pattern of rubber production traits within the asexual lines, the annual average plant yield of each asexual line, and the rubber production rules within the year were analyzed; the average dry rubber yield per plant is shown in Table 6.

[0114] Table 6 Record of trial cutting yield at the measuring point of Jinghong system (unit / g)

[0115]

[0116] Note: The rubber tapping period 0403-0411 refers to "April 3 to April 11", and the rest are the same.

[0117] The results in Table 6 show that Yunyan 314 has the highest yield, followed by Yunyan 272, and Yunyan 617 is equivalent to the control variety Yunyan 77-4.

[0118] S46 DUS testing and new variety registration

[0119] The selected excellent clones were subjected to DUS testing in accordance with the requirements of "NY / T 2749-2015 Guidelines for Specificity, Consistency and Stability Testing of New Plant Varieties - Rubber Trees", and simultaneously applied for new plant variety protection from the Ministry of Agriculture and Rural Affairs;

[0120] In the 14th and 15th years (2022-2023), based on the comprehensive evaluation results of stress resistance, rubber yield and small-area adaptability in steps S3 and S4, small-scale production promotion and planting will be carried out in suitable areas;

[0121] S5. Combining step S3 and step S4, varieties with excellent stress resistance, yield and growth adaptability can be screened out; the specific breeding technology route is as follows: Figure 3 The schematic diagram of plant treatment and growth during the entire cycle is shown in Figure 4 As shown; Figure 4 In the sequence, according to the direction of the arrows, they are: selected excellent individual plants → grafting of excellent individual scion → young propagation: after the scion sprouts, the adventitious buds that grow at the base of the plant after the bud piece grafted by the asexual line is bent → the growth of young branches → the growth of two leaves on the young branches → the situation when the young branches grow to three leaves, which can be used for bud grafting and expansion → the leaf sheaths that grow after bud grafting and expansion of young buds → the growth of young asexual line plants in the ratio area.

[0122] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for shortening the rubber tree breeding period, characterized in that: The steps include: S1 Selection of high-quality individual plants: In the first year, from April to October, select high-quality individual plants from the rubber tapping population for more than 5 years and collect scions; First, select the seedling trees with high rubber production; at the same time, the excellent individual trees must also have at least two of the following target traits: resistance to powdery mildew, cold resistance, drought resistance, fast growth, and straight and smooth trunks; The scions of excellent individual plants were collected and screened according to the following conditions: stem thickness of more than 8mm, length of more than 8cm, with terminal buds, facing the sun, and full buds; S2 Field rejuvenation and expanded reproduction S21 Grafting: Graft the scions collected in S1 onto 1-3 year old rootstocks by branch grafting or bud grafting; untie the scions after leaf buds emerge and the joints heal, and establish a clone system; S22 budding propagation: In the second year, from July to September, when the scion grows 3-4 leaves and is 60-100cm high, use the axillary buds on the S21 scion to carry out budding propagation to expand the number of plants; after the budding survives, saw the anvil in the same year to make the buds germinate to form grafted plants, and remove the axillary buds and scale buds within 15cm of the stem base when the first leaf is stable; S23 Promote rooting: In the third year, from February to June, bend the main stem to promote the germination of the adventitious buds at the base into upright plants; when the first leaf is stable, remove the axillary buds and scale buds within 15 cm below the stem, tie the stem with thick wire at the lower 5-10 cm, cut the stem at multiple locations within 3 cm above the binding position, apply naphthaleneacetic acid solution, and then cover the soil to 10 cm above the wound site to promote the production of adventitious roots in the stem; S24 Obtaining buds that can be grafted: In the fourth year, from April to June, check the growth of adventitious roots, bend the stems of plants with adventitious roots, and pay attention to removing buds to promote the germination of adventitious buds near the adventitious roots, so that they grow into stems with good uprightness and fast growth; if the stems have multiple buds with excellent traits, obtain buds that can be grafted; S3 Trait Identification Using the clones obtained after the second year of expanded propagation as materials, conducting seedling field drought stress experiments and seedling field low temperature stress experiments, as well as evaluating the rubber yield at the seedling stage, comprehensively screening out high-yield and high-resistance clones; this step is performed simultaneously with step S23 and step S24; S4. Field Planting Verification S41: Propagation of excellent clones: Based on the high-yield and high-resistance excellent clones selected in S3, the young buds of the same clone obtained in S24 are selected accordingly, and the young buds are budded and propagated in the fifth year to obtain young excellent clone seedlings; S42 Field planting verification in multiple locations in potential promotion areas During the fifth year of propagation, a systematic measurement point was selected in the breeding field. Multiple plots were selected from sunny or shady slopes, upper slopes, middle slopes or slope feet at an altitude of 100-1200m in the potential promotion area as verification points. The young and excellent clones propagated in S41 were planned to be planted. Two replicates were set for each clone, and 30 plants were planted in each replicate. A control variety was set at each test point. S43 Seedling planting and management In the sixth year, from May to August, seedlings were planted at various points selected in S42. After planting, the seedlings needed to be watered thoroughly, leaf buds and buds of seedlings were promptly removed, pests and diseases were observed at any time, and pesticides were sprayed at appropriate times. From the 7th to the 14th year, routine cultivation and management are carried out on the seedlings at each site. The annual growth of the trees is measured in mid-to-late December each year. The measurement standard is the stem circumference at 1.3m above the ground, and the data are recorded; When the breeding season reaches the 11th year, the tree growth analysis is conducted and plants with stem circumference ≥ 50 cm are selected for tapping in the next year. S44 Powdery Mildew Resistance Verification From the 7th to the 14th year, the powdery mildew resistance of the participating clones at each site was observed and the repeatability was evaluated with the disease resistance identified in S3.

2. S45 Rubber production measurement and evaluation In the 12th year, rubber tapping was carried out from September to January of the following year, based on the climate and stability of the rubber leaves at each location. The dry rubber yield of each plant was recorded. After the tapping was completed, the average rubber yield per plant of the clones and the yield stability between plants within the clones were analyzed. In the 13th to 15th year, based on the growth, rubber yield, and stress resistance of the plants at each verification point, combined with the corresponding traits of the plants at the systematic measurement points in the breeding site in step S42, the repeatability of the superior traits and the acceptability of the inferior traits are evaluated to determine the superior clones and their suitable planting areas; S46 DUS test Simultaneously, in the 13th to 15th year, the superior clones selected in step S45 are subjected to DUS test; In the 14th to 15th year, based on the comprehensive evaluation results of stress resistance, rubber yield and small-area adaptability in steps S3 and S4, small-scale production promotion planting is carried out in suitable areas; S5. According to step S3 and step S4, new varieties of rubber trees with excellent stress resistance, rubber yield and growth adaptability can be screened out.

3. The method for shortening the rubber tree breeding period according to claim 1, wherein: In step S23, the mass percentage concentration of the naphthylacetic acid solution is 3%-4%.

4. The method for shortening the rubber tree breeding period according to claim 1, wherein: In step S23, the mass percentage concentration of the naphthylacetic acid solution is 3.5%.

5. The method for shortening the rubber tree breeding period according to claim 1, wherein: In step S3, the seedling field drought stress experiment specifically includes: transplanting the plants obtained after the second year of expanded reproduction into flower pots, digging trenches in the field, placing the flower pots in the trenches, placing bricks underneath to isolate water absorption, and covering the upper surface with a shading net to ensure that they are only affected by drought stress and not affected by the temperature difference between day and night. After the stress is implemented, the tissue water content (PWD), protective enzymes (SOD, POD), malondialdehyde (MDA), soluble protein (SP) and recovery capacity index are measured in time gradients, the drought resistance and drought tolerance of each asexual line are analyzed, and the availability in production is comprehensively evaluated; Synchronously, the spatial distribution characteristics of chlorophyll at different leaf positions of seedlings without drought stress were studied, and the SPAD values ​​and leaf color changes at different developmental stages of leaves were determined; Synchronously, the anatomical structures of the middle and upper parts of the middle leaflets of mature leaves of normally growing seedlings were measured, including leaf thickness, upper epidermis thickness, palisade tissue thickness, spongy tissue thickness, lower epidermis thickness, vein thickness, and leaf compactness.

6. The method for shortening the rubber tree breeding period according to claim 1, wherein: In step S3, the seedling field low temperature stress experiment is specifically as follows: using the plants obtained after the second year of expansion and propagation as materials, controlling the low temperature and constant temperature stress at 3°C ​​in an incubator, collecting leaf samples every 2 days to measure the relative conductivity, restoring to normal temperature for 1 day after 8 days of stress, and measuring the relative conductivity again; Simultaneously, temperature gradient measurement was carried out: healthy branches of the current year were selected, and the second green branch with leaf canopy from the top was collected, and subjected to in vitro low-temperature stress; the temperature was lowered at a rate of 4°C per hour, and four temperature gradients of 4°C (CK), 0°C, -2°C, and -5°C were set, and constant temperature stress was applied for 12 hours, and then the temperature was raised to room temperature at a rate of 4°C per hour, and the relative conductivity of the branch bark was measured.

7. The method for shortening the rubber tree breeding period according to claim 1, wherein: In step S4, the control variety set is a variety that is productively planted locally at the planting site.

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