Integrated method for improved variety breeding, rapid propagation and container seedling cultivation of poplar pie suitable for semi-arid region

Abstract

The invention relates to the technical field of forest tree breeding and cultivation, in particular to an integrated method for improved variety breeding, rapid propagation and container seedling cultivation of poplar pie suitable for semi-arid regions. The integration method comprises the following steps: hybridizing populus arabinosa or populus sinkiang as a female parent and populus tomentosa or populus arabinosa as a male parent, screening by using a molecular marker to obtain F1-generation plants with salt-tolerant and drought-resistant characteristics, and sequentially carrying out rapid propagation, container seedling cultivation and afforestation planting on the F1-generation plants. Compared with the prior art, the method can solve the problem of rooting of the poplar pie, the afforestation survival rate is remarkably increased, and the method has the advantages of shortening the breeding period and accurately improving the stress resistance.

Description

Technical Field

[0001] This invention relates to the field of forest tree breeding and cultivation technology, and in particular to an integrated method for the selection, rapid propagation and container seedling cultivation of superior poplar varieties suitable for semi-arid regions. Background Technology

[0002] Poplar is a major tree species for shelterbelt construction and timber production in the Three-North region of my country. Currently, in poplar production in semi-arid areas, conventional breeding combined with bare-root seedling afforestation techniques are mainly used.

[0003] The existing technology has the following problems and drawbacks: 1. The problem of rooting poplar species: Poplar species, represented by white poplar and silver poplar, have excellent material and beautiful tree shape, but their cuttings contain rooting inhibitors, and the rooting rate of conventional hardwood cuttings is extremely low (usually less than 30%), which seriously restricts the promotion of superior clones.

[0004] 2. Long breeding cycle and poor stress resistance: Traditional hybridization breeding relies on phenotypic selection, requiring many years of observation to determine superior traits, with a cycle of 10-15 years. Moreover, there is a lack of specialized varieties for drought, salinity and other adverse conditions, and existing varieties have low survival rates in afforestation during drought years.

[0005] 3. Low survival rate of afforestation: When traditional bare-root seedlings are planted in the field in spring, due to the dry and windy conditions and poor soil moisture in semi-arid areas, the seedlings are prone to water loss and death, and the survival rate is often less than 60%, requiring multiple replantings, which increases the cost of afforestation.

[0006] 4. Environmental pollution problem: Currently, a large number of poplar varieties are female trees, which cause serious cotton-like fluff in spring, resulting in environmental pollution and fire hazards in urban and rural areas. There is an urgent need to breed new male-sterile (non-fluffy) varieties.

[0007] Therefore, there is an urgent need for an integrated technology system that combines modern biotechnology breeding with traditional asexual reproduction techniques, along with appropriate seedling cultivation and afforestation techniques, to achieve efficient propagation and precise afforestation of superior poplar varieties under difficult site conditions. Summary of the Invention

[0008] The purpose of this invention is to provide an integrated method for the selection, rapid propagation, and container seedling cultivation of superior Populus species suitable for semi-arid regions, thereby solving the problems existing in the prior art. The integrated method provided by this invention overcomes the problems of difficult rooting of Populus species through cuttings, long breeding cycles, low survival rates in semi-arid regions, and pollutant effects caused by flying catkins. It is an integrated method combining "stress-resistant breeding, resource conservation, efficient rapid propagation, container seedling cultivation, and rainy season afforestation," enabling the industrial-scale promotion of superior Populus species in arid regions.

[0009] To achieve the above objectives, the present invention provides the following solution: This invention provides an integrated method for the selection, rapid propagation, and container seedling cultivation of superior poplar varieties suitable for semi-arid regions. The method includes hybridization using silver poplar or Xinjiang poplar as the female parent and white poplar or silver gray poplar as the male parent, and screening for F1 generation plants with salt tolerance and drought resistance using molecular markers. The F1 generation plants are then subjected to rapid propagation, container seedling cultivation, and afforestation planting in sequence. The rapid propagation method includes one or more of grafting rejuvenation, root-inducing cuttings in a warm bed, and tissue culture.

[0010] More preferably, the hybridization includes multi-parent hybridization with controlled pollination, including single crosses and double crosses, in order to combine multiple excellent traits (drought resistance, cold resistance, fast growth, and no fluff).

[0011] Optionally, the molecular marker includes the PagHB7a molecular marker; the PagHB7a molecular marker is obtained by amplification using the upstream primer shown in SEQ ID NO.1 and the downstream primer shown in SEQ ID NO.2.

[0012] This invention utilizes functional markers related to drought and salt tolerance (such as PagHB7a and other stress-resistance gene-related markers) to screen hybrid offspring at an early stage. Individual plants with significant stress resistance can be accurately and efficiently identified during the seedling stage (1 year old), shortening the breeding cycle by 3-5 years.

[0013] Subsequently, the present invention will select superior germplasm resources and establish core breeding resource conservation nurseries in bases with different climate and ecological zones using a combination of "field germplasm bank + facility preservation" to preserve clonal germplasm.

[0014] In this invention, to address the problem of difficulty in rooting poplar, one or more of the following techniques are selected for rapid propagation, depending on the propagation material: grafting rejuvenation, root-inducing cuttings in a warm bed, and tissue culture.

[0015] Optionally, the grafting rejuvenation includes the step of using budded branches of the F1 generation plant as scions and grafting the scions onto the rootstock to cultivate grafted seedlings with self-rooted growth. The hotbed rooting and cutting propagation includes the step of using the root sprouts of the F1 generation plants as cuttings and inserting the cuttings into a hotbed for cultivation. The tissue culture uses young leaves of the F1 generation plants as explants, and includes differentiation and rooting cultures. The differentiation culture uses WPM medium as the basal medium, containing 1.0 mg / L 6-BA, 0.1 mg / L TDZ, 0.05 mg / L NAA, 30 g / L sucrose, and 6 g / L agar. The rooting culture uses 1 / 2 MS medium as the basal medium, containing 0.5 mg / L IBA, 0.1 mg / L NAA, 25 g / L sucrose, and 6 g / L agar. The differentiation culture includes dark culture and light culture. The dark culture is conducted at 23°C for 7 days; the light culture is conducted at 25°C for 18-20 days at a light intensity of 1500-2000 lx; ​​and the rooting culture is conducted at 23-25°C for 15-25 days.

[0016] In this invention, the grafting rejuvenation technique employs a "root-based propagation" strategy for superior poplar trees that are difficult to root. Superior scions are grafted onto the base or root system of rootstocks with strong compatibility and easy rooting (such as Populus tomentosa or Populus nigra). Utilizing the strong root system and rooting ability of the rootstock, grafted seedlings with self-roots are cultivated through the graft union (the superior variety's scion is grafted onto the easily rooting rootstock; through the influence of the rootstock's root system, adventitious roots are induced to grow from the base of the scion, forming a self-rooted grafted seedling). The specific operation involves: collecting rootstock root segments (0.5-1 cm in diameter, 10-15 cm in length) in winter; cleft grafting of superior variety scions onto the root segments in a greenhouse; moisturizing and sand storage to promote healing; and transplanting into nutrient pots in spring.

[0017] In this invention, the warm bed root-promoting cutting technique (winter warm bed root-promoting cutting technique) involves heating the lower part of the cuttings (25-28℃) in early spring (February-March) using a temperature-controlled electric heating bed to promote callus and root primordia formation; simultaneously, the upper part of the cuttings is kept at a low temperature (5-10℃) to inhibit bud sprouting, thus achieving "root promotion and bud control." After 25-30 days of treatment, roots develop at the base of the cuttings, which can then be transplanted into containers for further cultivation.

[0018] Optionally, the container seedling cultivation includes the step of transplanting the seedlings obtained from rapid propagation into a lightweight water-retaining substrate for cultivation. The lightweight water-retaining substrate comprises a substrate and functional substances; the substrate comprises 40-50% peat moss, 20-30% vermiculite, and 10-20% perlite by volume; the functional substances include a water-retaining agent and a slow-release fertilizer; the water-retaining agent is used at 1% of the substrate mass; and the slow-release fertilizer is used at 3% of the substrate mass. The afforestation includes the step of transplanting the container seedlings obtained from the container seedling cultivation; the afforestation time is 10-15 days before the rainy season, and the planting method is to plant in small pits with deep planting, and make the upper edge of the container 5cm below the ground to form a water collection trough.

[0019] This invention provides a culture medium for the asexual reproduction of poplar trees, the culture medium comprising a differentiation medium and a rooting medium; The differentiation culture was conducted using WPM medium as the basal medium, which also contained 1.0 mg / L 6-BA, 0.1 mg / L TDZ, 0.05 mg / L NAA, 30 g / L sucrose and 6 g / L agar. The rooting culture medium used is based on 1 / 2 MS medium, and also contains IBA 0.5 mg / L, NAA 0.1 mg / L, sucrose 25 g / L and agar 6 g / L.

[0020] This invention provides the application of the above-mentioned culture medium in the asexual reproduction of poplar trees.

[0021] This invention provides a method for asexual propagation of poplar trees, comprising the steps of using young poplar leaves as explants for differentiation culture and rooting culture to obtain poplar tissue culture seedlings; the differentiation culture medium is based on WPM medium and also contains 1.0 mg / L 6-BA, 0.1 mg / L TDZ, 0.05 mg / L NAA, 30 g / L sucrose and 6 g / L agar; The rooting medium is based on 1 / 2 MS medium and also contains IBA 0.5 mg / L, NAA 0.1 mg / L, sucrose 25 g / L and agar 6 g / L.

[0022] Optionally, the differentiation culture includes dark culture and light culture; the temperature of the dark culture is 23℃ and the time is 7 days; the temperature of the light culture is 25℃ and the time is 18-20 days, and the light intensity is 1500-2000 lx; ​​the temperature of the rooting culture is 23-25℃ and the time is 15-25 days.

[0023] This invention provides a method for cultivating poplar tissue culture seedlings, including the step of transplanting the poplar tissue culture seedlings obtained by the above method into a lightweight water-retaining substrate for cultivation.

[0024] Optionally, the lightweight water-retaining matrix includes a matrix and functional substances; The matrix comprises 40-50% peat moss, 20-30% vermiculite, and 10-20% perlite by volume. The functional substances include a water-retaining agent and a slow-release fertilizer; the amount of the water-retaining agent is 1% of the substrate mass; the amount of the slow-release fertilizer is 3% of the substrate mass.

[0025] The present invention discloses the following technical effects: 1. Solved the rooting problem of Populus tomentosa: Through a combination of grafting rejuvenation + tissue culture for rapid propagation + temperature-controlled rooting, the rooting rate of Populus tomentosa cuttings was increased from less than 30% to over 90%, clearing away technical obstacles for the promotion of superior varieties.

[0026] 2. Shortened breeding cycle and precise improvement of stress resistance: Combined with molecular marker-assisted selection, drought-resistant and salt-resistant genotypes can be screened out in the seedling stage, shortening the breeding cycle from 10-15 years to 5-8 years.

[0027] 3. Significantly improved afforestation survival rate: The use of lightweight substrate container seedlings combined with rainy season afforestation technology effectively avoids the impact of spring drought winds. Utilizing the characteristics of container seedlings with intact root systems and original soil clumps, the afforestation survival rate can reach over 95%, achieving the effect of seedling cultivation, afforestation, and forest formation all within the same year.

[0028] 4. Significant ecological benefits: By breeding new poplar varieties that do not produce flying catkins (male sterile lines), the problem of urban environmental pollution caused by poplar catkins has been solved at the source, while increasing the forest coverage rate in arid areas. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This shows the rooting status of the test-tube seedlings. Detailed Implementation

[0031] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0032] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0033] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0034] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0035] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0036] Example 1: Application of Bofeng No. 3 Poplar (a hybrid of Populus tomentosa) in semi-arid regions 1. Breeding and resource conservation Using drought-resistant and cold-hardy Populus tomentosa as the female parent and fast-growing and aesthetically pleasing Populus tomentosa as the male parent, F1 generation seeds were obtained. DNA was extracted from the seedlings, and PCR amplification was performed using the PagHB7a molecular marker (the primer pair used to amplify this molecular marker is disclosed in Chinese application number "CN202410569849.4", as shown in SEQ ID NO. 5-SEQ ID NO. 6 of that application). Twenty individual plants possessing the target stress-resistance gene fragment (with salt-tolerance and drought-resistance characteristics) were selected and transplanted to a resource conservation nursery as core germplasm.

[0037] 2. Rapid propagation via tissue culture Differentiation culture: Take young leaves from the above-mentioned superior single plants, disinfect them with 75% (v / v) alcohol for 30 seconds and 0.1wt% mercuric chloride for 6 minutes, then cut them into 0.5cm pieces. 2Leaf discs were inoculated onto differentiation medium (WPM medium as the basal medium, also containing 1.0 mg / L 6-BA, 0.1 mg / L TDZ, 0.05 mg / L NAA, 30 g / L sucrose, and 6 g / L agar, pH 5.8). After 7 days of dark incubation at 23°C, adventitious shoots differentiated from the leaf cuts. Subsequently, the discs were transferred to 25°C for light incubation (1500-2000 lx light intensity, 16 h light exposure, 8 h dark exposure). After 25 days, clustered shoots were obtained, and the adventitious shoot induction rate reached 92.5%. MS medium was used as a control, with an adventitious shoot induction rate of only 45%.

[0038] Rooting culture: After 25 days of differentiation culture, 3cm high adventitious shoots were excised and inoculated into rooting medium (based on 1 / 2 MS medium, also containing IBA 0.5mg / L, NAA 0.1mg / L, sucrose 25g / L and agar 6g / L, pH 5.8). Rooted tissue culture seedlings were obtained after 15 days at 23℃, and their rooting rate, average number of roots, and root length were investigated. The results showed that the rooting rate was 100%, the average number of roots was 8.2 per plant, and the root length was 3-5cm.

[0039] 3. Container seedling cultivation After 25 days of rooting culture, the rooted tissue culture seedlings were transplanted into a lightweight water-retaining substrate (the lightweight water-retaining substrate consists of a substrate and functional materials, wherein the substrate is 40-50% (v / v) peat moss, 20-30% (v / v) vermiculite, and 10-20% (v / v) perlite (in this example, peat moss:vermiculite:perlite = 5:3:2 (volume ratio), that is, the substrate is 50% (v / v) peat moss, 30% (v / v) vermiculite, and 10% (v / v) perlite). The substrate consists of vermiculite and 20% (v / v) perlite. Functional substances include a water-retaining agent (polyacrylamide, manufactured by Henan Huaquan Water Supply Materials Plant) and Stanley slow-release fertilizer (a nitrogen-phosphorus-potassium compound fertilizer with a 6-month release period). The water-retaining agent is used at 1% of the substrate mass, and the slow-release fertilizer at 3% of the substrate mass. The substrate is placed in a non-woven fabric container (10cm x 15cm, with good air permeability, allowing roots to naturally penetrate without root entrapment, and is biodegradable). Routine management involves spraying water twice daily and applying 0.1wt% urea every 15 days at a rate of 30 liters per acre. With standard water and fertilizer management, after 90-120 days of cultivation, standard container seedlings with a height of 40-60cm, a ground diameter of over 0.5cm, well-developed root systems, and compact root clusters are obtained. After 100 days of cultivation, the seedlings in this embodiment reached an average height of 55cm and a ground diameter of 0.6cm, with well-developed, white, and tightly intertwined root systems. The lightweight, water-retaining substrate provided in this embodiment is formulated specifically for the water-scarce and infertile soil conditions of semi-arid regions. This substrate is characterized by its lightweight, water retention, breathability, and comprehensive nutrient content.

[0040] 4. Afforestation during the rainy season Choose to carry out the procedure 10-15 days before the local rainy season (usually from late June to late July). At this time, rainfall increases and soil moisture improves. Taking advantage of the fact that container seedlings have no slow-release period, the seedling roots can directly absorb natural rainfall from the soil.

[0041] This example demonstrates afforestation conducted on July 5th in Chifeng City, Inner Mongolia Autonomous Region (10 days before the rainy season), on a plot of land previously used for reclaiming farmland. The method of planting seedlings in small, deep pits (30cm x 30cm x 30cm) was employed. The non-woven fabric of the containers was removed, the seedlings were placed inside, and the soil was backfilled and compacted, ensuring the top edge of the container was 5cm below the ground level. A key operation was ensuring the top edge of the container was 5cm below the ground level, forming a pot-shaped drainage trough to maximize the interception of surface runoff and rainwater, thereby increasing soil moisture content. Within 30 days of afforestation, a total of 120mm of rainfall was recorded. The autumn survey of that year showed that the survival rate of afforestation was 96.7% (the conventional control group (the conventional bare-root seedlings (non-container seedlings, without the use of lightweight water-retaining substrate) cultivated in the same batch were planted in the spring of that year (April 10th) using conventional afforestation methods (planting in large pits, 50cm×50cm×50cm, with the seedling roots exposed, and watered once after planting) on ​​the same plot of land that had been converted from farmland) had a survival rate of 52% in spring afforestation). The new shoots grew to 45cm in that year.

[0042] Example 2 This embodiment focuses on the study of cytokinin (6-BA) and inorganic salt concentrations, as detailed below: 1. Study on inorganic salt concentration Following the steps in Example 1, a sterilized 0.5cm sample was obtained. 2 Leaf discs were used as explants. Sterilized explants were inoculated into four different inorganic salt concentrations (1 / 2 MS, MS, WPM, 1 / 2 WPM) in Table 1 and cultured at 23°C under the same materials and conditions (culture conditions: first, 7 days of dark culture at 23°C; then 18 days of light culture at 25°C, with a light intensity of 1500-2000 lx). The results are shown in Table 1. The results showed that the MS, 1 / 2 MS, and 1 / 2 WPM treatments resulted in lower induction rates and fewer shoots, while WPM showed the best induction effect.

[0043] Table 1. Effects of inorganic salts on in vitro seedling induction 2. 6-BA (0.5, 0.8, 1.0, 1.5, 2 mg·L -1 Concentration study Following the steps in Example 1, a sterilized 0.5cm sample was obtained. 2Leaf discs were used as explants. Sterilized explants were inoculated into five different 6-BA concentrations (WPM + 6-BA) culture media as shown in Table 1, and cultured at 23°C under the same materials and conditions (culture conditions: first, 7 days of dark culture at 23°C; then 18 days of light culture at 25°C, with a light intensity of 1500-2000 lx). The results are shown in Table 2. The results indicate that cytokinin concentration affects the induction of in vitro seedlings. In summary, the cytokinin concentration should be controlled at 1 mg / L. -1 .

[0044] Table 2 Effects of cytokinins on in vitro seedling induction Example 3 This example studies the effect of different concentrations of NAA on root induction, as detailed below: Vigorous, young, and robust test-tube seedlings were selected as materials. Leaf buds (i.e., adventitious buds obtained from differentiation culture in Example 1) were cut and rooted. The rooting culture conditions were the same as in Example 1. The results are shown in Table 3 and... Figure 1 As shown. In the culture medium with the other hormones unchanged (i.e., the rooting medium in Example 1), the rooting rate gradually increased with the addition of NAA. When the NAA concentration was 0.1 mg·L⁻¹ -1 The rooting rate was highest when the concentration of NAA exceeded 0.3 mg / L, and the resulting roots exhibited good growth indicators and robust root systems. -1 As time progressed, the rooting rate gradually decreased, and the average number of roots and root length also showed a downward trend. Therefore, the optimal NAA concentration for inducing rooting culture was 0.1 mg·L⁻¹. -1 .

[0045] Table 3 Effects of different NAA concentrations on root induction The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An integrated method for the selection, rapid propagation, and container seedling cultivation of superior varieties of Populus tomentosa suitable for semi-arid regions, characterized in that, The process includes hybridization using silver poplar or Xinjiang poplar as the female parent and white poplar or silver gray poplar as the male parent, and screening for F1 generation plants with salt and drought resistance characteristics using molecular markers. The F1 generation plants are then subjected to rapid propagation, container seedling cultivation and afforestation. The rapid propagation method includes one or more of grafting rejuvenation, root-inducing cuttings in a warm bed, and tissue culture.

2. The integration method according to claim 1, characterized in that, The molecular marker includes the PagHB7a molecular marker; the PagHB7a molecular marker is obtained by amplification using the upstream primer shown in SEQ ID NO.1 and the downstream primer shown in SEQ ID NO.

2.

3. The integration method according to claim 1, characterized in that, The grafting rejuvenation includes the step of using budded branches of the F1 generation plant as scions and grafting the scions onto the rootstock to cultivate grafted seedlings with self-rooted growth. The hotbed rooting and cutting propagation includes the step of using the root sprouts of the F1 generation plants as cuttings and inserting the cuttings into a hotbed for cultivation. The tissue culture includes the steps of differentiation culture and rooting culture using young leaves of the F1 generation plants as explants. The differentiation culture uses WPM medium as the basal medium, which also contains 1.0 mg / L 6-BA, 0.1 mg / L TDZ, 0.05 mg / L NAA, 30 g / L sucrose, and 6 g / L agar. The rooting culture uses 1 / 2 MS medium as the basal medium, which also contains 0.5 mg / L IBA, 0.1 mg / L NAA, 25 g / L sucrose, and 6 g / L agar. The differentiation culture includes dark culture and light culture. The dark culture is conducted at 23°C for 7 days. The light culture is conducted at 25°C for 18-20 days, with a light intensity of 1500-2000 lx. The rooting culture is conducted at 23-25°C for 15-25 days.

4. The integration method according to claim 1, characterized in that, The container seedling cultivation includes the step of transplanting seedlings obtained from rapid propagation into a lightweight, water-retaining substrate for cultivation. The lightweight, water-retaining substrate comprises a substrate and functional substances. The substrate comprises 40-50% peat moss, 20-30% vermiculite, and 10-20% perlite by volume. The functional substances include a water-retaining agent and a slow-release fertilizer. The water-retaining agent is used at 1% of the substrate mass; the slow-release fertilizer is used at 3% of the substrate mass. The afforestation includes the step of transplanting the container seedlings obtained from the container seedling cultivation; the afforestation time is 10-15 days before the rainy season, and the planting method is deep planting in small pits.

5. A culture medium for the asexual propagation of poplar trees, characterized in that, The culture medium includes differentiation medium and rooting medium; The differentiation medium is based on WPM medium and also contains 1.0 mg / L 6-BA, 0.1 mg / L TDZ, 0.05 mg / L NAA, 30 g / L sucrose and 6 g / L agar; The rooting medium is based on 1 / 2 MS medium and also contains IBA 0.5 mg / L, NAA 0.1 mg / L, sucrose 25 g / L and agar 6 g / L.

6. The application of the culture medium according to claim 5 in the asexual reproduction of poplar.

7. A method for asexual propagation of poplar trees, characterized in that, The procedure includes the steps of using young poplar leaves as explants for differentiation and rooting culture to obtain poplar tissue culture seedlings; the differentiation culture uses WPM medium as the basal medium, which also contains 1.0 mg / L 6-BA, 0.1 mg / L TDZ, 0.05 mg / L NAA, 30 g / L sucrose and 6 g / L agar; The rooting culture medium used is based on 1 / 2 MS medium, and also contains IBA 0.5 mg / L, NAA 0.1 mg / L, sucrose 25 g / L and agar 6 g / L.

8. The method according to claim 7, characterized in that, The differentiation culture includes dark culture and light culture; the temperature of the dark culture is 23℃ and the time is 7 days; the temperature of the light culture is 25℃ and the time is 18-20 days, with a light intensity of 1500-2000 lx. The rooting culture was conducted at a temperature of 23-25℃ for 15-25 days.

9. A method for cultivating poplar tissue culture seedlings, characterized in that, The method includes the step of obtaining poplar tissue culture seedlings using the method described in claim 7 or 8, and then transplanting them into a lightweight, water-retaining substrate for cultivation.

10. The cultivation method according to claim 9, characterized in that, The lightweight water-retaining matrix includes a matrix and functional substances; The matrix comprises 40-50% peat moss, 20-30% vermiculite, and 10-20% perlite by volume. The functional substances include a water-retaining agent and a slow-release fertilizer; the amount of the water-retaining agent is 1% of the substrate mass; the amount of the slow-release fertilizer is 3% of the substrate mass.

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