Ambusa activation-based axillary bud-free populus nigra microbranch efficient seed ear propagation method

Abstract

The invention relates to a cambium activation-based axillary bud-free poplar nigra microbranch efficient ear breeding method, and belongs to the technical field of forest vegetative propagation. In order to solve the problems that existing small black poplar seed ear propagation depends on axillary buds, and the seed ear yield is low, the axillary bud-free small black poplar micro-branch efficient seed ear propagation method based on cambium activation is provided, axillary bud-free micro-branches are selected, subjected to sterile disinfection treatment and then cut into a breathable moisturizing matrix containing a nutrient solution and with the humidity being 80-120%, the air humidity is maintained to be 95 + / -5%, and the seed ear yield is low. And activating cambium cell division by the breathable moisturizing matrix and the air humidity synergistic nutrient solution, shearing adventitious buds for conventional rooting, and transplanting and culturing to obtain the populus nigra seed ears. According to the method, the traditional propagation logic depending on axillary buds is broken through, through directional activation of axillary bud-free populus nigra microbranch cambium cell viability and in combination with coordinated regulation and control of humidity, a matrix and a nutrient solution, efficient seed ear propagation of directly inducing sprout tillers through axillary bud-free microbranches is achieved, and the yield of the seed ears of populus nigra is greatly increased.

Description

Technical Field

[0001] The invention belongs to the technical field of forest tree seedling cultivation, in particular to the technical field of forest tree asexual propagation, and specifically to a method for efficiently propagating small black poplar micro-branches without axillary buds based on cambium activation. Background Art

[0002] Populus simonii × P. nigra belongs to the genus Populus in the family Salicaceae and is bred by artificial hybridization of Populus simonii and Populus nigra. This tree species prefers cold and humid climates, grows fast, has strong adaptability, has stable traits, is cold-resistant, drought-resistant, and resistant to diseases and insects. It can be used for industrial timber, carbon sink afforestation, environmental protection, and urban greening. It is an extremely important ecological resource and bioenergy with high ecological, economic, and social value.

[0003] However, the aging and degeneration of the small black poplar variety, as well as the multiple and mixed strains, are common, mainly manifested in the decline of forest growth, yellowing and falling leaves, serious pests and diseases, severe sunburn of seedlings, windfall and wind breakage, low afforestation survival rate, weakened winter resistance to cold and drought, and reduced protection effectiveness. Maintaining the excellent species of small black poplar has become an important issue that urgently needs to be paid attention to and resolved in forestry production and environmental construction.

[0004] The seed spike propagation of forest trees is asexual reproduction, using the vegetative organs of forest trees for reproduction, which has the advantages of maintaining the excellent traits of the mother plant and fast reproduction speed. The seed spike propagation of small black poplars usually adopts the cutting method, which is carried out once a year. It is more convenient when there are sufficient propagation materials. However, if there is a lack of propagation materials, cuttings are only carried out once a year, and only one branch is retained, which greatly limits the scale reproduction speed of small black poplars.

[0005] Moreover, when using conventional cuttings for Populus dasyphylla, cuttings with a length of 12 to 15 cm and 2 to 3 full axillary buds are required, and the cuttings are cut into a flat upper incision and a horseshoe-shaped lower incision. The upper incision should be 2 cm away from the top bud to prevent the bud from drying out. This cutting method requires more propagation materials, and a lot of materials will be wasted during the actual operation. Moreover, the traditional cutting method relies on the axillary buds to initiate growth. If the axillary buds are damaged or grow poorly, it will affect the effective absorption of nutrients and water by the heading, and thus affect its overall growth condition. So far, there have been no reports of any tree species achieving efficient seed spike propagation through axillary bud-free micro-branches at home and abroad. How to achieve efficient seed spike propagation of Populus dasyphylla is still a problem that needs to be solved in the field of asexual reproduction of forest trees. Summary of the invention

[0006] In order to solve the problem that the existing black poplar seed spike reproduction is too dependent on axillary buds and the seed spike yield is low, the present invention provides a method for efficiently reproducing black poplar seed spikes with micro-branches without axillary buds based on cambium activation.

[0007] Technical solution of the present invention:

[0008] A method for efficient propagation of seed spikes of Populus simonii×P. nigra micro-branches without axillary buds based on cambium activation. Select Populus simonii×P. nigra micro-branches without axillary buds. After subjecting the Populus simonii×P. nigra micro-branches without axillary buds to aseptic disinfection treatment, insert them into a breathable and moisturizing substrate with a humidity of 80-120% containing nutrient solution, and maintain the air humidity at 95±5%. The breathable and moisturizing substrate and the air humidity cooperate with the nutrient solution to activate the cambium cell division, and adventitious buds are formed through cultivation. Cut the adventitious buds for conventional rooting and transplanting cultivation to obtain Populus simonii×P. nigra seed spikes.

[0009] Furthermore, the Populus simonii×P. nigra micro-branches without axillary buds are selected from the axillary-bud-free parts of rejuvenated semi-lignified spikelets of excellent individual plants over 40 years old, and cut to obtain 3-4 cm.

[0010] Furthermore, for the aseptic disinfection treatment, soak the Populus simonii×P. nigra micro-branches without axillary buds in 75% ethanol for 30-60 seconds, rinse with sterile water, and then sterilize with 0.1% HgCl2 for 2-10 minutes.

[0011] Furthermore, the breathable and moisturizing substrate is a mixed substrate of peat soil and perlite, and the volume ratio of the peat soil to the perlite is 2:1.

[0012] Furthermore, the humidity of the breathable and moisturizing substrate is 80%.

[0013] Furthermore, the nutrient solution is 1 / 2MS macroelement nutrient solution.

[0014] Furthermore, the temperature for the cultivation is 25-28 °C, and the light time is 16 hours of light / 8 hours of darkness.

[0015] Furthermore, the time for the cultivation to form adventitious buds is 35-45 days.

[0016] Beneficial effects of the present invention:

[0017] The present invention breaks through the traditional propagation logic relying on axillary buds. Through the directional activation of the cambium cell activity of Populus simonii×P. nigra micro-branches without axillary buds, combined with the coordinated regulation of humidity, substrate and nutrient solution, efficient propagation of seed spikes with direct induction of tillering from micro-branches without axillary buds is realized, significantly improving the yield and quality of Populus simonii×P. nigra seed spikes. The incidence rate of adventitious buds from the cambium of the seed spike propagation method of the present invention is 100%, the average number of germinated buds per branch reaches 4.9±0.88, the seed spike yield is increased by 4.8 times compared with the traditional cutting method relying on axillary buds, and the propagation cycle is also shortened from 6-8 months of the traditional cutting method to 3 months.

[0018] Applying the method for highly efficient propagation of axillary-bud-free Populus simonii Carr. micro-branch based on cambium activation of the present invention to asexual propagation of excellent germplasm resources of Populus simonii Carr. has a positive effect on promoting the establishment of Populus simonii Carr. cutting stock orchards and improving the yield and propagation ability of cuttings. It not only helps to protect the excellent germplasm resources of Populus simonii Carr., effectively promotes the propagation and popularization of excellent germplasm resources of Populus simonii Carr., but also can provide high-quality seedling resources for forestry production and promote the sustainable development of forestry. Description of the Drawings

[0019] Figure 1 It is a physical photograph of adventitious buds of the cambium of Populus simonii Carr. one week after cutting inoculation in Example 3;

[0020] Figure 2 It is a physical photograph of the growth state of adventitious buds of the cambium 30 days after growth in Example 3;

[0021] Figure 3 It is a physical photograph of the container seedlings obtained after culturing for 30 days after rooting and transplanting of the adventitious buds of the cambium after cutting in Example 3;

[0022] Figure 4 It is a physical photograph of the growth state of adventitious buds of the cambium 38 days after growth in Example 2;

[0023] Figure 5 It is a physical photograph of the growth state of adventitious buds without nutrient solution substrate culture for 30 days in Comparative Example 4. Detailed Embodiments

[0024] The technical solutions of the present invention will be further described below in conjunction with the embodiments, but are not limited thereto. Any modification or equivalent replacement of the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention shall be covered by the protection scope of the present invention. The process equipment or devices not specifically noted in the following embodiments are all conventional equipment or devices in the art. If not specifically indicated, the raw materials used in the embodiments of the present invention can be obtained commercially; if not specifically indicated, the technical means used in the embodiments of the present invention are all conventional means well known to those skilled in the art.

[0025] Example 1

[0026] This example provides a method for highly efficient propagation of axillary-bud-free Populus simonii Carr. micro-branch based on cambium activation.

[0027] Source of axillary bud - free Populus simonii×P. nigra micro - branches used in this example: In 2022, at the National Fine Tree Seeds Base of Populus and Pinus sylvestris var. mongolica in Fularji District, Qiqihar City, Heilongjiang Province (123°56'35.378"E, 47°20'52.151"N), rejuvenation treatments of burying stems and roots were carried out on 40 - year - old mature Populus simonii×P. nigra clones with excellent individual plants. In March 2023, the sprouting spikes obtained from the stem - burying treatment and root - burying treatment, as well as the branches of superior trees collected, were screened and cut into cuttings with a length of 10 - 12 cm and a diameter of 1.5 - 2 cm. The cuttings were cultured by film - covering cutting in the greenhouse of Qiqihar University. After 6 months of cutting, a certain number of seed spikes were obtained.

[0028] Select the axillary - bud - free part of the semi - lignified spike, cut 3 - 4 cm to obtain axillary - bud - free Populus simonii×P. nigra micro - branches. Soak the axillary - bud - free Populus simonii×P. nigra micro - branches in 75% ethanol for 30 seconds, rinse with sterile water 3 times, and then sterilize with 0.1% HgCl2 for 5 minutes for standby.

[0029] Prepare a mixed matrix by mixing peat soil and perlite in a volume ratio of 2:1, add 1 / 2MS macro - element nutrient solution to the obtained mixed matrix to make the matrix humidity reach 100% saturation state to obtain a breathable and moisturizing matrix. Put the breathable and moisturizing matrix into a tissue culture bottle for autoclaving and cool down for standby.

[0030] On a sterile operating table, insert the axillary - bud - free Populus simonii×P. nigra micro - branches that have been sterilized aseptically into the breathable and moisturizing matrix, tighten the tissue culture bottle, and maintain the air humidity in the bottle at 95±5%. After inoculation, place the tissue culture bottle in an incubator for cultivation. The indoor cultivation temperature is 25°C, the light intensity of the lamp rack in the tissue culture room is 2500 Lux, and the light time is 16 hours of light / 8 hours of darkness.

[0031] The 1 / 2MS macro - element nutrient solution in the breathable and moisturizing matrix can activate the cambium cell division and enhance the growth potential of the bud bodies. After 40 days of cultivation, adventitious buds are formed. Cut the adventitious buds for conventional rooting and transplanting cultivation to obtain Populus simonii×P. nigra seed spikes.

[0032] Example 2

[0033] This example provides a method for efficient propagation of axillary - bud - free Populus simonii×P. nigra seed spikes based on cambium activation.

[0034] The difference between this example and Example 1 is that the axillary - bud - free part of the semi - lignified spike is selected, cut 3 - 4 cm to obtain axillary - bud - free Populus simonii×P. nigra micro - branches, soak the axillary - bud - free Populus simonii×P. nigra micro - branches in 75% ethanol for 60 seconds, rinse with sterile water 5 times, and then sterilize with 0.1% HgCl2 for 10 minutes for standby.

[0035] Prepare a mixed substrate by mixing peat soil and perlite in a volume ratio of 2:1. Add 1 / 2MS macroelement nutrient solution to the obtained mixed substrate to make the substrate humidity reach 120% saturation state, obtaining a breathable and moisture-retaining substrate. Put the breathable and moisture-retaining substrate into a tissue culture bottle for autoclaving, and cool it for later use.

[0036] On a sterile operating table, insert the axillary bud-free micro-branches of Populus simonii Carr. that have been sterilized aseptically into the breathable and moisture-retaining substrate, tighten the tissue culture bottle, and maintain the air humidity in the bottle at 95±5%. After inoculation, place the tissue culture bottle in an incubator for cultivation. The indoor cultivation temperature is 28°C, the light intensity of the lamp rack in the tissue culture room is 2500 Lux, and the light duration is 16 hours of light / 8 hours of darkness.

[0037] The 1 / 2MS macroelement nutrient solution in the breathable and moisture-retaining substrate can activate the division of cambium cells and enhance the growth of bud bodies. Adventitious buds are formed after 38 days of cultivation. Cut the adventitious buds for conventional rooting and transplanting cultivation to obtain Populus simonii Carr. seed spikes.

[0038] Figure 4 Figure; for the physical photo of the growth state of adventitious buds at 38 days of the adventitious bud growth of the cambium in Example 2; from Figure 4 It can be seen that the adventitious buds formed by the propagation method provided by the present invention are numerous and of good quality, and can improve the yield and propagation ability of Populus simonii Carr. spikelets.

[0039] Example 3

[0040] This example provides a high-efficiency seed spike propagation method for axillary bud-free micro-branches of Populus simonii Carr. based on cambium activation.

[0041] The difference between this example and Example 1 is that the axillary bud-free part of the semi-lignified spike is selected, cut into 3-4 cm to obtain axillary bud-free micro-branches of Populus simonii Carr., soak the axillary bud-free micro-branches of Populus simonii Carr. in 75% ethanol for 50 seconds, rinse 4 times with sterile water, and then sterilize with 0.1% HgCl2 for 8 minutes for later use.

[0042] Prepare a mixed substrate by mixing peat soil and perlite in a volume ratio of 2:1. Add 1 / 2MS macroelement nutrient solution to the obtained mixed substrate to make the substrate humidity reach 80% saturation state, obtaining a breathable and moisture-retaining substrate. Put the breathable and moisture-retaining substrate into a tissue culture bottle for autoclaving, and cool it for later use.

[0043] On a sterile operating table, insert the axillary bud-free micro-branches of Populus simonii Carr. that have been sterilized aseptically into the breathable and moisture-retaining substrate, tighten the tissue culture bottle, and maintain the air humidity in the bottle at 95±5%. After inoculation, place the tissue culture bottle in an incubator for cultivation. The indoor cultivation temperature is 26°C, the light intensity of the lamp rack in the tissue culture room is 2500 Lux, and the light duration is 16 hours of light / 8 hours of darkness.

[0044] The 1 / 2MS macroelement nutrient solution in the breathable and moisturizing substrate can activate the cambial cell division and enhance the growth of bud bodies. Adventitious buds are formed after 42 days of culture. The adventitious buds are cut and subjected to conventional rooting and transplanting culture to obtain the seed ears of Populus simonii×P. nigra.

[0045] Figure 1 It is a physical photo of the adventitious buds formed in the cambium of Populus simonii×P. nigra one week after cutting inoculation in Example 3; Figure 2 It is a physical photo of the growth state of adventitious buds when the adventitious buds formed in the cambium of Example 3 grow for 30 days; Figure 3 It is a physical photo of the container seedlings obtained after 30 days of culture after rooting and transplanting of the adventitious buds formed in the cambium of Example 3 after cutting; It can be seen from Figures 1-3 that the propagation method provided by the present invention realizes the direct sprouting of the cambium of micro-branches of Populus simonii×P. nigra without axillary buds, and significantly shortens the propagation cycle of the seed ears of Populus simonii×P. nigra.

[0046] Comparative Example 1

[0047] The difference between this comparative example and Example 1 is that the axillary-bud-free part of the semi-lignified ear shoots is selected, and 3-4 cm is cut to obtain the axillary-bud-free micro-branches of Populus simonii×P. nigra. The axillary-bud-free micro-branches of Populus simonii×P. nigra are soaked in 75% ethanol for 30 seconds, rinsed 3 times with sterile water, and then sterilized with 0.1% HgCl2 for 5 minutes for standby.

[0048] A mixed substrate is prepared with peat soil and perlite in a volume ratio of 2:1. The 1 / 2MS macroelement nutrient solution is added to the obtained mixed substrate to make the humidity of the substrate reach 100% saturation state to obtain a breathable and moisturizing substrate. The breathable and moisturizing substrate is autoclaved and then placed in a plug tray, and cooled for standby.

[0049] The axillary-bud-free micro-branches of Populus simonii×P. nigra that have been sterilized aseptically are cut and inserted into the breathable and moisturizing substrate. After inoculation, the plug tray is placed in a culture room for culture. The indoor air humidity is maintained at 50±5%, the indoor culture temperature is 25°C, the light intensity of the lamp rack in the tissue culture room is 2500 Lux, and the light time is 16 hours of light / 8 hours of darkness. Observe the formation of adventitious buds during the culture.

[0050] Comparative Example 2

[0051] The difference between this comparative example and Example 1 is that the axillary-bud-free part of the semi-lignified ear shoots is selected, and 3-4 cm is cut to obtain the axillary-bud-free micro-branches of Populus simonii×P. nigra. The axillary-bud-free micro-branches of Populus simonii×P. nigra are soaked in 75% ethanol for 30 seconds, rinsed 3 times with sterile water, and then sterilized with 0.1% HgCl2 for 5 minutes for standby.

[0052] A mixed substrate is prepared with peat soil and perlite in a volume ratio of 2:1. The 1 / 2MS macroelement nutrient solution is added to the obtained mixed substrate to make the humidity of the substrate reach 30% saturation state to obtain a breathable and moisturizing substrate. The breathable and moisturizing substrate is autoclaved in a tissue culture bottle and cooled for standby.

[0053] On the aseptic workbench, insert the axillary-budless Populus simonii×P. nigra micro-branches that have been aseptically disinfected into the breathable and moisture-retaining substrate, tighten the tissue culture bottle, and maintain the air humidity in the bottle at 95±5%. After inoculation, place the tissue culture bottle in the culture room for cultivation. The indoor cultivation temperature is 25°C, the light intensity of the lamp rack in the tissue culture room is 2500 Lux, and the light duration is 16 hours of light / 8 hours of darkness. Cultivate and observe the formation of adventitious buds.

[0054] Comparative Example 3

[0055] The difference between this comparative example and Example 1 is that the axillary-budless part of the semi-lignified spike is selected, and axillary-budless Populus simonii×P. nigra micro-branches are cut to obtain 3-4 cm, and the axillary-budless Populus simonii×P. nigra micro-branches are soaked in 75% ethanol for 30 seconds, rinsed 3 times with sterile water, and then sterilized with 0.1% HgCl2 for 5 minutes for standby.

[0056] Prepare a mixed substrate by mixing peat soil and perlite in a volume ratio of 2:1, add 1 / 2MS macroelement nutrient solution to the obtained mixed substrate to make the substrate humidity reach 50% saturation state to obtain a breathable and moisture-retaining substrate, put the breathable and moisture-retaining substrate into the tissue culture bottle for high-pressure sterilization, and cool it for standby.

[0057] On the aseptic workbench, insert the axillary-budless Populus simonii×P. nigra micro-branches that have been aseptically disinfected into the breathable and moisture-retaining substrate, tighten the tissue culture bottle, and maintain the air humidity in the bottle at 95±5%. After inoculation, place the tissue culture bottle in the culture room for cultivation. The indoor cultivation temperature is 25°C, the light intensity of the lamp rack in the tissue culture room is 2500 Lux, and the light duration is 16 hours of light / 8 hours of darkness. Cultivate and observe the formation of adventitious buds.

[0058] Comparative Example 4

[0059] The difference between this comparative example and Example 1 is that the axillary-budless part of the semi-lignified spike is selected, and axillary-budless Populus simonii×P. nigra micro-branches are cut to obtain 3-4 cm, and the axillary-budless Populus simonii×P. nigra micro-branches are soaked in 75% ethanol for 30 seconds, rinsed 3 times with sterile water, and then sterilized with 0.1% HgCl2 for 5 minutes for standby.

[0060] Prepare a mixed substrate by mixing peat soil and perlite in a volume ratio of 2:1, add pure water to the obtained mixed substrate to make the substrate humidity reach 100% saturation state to obtain a breathable and moisture-retaining substrate, put the breathable and moisture-retaining substrate into the tissue culture bottle for high-pressure sterilization, and cool it for standby.

[0061] On the aseptic workbench, insert the axillary-budless Populus simonii×P. nigra micro-branches that have been aseptically disinfected into the breathable and moisture-retaining substrate, tighten the tissue culture bottle, and maintain the air humidity in the bottle at 95±5%. After inoculation, place the tissue culture bottle in the culture room for cultivation. The indoor cultivation temperature is 25°C, the light intensity of the lamp rack in the tissue culture room is 2500 Lux, and the light duration is 16 hours of light / 8 hours of darkness. Cultivate and observe the formation of adventitious buds.

[0062] Figure 5 Figure 30 shows the physical photo of the adventitious bud growth state during the 30-day culture in the non-nutrient solution substrate for Comparative Example 4. It can be seen from Figure 5 that in the case of lacking the activation effect of nutrient solution on cambium cells, the number of adventitious buds formed is small, the bud bodies are weak, and the quality is poor, which is not conducive to the propagation of the seed ears of Populus simonii×P. nigra.

[0063] Comparative Example 5

[0064] The difference between this comparative example and Example 1 is that the axillary-budless part of the semi-lignified spike is selected, and the axillary-budless Populus simonii×P. nigra micro-branches are cut to 3-4 cm, soaked in 75% ethanol for 30 seconds, rinsed 3 times with sterile water, and sterilized with 0.1% HgCl2 for 5 minutes, and then reserved.

[0065] The mixed substrate is prepared with peat soil and perlite in a volume ratio of 2:1, and 1 / 4MS macroelement nutrient solution is added to the obtained mixed substrate to make the substrate humidity reach 100% saturation state to obtain a breathable and moisturizing substrate. The breathable and moisturizing substrate is put into a tissue culture bottle for autoclaving, and then cooled for standby.

[0066] On the sterile operating table, the axillary-budless Populus simonii×P. nigra micro-branches after aseptic disinfection treatment are inserted into the breathable and moisturizing substrate, and the tissue culture bottle is tightened, and the air humidity in the bottle is maintained at 95±5%. After inoculation, the tissue culture bottle is placed in the culture room for cultivation. The indoor culture temperature is 25 °C, the light intensity of the lamp rack in the tissue culture room is 2500 Lux, and the light time is 16 hours of light / 8 hours of darkness. Observe the formation of adventitious buds during cultivation.

[0067] The adventitious bud incidence rate, average germination number and bud growth vigor of Examples 1-3 and Comparative Examples 1-5 were counted, and the results are shown in Tables 1, 2 and 3.

[0068] Table 1 shows the comparison results of the formation of adventitious buds in the cambium of Populus simonii×P. nigra micro-branches under different air humidities in Example 3 and Comparative Example 1.

[0069] Table 1

[0070]

[0071] Table 2 shows the comparison results of the formation of adventitious buds in the cambium of Populus simonii×P. nigra micro-branches under different substrate humidities in Examples 1-3 and Comparative Examples 2-3.

[0072] Table 2

[0073]

[0074] Table 3 shows the comparison results of the formation of adventitious buds in the cambium of Populus simonii×P. nigra micro-branches under different nutritional conditions in Example 3 and Comparative Examples 4 and 5.

[0075] Table 3

[0076]

[0077] It can be seen from the data comparison in Table 1 - Table 3 that, compared with substrate humidity and nutrient solution concentration, air humidity has a more significant impact on the germination of adventitious buds in the cambium of Populus simonii×P. nigra. In a high - humidity environment (such as 95±5%), the turgor pressure of plant cells is relatively high, and there is sufficient water in the cells, which helps to maintain the activity and metabolic processes of cells. For cambium cells, sufficient water enables them to maintain good division and differentiation abilities, thus promoting the formation of adventitious buds. The high - humidity environment reduces the water loss of plants, enabling plants to use more energy and substances for the induction and growth of adventitious buds. In a low - humidity environment (50±5%), the risk of water loss from plant cells increases, and the cell turgor pressure decreases, resulting in a slowdown in the metabolism of cambium cells. In order to reduce water loss, cambium cells will enter a self - protection state, inhibiting their division and differentiation activities, and thus leading to a significant reduction or even zero in the induction rate of adventitious buds. The principles by which these humidities affect adventitious buds in the cambium further explain the experimental results and also provide a theoretical basis for plant micropropagation technology.

Claims

1. An efficient method for propagating micro-branch spike of Populus simonii×P. nigra without axillary buds based on cambium activation, characterized in that Select the micro-branches of Populus simonii Carr. without axillary buds. After subjecting the micro-branches of Populus simonii Carr. without axillary buds to aseptic disinfection treatment, insert them into a breathable and moisture-retaining substrate with a humidity of 80 - 120% containing nutrient solution, and maintain the air humidity at 95 ± 5%. The breathable and moisture-retaining substrate and the air humidity synergistically activate the cambial cell division with the nutrient solution, and adventitious buds are formed through cultivation. Cut the adventitious buds and conduct conventional rooting and transplanting cultivation to obtain the seed spikes of Populus simonii Carr.

2. The method for highly efficient propagation of micro-branch ear of Populus simonii Carr. without axillary buds based on cambium activation according to claim 1, wherein The micro-branches of Populus simonii Carr. without axillary buds are selected from the axillary-bud-free parts of the rejuvenated semi-lignified spikelets of excellent individual plants over 40 years old, and cut to obtain 3 - 4 cm.

3. The efficient propagation method of the spike of Populus simonii×P. nigra micro-branches without axillary buds based on cambium activation according to claim 1 or 2, characterized in that, For the aseptic disinfection treatment, soak the micro-branches of Populus simonii Carr. without axillary buds in 75% ethanol for 30 - 60 seconds, rinse with sterile water, and then sterilize with 0.1% HgCl2 for 2 - 10 minutes.

4. The efficient propagation method of micro-branch spike of Populus simonii Carr. without axillary buds based on cambium activation according to claim 3, characterized in that, The breathable and moisture-retaining substrate is a mixed substrate of peat soil and perlite, and the volume ratio of peat soil to perlite is 2:

1.

5. The highly efficient seed spike propagation method of Populus simonii×P. nigra micro-branches without axillary buds based on cambium activation according to claim 4, characterized in that, The humidity of the breathable and moisture-retaining substrate is 80%.

6. The highly efficient seed ear propagation method of Populus simonii×P. nigra micro-branches without axillary buds based on cambium activation according to claim 5, characterized in that, The nutrient solution is 1 / 2MS macroelement nutrient solution.

7. The method for highly efficient propagation of seed spikes of Populus simonii×P. nigra micro-branches without axillary buds based on cambium activation according to claim 6, characterized in that, The temperature for the cultivation is 25 - 28 °C, and the light time is 16 hours of light / 8 hours of darkness.

8. The method for highly efficient seed ear propagation of Populus simonii×P. nigra micro-branches without axillary buds based on cambium activation according to claim 7, wherein, The time for cultivating adventitious buds is 35 - 45 days.

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