Method for improving cold resistance of hybrid pennisetum

Abstract

The present application relates to the domestication technical field of Pennisetum, and more particularly to a method for improving the cold resistance of hybrid Pennisetum.The present application takes hybrid Pennisetum in the seedling stage and the whole growth period as the research object, gradually improves the cold resistance of the hybrid Pennisetum by combining the artificial control of low-temperature domestication and the field overwintering domestication, and greatly improves the overwintering rate of the hybrid Pennisetum in the north.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of Pennisetum, and particularly relates to a method for improving cold resistance of hybrid Pennisetum. BACKGROUND

[0002] Hybrid Pennisetum is a perennial grass, which is originally from Africa and is mainly distributed in tropical and subtropical regions. Hybrid Pennisetum has the advantages of rapid growth, high plant height, more leaves, strong tillering ability, good regeneration, high biomass yield and excellent quality. At present, hybrid Pennisetum has been widely studied and applied as a high-yield and high-quality forage grass. However, hybrid Pennisetum prefers warm and humid climate and is not resistant to low temperature and frost, and therefore cannot naturally survive in the north of the Yangtze River, which is an important bottleneck hindering the wide application of hybrid Pennisetum. In the prior art, there is no related report on improving the cold resistance of hybrid Pennisetum. In other plants, the cold resistance of plants is improved by means of transgenic and gene editing technologies to introduce cold resistance genes, or by spraying some hormone and nutrient agents to enhance the cold resistance of plants, or by using some cultivation and management measures to help plants improve the cold resistance, or by using a technology of microwave treatment combined with low-temperature acclimatization to improve the cold resistance of seeds. These methods have defects such as high cost, difficult breakthrough in technical bottleneck or easy loss of cold resistance traits, and the methods are too specific and are difficult to be directly applied to other plants.

[0003] Low temperature stress is a kind of abiotic stress that plants often suffer from. After suffering from low temperature stress, different organs of plants will be damaged to different degrees, and cell membranes will be ruptured to produce a large amount of malondialdehyde, so that the content of the substance increases sharply. Plants themselves can also reduce the adverse effects of low temperature stress on plants by increasing the contents of main osmotic regulation substances such as soluble sugar and proline, and the activities of some antioxidant enzymes such as superoxide dismutase and peroxidase. SUMMARY

[0004] The present application provides a method for improving the cold resistance of hybrid Pennisetum. The hybrid Pennisetum at the seedling stage and the whole growth period is taken as the research object, and artificial control low-temperature continuous intermittent acclimatization and overwintering acclimatization under a low-cost field management mode are adopted to improve the cold resistance of hybrid Pennisetum year by year, so that a hybrid Pennisetum plant with high cold resistance is finally obtained, which can tolerate low temperature of-1℃ for more than 60 days.

[0005] The present application provides a method for improving the cold resistance of hybrid Pennisetum, which comprises a first stage acclimatization.

[0006] The hybrid Pennisetum seedlings are subjected to the first stage acclimatization, and the first stage acclimatization is sequentially divided into different acclimatization periods according to time, and each acclimatization period is first subjected to low-temperature acclimatization and then subjected to growth recovery.

[0007] The acclimation temperature of the latter acclimation stage is lower than that of the former acclimation stage, the stress duration is longer than that of the former acclimation stage, the recovery duration is shorter than that of the latter acclimation stage, and the stress frequency is higher than that of the former acclimation stage.

[0008] Preferably, the seedlings after the first stage of acclimation are moved to the field for the second stage of acclimation.

[0009] The second stage of acclimation is divided into different growth stages in time sequence, and the hybrid vetiver plants with better overwintering and greening are selected for the next growth stage of acclimation.

[0010] During the overwintering of the vetiver, the covering material is covered, and the thickness of the covering material in the latter growth stage is lower than that in the former growth stage.

[0011] Preferably, it comprises: cold tolerance acclimation of the hybrid vetiver at different time stages; artificial control of the temperature of low temperature acclimation to gradually decrease to -1℃, field overwintering acclimation with the thickness of the covering soil gradually decreasing to 20-30cm, or the thickness of the litter covering decreasing to 35-45cm, and the temperature treatment of the vetiver in the latter acclimation time stage being lower than that in the former time acclimation stage. The low temperature acclimation of the seedling stage hybrid vetiver by artificial control of the low temperature, combined with field planting of the hybrid vetiver, and the use of low-cost overwintering maintenance measures for field overwintering acclimation can improve the cold resistance of the hybrid vetiver.

[0012] Preferably, the first acclimation culture stage is carried out in a low-temperature light incubator, a greenhouse or a big shed.

[0013] According to the method for improving the cold resistance of the hybrid vetiver, the first stage of acclimation comprises in time sequence a first acclimation stage, a second acclimation stage and a third acclimation stage.

[0014] The first acclimation stage: the acclimation temperature is 2-4℃, the stress duration is 10-20 days each time, the recovery growth duration is 12-18 days, and the stress is 3-5 times in total.

[0015] The second acclimation stage: the stress acclimation temperature is 0-2℃, the stress duration is 15-25 days each time, the recovery growth duration is 7-13 days, and the stress is 5-7 times in total.

[0016] The third acclimation stage: the stress acclimation temperature is -2-0℃, the stress duration is 25-35 days each time, the recovery growth duration is 2-8 days, and the stress is 7-9 times in total.

[0017] According to the method for improving the cold resistance of the hybrid vetiver, after the seedlings are moved to the field, the covering material can increase the diurnal temperature difference of the soil.

[0018] Preferably, the covering material is one or more of pebbles, gravel sand and sand.

[0019] Preferably, the hybrid pennisetum plant is covered with sand around the whole plant. After the soil surface is covered with sand or a material with similar specific heat capacity, such as pebbles, gravel sand, fine sand, etc., the effect of increasing the diurnal temperature difference of the soil is achieved, which is beneficial to the accumulation of photosynthetic products such as soluble sugar in the rhizome of hybrid pennisetum. Soluble sugar, as an important osmoregulatory substance for plant resistance to low temperature stress, plays an important role in improving the cold resistance of plants.

[0020] Preferably, the sand covering radius is 30-50 cm, and further preferably 35-45 cm.

[0021] Preferably, the sand covering thickness is 8-30 cm, and further preferably 10-20 cm.

[0022] The technical principle of the hybrid pennisetum plant covered with sand around the whole plant is to increase the diurnal temperature difference of the soil, which is beneficial to the accumulation of photosynthetic products such as soluble sugar in the rhizome of hybrid pennisetum, thereby achieving stronger tolerance to low temperature stress.

[0023] Further preferably, the covering material is one or more of fine sand, river sand, sea sand, mountain sand, and desert sand.

[0024] Preferably, the sand covering treatment is used throughout the second domestication stage.

[0025] The seedling stage hybrid pennisetum is artificially controlled for low temperature domestication, combined with field planting and sand covering treatment, and natural overwintering domestication under simple overwintering maintenance measures. The domestication temperature of the seedling stage pennisetum in the post-domestication stage is lower than that in the pre-domestication stage, and the heat preservation effect of the field overwintering maintenance measures is worse. The cold resistance of hybrid pennisetum can be improved.

[0026] According to the method for improving the cold resistance of hybrid pennisetum, the second stage domestication comprises a first growth period, a second growth period and a third growth period in sequence.

[0027] Preferably, the duration of one growth period is 1 year.

[0028] According to the method for improving the cold resistance of hybrid pennisetum, after the domestication of each growth period is completed, the hybrid pennisetum plants with good overwintering and green return are selected for further domestication until the target plants are screened out.

[0029] According to the method for improving the cold resistance of hybrid pennisetum, the temperature of the second stage domestication is controlled to be above -4℃.

[0030] According to the method for improving the cold resistance of hybrid pennisetum, in the second stage domestication, the covering material is one or more of soil, litter, and artificial heat preservation material.

[0031] Preferably, the artificial heat preservation material is one or more of a heat preservation quilt and a ground cloth.

[0032] According to the method for improving the cold resistance of hybrid Pennisetum, in the second stage of domestication, the covering is soil.

[0033] Preferably, the thickness of the soil covering in the first year is 35-45 cm, and then gradually decreases year by year until it is 20-30 cm in the third year.

[0034] Alternatively, the covering is in the form of litter.

[0035] The thickness of the litter covering in the first year is 55-65 cm, and gradually decreases to 25-35 cm in the third year.

[0036] According to the method for improving the cold resistance of hybrid Pennisetum, during the artificial controlled low-temperature domestication of the hybrid Pennisetum in the seedling stage, the domestication temperature gradually decreases in the first, second, and third growth periods, and the wintering maintenance effect gradually weakens in the field, which is manifested as a gradual decrease in the thickness of the covering (soil or litter). At the same time, during the field planting in the three growth periods, the surface of the soil is treated with sand covering.

[0037] Preferably, the hybrid Pennisetum planted in the field is used as the research object, after the aboveground biomass is harvested at the end of the growing season, the hybrid Pennisetum is maintained and managed for wintering by simply covering the soil or litter, the thickness of the soil covering in the first year is about 40 cm, and then gradually decreases year by year until it is 20 cm in the fourth year, the thickness of the litter covering gradually decreases from the initial 60 cm to 30 cm in the fourth year, the wintering rate is counted and investigated at the beginning of each year, and the hybrid Pennisetum plants with better wintering and greening are screened out, and then the hybrid Pennisetum plants are continuously planted and domesticated, and finally the hybrid Pennisetum plants with stronger cold resistance are screened out.

[0038] According to the method for improving the cold resistance of hybrid Pennisetum, in the first growth period, the environmental temperature of the hybrid Pennisetum is controlled to be -2-0℃ at night during the wintering period.

[0039] In the second growth period, the environmental temperature of the hybrid Pennisetum is controlled to be -3-0℃ at night during the wintering period.

[0040] In the third growth period, the environmental temperature of the hybrid Pennisetum is controlled to be -3-0℃ at night during the wintering period.

[0041] Preferably, in the second domestication stage, the temperature during the day is controlled to be higher than 2℃, preferably higher than 6℃, during the wintering period.

[0042] According to the method for improving the cold resistance of hybrid Pennisetum, in the second domestication stage, the hybrid Pennisetum is domesticated in a greenhouse.

[0043] Preferably, the greenhouse is opened after the first growth period.

[0044] According to the method for improving the cold resistance of the hybrid pennisetum, the hybrid pennisetum after the second domestication stage is transplanted, and the soil is covered by 15-25cm or the litter is covered by 20-30cm in the first overwintering period after the transplantation.

[0045] The beneficial effects of the present application are:

[0046] The present application does not use any biological technology, agent spraying treatment, sound wave treatment and equipment assisted treatment and other high cost treatment methods, and adopts a low cost management and protection method to gradually improve the cold resistance of the hybrid pennisetum.

[0047] The technical principle involved in the present application is the stress memory of plants. When the hybrid pennisetum repeatedly suffers from low temperature stress for a certain period of time, the plant will produce a memory response to low temperature stress. The osmotic adjustment substances in the plant, such as soluble sugar, soluble protein and proline, will respond faster and accumulate more. The enzyme activities of superoxide dismutase and peroxidase will also be quickly improved. The present application can make the hybrid pennisetum have strong cold resistance, and can resist the low temperature stress in the whole winter under the simple overwintering management and protection measures in the northern region.

[0048] The present application also effectively improves the accumulation of energy substances such as soluble sugar in the hybrid pennisetum plant by combining the sand covering treatment around the hybrid pennisetum plant, which can further improve the cold resistance of the hybrid pennisetum.

[0049] The present application can improve the cold resistance of the hybrid pennisetum, and significantly improve the overwintering rate of the hybrid pennisetum under the natural growth conditions in the field.

[0050] The technical scheme adopted by the present application is simple and low in cost, and the effect is obvious. The hybrid pennisetum material with significantly improved cold resistance can be selected, and the hybrid pennisetum can safely overwinter in the northern region of China through low-cost overwintering maintenance measures. BRIEF DESCRIPTION OF DRAWINGS

[0051] In order to more clearly illustrate the technical solutions in the present application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0052] Figure 1 is a flowchart for screening hybrid pennisetum plants with strong cold resistance provided by the present application. DETAILED DESCRIPTION

[0053] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the protection scope of the present application.

[0054] The present application takes hybrid kangaroo grass at the seedling stage and hybrid kangaroo grass planted in the field as the research object. Firstly, artificial low-temperature control is used for continuous intermittent acclimation. The low-temperature acclimation temperature in the first acclimation period is 3℃, and gradually decreases to-1℃ in the third year. After acclimation, the hybrid kangaroo grass seedlings are transplanted to the field, and sand is covered around the hybrid kangaroo grass plants (radius of about 40 cm, thickness of about 15 cm). After harvesting the aboveground biomass at the end of the growing season, the hybrid kangaroo grass is maintained and managed in a simple overwintering way by using simple soil covering or litter covering. The soil covering thickness is about 40 cm in the first year, and then decreases year by year until it is 25 cm in the third year. The litter is gradually reduced from 60 cm at the beginning to 30 cm in the third year. The overwintering rate is counted and investigated at the beginning of each year, and the hybrid kangaroo grass plants with good overwintering and greening are screened out. Then the hybrid kangaroo grass plants are continuously planted and acclimated, and finally the hybrid kangaroo grass plants with strong cold resistance are screened out. The specific process can be seen in Figure 1 .

[0055] Example 1

[0056] The experiment was carried out in Wuqiang County, Hengshui City, Hebei Province. The test site is 65 meters above sea level, and the longitude and latitude are 115°34'E and 37°49'N.

[0057] Firstly, the hybrid kangaroo grass at the 5-leaf stage is placed in a low-temperature light incubator for continuous intermittent low-temperature acclimation. The light intensity of the light incubator is 35000 lux, the light (D) duration is 10 hours, the dark (N) duration is 14 hours, and the humidity is 50%.

[0058] The artificial low-temperature acclimation scheme is as follows:

[0059] The first acclimation period: the stress acclimation temperature is 3℃, the stress duration is 15 days each time, the recovery growth duration is 15 days between stresses, and the stress is 4 times in total;

[0060] The second acclimation period: the stress acclimation temperature is 1℃, the stress duration is 20 days each time, the recovery growth duration is 10 days, and the stress is 6 times in total;

[0061] The third acclimation period: the stress acclimation temperature is -1°C, each stress duration is 30 days, and the recovery growth is 5 days, a total of 8 times of stress; then the hybrid pennisetum seedlings are transplanted to the field. The hybrid pennisetum plants are covered with river sand with a thickness of about 15 cm and a radius of about 40 cm, and the hybrid pennisetum is transplanted to pour enough home water, and then no artificial irrigation and fertilization are performed, and weeds are removed in time. When the hybrid pennisetum grows to the end of the growing season, the above-ground biomass is cut, and the stubble height is about 10 cm. Then the acclimation is performed under the field simple overwintering maintenance condition, and the specific acclimation scheme is as follows:

[0062] The first growth period: the simple greenhouse overwintering maintenance management is performed, and the hybrid pennisetum stubble is covered with soil of 40 cm in winter. In the spring of the next year, the hybrid pennisetum plants that can normally overwinter and return green are selected, and then hybrid pennisetum seedlings are obtained by rhizome breeding, and artificial low-temperature acclimation is continued.

[0063] The second growth period: the simple greenhouse overwintering maintenance management is performed, and the greenhouse is not subjected to any heat preservation treatment, and all the ventilation windows of the greenhouse are opened. And in winter, the hybrid pennisetum stubble is covered with soil of 30 cm. In the spring of the next year, the hybrid pennisetum plants that can normally overwinter and return green are selected, and then hybrid pennisetum seedlings are obtained by rhizome breeding, and artificial low-temperature acclimation is continued.

[0064] The third growth period: the simple greenhouse overwintering maintenance management is performed, and the greenhouse is not subjected to any heat preservation treatment, and all the ventilation windows of the greenhouse are opened. And in winter, the hybrid pennisetum stubble is covered with soil of 25 cm. In the spring of the next year, the hybrid pennisetum plants that can normally overwinter and return green and have good growth are selected, and the hybrid pennisetum plants with high cold resistance are obtained.

[0065] After the acclimation, the hybrid pennisetum plants can reach an overwintering rate of more than 70% under the simple overwintering maintenance measures, that is, by covering soil of 20 cm.

[0066] Example 2

[0067] It is implemented in Jiangxia District, Wuhan City, Hubei Province. The test site is 112 m above sea level, and the latitude and longitude is 30.15N, 114.30E.

[0068] The hybrid pennisetum plants acclimated in Wujun County, Hengshui City, Hebei Province in Example 1 are planted in the area, and enough home water is poured once after planting, and then no artificial irrigation and fertilization are performed during the growth and development process, and weeds are appropriately removed as appropriate, and the above-ground biomass is cut at the end of the growing season, and the stubble height is about 10 cm. No overwintering maintenance management is performed in the area, and the hybrid pennisetum plants are directly overwintered under natural conditions. In the next year, the overwintering rate of the hybrid pennisetum is 100%.

[0069] Example 3

[0070] The test was carried out in the test base of Huazhong Agricultural University in Hongshan District of Wuhan City, Hubei Province. The longitude and latitude of the test site is 114°35'E, 30°48'N, and the altitude is 54 m.

[0071] The hybrid kikuyu grass plants in Example 1, which were domesticated in Wujun County, Hengshui City, Hebei Province, were planted in the field in this area. After planting, the plants were watered with enough water for the first time, and then no artificial irrigation and fertilization were performed during the growth and development process. Weeds were removed as appropriate. The above-ground biomass was harvested at the end of the growing season, leaving a stubble height of about 10 cm. No overwintering maintenance and management was performed in this area, and the plants were directly overwintered under natural conditions. The overwintering rate of hybrid kikuyu grass was 100% the following year.

[0072] In the above three examples, hybrid kikuyu grass plants that had not been subjected to any domestication treatment were planted, and all other field maintenance measures were the same as for hybrid kikuyu grass plants that had been domesticated. The overwintering rate results showed that the overwintering rate of hybrid kikuyu grass domesticated in the test site in Wujun County, Hengshui City, Hebei Province, was more than 70% under the same conditions, while the overwintering rate of hybrid kikuyu grass that had not been domesticated was 0. The overwintering rate of hybrid kikuyu grass domesticated in the test site in Jiangxia District, Wuhan City, Hubei Province, was 100%, while the overwintering rate of hybrid kikuyu grass that had not been domesticated was only 34.26%. The overwintering rate of hybrid kikuyu grass domesticated in the test base of Huazhong Agricultural University in Hongshan District, Wuhan City, Hubei Province, was 100%, while the overwintering rate of hybrid kikuyu grass that had not been domesticated was only 36.78%.

[0073] After repeated low temperature stress, the overwintering rate of hybrid kikuyu grass in the field under natural conditions was significantly improved

[0074] A field planting test was carried out in the test base in Jiangxia District, Wuhan City, Hubei Province. The altitude of the test site is 112 m, and the longitude and latitude is 30.15N, 114.30E. The seedlings were grown in a greenhouse in November using 12 cm nutrient pots. The substrate was grass charcoal soil. The treatment group used hybrid kikuyu grass seedlings that had been domesticated by artificial low temperature control according to Example 1, and the control group used hybrid kikuyu grass seedlings that had not been subjected to artificial low temperature control. The seedlings were planted in the field in early June the following year. The spacing of hybrid kikuyu grass plants was set to 1 m. After watering with enough water for the first time, no fertilization or irrigation was performed in the later period, and weeds were removed in a timely manner. The above-ground biomass was harvested in early November, leaving a stubble height of about 10 cm. No overwintering maintenance and management was performed, and the plants were directly overwintered under natural conditions. The test results showed that the overwintering rate of hybrid kikuyu grass in the treatment group was 100%, and the overwintering rate of hybrid kikuyu grass in the control group was 34%. The field planting test directly showed that hybrid kikuyu grass treated by the technical means described in the present invention had a stronger cold resistance, and the overwintering rate in the field was significantly improved.

[0075] After repeated low temperature stress, the overwintering rate of hybrid kikuyu grass in the field under natural conditions was significantly improved

[0076] The hybrid pennisetum seedlings (treatment) and the hybrid pennisetum seedlings (control) not subjected to repeated low temperature stress were grown in a greenhouse after the third acclimation period of artificial low temperature acclimation in Example 1, and after growing for one month, the artificial low temperature stress treatment was carried out in a light incubator. The daytime (D) 12℃ + night (N) 1℃ was set as the low temperature stress treatment condition, and the light intensity was 35000 lux. After 3 days of stress treatment, the physiological and biochemical indexes of the tillering nodes of the hybrid pennisetum were measured, and the activity of the tillering nodes was measured to reflect the size of the cold resistance. The specific results are as follows:

[0077] Difference in physiological indexes of two hybrid pennisetum seedlings after low temperature stress treatment

[0078]

[0079] In the table, control represents the hybrid pennisetum seedlings grown from the seedlings not subjected to repeated low temperature stress treatment, and treatment represents the hybrid pennisetum seedlings grown from the seedlings subjected to repeated low temperature stress treatment. DHA represents the dehydrogenase activity of the tillering nodes, which can reflect the size of the tissue activity of the tillering nodes, MDA represents malondialdehyde, SS represents soluble sugar, sPRO represents soluble protein, SOD represents superoxide dismutase, and POD represents peroxidase.

[0080] The data of each index in the table shows that after the set artificial low temperature stress treatment, the tissue activity of the tillering nodes of the treatment hybrid pennisetum seedlings is significantly higher than that of the control, the contents of soluble sugar and soluble protein are significantly higher than those of the control, the activities of superoxide dismutase and peroxidase are significantly higher than those of the control, and the content of malondialdehyde is significantly lower than that of the control. In summary, the cold resistance of the seedlings in the treatment group is significantly stronger than that of the seedlings in the control group.

[0081] Example 6: Repeated low temperature stress combined with sand covering treatment significantly improves the cold resistance of hybrid pennisetum

[0082] The field planting test was carried out in the test base in Jiangxia District, Wuhan, Hubei Province. The test site is 112 m above sea level, and the latitude and longitude is 30.15N, 114.30E. The seedlings were grown in a greenhouse in November using 12 cm pots, and the substrate was grass charcoal soil. The seedlings were grown using the hybrid pennisetum seedlings obtained by the artificial low temperature acclimation scheme in Example 1, and were planted in the field in early June of the next year. The plant spacing of hybrid pennisetum was set to 1 m. After watering enough to settle in, no fertilization and irrigation maintenance was carried out in the later period, and weeds were removed in time by hand. This test set two groups, the control group was not treated with sand covering, and the treatment group was covered with sand (10-20 cm thick) around the hybrid pennisetum plants (30-50 cm radius). The aboveground biomass was harvested in early November, the stubble height was about 10 cm, and no wintering maintenance treatment was carried out, and it was placed in the natural conditions for wintering.

[0083] The test results show that the overwintering rates of the two groups of hybrid kikuyu grasses are both 100%, but the plants of the sand covering treatment group turn green about 5 days earlier than those of the non-sand covering treatment group, and 15 days after turning green, the results of measuring the tiller number and plant height of the two groups of hybrid kikuyu grasses show that the tiller number of the sand covering group is 21% higher than that of the control group, and the plant height of the sand covering group is 34% higher than that of the control group. Comprehensive analysis of the above test results shows that sand covering around the hybrid kikuyu grass plants in the same year can promote the hybrid kikuyu grass to turn green earlier, and significantly promote the growth of the hybrid kikuyu grass. Therefore, sand covering combined with repeated low temperature stress treatment can better improve the cold resistance of the hybrid kikuyu grass.

[0084] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for improving cold tolerance of hybrid Pennisetum, the method comprising, The first stage domestication comprises a first domestication period, a second domestication period and a third domestication period. The hybrid pennisetum seedlings are subjected to the first stage domestication, which is sequentially divided into different domestication periods according to time, and each domestication period is subjected to low-temperature domestication and then growth recovery. The domestication temperature of the later domestication period is lower than that of the previous domestication period, the stress duration is longer than that of the previous domestication period, the recovery duration is shorter than that of the later domestication period, and the stress frequency is more than that of the previous domestication period. The first stage domestication comprises a first domestication period, a second domestication period and a third domestication period. The first domestication period: the domestication temperature is 2-4℃, the stress duration is 10-20 days each time, the recovery duration is 12-18 days between stresses, and the stress frequency is 3-5 times. The second domestication period: the stress domestication temperature is 0-2℃, the stress duration is 15-25 days each time, the recovery duration is 7-13 days, and the stress frequency is 5-7 times. The third domestication period: the stress domestication temperature is -2-0℃, the stress duration is 25-35 days each time, the recovery duration is 2-8 days, and the stress frequency is 7-9 times. The seedlings subjected to the first stage domestication are transplanted to the field to be subjected to the second stage domestication. The second stage domestication is sequentially divided into different growth periods according to time, and the hybrid pennisetum plants with better overwintering and greening are selected for domestication in the next growth period. When the hybrid pennisetum overwinters, mulch is covered on the stubble of the hybrid pennisetum, and the thickness of the mulch in the later growth period is lower than that in the previous growth period. In the second stage domestication, the mulch is soil; the thickness of the soil is 35-45 cm in the first year, and then gradually decreases to 20-30 cm in the third year. Alternatively, the mulch is in the form of litter; the thickness of the litter is 55-65 cm in the first year, and gradually decreases to 25-35 cm in the third year.

2. The method for improving cold resistance of hybrid pampas grass according to claim 1, characterized in that, After the seedlings are transplanted to the field, one or more of pebbles, gravel sand, and sand are covered around the hybrid pennisetum plants.

3. The method for improving cold resistance of hybrid pampas grass according to claim 2, wherein, After the seedlings are transplanted to the field, one or more of fine silk sand, river sand, sea sand, mountain sand, and desert sand are covered around the hybrid pennisetum plants.

4. The method for improving cold resistance of hybrid pampas grass according to claim 2 or 3, characterized in that, The sand covering radius is 30-50 cm, and the sand covering thickness is 8-30 cm.

5. The method for improving cold resistance of hybrid pampas grass according to claim 4, wherein, The sand covering radius is 35-45 cm, and the sand covering thickness is 10-20 cm.

6. The method for improving cold resistance of hybrid pampas grass according to any one of claims 1 to 3, wherein, The second stage domestication comprises a first growth period, a second growth period and a third growth period.

7. The method for improving cold resistance of hybrid Pennisetum according to any one of claims 1-3, characterized in that, The temperature of the second stage domestication is controlled to be above -4℃.

8. The method for improving cold resistance of hybrid pampas grass according to claim 6, wherein, The first growth period: the environmental temperature of the hybrid pennisetum is controlled to be -2-0℃ at night during the overwintering period. The second growth period: the environmental temperature of the hybrid pennisetum is controlled to be -3-0℃ at night during the overwintering period. The third growth period: the environmental temperature of the hybrid pennisetum is controlled to be -3-0℃ at night during the overwintering period.

9. The method for improving cold tolerance of hybrid pampas grass according to any one of claims 1 to 3, wherein, In the second stage domestication, the temperature during the day is controlled to be higher than 2℃ during the overwintering period.

10. The method for improving cold resistance of hybrid pampas grass according to claim 9, wherein, In the second stage domestication, the temperature during the day is controlled to be higher than 6℃ during the overwintering period.

11. The method for improving cold resistance of hybrid Pennisetum according to claim 6, wherein, In the second stage domestication, the hybrid pennisetum is domesticated in a greenhouse. The window is opened after the first growth period.

12. The method for improving cold tolerance of hybrid pampas grass according to any one of claims 1 to 3, wherein, The hybrid pennisetum subjected to the second stage domestication is transplanted, and the soil is covered to a thickness of 15-25 cm or the litter is covered to a thickness of 20-30 cm during the first overwintering period after the transplantation.

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