Cultivation method of arbor type ornamental cold-resistant cotton

Abstract

The invention belongs to the technical field of cotton variety cultivation, and particularly relates to a cultivation method of arbor type ornamental cold-resistant cotton. The invention provides a cultivation method of arbor type ornamental cold-resistant cotton. The cultivation method comprises the following steps: mutagenizing seeds of Kaiyuan kapok, and performing selfing screening to obtain Kaiyuan kapok mutants resistant to low temperature of less than or equal to 0 DEG C; hybridizing by taking the Kaiyuan kapok mutant as a female parent and a cotton variety with an ornamental character as a male parent to obtain an F1 generation; the seeds of the F1 generation are harvested for continuous selfing, and selfing generations are obtained; screening from the F1 generation and the selfing generation according to the arbor type, the cold resistance and the ornamental value to obtain arbor type ornamental cold-resistant cotton; and the screening standard is limited. By means of the method, perennial arbor type cold-resistant cotton with diversified ornamental characters can be obtained, and the result of the embodiment shows that the arbor type cold-resistant ornamental cotton can be screened from F1-generation plants.

Description

Technical Field

[0001] The present invention belongs to the technical field of cotton variety cultivation, and particularly relates to a cultivation method for arbor-shaped ornamental cold-resistant cotton. Background Art

[0002] Cotton, as a plant of the Malvaceae family and Gossypium genus, occupies an important position in the national economy. It is mainly used as fiber and oil resources and is widely applied in fields such as textiles, vegetable oils, and feeds. In recent years, with the continuous improvement of living standards, people's pursuit of beauty and environmental requirements have been increasing. In the field of ornamental plants, the demand for diversification has become increasingly strong. Cotton, with its unique shape and rich colors, has gradually entered the ornamental field. The cotton bolls with open bolls are highly favored in the cut flower market as cut flower materials.

[0003] However, there is currently no arbor-shaped ornamental cotton in the garden field. Moreover, most cotton varieties are not cold-resistant, and it is extremely difficult to improve their cold resistance. Although relevant research has been continuously carried out, no major breakthrough has been achieved. Therefore, at this stage, a method for cultivating arbor-shaped ornamental cold-resistant cotton is urgently needed. Summary of the Invention

[0004] The purpose of the present invention is to provide a cultivation method for arbor-shaped ornamental cold-resistant cotton. By using the method of the present invention, cold-resistant cotton with perennial arbor-shaped and diverse ornamental traits can be obtained.

[0005] The present invention provides a cultivation method for arbor-shaped ornamental cold-resistant cotton, which includes the following steps:

[0006] Mutagenize the seeds of Bombax oblongatum, and self-cross and screen to obtain a Bombax oblongatum mutant resistant to low temperatures of ≤0°C;

[0007] Using the Bombax oblongatum mutant as the female parent and a cotton variety with ornamental traits as the male parent, perform hybridization to obtain the F1 generation; harvest the seeds of the F1 generation and perform continuous self-crossing to obtain self-crossing generations;

[0008] From the F1 generation and the self-crossing generations, screen out arbor-shaped ornamental cold-resistant cotton according to arbor shape, cold resistance, and ornamental properties;

[0009] The criteria for the arbor shape include a plant height ≥6 meters and a straight main stem;

[0010] The criteria for cold resistance include resistance to low temperatures of ≤3°C;

[0011] The ornamental properties include one or more of the following phenotypic traits: flower color, leaf color, leaf shape, fruit color, plant shape, and overall state.

[0012] As a preferred embodiment, the mutagenesis includes chemical mutagenesis.

[0013] As a preferred embodiment, the chemical mutagenesis includes EMS mutagenesis.

[0014] As a preferred embodiment, the EMS mutagenesis includes soaking the seeds of Bombax ceiba var. rotundata with an aqueous solution of EMS.

[0015] As a preferred embodiment, the volume concentration of EMS in the aqueous solution of EMS is 3%; the soaking time is 6 h.

[0016] As a preferred embodiment, the cotton varieties with ornamental traits include Gossypium gossypioides and / or Gossypium hirsutum f. variegatum.

[0017] As a preferred embodiment, the Gossypium gossypioides is shrubby upland cotton.

[0018] As a preferred embodiment, the tolerance to low temperature ≤ 0 °C means that there will be no leaf withering within 6 h under low temperature conditions below 0 °C.

[0019] As a preferred embodiment, the plant type includes at least one of umbrella shape, tower shape and hemispherical shape.

[0020] As a preferred embodiment, after screening out the arbor-type ornamental cold-resistant cotton, it further includes fixing the heterosis by asexual reproduction.

[0021] Beneficial effects: The present invention provides a cultivation method for arbor-type ornamental cold-resistant cotton, which includes the following steps: mutagenizing the seeds of Bombax ceiba var. rotundata, self-crossing and screening to obtain a mutant of Bombax ceiba var. rotundata with tolerance to low temperature ≤ 0 °C; using the mutant of Bombax ceiba var. rotundata as the female parent and a cotton variety with ornamental traits as the male parent for hybridization to obtain the F1 generation; harvesting the seeds of the F1 generation for continuous self-crossing to obtain self-crossing generations; screening out arbor-type ornamental cold-resistant cotton from the F1 generation and the self-crossing generations according to arbor type, cold resistance and ornamental value; the standard of the arbor type includes a plant height ≥ 6 m and a straight main stem; the standard of cold resistance includes tolerance to low temperature ≤ 3 °C; the ornamental value includes one or several of the following phenotypic traits: flower color, leaf color, leaf shape, fruit color, plant type and overall state. The present invention uses a mutant of Bombax ceiba var. rotundata with tolerance to low temperature ≤ 0 °C as the female parent to hybridize with cotton with ornamental traits, and directly selects target individuals in each generation according to three indexes of arbor type, cold resistance and ornamental value, and can obtain cold-resistant cotton with perennial arbor type and diverse ornamental traits. The results of the examples show that by using the method of the present invention, arbor-type, cold-resistant and ornamental Yunda Hongfeng cotton can be screened out in the F1 generation plants; after continuously self-crossing Yunda Hongfeng cotton for 2 generations, arbor-type, cold-resistant and ornamental Yunda Zi cotton can be screened out. Description of the Drawings

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings required in the embodiments will be briefly introduced below.

[0023] Figure 1 It is the cultivation flow chart of the arbor-type ornamental cold-resistant cotton of the present invention;

[0024] Figure 2 It is the phenotypic map of Yunda Hongfeng cotton in Example 2; where A is a 2-month-old seedling; B is a flower in the early blooming stage; C is a flower in the fully open stage; D is an immature fruit, E is a cotton boll in the boll-opening stage; F is a seed covered with green short lint;

[0025] Figure 3 It is the phenotypic map of Yunda Zijin in Example 3, where A is a 2-month-old potted seedling; B is a flower in the early blooming stage; C is a flower in the fully open stage; D is an immature fruit. Detailed implementation manners

[0026] The present invention provides a cultivation method for arbor-type ornamental cold-resistant cotton, comprising the following steps: mutagenizing the seeds of Kainanthesia alba, and self-crossing and screening to obtain a Kainanthesia alba mutant resistant to low temperature of ≤0°C; using the Kainanthesia alba mutant as the female parent and a cotton variety with ornamental traits as the male parent for hybridization to obtain the F1 generation; harvesting the seeds of the F1 generation for continuous self-crossing to obtain self-crossing generations; screening arbor-type ornamental cold-resistant cotton from the F1 generation and the self-crossing generations according to arbor type, cold resistance and ornamental value; the standard for the arbor type includes a plant height of ≥6 meters and a straight main stem; the standard for cold resistance includes resistance to low temperature of ≤3°C; the ornamental value includes one or more of the following phenotypic traits: flower color, leaf color, leaf shape, fruit color, plant type and overall state.

[0027] The present invention mutagenizes the seeds of Kainanthesia alba, and self-crosses and screens to obtain a Kainanthesia alba mutant resistant to low temperature of ≤0°C. Most cotton stops growing below 10°C and dies below 4°C, while Kainanthesia alba has stronger cold resistance and can tolerate low temperature of 0°C - 4°C for a short time (about 4 hours). By mutagenizing the seeds of Kainanthesia alba, a Kainanthesia alba mutant resistant to low temperature of ≤0°C can be screened.

[0028] As an implementation method, the mutagenesis in the present invention includes chemical mutagenesis; as an implementation method, the chemical mutagenesis includes EMS mutagenesis; the EMS mutagenesis includes: soaking the seeds of Bombax austrosinense with an EMS aqueous solution. As an implementation method, the volume concentration of EMS in the EMS aqueous solution is 3%; the soaking time is 6 h. EMS (ethyl methanesulfonate) mutagenesis is a commonly used chemical mutagenesis method, which has the advantages of low cost, simple operation, multi-directional mutation, and narrow mutation range. EMS can cause base deamination in DNA, resulting in point mutations or other types of gene mutations, which will then change the function or expression level of proteins, thus affecting the traits of plants and obtaining cold-resistant mutants. For example, Chinese patents CN112931198B and CN113875589B use EMS mutagenesis to obtain cold-resistant germplasms.

[0029] In a specific embodiment of the present invention, the tolerance to low temperature ≤ 0 °C means that the leaves will not turn yellow within 6 h at low temperature below 0 °C. In a specific embodiment of the present invention, the seeds of Bombax austrosinense are mutagenized by EMS to obtain the mutagenized seeds; the mutagenized seeds are planted and self-crossed to harvest T1 seeds; the T1 seeds are planted and self-crossed to obtain T2 seeds; the cold-resistant mutants of Bombax austrosinense with tolerance to low temperature ≤ 0 °C are screened. Mutagenesis generally shows mutant characteristics in the second generation. Therefore, in the present invention, the target plants are screened by self-crossing after mutagenesis.

[0030] The present invention uses the cold-resistant mutant of Bombax austrosinense as the female parent and a cotton variety with ornamental traits as the male parent for hybridization to obtain the F1 generation. As an implementation method, the cotton variety with ornamental traits in the present invention includes Gossypium barbadense L. var. punctatum and / or colored cotton. As an implementation method, the Gossypium barbadense L. var. punctatum is shrubby upland cotton; the colored cotton includes at least one of Gossypium hirsutum L. cv. Jiyezongzi, Gossypium hirsutum L. cv. Ziye, and Gossypium hirsutum L. cv. Hongjijiaoye. In the present invention, the colored cotton includes cotton with colored leaves, which is upland cotton or sea-island cotton. In a specific example of the present invention, the Gossypium barbadense L. var. punctatum is a shrubby upland cotton variety, the leaves are pink with white spots, the fruits have red pericarp with white stripes at uniform intervals, the flowers are pink, and it has high ornamental value. Bombax austrosinense is a perennial, arbor-type cotton, with a tall plant, fast growth rate, good resistance, and strong adaptability; the leaves are large and smooth, the branches are numerous and lush, and the crown is in an umbrella shape; the flowers are yellow, the petals are thick and have a transparent texture, and the flowers bloom continuously, with high ornamental value. The present invention uses the cold-resistant mutant of Bombax austrosinense with tolerance to low temperature ≤ 0 °C as the female parent and a cotton variety with ornamental traits as the male parent for hybridization, and various hybrid offspring can be obtained, which is beneficial to screening for arbor-type ornamental cold-resistant cotton.

[0031] The seeds of the F1 generation of the present invention are harvested for continuous self-crossing to obtain self-crossing generations; from the F1 generation and the self-crossing generations, tree-type ornamental cold-resistant cotton is screened according to tree type, cold resistance, and ornamental value. In a specific embodiment of the present invention, the ornamental tree-type cold-resistant material 'Yun Dahongfeng Cotton' can be screened in the F1 generation. By continuously self-crossing the seeds of the F1 generation of the present invention, a variety of ornamental tree-type cold-resistant materials can be further screened out.

[0032] The criteria for the tree type in the present invention include a plant height ≥ 6 m and a straight main stem; the criteria for cold resistance include tolerance to a low temperature of ≤ 3°C; the ornamental value includes one or more of the following phenotypic traits: flower color, leaf color, leaf shape, fruit color, plant type, and overall state. As an implementation method, the plant type includes at least one of an umbrella shape, a tower shape, and a hemispherical shape. In a specific embodiment of the present invention, the leaf color and fruit color include the red series; the flower color has both light pink and yellow, and then turns into magenta; the leaf shape includes large palmate leaves; the overall state includes the harmonious overall combination of the flower color, leaf color, fruit color, and plant type of the cotton.

[0033] As an implementation method, after screening the tree-type ornamental cold-resistant cotton in the present invention, it further includes fixing heterosis by asexual reproduction. As an implementation method, the asexual reproduction includes at least one of cutting, tissue culture, and grafting.

[0034] To further illustrate the present invention, the following describes in detail a cultivation method of a tree-type ornamental cold-resistant cotton provided by the present invention in combination with the drawings and embodiments, but they cannot be understood as limiting the protection scope of the present invention.

[0035] Example 1

[0036] Most cotton stops growing below 10°C and dies below 4°C. Relatively speaking, the kapok in Kaiyuan has stronger cold resistance and can tolerate a low temperature of 0 - 4°C for a short time (about 4 h). Due to the lack of suitable cold-resistant cotton germplasm, it is difficult to improve the cold tolerance of the kapok in Kaiyuan through cross-breeding methods. Therefore, the Kaiyuan kapok is chemically mutagenized by the method of soaking with EMS (ethyl methyl sulfonate).

[0037] (1) Determination of EMS concentration

[0038] In March 2017, EMS aqueous solutions with 5 volume concentrations (1%, 2%, 3%, 5%, and 8%) were prepared; the mature dry seeds of the Kaiyuan kapok were soaked in the above-mentioned EMS aqueous solutions with different volume concentrations for 3 h, 6 h, and 9 h respectively; after the soaking ended, they were rinsed with clean water for 3 h and then sown in seedling trays. The semi-lethal rate was counted in April 2017, and the results are shown in Table 1.

[0039] Table 1 Semi-lethal rates of different EMS concentrations

[0040] EMS concentration 3h 6h 9h 1％ 0 0 0 2％ 0 0 10％ 3％ 15％ 52％ 67％ 5％ 47％ 73％ 80％ 8％ 65％ 85％ 93％

[0041] According to the semi - lethal rate of Bombax oblongatum in Table 1, select to soak in 3% EMS aqueous solution for 6 h as the standard treatment method.

[0042] (2) Frost - resistance mutagenesis of Bombax oblongatum

[0043] A. Select 1000 mature seeds of Bombax oblongatum and soak them in 3% EMS aqueous solution by volume concentration; after soaking for 6 h, rinse with clear water for 3 h to remove the residual medicinal solution.

[0044] B. Plant the seeds treated in step A in the greenhouse of Yunnan University (Kunming) to obtain 460 T0 (treated contemporary) plants. Let the T0 plants self - cross to obtain T1 seeds; select 3 T1 seeds from each T0 plant for planting, and a total of 1200 T1 plants are obtained. Let them self - cross during the flowering period to obtain T2 seeds.

[0045] C. Select 2 healthy T2 seeds from each T1 plant and plant them in the outdoor experimental field of Yunnan University in March 2019 (at the top of Yunshan, Chenggong Campus, Yunnan University, Kunming, 24.82°N, 102.85°E, altitude 1994 m) to obtain T2 plants, and conduct selection under the natural environment in winter in Kunming. The extreme low temperature in December 2019 was - 1°C, the number of days below 3°C accounted for 54% of the whole month, and the number of consecutive days below 3°C was 11 days. In January 2020, the extremely low temperature was - 2°C, the number of days below 3°C accounted for 60% of the whole month, and the number of consecutive days below 3°C was 9 days.

[0046] D. After the experiment under the natural environment in winter, in April 2021, count 2400 T2 plants, and only 1 living plant is obtained, denoted as T2 - 1, and the rest of the plants are all frozen to death.

[0047] E. Cold - resistance identification of T2 - 1 plants

[0048] A. Obtaining cuttings: Take healthy vegetative branches from the T2 - 1 plants obtained in step D, cut 5 - cm stem segments with 2 buds as cuttings, remove the larger leaves, and make the lower end of the cuttings into a slanting cut. Then soak the cuttings in carbendazim solution with a concentration of 1 g / L for 10 min; then soak the lower end of the cuttings in 10% sucrose solution for 30 min; then take out the cuttings from the sucrose solution and soak them in NAA solution with a concentration of 125 mg / L for 2 h. Finally, take out the cuttings, let them dry slightly, and vertically insert them into moist vermiculite (about 2 cm deep). Keep moist for 15 - 20 days, and they can take root and grow leaves and grow normally to obtain T2 - 1 cuttings. Take ordinary Bombax oblongatum as the object, and use the same method to prepare cuttings of Bombax oblongatum as the control group.

[0049] B. Identification in artificial climate chamber: The cuttings of T2-1 and the cuttings of Bombax ceiba var. kerrii (control group) in step A were respectively identified in the low-temperature artificial climate chamber HCLI-150A. Four temperature gradients of 3°C, 1°C, 0°C, and -1°C were set respectively, and the continuous placement time was set at 3 h, 6 h, and 9 h. Under dark conditions, 5 cuttings (1-month-old) of each treatment of each material were used, and three replicates were set up.

[0050] The results showed that when the cuttings of Bombax ceiba var. kerrii (control group) were placed at 3°C for 6 h, the leaves were in a wilting state and could continue to survive after returning to normal temperature; at 3°C for 9 h, 1°C, 0°C, and -1°C for 3 treatment times, the leaves were in a severely wilting state and could not survive after returning to normal temperature. However, for the mutagenic material T2-1 of Bombax ceiba var. kerrii, the leaves were not damaged at any treatment time of 3°C, 1°C, and 0°C; under the treatment of -1°C for 6 h, only the young leaves showed slight wilting and grew normally after returning to normal temperature; under the treatment of -1°C for 9 h in the dark, the leaves showed severe wilting, and most of the treated materials died after returning to normal temperature treatment. It can be seen that the cuttings of T2-1 cotton can still survive after being treated in the dark environment at -1°C for 6 h, initially indicating that the cold resistance of Bombax ceiba var. kerrii T2-1 has been enhanced, and a mutant of Bombax ceiba var. kerrii resistant to low temperatures ≤0°C is obtained.

[0051] Example 2

[0052] (1) In June 2021, using the mutant of Bombax ceiba var. kerrii in Example 1 as the female parent and Gossypium barbadense with variegated leaves as the male parent for hybridization to obtain F1 seeds. The Gossypium barbadense with variegated leaves is a shrubby upland cotton, with leaves being pink with white spots, fruits having red pericarp with evenly spaced white stripes, and flowers being pink, with high ornamental value.

[0053] (2) In August 2021, 50 F1 seeds in step (1) were planted in flowerpots outside the greenhouse of Yunnan University to obtain 5 types of F1 plants, namely arbor with large red palmate leaves (F1-1), arbor with large purple palmate leaves (F1-2), shrub with small red round leaves (F1-3), arbor with small purple-red round leaves (F1-4), and arbor with palmate leaves with red spots (F1-5). The leaves and fruits of the obtained F1 plants are all in the red series, the outer layer of the petals is light pink, and the inner layer is yellow. After the flowers fully bloom, they gradually turn into rose red. The leaf shape, plant type, fruit type, and cold resistance show diversity.

[0054] (3) Obtaining of Yunda red maple cotton

[0055] A. After comprehensively identifying the morphologies of the 5 types of F1 plants in step (2), in March 2022, 2 types of F1 plants (F1-1 and F1-4) with arbor form (plant height ≥ 6 m), good plant type (umbrella-shaped, tower-shaped or hemispherical crown width), high ornamental value of leaves, flowers and fruits (harmonious leaf shape, leaf color, flower color, fruit color and overall morphology), and good cold resistance under natural conditions (tolerant to low temperature of about 0 °C) were selected for in-depth observation and investigation, including indicators such as resistance, stability of ornamental traits, fiber and seed oil content.

[0056] B. In September 2022, the cuttings of these two types of F1 were respectively subjected to low-temperature identification: The cuttings were obtained in the same way as in Example 1. The cuttings were randomly divided into 2 groups. One group was treated with low temperature in an artificial climate chamber, and the operation method was the same as in Example 1; one group of cuttings was placed in Yongzhou City, Hunan Province for field trials to observe their performance in winter (environment of -2 °C - 4 °C). The average temperature of the field trial was 4 °C, and the lowest temperature was -4 °C. The management method adopted normal field cotton production management. The results showed that the cold resistance performance of F1-1 plants, namely Yunda Hongfeng Cotton, was better.

[0057] (4) Observation on the cold resistance of Yunda Hongfeng Cotton

[0058] In March 2023, the Yunda Hongfeng Cotton in step (3) was planted on the top of Yun Mountain (a place with strong wind, low temperature and very poor soil), and its performance was further observed. The growth diagrams of each stage of Yunda Hongfeng Cotton are as Figure 2 shown, where A is a 2-month-old seedling; B is a flower in the initial blooming stage; C is a flower in the fully open stage; D is an immature fruit, E is a boll with lint; F is a seed covered with short green lint.

[0059] Yunda Hongfeng Cotton is a perennial arbor form, with a fast growth rate (the plant height of the first-year plant is more than 3 m, the stem diameter is about 4 cm, the crown width is umbrella-shaped, and the diameter is 2 m). The leaves are red throughout the growth period, but under the conditions of insufficient light (daily light time is less than 8 h, or light intensity is insufficient) or a diurnal temperature difference of less than 10 °C, the leaf color gradually fades to green, and the leaves are large and smooth; the flowers are gradually pink from bottom to top on the outer periphery of the corolla at the bud stage and initial blooming stage, and the inner crown, that is, the inner side of the petals, is yellow. After the flowers are fully open, they are rose red; the fruits are red, round, with fruit tips, and the fibers are yellowish-white; there are fruiting branches, and the number of fruiting branches is about 10. The amount of flowers and fruits is large, and the flowers bloom continuously throughout the four seasons; it can tolerate a low temperature of -1 °C for a short time. Under natural conditions, it has good resistance.

[0060] Example 3

[0061] Obtaining of arbor-type ornamental and cold-resistant cotton 'Yunda Purple Cotton'

[0062] After continuously self-crossing the 'Yunda Hongfeng Cotton' in Example 2 for 2 generations, 1 purple-leaf cotton plant, namely 'Yunda Purple Cotton', was screened from 210 F3 plants with trait segregation. The growth stages of Yunda Purple Cotton are asFigure 3 As shown in the figure, where A is a 2-month-old potted seedling; B is a flower at the initial blooming stage; C is a flower at the fully open stage; D is an immature fruit. After phenotypic observation and cold resistance identification (the same as in Example 2), 'Yunda Zimian' has the following characteristics: perennial, arbor type, fast growth rate, good resistance, and can grow in an environment with a minimum temperature of -2°C. It has a good plant type, an umbrella-shaped crown, large and smooth leaves, and lush branches and leaves; the leaves are purple throughout the growth period and are not easily faded; the upper half of the petals at the initial stage of the flower is pink, the lower half is yellowish-white, and it is rose-red in the middle and late stages; the fruit is purple, round with a fruit tip, and the fiber is white.

[0063] Example 4

[0064] (1) Using the cold-resistant Kaiyuan kapok mutant of Example 1 as the female parent and colored cotton as the male parent for hybridization to obtain F1 seeds. The colored cotton is shrubby upland cotton with red chicken-foot leaves.

[0065] (2) The operation method is the same as in Example 2. The F1 plants of Kaiyuan kapok mutant and red chicken-foot leaves are tall, arbor type, with red leaf color, large leaves with long villi, and white fibers.

[0066] Example 5

[0067] (1) Using the cold-resistant Kaiyuan kapok mutant of Example 1 as the female parent and colored cotton as the male parent for hybridization to obtain F1 seeds. The colored cotton is shrubby upland cotton with chicken leaf brown-purple.

[0068] (2) The operation method is the same as in Example 2. The F1 plants of Kaiyuan kapok mutant and chicken leaf brown-purple are tall, arbor type, with purplish-red leaf color, large and smooth leaves, and brown fibers.

[0069] The present invention uses the cold-resistant Kaiyuan kapok as the female parent and hybridizes it with cotton with ornamental traits. According to the three indicators of arbor type, cold resistance, and ornamental value, direct selection of target individuals is carried out in each generation. By using the method of the present invention, cold-resistant cotton with perennial arbor type and diverse ornamental traits can be obtained.

[0070] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, not all of them. People can also obtain other embodiments based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A cultivation method of an arbor-shaped ornamental cold-resistant cotton, characterized in that, It includes the following steps: Mutagenize the seeds of Kaiyuan kapok, and self-cross and screen to obtain a Kaiyuan kapok mutant resistant to low temperature of ≤0°C; Use the Kaiyuan kapok mutant as the female parent and a cotton variety with ornamental traits as the male parent for hybridization to obtain the F1 generation; Harvest the seeds of the F1 generation and conduct continuous self-crossing to obtain self-crossing generations; From the F1 generation and the self-crossing generations, screen for arbor-type ornamental cold-resistant cotton according to arbor-type, cold resistance, and ornamental properties; The criteria for the arbor-type include a plant height of ≥6 m and a straight main stem; The criteria for cold resistance include resistance to low temperature of ≤3°C; The ornamental properties include one or more of the following phenotypic traits: flower color, leaf color, leaf shape, fruit color, plant type, and overall state.

2. The cultivation method according to claim 1, wherein The mutagenesis includes chemical mutagenesis.

3. The cultivation method according to claim 2, characterized in that, The chemical mutagenesis includes EMS mutagenesis.

4. The cultivation method according to claim 3, characterized in that, The EMS mutagenesis includes: soaking the seeds of Kaiyuan kapok with an EMS aqueous solution.

5. The cultivation method according to claim 4, wherein The volume concentration of EMS in the EMS aqueous solution is 3%; the soaking time is 6 h.

6. The cultivation method according to claim 1, characterized in that The cotton variety with ornamental traits includes variegated cotton and / or colored leaf cotton.

7. The cultivation method according to claim 6, characterized in that, The variegated cotton is shrubby upland cotton.

8. The cultivation method according to claim 1, characterized in that, The resistance to low temperature of ≤0°C means that leaf withering and yellowing will not occur within 6 h under low temperature conditions below 0°C.

9. The cultivation method according to claim 1, characterized in that The plant type includes at least one of umbrella shape, tower shape, and hemispherical shape.

10. The cultivation method according to claim 1, characterized in that, After screening for arbor-type ornamental cold-resistant cotton, it also includes using asexual reproduction to fix heterosis.

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