A seedling raising method of xanthoceras sorbifolia bunge current-year seedling

Abstract

The application discloses a kind of Xingguo fruit year-old seedling's seedling raising method, belongs to Xingguo fruit seedling raising technical field.The seedling raising method includes the following steps: (1) stock seedling cultivation;(2) stock seedling management;(3) scion collection;(4) grafting;(5) post-grafting management, through Xingguo fruit seed in the year of harvest germination sowing, overwintering culture stock seedling in shed, the following year is managed by spraying nutrient solution and chlormequat, etc., so that stock seedling is consistent with the phenophase time of shoot strip in seedling nursery in May, and the growth and roughness are completely matched with scion, and the survival rate of grafting cutting is high, and it can be out of the nursery after grafting survival in the same year.The method is simple in operation, and the time and space limit is small, and the seedling raising period is shortened to 1 year from 2-3 years of traditional method, and the diameter of grafted seedling can reach 1cm when it is out of the nursery in the grafting year, and the survival rate of grafting is as high as more than 90%, so it is easy to popularize.

Description

Technical Field

[0001] This invention relates to the field of *Xanthoceras sorbifolium* seedling technology, and more specifically to a method for cultivating *Xanthoceras sorbifolium* seedlings in the same year. Background Technology

[0002] *Xanthoceras sorbifolium* Bunge, a deciduous shrub or small tree belonging to the Sapindaceae family and the *Xanthoceras* genus, is a woody oilseed tree species endemic to my country, mainly distributed in Gansu, Shaanxi, Inner Mongolia, Liaoning, and Shandong provinces. *Xanthoceras sorbifolium* has wide applications in food, medicine, and afforestation of barren hills. In particular, its seeds have an oil content of 30%–50%, and the kernels have an oil content as high as 65%, making them not only suitable for producing edible oil but also a raw material for biodiesel production.

[0003] However, due to the low utilization rate of improved varieties and the lack of efficient and reliable breeding methods, low yield and low efficiency have become bottlenecks in the development of the *Xanthoceras sorbifolium* industry. *Xanthoceras sorbifolium* can be propagated through tissue culture, seed propagation, and grafting. However, due to its high cost, tissue culture is often limited to large-scale use in practice. Therefore, seed propagation and grafting have become the commonly used propagation methods for *Xanthoceras sorbifolium*. For example, most new *Xanthoceras sorbifolium* afforestation is propagated from seed seedlings. However, the genetic material of seed seedlings can recombine and mutate, failing to fully retain the superior characteristics of the parent tree, making large-scale promotion of seed seedlings risky. Therefore, grafting is often used to select superior *Xanthoceras sorbifolium* varieties to stably and efficiently achieve fixed superior traits and large-scale propagation, thus meeting the demand for high-quality seedlings through asexual propagation in the large-scale industrialization of *Xanthoceras sorbifolium*.

[0004] Patent CN101627713A discloses a seedling cultivation technique for *Xanthoceras sorbifolium*, which involves bud grafting with large sections of xylem. The first year involves propagating rootstock seedlings. After one year of growth, in late April of the second year, seedlings with a diameter of 1 cm or more are selected as rootstocks, and vigorous, well-developed branches are used as scions for grafting. After grafting, the buds are allowed to grow and develop until the seedlings are ready for sale. This technique takes one year to cultivate rootstock seedlings, and another nearly one and a half years for the grafted seedlings to mature, resulting in a relatively long seedling cultivation cycle. CN105917974A discloses a method for propagating grafted container seedlings of *Vernicia fordii*, outlining the following steps: "1. Seedling cultivation: a. Seed selection, b. Seed storage, c. Germination; 2. Selection of scion branches; 3. Grafting: a. Rootstock preparation, b. Scion preparation, c. Rootstock preparation, d. Grafting; 4. Planting and management of grafted seedlings." However, this method is problematic because, during spring and summer grafting, the seedlings are not yet of the required thickness for grafting and cannot match the scions, resulting in strict scion selection and a low grafting survival rate. Furthermore, when seedlings cease growth in autumn, their diameter at ground level is less than 6mm, their growth cycle is short, and their growth is weak. If grafting is done in autumn, the grafted seedlings need to grow to maturity the following year to meet the requirements for transplanting, still exhibiting the drawback of a long seedling cultivation cycle.

[0005] Therefore, it is of great significance to provide a seedling cultivation method for *Xanthoceras sorbifolium* that can produce seedlings in the same year, ensuring both high survival rate and a shorter seedling cultivation period, so that seedlings can be transplanted in the same year. Summary of the Invention

[0006] To address the above problems, this invention provides a method for cultivating *Sapindus mukorossi* seedlings in the same year.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for cultivating *Xanthoceras sorbifolium* seedlings in the same year includes the following steps:

[0009] (1) Rootstock seedling cultivation:

[0010] Harvest fully mature *Xanthoceras sorbifolium* fruits in mid-to-late July. Select plump, uniformly sized seeds, air dry them naturally, and then store them in a dry, ventilated place at 4℃ until late October. After that, take them out and soak them in 45℃ warm water for 4-8 hours. During this period, select the cracked seeds and sow them in seedling bags, and then move them to a greenhouse for seedling cultivation.

[0011] (2) Rootstock seedling management:

[0012] From late November to mid-December, after the rootstock seedlings sprout, adjust the temperature and soil moisture in the greenhouse for overwintering cultivation;

[0013] In March of the following year, after the rootstock seedlings have become semi-lignified, thinning is carried out, leaving one of the best-growing *Xanthoceras sorbifolium* seedlings in each bag, and transferring the excess rootstock seedlings to nutrient pots, one seedling per pot; in early and mid-April, each seedling is irrigated with nutrient solution once; in early and late May, each seedling is irrigated with chlormequat chloride once.

[0014] (3) Scion collection:

[0015] In late May to early June of the following year, collect scions from mother trees of superior varieties of *Sapindus mukorossi* that are ≥10cm long, with well-developed buds and free from pests and diseases. Remove the leaves and leave petioles 0.8-1.2cm long as scions.

[0016] (4) Grafting:

[0017] In mid-June of the following year, the buds with woody parts on the scion were removed using the T-shaped three-cut bud removal method. Rootstock seedlings with stems 0.4cm to 0.7cm in diameter were selected for grafting. After grafting, the graft union was bound, and the binding was removed 15 days later.

[0018] (5) Post-grafting management:

[0019] After the bud sprouts, remove the sprouts promptly, removing all sprouts on the rootstock except for the bud. When the grafted seedling grows to a ground diameter of ≥1cm, it can be transplanted.

[0020] Preferably, the sowing in step (1) is as follows: 2-3 seeds are placed in each seedling bag, the sowing depth is 4cm-5cm, the soil depth is 2cm-3cm, and then the soil is compacted. Water is then applied until water seeps out from the bottom of the seedling bag.

[0021] Preferably, the nutrient solution in step (2) consists of the following components by weight: 0.2% urea, 0.6% ammonium phosphate and 1% potassium dihydrogen phosphate, with the remainder being water; the amount of the nutrient solution applied each time is 20 ml / plant.

[0022] Preferably, the concentration of chlormequat chloride in step (2) is 100 mg / L, and the application amount is 20 ml / plant each time.

[0023] Preferably, the grafting in step (4) specifically involves: making a 4-6 mm horizontal cut on a smooth part of the rootstock seedling 5 cm from the ground, reaching the xylem; making a 4-6 mm vertical cut downwards in the middle of the horizontal cut, reaching the xylem; placing the bud into the cut of the rootstock and pushing it downwards so that the horizontal cut of the bud is aligned with the horizontal cut of the rootstock.

[0024] As can be seen from the above technical solution, this invention discloses a method for cultivating *Xanthoceras sorbifolium* seedlings in the same year. This invention involves germinating and sowing *Xanthoceras sorbifolium* seeds in the year of harvest, overwintering rootstock seedlings in a greenhouse, and then using nutrient solution spraying and chlormequat chloride treatment in the following year. This ensures that the phenological time of the rootstock seedlings coincides with that of the scions in the scion nursery by the end of May, resulting in a perfect match in growth rate and thickness. This facilitates grafting, leads to a high survival rate, and allows the grafted seedlings to be ready for transplanting in the same year.

[0025] The seedling cultivation method of this invention shortens the seedling cultivation cycle from the traditional 2-3 years to 1 year. Grafted seedlings can reach a diameter at birth of 1 cm in the same year they are transplanted, ensuring high seedling quality and transplant survival rate, thus improving land and capital utilization. This method is simple to operate, has few time and space limitations, and achieves a grafting survival rate of over 90%, making it easy to promote. Attached Figure Description

[0026] Figure 1 Germination of rootstock seedlings after sowing *Sapindus mukorossi* seeds in seedling bags;

[0027] Figure 2 Photo showing the overwintering status of *Xanthoceras sorbifolium* rootstock seedlings;

[0028] Figure 3 Photo showing the thinning of *Vernicia fordii* rootstock seedlings;

[0029] Figure 4 Image of *Xanthoceras sorbifolium* rootstock seedlings before grafting; stem diameter 0.4cm–0.7cm.

[0030] Figure 5 Image of grafted *Xanthoceras sorbifolium* (Chinese pistache).

[0031] Figure 6 Diagram showing the untying of the graft union on a grafted *Xanthoceras sorbifolium* seedling. Detailed Implementation

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] All reagents used in the embodiments of this invention were purchased from commercial channels. Methods not mentioned are conventional experimental methods and will not be described in detail here.

[0034] Example 1

[0035] A method for cultivating *Xanthoceras sorbifolium* seedlings in the same year includes the following steps:

[0036] (1) In mid-to-late July 2023, fully mature *Sapindus mukorossi* fruits were harvested. High-quality seeds of the current year with plump, uniform size and fully mature seeds were selected as seeds for rootstock seedling cultivation. After harvesting, the seeds were naturally dried and stored at 4℃. The storage location was kept dry and ventilated.

[0037] In late October 2023, the seeds were taken out and soaked in 45℃ warm water for 4-8 hours. During this period, the cracked seeds were selected and sown in seedling bags, with 2-3 seeds in each seedling bag at a depth of 4-5cm. The soil was covered with 2-3cm and compacted. After sowing, the seeds were watered until water seeped out from the bottom of the seedling bag. A total of 263 seedling bags were sown.

[0038] (2) The seedling bags were moved into the greenhouse for seedling cultivation, and natural light was maintained in the greenhouse during this period. On November 13, 2023, rootstock seedlings began to sprout (see...). Figure 1 Maintaining a minimum soil temperature of ≥10℃, soil moisture content of 15-20%, and natural light, the seedlings underwent overwintering cultivation. By February 19, 2024, 715 seedlings had sprouted, representing a sprouting rate of 90.62%. The thickest rootstock seedlings reached a diameter of 3-4 mm (see...). Figure 2 );

[0039] On March 18, 2024, the rootstock seedlings were semi-lignified. Thinning began that day, selecting the best-growing *Xanthoceras sorbifolium* seedlings and leaving one seedling per seedling bag. Excess rootstock seedlings were transferred to nursery pots, one seedling per pot (see...). Figure 3 );

[0040] On April 4, 2024, each rootstock seedling was irrigated with 20ml of nutrient solution (nutrient solution concentration (m / m%): 0.2% urea + 0.6% ammonium phosphate + 1% potassium dihydrogen phosphate) once. On April 15, a second application was made, using the same method as the first application. On May 1, each rootstock seedling was irrigated with 20ml of chlormequat chloride (concentration 100mg / L) once. On May 15, a second application was made, using the same method as the first application.

[0041] (3) On June 2, 2024, collect scions that are ≥10cm long, with full bud development and free from pests and diseases from the mother trees of superior varieties of Sapindus mukorossi in suitable habitats. Cut off the leaves and leave petioles 0.8-1.2cm long as scions (if grafting is not done on the same day, it is necessary to keep the temperature low and moist, and complete the grafting within 1 week).

[0042] (4) Select rootstock seedlings with a diameter of 0.4cm to 0.7cm (see...) Figure 4 Make a 4-6mm horizontal cut on a smooth part 5cm from the ground, then make a 4-6mm vertical cut downwards from the middle of the horizontal cut. Both horizontal and vertical cuts should reach the xylem, forming a T-shape. Use the T-shaped three-cut bud removal method to remove the bud with xylem from the scion. Place the bud into the cut on the rootstock and push it downwards until the horizontal cut of the bud aligns with the horizontal cut on the rootstock. After grafting, bind the graft union with a plastic strip (see...). Figure 5 ), unbinding after 15 days (see Figure 6 ).

[0043] (5) Remove the buds promptly after they sprout. Remove all buds on the rootstock except for the buds. A total of 256 grafted seedlings were grafted, and 240 survived, with a survival rate of 93.75%. By the end of September 2024, most of the grafted seedlings will have grown to a diameter of more than 1 cm and can be transplanted to the nursery or transplanted with a pot the following spring.

[0044] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0045] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for cultivating *Sapindus mukorossi* seedlings in the same year, characterized in that, Includes the following steps: (1) Rootstock seedling cultivation: Harvest fully mature *Xanthoceras sorbifolium* fruits in mid-to-late July. Select plump, uniformly sized seeds, air dry them naturally, and then store them in a dry, ventilated place at 4℃ until late October. After that, take them out and soak them in 45℃ warm water for 4-8 hours. During this period, select the cracked seeds and sow them in seedling bags, and then move them to a greenhouse for seedling cultivation. (2) Rootstock seedling management: From late November to mid-December, after the rootstock seedlings sprout, adjust the temperature and soil moisture in the greenhouse for overwintering cultivation; In March of the following year, after the rootstock seedlings have become semi-lignified, thinning is carried out. One of the best-growing *Xanthoceras sorbifolium* seedlings is left in each seedling bag, and the excess rootstock seedlings are transferred to nutrient pots, one seedling per pot. In early and mid-April, each seedling is irrigated with nutrient solution once. In early and late May, each seedling is irrigated with chlormequat chloride once. (3) Scion collection: In late May to early June of the following year, collect scions from mother trees of superior varieties of *Sapindus mukorossi* that are ≥10cm long, with well-developed buds and free from pests and diseases. Remove the leaves and leave petioles 0.8-1.2cm long as scions. (4) Grafting: In mid-June of the following year, the buds with woody parts on the scion were removed using the T-shaped three-cut bud removal method. Rootstock seedlings with stems 0.4cm to 0.7cm in diameter were selected for grafting. After grafting, the graft union was bound, and the binding was removed 15 days later. (5) Post-grafting management: After the bud sprouts, remove the sprouts promptly, removing all sprouts on the rootstock except for the bud. When the grafted seedling grows to a ground diameter of ≥1cm, it can be transplanted.

2. The method for cultivating *Sapindus mukorossi* seedlings in the same year according to claim 1, characterized in that, The sowing process in step (1) is as follows: put 2-3 seeds into each seedling bag, sow at a depth of 4-5cm, cover with soil at a depth of 2-3cm, compact the soil, and then water until water seeps out from the bottom of the seedling bag.

3. The method for cultivating *Sapindus mukorossi* seedlings in the same year according to claim 1, characterized in that, The conditions for overwintering cultivation in step (2) are: soil temperature ≥10℃, natural light, and soil moisture content 15-20%.

4. The method for cultivating *Sapindus mukorossi* seedlings in the same year according to claim 1, characterized in that, The nutrient solution described in step (2) consists of the following components by total mass: 0.2% urea, 0.6% ammonium phosphate, and 1% potassium dihydrogen phosphate, with the remainder being water; The amount of nutrient solution applied each time is 20 ml per plant.

5. A method for cultivating *Sapindus mukorossi* seedlings in the same year according to claim 1, characterized in that, The concentration of chlormequat chloride in step (2) is 100 mg / L, and the application amount is 20 ml / plant each time.

6. The method for cultivating *Sapindus mukorossi* seedlings in the same year according to claim 1, characterized in that, The grafting in step (4) is as follows: make a horizontal cut of 4-6 mm deep to the xylem on a smooth part of the rootstock seedling 5 cm from the ground, and make a vertical cut of 4-6 mm deep to the xylem in the middle of the horizontal cut. Place the bud into the cut of the rootstock and push it downward so that the horizontal cut of the bud is aligned with the horizontal cut of the rootstock.

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