A method for staged regulation of fertilization of Sapindus mukorossi based on phenological stages and its application

Abstract

This invention discloses a method and application for staged fertilization of Sapindus mukorossi based on phenological stages, belonging to the field of fertilizer production and application technology. Addressing the technical contradiction between excessive vegetative growth and insufficient flower bud differentiation in conventional fertilization of Sapindus mukorossi in the low-heat river valley of the Beipanjiang River, this invention constructs a sequentially linked stage based on the annual growth cycle of Sapindus mukorossi: autumn shoot basal fertilizer stage, budding and flowering promotion stage, summer shoot control stage, and fruit ripening stage. Through the synergistic coordination of fertilizer types, ratios, application methods, and dosages at each stage, it significantly improves the quality of fruiting branches, the proportion of female flowers, and the fruit set rate of Sapindus mukorossi, and enhances the tree's winter hardiness. This method is suitable for large-scale cultivation and management of Sapindus mukorossi fruit orchards and ecological landscape forests.

Description

Technical Field

[0001] This invention belongs to the field of fertilizer production and application technology, specifically involving a method and application of fertilization of Sapindus mukorossi based on phenological stage regulation, which is applicable to the efficient cultivation and large-scale management of Sapindus mukorossi fruit forests and ecological landscape forests in the low-heat river valley of Beipanjiang. Background Technology

[0002] Soapberry ( Sapindus *Sapindus mukorossi* Gaertn., also known as the soap tree or bodhi tree, is a deciduous tree belonging to the genus *Sapindus* in the family Sapindaceae. Its fruit peel is rich in saponins, an important raw material for the production of natural surfactants, biodiesel, and daily chemical products. It is also an excellent landscaping tree species. In recent years, with the increasing demand for natural detergents, the planting area of ​​*Sapindus mukorossi* plantations in the low-heat river valley of the Beipan River has expanded. However, the following technical challenges are commonly encountered in the cultivation of *Sapindus mukorossi* fruit-bearing forests: (I) The contradiction between vegetative growth and reproductive growth is prominent. Sapindus mukorossi has a vigorous ability to sprout and branch, especially after the spring shoots stop growing, the summer and autumn shoots often emerge in large numbers, resulting in a large consumption of photosynthetic products in the construction of vegetative organs, leading to insufficient nutrient supply during the flower bud differentiation period. Current conventional fertilization methods mostly adopt the pattern of "applying high nitrogen fertilizer in spring" or "applying compound fertilizer in one go", which can easily further stimulate vegetative growth, causing excessive tree growth, dense canopy, and significantly low flower bud differentiation rate and female flower ratio, directly affecting fruit yield; (II) Lack of targeted regulation of flower bud differentiation induction mechanism. Flower bud differentiation of Sapindus mukorossi exhibits a clear phenological dependence, with physiological differentiation mainly concentrated around the time of spring shoot emergence, while morphological differentiation extends until after spring shoot cessation. Existing fertilization techniques do not provide precise nutrient supply for these key phenological periods, especially lacking a synergistic supplementation plan for nutrients closely related to flower bud differentiation and pollen fertility, such as phosphorus, zinc, and boron, leading to poor flower development and severe flower and fruit drop. (III) Insufficient lignification of branches leads to poor overwintering safety. Sapindus mukorossi is a subtropical species. When introduced to northern cultivation areas or encountering years of extreme low temperatures, the current year's shoots often suffer from "frozen shoots" due to insufficient lignification. This can range from affecting flower bud production the following year to causing damage to the tree canopy structure. Traditional fertilization methods tend to focus on topdressing during the early stages of vegetative growth, lacking targeted high-potassium supplementation programs during fruit enlargement and branch maturation, making it difficult to simultaneously achieve the dual goals of "high yield" and "cold resistance." To address the aforementioned issues, there is an urgent need to develop a systematic fertilization method for the low-heat river valley area of ​​Beipanjiang, based on the phenological patterns of Sapindus mukorossi, and taking into account both branch cultivation and flower bud differentiation. This method would have significant industrial application value. Summary of the Invention

[0003] This invention addresses the shortcomings of existing fertilization techniques for Sapindus mukorossi in the low-heat valleys of the Beipanjiang River, which often result in excessive vegetative growth, insufficient flower bud differentiation, and poor lignification of branches. It provides a fertilization method for Sapindus mukorossi based on staged regulation according to phenological stages. This method, by precisely matching the type, ratio, application method, and dosage of fertilizer according to the physiological needs of different stages of the annual growth cycle of Sapindus mukorossi, achieves synergistic optimization of vegetative and reproductive growth, thereby improving fruit set rate and enhancing the tree's cold resistance.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0005] The method for fertilizing Sapindus mukorossi based on staged regulation of phenological periods is characterized by the following steps:

[0006] Step 1: Base Fertilizer Application Stage for Autumn Shoots

[0007] The autumn shoot basal fertilizer stage refers to the period from after the harvest of Sapindus mukorossi fruit to before leaf fall (late October to December). Dig four diagonal arc trenches along the drip line of the tree canopy, with a depth of 15cm to 30cm and a length of 50cm to 100cm. Apply 10kg to 15kg of basal fertilizer to each tree. After applying the fertilizer, cover the soil and water thoroughly.

[0008] Step Two: Budding and Flowering Stage

[0009] The budding and flowering stage refers to applying base fertilizer to promote flower bud differentiation before the spring shoots sprout the following year (February to March), and applying high-phosphorus and low-potassium water-soluble fertilizer to the roots. At the same time, on sunny evenings, a plant protection drone is used to spray the leaves with a mixed water-soluble fertilizer (potassium dihydrogen phosphate: zinc sulfate: boric acid = 10:1:1) until both sides of the leaves are evenly moistened. The number of sprays is 5 times at 15-day intervals.

[0010] Step 3: Summer Shoot Control Stage

[0011] The summer shoot control stage refers to the period after the spring shoots stop growing (mid to late April), when root fertilization is stopped and a mixture of paclobutrazol and potassium dihydrogen phosphate is sprayed on the leaves, focusing on the terminal buds and lateral buds of the spring shoots on the outer edge of the canopy.

[0012] Step 4: Fruit ripening stage

[0013] The fruit ripening stage refers to the fruit enlargement period (May to July), during which high-potassium compound fertilizer is applied and spread within the canopy projection area after rain.

[0014] The specific fertilizer types, ratios, and dosages for each stage are further optimized as follows:

[0015] In step one, the fertilizer used for cultivating branches is a combination fertilizer of well-rotted black goat manure, superphosphate, and borax (in a ratio of 100:10:1), and the application rate is 10 kg to 15 kg per plant;

[0016] In step two, the nitrogen-phosphorus-potassium mass ratio of the high-phosphorus, low-potassium water-soluble fertilizer is 10-50-10, and the root application rate is 0.5 kg to 1.0 kg per plant. In the foliar spray mixture, the mass percentage concentrations of potassium dihydrogen phosphate, zinc sulfate, and boric acid are 0.2%.

[0017] In step three, the mixed regulator is a mixture of a 200-fold dilution of 10% paclobutrazol wettable powder and a 0.3% (w / w) potassium dihydrogen phosphate solution, mixed at a volume ratio of 1:1 before use.

[0018] In step four, the nitrogen-phosphorus-potassium mass ratio of the high-potassium compound fertilizer is 15-5-30, and the application rate is 1.0 kg to 1.5 kg per plant. The method described in this invention is preferably applicable to Sapindus mukorossi fruit forests or ecological landscape forests in the low-heat river valley area of ​​the Beipan River.

[0019] Beneficial effects

[0020] Compared with the prior art, the present invention has the following significant advantages;

[0021] First, precise adaptation to phenological periods: This invention is the first to construct a four-stage closed-loop regulation system for the annual growth cycle of Sapindus mukorossi: "Autumn application of base fertilizer to promote root storage → Spring control of nitrogen and increase of phosphorus to start differentiation → Summer spraying of retardant to inhibit excessive growth → Autumn supplementation of high potassium to simultaneously strengthen fruit and mature the fruit," overcoming the blindness of conventional fertilization's "one fertilizer to the end" or random application;

[0022] Secondly, it efficiently drives flower bud differentiation: This invention strictly controls the input of pure nitrogen during the budding and flowering stage, replacing conventional high-nitrogen compound fertilizer with high-phosphorus water-soluble fertilizer, and combining it with foliar spraying of potassium dihydrogen phosphate, zinc sulfate and boric acid in a synergistic combination. Among them, phosphorus directly participates in nucleic acid and ATP synthesis during flower bud differentiation, zinc promotes pollen tube elongation, and boron improves stigma pollination affinity. The synergistic effect of the three significantly improves the proportion of female flowers and fruit setting rate of Sapindus mukorossi.

[0023] Third, chemical control and nutrient-based growth regulation are coupled: During the critical period of summer shoot emergence, this invention uses a mixture of paclobutrazol and potassium dihydrogen phosphate as a foliar spray to regulate growth. On the one hand, paclobutrazol inhibits gibberellin synthesis and dwarfs new shoots. On the other hand, potassium dihydrogen phosphate directly supplements the energy substances required for flower bud morphogenesis. This achieves an integrated operation of "chemical shoot control" and "flower bud nutrient supplementation", replacing physical growth control methods such as girdling. The operation is simple and does not damage the tree. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 An overall flowchart is provided for embodiments of the present invention.

[0026] Figure 2 A diagram illustrating step one of digging a trench for a single Sapindus mukorossi plant, provided as an embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments, but the embodiments of this invention are not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the concept of this invention are all within the protection scope of this invention.

[0028] Example 1

[0029] This embodiment was conducted at the Sapindus mukorossi fruit forest base in Lihuai Village, Shaping Town, Zhenfeng County (0.765km from Beipanjiang River). The test trees were 10-year-old Sapindus mukorossi trees in their peak fruiting period, with a plant spacing of 4.5m × 4.5m and an altitude of 392.2m, which is a typical low-heat valley climate.

[0030] The specific fertilization steps are as follows:

[0031] Autumn shoot basal fertilizer stage: On November 10, 2024 (8 days after fruit harvest), dig four arc-shaped trenches diagonally outside the drip line of each tree canopy. Each trench should be 30cm wide, 25cm deep, and 80cm long. Apply 12kg of basal fertilizer evenly into the four trenches, cover each trench with soil and compact it, then water thoroughly once.

[0032] During the budding and flowering stage: On February 23, 2025 (5 days before the spring shoots begin to sprout), dissolve 0.6 kg of high-phosphorus water-soluble fertilizer (nitrogen-phosphorus-potassium ratio 10-50-10) in 20 L of water per tree and apply it in a ring along the inner edge of the tree canopy projection;

[0033] On the same day, a plant protection drone was used to spray the leaves with a mixed water-soluble fertilizer (potassium dihydrogen phosphate: zinc sulfate: boric acid = 10:1:1), and the spraying was repeated once every 3 days.

[0034] Summer shoot control stage: On May 23, 2025 (6 days after spring shoots stop growing), dilute 10% paclobutrazol wettable powder to a 200-fold dilution and mix it with a 0.3% potassium dihydrogen phosphate solution at a 1:1 volume ratio to prepare a mixed regulator. On a sunny evening, focus on spraying the terminal buds and lateral buds of the current year's spring shoots on the outer edge of the canopy. The amount of spray should be enough to moisten the shoots without dripping.

[0035] Fruit ripening stage: On July 7, 2025 (when the young fruit diameter is about 1.8cm), select a high-potassium compound fertilizer with a nitrogen-phosphorus-potassium ratio of 15-5-30, apply 1.2kg per tree, and spread evenly within the canopy projection area while the soil is moist after rain;

[0036] Results: Compared with Control Example 1, this example showed that the average proportion of female flowers per tree of 10-year-old Sapindus mukorossi trees increased by 63.59%, the number of fruits per tree increased by 35.76%, and the total saponin content of the pericarp increased by 23.49%.

[0037] Example 2

[0038] This embodiment was conducted in the Sapindus mukorossi ecological landscape forest belt of Bike Village, Yongfeng Street, Zhenfeng County (12.20 km from Beipanjiang River). The test trees were 12-year-old Sapindus mukorossi trees at an altitude of 1148.1 m. This embodiment verified the fertilization scheme for mature trees. The specific operation was basically the same as in embodiment 1, except that the amount of fertilizer was adjusted according to the size of the tree and the yield level.

[0039] In step one, apply 15 kg of fertilizer per plant and dig a trench 30 cm deep;

[0040] In step two, apply 0.8 kg of high-phosphorus water-soluble fertilizer per plant, and maintain the same foliar spray formula and frequency.

[0041] In step three, the concentration and method of spraying the mixed regulator remain unchanged;

[0042] In step four, apply 1.2 kg of high-potassium compound fertilizer per plant.

[0043] Results: Compared with Control Example 2, this example showed that the average proportion of female flowers per tree of 10-year-old Sapindus mukorossi trees increased by 105.11%, the number of fruits per tree increased by 40.64%, and the total saponin content of the pericarp increased by 16.11%.

[0044] Example 3

[0045] This embodiment was conducted in a Sapindus mukorossi fruit orchard in Xinzai Village, Shuangfeng Street, Zhenfeng County, Guizhou Province (13.52 km from Beipanjiang River). The test trees were 10-year-old Sapindus mukorossi trees, with distinct dry and wet seasons, at an altitude of 1092.4 m. This embodiment verifies the adaptability of the method of the present invention to different ecological conditions in various regions.

[0046] In step one, apply 10 kg of fertilizer per plant for branch cultivation;

[0047] In step two, apply 0.5 kg of high-phosphorus water-soluble fertilizer per plant;

[0048] In step three, after the spring shoots stop growing, a mixed growth regulator is sprayed once, with the spraying time delayed by about 10 days compared to Example 1;

[0049] In step four, apply 0.8 kg of high-potassium compound fertilizer per plant.

[0050] Results: Compared with control example 3, this example showed that the average proportion of female flowers per tree of 10-year-old Sapindus mukorossi trees increased by 86.06%, the number of fruits per tree increased by 30.52%, and the total saponin content of the pericarp increased by 14.85%.

[0051] Compare with Example 1

[0052] To verify the superiority of the technical solution of the present invention, a control example was set up in the same site as in Example 1. The test trees were 10-year-old Sapindus mukorossi trees with basically the same age, growth vigor, and site conditions as in Example 1.

[0053] The fertilization plan for the control example is as follows: In early March each year (during the spring shoot budding period), apply 1.2 kg / plant of general-purpose compound fertilizer with a nitrogen-phosphorus-potassium ratio of 15-15-15; in mid-June (during the fruit enlargement period), apply 0.3 kg / plant of urea as a top dressing. No organic fertilizer is applied throughout the year, no foliar spraying is carried out, and no plant growth regulators such as paclobutrazol are used. Other field management measures such as irrigation and pruning are consistent with those in Example 1.

[0054] Summary of the effect comparison data between Example 1 and Control Example 1 (average): Proportion of female flowers (%) 30.51 18.65 ＋63.59% Number of fruits per plant (fruits / plant) 410 302 ＋35.76% Total saponin content in fruit peel (%) 11.25 9.11 ＋23.49%

[0055] Compare with Example 2

[0056] To verify the superiority of the technical solution of the present invention, a control example was set up in the same site as in Example 2. The test trees were 12-year-old Sapindus mukorossi trees with basically the same age, growth vigor, and site conditions as in Example 2.

[0057] The fertilization plan for the control example is as follows: In early March each year (during the spring shoot budding period), apply 1.2 kg / plant of general-purpose compound fertilizer with a nitrogen-phosphorus-potassium ratio of 15-15-15; in mid-June (during the fruit enlargement period), apply 0.3 kg / plant of urea as a top dressing. No organic fertilizer is applied throughout the year, no foliar spraying is carried out, and no plant growth regulators such as paclobutrazol are used. Other field management measures such as irrigation and pruning are consistent with those in Example 2.

[0058] Summary of the effect comparison data between Example 2 and Control Example 2 (average): Proportion of female flowers (%) 35.32 17.22 ＋105.11% Number of fruits per plant (fruits / plant) 436 310 ＋40.64% Total saponin content in fruit peel (%) 10.59 9.12 ＋16.11%

[0059] Compare with Example 3

[0060] To verify the superiority of the technical solution of the present invention, a control example was set up in the same site as Example 3. The test trees were 10-year-old Sapindus mukorossi trees with basically the same age, growth vigor, and site conditions as in Example 3.

[0061] The fertilization plan for the control example is as follows: In early March each year (during the spring shoot budding period), apply 1.2 kg / plant of general-purpose compound fertilizer with a nitrogen-phosphorus-potassium ratio of 15-15-15; in mid-June (during the fruit enlargement period), apply 0.3 kg / plant of urea as a top dressing. No organic fertilizer is applied throughout the year, no foliar spraying is carried out, and no plant growth regulators such as paclobutrazol are used. Other field management measures such as irrigation and pruning are consistent with those in Example 2.

[0062] Summary of the effect comparison data between Example 3 and Control Example 3 (average): Proportion of female flowers (%) 33.25 17.87 ＋86.06% Number of fruits per plant (fruits / plant) 419 321 ＋30.52% Total saponin content in fruit peel (%) 10.36 9.02 ＋14.85%

[0063] The above data show that the method of the present invention is significantly superior to conventional fertilization methods in terms of female flower ratio, fruit set quantity, and fruit quality, fully verifying the technical superiority and industrial application value of the present invention.

Claims

1. A method for staged fertilization of Sapindus mukorossi based on phenological stages, characterized in that, Includes the following steps: Step 1: Base Fertilizer Application Stage for Autumn Shoots The autumn shoot basal fertilizer stage refers to the application of branch-building fertilizer in trenches dug along the drip line of the tree canopy from after the harvest of Sapindus mukorossi fruit until before leaf fall. Step Two: Budding and Flowering Stage The budding and flowering stage refers to applying a base fertilizer to promote flower bud differentiation before the spring shoots sprout the following year, applying a high-phosphorus, low-potassium water-soluble fertilizer to the roots, and spraying a mixed water-soluble fertilizer on the leaves. Step 3: Summer Shoot Control Stage The summer shoot control stage refers to the application of a mixture of paclobutrazol and potassium dihydrogen phosphate as a regulator after the spring shoots have stopped growing. Step 4: Fruit ripening stage The fruit ripening stage refers to the fruit enlargement period, during which high-potassium compound fertilizer is applied.

2. The method for fertilizing Sapindus mukorossi based on staged regulation of phenological periods according to claim 1, characterized in that, The fertilizer used in step one is a combination fertilizer of well-rotted black goat manure, superphosphate, and borax (in a ratio of 100:10:1). The depth of the trench is 15cm to 30cm, and the amount of fertilizer used is 10kg to 15kg per plant.

3. The method for fertilizing Sapindus mukorossi based on staged regulation of phenological periods according to claim 1, characterized in that, The high-phosphorus, low-potassium water-soluble fertilizer (nitrogen-phosphorus-potassium mass ratio of 10-50-10) applied to the roots in step two is 0.5 kg to 1.0 kg per plant.

4. The method for fertilizing Sapindus mukorossi based on staged regulation of phenological periods according to claim 1, characterized in that, The foliar spraying mixture water-soluble fertilizer mentioned in step two is composed of potassium dihydrogen phosphate, zinc sulfate and boric acid in a ratio of 10:1:

1. The mass percentage concentration of potassium dihydrogen phosphate is 0.2%, the mass percentage concentration of zinc sulfate is 0.2%, and the mass percentage concentration of boric acid is 0.2%. The spraying is carried out 5 times consecutively at 15-day intervals.

5. The method for fertilizing Sapindus mukorossi based on staged regulation of phenological periods according to claim 1, characterized in that, The mixed regulator mentioned in step three is a mixture of 200 times dilution of 10% paclobutrazol wettable powder and 0.3% potassium dihydrogen phosphate solution.

6. The method for fertilizing Sapindus mukorossi based on staged regulation of phenological periods according to claim 1, characterized in that, The nitrogen-phosphorus-potassium mass ratio of the high-potassium compound fertilizer mentioned in step four is 15-5-30, and the application rate is 1.0 kg to 1.5 kg per plant.

7. The method for fertilizing Sapindus mukorossi based on staged regulation of phenological periods according to claim 1, characterized in that, The application method for the high-potassium compound fertilizer mentioned in step four is to apply it after rain.

8. The fertilization method for Sapindus mukorossi based on staged regulation of phenological periods according to any one of claims 1 to 7, characterized in that, The method is applicable to Sapindus mukorossi fruit forests or ecological landscape forests in the low-heat river valley of the Beipanjiang River.

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