Sweet potato seedling rooting promoting compound preparation and use method thereof

Abstract

The present application relates to the technical field of plant growth regulators, in particular to a sweet potato seedling rooting promoting compound preparation and a use method thereof. The compound preparation is composed of component one for soil base application, component two for sweet potato seedling root dipping treatment, and component three for sweet potato seedling post-planting root irrigation treatment. The component one is humic acid raw powder with a humic acid mass content of greater than or equal to 75%, and the field application dosage is 550 g / m 2 ~ 600 g / m 2 . The component two is a naphthalene acetic acid aqueous solution, wherein the concentration of naphthalene acetic acid is 50 mg / L. The component three is a fish protein aqueous solution, wherein the concentration of fish protein is 1 g / L, the fish protein raw material for preparing the fish protein aqueous solution is 1000-fold concentrated original plasma, the total protein content in the concentrated original plasma is greater than or equal to 510 g / L, and the amino acid mass content is greater than or equal to 23%. The present application is green and safe, simple to apply, suitable for sweet potato field cultivation production, and has good popularization and application value.

Description

Technical Field

[0001] This invention relates to the field of plant growth regulator technology, specifically to a compound preparation for promoting root growth in sweet potato seedlings and its application method. Background Technology

[0002] Sweet potato is my country's fourth largest food crop, serving multiple purposes including as feed, industrial raw material, and energy crop. It plays a crucial role in ensuring national food security, promoting agricultural efficiency, and increasing farmers' income. Sweet potato is an asexually propagated crop, primarily grown through stem cuttings. The rate of adventitious root development and the quality of root system formation after cutting are key factors determining the survival rate, the length of the seedling establishment period, and the seedling's resistance to adverse conditions. These factors directly affect the growth and development of sweet potato throughout its entire life cycle and the final tuber yield.

[0003] Traditional sweet potato cutting cultivation methods generally suffer from problems such as slow rooting of seedlings, few adventitious roots, weak root development, poor stress resistance, and long seedling recovery period. Especially under adverse cultivation conditions such as high temperature and drought, low temperature and rain, the survival rate of seedlings is very low and the seedling condition is uneven, which has become an important bottleneck restricting the stable and high yield of sweet potatoes.

[0004] To address the aforementioned issues, plant growth regulators are commonly used in current production for rooting treatment, with auxin-based regulators such as naphthaleneacetic acid (NAA), indolebutyric acid (IBA), and ABT rooting powder being the most widely applied. These regulators can promote the differentiation of adventitious root primordia in potato seedlings by regulating the levels of endogenous plant hormones, thus shortening rooting time and increasing rooting rate to some extent. However, they have significant drawbacks in practical applications: their function is singular, only achieving short-term root induction and failing to simultaneously achieve the comprehensive effects of soil improvement, sustained seedling growth, and enhanced stress resistance; their effect is short-lived, only taking effect in the early stages of cutting and failing to provide long-term support for subsequent root development; and their stress resistance enhancement effect is poor, with limited improvement in survival rate under adverse cultivation conditions, and they are even prone to phytotoxicity due to improper concentration control, inhibiting normal seedling growth.

[0005] In recent years, organic nutrient-based growth regulators such as humic acid, alginic acid, and fish protein have been gradually promoted and applied in crop rooting cultivation. These substances are rich in organic matter, amino acids, minerals, and active growth factors, and have multiple effects such as improving soil physicochemical properties, promoting root development, and enhancing crop stress resistance. They are also environmentally friendly and have high safety profiles, and can be used in combination with hormone-based regulators. However, the root-promoting effect of these substances is subject to a strict concentration effect, and excessive application can easily inhibit crop root growth. Furthermore, currently, there is a lack of scientific compounding systems and corresponding phased application methods specifically for the growth characteristics of sweet potato cutting cultivation. This makes it impossible to achieve the synergistic effect of hormone-based regulators and organic nutrient-based substances, and it is difficult to simultaneously meet the production needs of rapid rooting, sustained root strengthening, and improved stress resistance in sweet potato seedlings. This has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a compound preparation for promoting root growth in sweet potato seedlings and its application method, solving the problems of existing sweet potato rooting agents having single function, short duration of effect, poor synergistic effect, and insufficient stress-enhancing effect.

[0007] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: a compound preparation for promoting root growth in sweet potato seedlings, comprising component one for soil basal application, component two for root dipping treatment of sweet potato seedlings, and component three for root irrigation treatment after planting of sweet potato seedlings; wherein component one is humic acid powder with a humic acid content ≥75% by mass, and its field application dosage is 550 g / m². 2 ~600g / m 2 Component 2 is an aqueous solution of naphthaleneacetic acid, wherein the concentration of naphthaleneacetic acid is 50 mg / L; Component 3 is an aqueous solution of fish protein, wherein the concentration of fish protein is 1 g / L, and the fish protein raw material for preparing the aqueous solution of fish protein is a 1000-fold concentrated slurry, wherein the total protein content of the concentrated slurry is ≥510 g / L and the amino acid mass content is ≥23%.

[0008] Furthermore, the dosage of the humic acid raw powder in component one is 575 g / m³. 2 .

[0009] Furthermore, the humic acid powder of component one can be applied alone to the soil surface, or mixed with conventional chemical fertilizers before application, and then tilled to ensure thorough mixing with the soil.

[0010] Furthermore, the aqueous solution of naphthaleneacetic acid of component two is prepared by the following steps: weigh naphthaleneacetic acid with a purity of 99%, dissolve it completely in anhydrous ethanol, and then dilute it with pure water to obtain an aqueous solution with a naphthaleneacetic acid concentration of 50 mg / L.

[0011] Furthermore, the fish protein aqueous solution of component three is prepared by mixing and diluting the fish protein concentrate (1000 times concentrated) with pure water at a mass ratio of 1:1000.

[0012] This invention also provides a method for using a compound preparation for promoting root growth in sweet potato seedlings, comprising the following steps: Step 1: Apply the components one by one to the target field, plow to mix them thoroughly with the soil, then rid the field with soil and set aside. Step 2: After soaking the base of the sweet potato seedling stems in component two, remove them, air dry them, and then plant them in the field treated in step 1. Step 3: After the sweet potato seedlings are planted, the roots of the sweet potato seedlings are irrigated with the following three components in three separate applications.

[0013] Furthermore, in step 2, the base length of the sweet potato seedling stems in the second immersion component is 10cm to 15cm, and the immersion time is 15 seconds; after immersion, place them in a ventilated and shady place to air dry naturally for 5 to 10 minutes before planting.

[0014] Furthermore, in step 3, the time points for the multiple root irrigations are the 3rd day, the 8th day, and the 13th day after the sweet potato seedlings are planted, for a total of three root irrigations.

[0015] Furthermore, in step 3, the dosage of the three components for each root irrigation is 150L per acre of field.

[0016] Furthermore, in step 3, the root irrigation is carried out by drip irrigation. During drip irrigation, water is dripped for 20 to 30 minutes first, and then the three components are introduced for drip application. After the drip application is completed, water continues to drip for 20 to 30 minutes.

[0017] (III) Beneficial Effects Compared with the prior art, the present invention provides a compound preparation for promoting root growth in sweet potato seedlings and its application method, which has the following beneficial effects: This invention relates to a compound preparation for promoting root growth in sweet potato seedlings and its application method. It scientifically combines naphthaleneacetic acid (NAA), humic acid, and fish protein to form a three-dimensional synergistic regulatory system that rapidly induces root growth, improves the environment, and continuously strengthens roots. NAA can rapidly increase the level of endogenous auxin in sweet potato seedlings, initiating the differentiation of adventitious root primordia and addressing the core pain point of slow root initiation in the early stages of sweet potato cutting propagation. Humic acid simultaneously improves the physicochemical properties of the rhizosphere soil, stimulating the division and elongation of root tip meristems, thus constructing an excellent rhizosphere microenvironment for the entire root growth cycle. Fish protein provides active stimulation and direct nutrient substrate for continuous root growth, promoting the abundant germination of lateral roots and capillary roots, thus compensating for the short-lasting effect of hormone-based regulators. The three components work together in a coordinated and interconnected manner. Through experiments, it has been verified that the combined application of these three components can increase the total root length of sweet potato seedlings to 280.97 cm / plant 15 days after planting. The core indicators such as total root projection area, root surface area, root volume, and root dry weight are all significantly improved, achieving a comprehensive effect of rapid rooting, dense and robust root system, significantly shortened seedling establishment period, and significantly enhanced seedling resistance.

[0018] This invention targets the root growth rhythm of sweet potato cuttings and precisely screens 50 mg / L naphthaleneacetic acid and 575 g / m³ using single-factor gradient experiments. 2The optimal application parameters for humic acid and 1 g / L fish protein ensure the maximum root-promoting effect of each component while strictly avoiding the risk of growth inhibition caused by excessive application of organic nutrients, and also avoiding phytotoxicity caused by excessive concentration of hormone regulators. The accompanying phased application mode, including pre-planting basal application, pre-planting root dipping, and post-planting root irrigation, precisely matches the entire growth cycle of sweet potato root primordia differentiation, adventitious root elongation, and abundant lateral root sprouting. This ensures that the action window of each component is perfectly aligned with the root growth rhythm, maximizing synergistic effects while ensuring uniform growth of sweet potato seedlings throughout the field and stable and controllable effects between batches.

[0019] The humic acid and fish protein used in this invention are both natural biological extracts without any chemical additives. They are friendly to sweet potato plants, soil microorganisms, and the farmland environment, have high safety, and pose no risk of pesticide residues. Long-term application can effectively increase soil organic matter content, improve soil aggregate structure, and regulate soil pH, thereby achieving continuous improvement in arable land quality. It overcomes the adverse effects of long-term use of traditional hormone-based rooting agents on soil microecology, and has both economic and ecological benefits. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the component composition of the sweet potato seedling root-promoting compound of the present invention; Figure 2 This is a schematic diagram illustrating the entire process of preparing and applying the sweet potato seedling root-promoting compound combination of the present invention; Figure 3 This is a schematic diagram illustrating the synergistic root-promoting mechanism of the three-component compound combination of the present invention; Figure 4 This is a schematic diagram of the operation process for drip irrigation application of the fish protein aqueous solution of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0022] Please see Figures 1 to 4 This invention relates to a compound preparation for promoting root growth in sweet potato seedlings, comprising component one for basal application to the soil, component two for root dipping treatment of sweet potato seedlings, and component three for root irrigation treatment after planting. Component one is humic acid powder with a humic acid content ≥75%, and its field application dosage is 550 g / m². 2 ~600g / m 2Component 2 is an aqueous solution of naphthaleneacetic acid, wherein the concentration of naphthaleneacetic acid is 50 mg / L; Component 3 is an aqueous solution of fish protein, wherein the concentration of fish protein is 1 g / L, and the fish protein raw material for preparing the aqueous solution of fish protein is a 1000-fold concentrated slurry, wherein the total protein content of the concentrated slurry is ≥510 g / L and the amino acid mass content is ≥23%. In this embodiment, humic acid is rich in active functional groups such as quinone groups and phenolic hydroxyl groups. On the one hand, it can enhance the respiration of root cells and the activity of key enzymes such as polyphenol oxidase, stimulating the division and elongation of root tip meristem. On the other hand, it can increase soil organic matter, regulate soil pH, and improve soil aggregate structure, thus creating a long-term stable and excellent rhizosphere microenvironment for root growth. Naphthaleneacetic acid is an auxin regulator. After being absorbed by sweet potato stem segments, it can rapidly increase the plant's endogenous auxin level, directly promote cell division and tissue differentiation, and initiate the formation of adventitious root primordia, solving the core pain point of slow rooting initiation in the early stage of sweet potato cutting. The small molecule peptides and endogenous growth factors in fish protein can directly stimulate root tip meristem, accelerate cell division and elongation, promote the thickening of the main root, and promote the germination of a large number of lateral roots and capillary roots. At the same time, its rich amino acids can be directly absorbed by the root system, providing a direct nitrogen source and carbon skeleton for the continuous growth of root tips, ensuring the robust development of the root system throughout the entire cycle, and making up for the short-lasting effect of hormone regulators. It completely overcomes the shortcomings of single rooting agents, such as limited function, short duration of effect, and poor effect under adverse conditions. The three agents work synergistically to significantly accelerate the rooting speed of sweet potato seedlings and greatly improve core indicators such as total root length, root surface area, root volume, and root dry weight, achieving a comprehensive effect of promoting root growth, strengthening seedlings, and resisting adverse conditions.

[0023] In this scheme, the dosage of humic acid raw powder of component one is 575 g / m³. 2 The root-promoting and soil-improving effects of humic acid exhibit a strict dose-response relationship: too low a dose will not fully realize its soil-improving and root-stimulating effects, while too high a dose will lead to an imbalance in soil solution osmotic pressure, thus inhibiting root growth; 575 g / m³ 2 The dosage is the result of comprehensive optimization based on sweet potato root growth characteristics, soil improvement needs, and cost control. It can accurately match the response threshold of sweet potato seedling root growth, balancing effectiveness and economy. At this dosage, the root-promoting effect of humic acid can be maximized. Compared with higher dosage treatments, the core indicators such as total root length and root surface area of ​​sweet potato seedlings are better, and root elongation and expansion can be significantly promoted.

[0024] In this method, the humic acid powder of component one is applied alone to the soil surface or mixed with conventional chemical fertilizers before application. After application, it is thoroughly mixed with the soil by tilling. One of the core functions of humic acid is to improve the topsoil layer, the main distribution layer of sweet potato roots. Only by being fully mixed with the topsoil can it evenly regulate the physical and chemical properties of the soil throughout the field, providing a consistent and excellent environment for the growth of the entire sweet potato root system. At the same time, humic acid can adsorb nitrogen, phosphorus, and potassium nutrients from chemical fertilizers, reducing nutrient loss and forming a synergistic effect with chemical fertilizers, thereby improving fertilizer utilization. Ensuring that the humic acid is fully mixed with the topsoil maximizes its soil improvement and root stimulation effects, avoiding the problem of poor local root-promoting effects caused by uneven application. It can be completely integrated with the conventional sweet potato base fertilizer application process without adding extra field operation procedures, adapting to existing sweet potato cultivation techniques and being easy to operate. When mixed with chemical fertilizers, it can reduce fertilizer loss and improve fertilizer utilization, achieving both fertilizer-saving and environmental protection effects.

[0025] In this solution, the naphthaleneacetic acid (NAA) aqueous solution of component two is prepared using the following steps: Weigh 99% pure NAA, dissolve it completely in a small amount of anhydrous ethanol, and then dilute with pure water to obtain an aqueous solution with a NAA concentration of 50 mg / L. NAA is an organic acid compound with extremely low solubility in pure water; direct addition of water cannot achieve complete dissolution, easily leading to the precipitation of effective components and uneven solution concentration, resulting in fluctuations in root dipping effects. Anhydrous ethanol is a good solvent for NAA, completely dissolving it to form a homogeneous mother liquor. Diluting with water then yields a stable and uniformly dispersed NAA aqueous solution, ensuring that sweet potato stem segments can uniformly absorb the effective components. The preparation method is simple and easy to implement, requiring no complex equipment, and can be prepared on a large scale in field production, perfectly suited to the actual use scenarios of growers.

[0026] In this scheme, the fish protein aqueous solution of component three is prepared by diluting a 1000-fold concentrated fish protein slurry with pure water at a mass ratio of 1:1000. The concentrated fish protein slurry has an extremely high concentration of active ingredients; direct application would lead to excessively high local concentrations in the rhizosphere, causing osmotic stress and growth inhibition in sweet potato seedlings. Diluting at a 1:1000 ratio yields a precise 1 g / L fish protein aqueous solution. This concentration perfectly matches the nutrient requirements and active ingredient response thresholds for sweet potato root growth, fully leveraging the root-promoting and energy-supplying effects of small molecule peptides and amino acids without causing growth inhibition. The dilution method is simple and easy to operate, allowing for precise control of the fish protein aqueous solution concentration, avoiding growth inhibition due to excessive concentration or insufficient root-promoting effect due to excessively low concentration, ensuring stable root irrigation results. The fish protein aqueous solution at this dilution ratio exhibits the optimal root-promoting effect, with significant improvements in core indicators such as total root length and root dry weight of sweet potato seedlings compared to higher concentration treatments.

[0027] This invention also provides a method for using a compound preparation for promoting root growth in sweet potato seedlings, comprising the following steps: Step 1: Apply the components one by one to the target field, plow to mix them thoroughly with the soil, then rid the field with soil and set aside. Step 2: After soaking the base of the sweet potato seedling stems in component two, remove them, air dry them, and then plant them in the field treated in step 1. Step 3: After the sweet potato seedlings are planted, the roots of the sweet potato seedlings are irrigated with the following three components in three separate applications.

[0028] In this protocol, in step 2, the base of the sweet potato seedlings immersed in component two should be 10-15 cm long, and the immersion time should be 15 seconds. After immersion, the seedlings should be placed in a well-ventilated, shady place to air dry naturally for 5-10 minutes before planting. Sweet potato adventitious roots mainly sprout from the stem nodes. An immersion length of 10-15 cm can cover 2-3 stem nodes of the seedling, ensuring that all stem nodes prone to adventitious root growth are fully in contact with the naphthaleneacetic acid (NAA) solution, achieving root induction at all nodes. The 15-second immersion time ensures that the stem segments fully absorb the effective components, while avoiding excessive absorption of NAA due to prolonged immersion, which could cause phytotoxicity or inhibit above-ground growth. Air drying after immersion allows NAA to fully penetrate the stem tissue, while preventing high-concentration solutions from dripping into the soil after planting, which could lead to excessively high local concentrations affecting root growth and reducing the risk of stem rot after planting. Precise operating parameters can maximize the root-inducing effect of naphthaleneacetic acid while avoiding the risk of phytotoxicity. The root growth indicators of sweet potato seedlings under this treatment are significantly better than those under treatment with longer soaking time. The air-drying operation further ensures the stability of the root-dipping effect, reduces problems such as stem rot and phytotoxicity, and improves the survival rate of sweet potato seedlings. The single-bundle root-dipping operation mode can process 100 to 200 seedlings at a time, with high work efficiency, which is suitable for the pace of large-scale field planting.

[0029] In this plan, step 3 involves three separate root irrigations: the 3rd, 8th, and 13th day after planting the sweet potato seedlings. The rooting process of sweet potato seedlings after cutting propagation consists of three key stages: approximately 3 days after planting, the root primordia differentiation begins; approximately 8 days after planting, the adventitious root rapid elongation stage occurs; and approximately 13 days after planting, the lateral and capillary root germination occurs. These three separate root irrigations precisely match the growth rhythm of the sweet potato root system, providing continuous active stimulation and nutrient supply to the roots at each key growth stage. This solves the problem of short-lasting active ingredients in single root irrigations, which cannot meet the full-cycle growth needs of the root system. Precisely targeting key nodes in root growth, it continuously supports root growth. Compared to a single root irrigation, it can significantly increase the total root length, the number of lateral roots and capillary roots, resulting in a denser and stronger root system. Multiple root irrigations can avoid growth inhibition caused by excessively high concentrations in a single application, while extending the action time of active ingredients to achieve a sustained root-strengthening effect. It effectively shortens the seedling establishment period of sweet potato seedlings, enhances the seedlings' resistance to stress, and ensures uniform and robust growth of sweet potato seedlings.

[0030] In this plan, step 3 involves applying 150L of the three components per acre for each root irrigation. This 150L dosage per acre precisely matches the root distribution range of sweet potato seedlings and the water-holding capacity of the soil. This ensures the rhizosphere soil is fully moistened by the fish protein solution, allowing the roots to fully contact and absorb the active ingredients. It also avoids the problems of insufficient root wetting and uneven distribution of active ingredients due to insufficient dosage, or loss of active ingredients and reduced utilization due to excessive dosage. Ensuring the fish protein solution fully covers the rhizosphere area of ​​the sweet potato seedlings guarantees uniform absorption of active ingredients by each seedling, achieving consistent root-promoting effects across the field and avoiding uneven seedling growth. Precise control of the irrigation dosage ensures root-promoting effects while preventing loss of active ingredients, improving fish protein utilization, and reducing application costs.

[0031] In this scheme, step 3 involves drip irrigation. During drip irrigation, water is dripped for 20-30 minutes before the components are introduced for further application. After application, drip irrigation continues for another 20-30 minutes. This drip irrigation method precisely and evenly delivers the fish protein solution to the roots of each potato seedling, avoiding the uneven distribution and significant loss of active ingredients caused by flood irrigation, thus improving fertilizer utilization. The pre-drip irrigation moistens the drip irrigation pipes and rhizosphere soil, preventing dry soil from rapidly absorbing the active ingredients in the solution and ensuring even diffusion of the fish protein solution around the roots. The subsequent drip irrigation flushes any remaining fish protein solution from the pipes into the field, preventing waste of active ingredients and simultaneously washing the active ingredients from the rhizosphere surface to the main root distribution layer, maximizing absorption and utilization. It significantly improves the absorption and utilization rate of fish protein aqueous solution and reduces the loss of effective ingredients. Compared with traditional flood irrigation, it has a better root-promoting effect and lower application cost. It ensures that the root irrigation dosage of each potato seedling in the field is uniform and consistent, ensuring the uniformity of seedling growth. It can realize integrated water and fertilizer application, eliminating the need for additional manual root irrigation, greatly reducing the labor cost of field operations, and adapting to the production needs of large-scale and standardized sweet potato planting bases.

[0032] The humic acid powder, naphthaleneacetic acid, and fish protein concentrate involved in the following examples are all commercially available conventional products. The humic acid powder contains ≥75% humic acid by mass, the naphthaleneacetic acid has a purity of 99%, and the fish protein is a 1000-fold concentrated concentrate with a total protein content ≥510g / L and an amino acid content ≥23%. Unless otherwise specified, the environmental conditions such as temperature, light, and humidity for sweet potato seedling cultivation in the examples are consistent with the conventional field cultivation conditions for sweet potatoes.

[0033] Example 1: Optimization of the application rate of humic acid raw powder.

[0034] This embodiment focuses on optimizing the basal application rate of humic acid powder. The specific experimental method is as follows: 75% humic acid powder is spread on the soil surface, tilled to mix it thoroughly with the soil, and then ridged. Sweet potato seedlings are then planted in the ridges for cultivation. The humic acid powder dosage is set at 575 g / m². 2 1150g / m 2 1725g / m 2 Three treatment levels were established, along with a blank control without humic acid application. Ten sweet potato seedlings were planted in each treatment. On day 18 after planting, the roots of the plants were completely dug up, and root morphology and root dry weight were measured using the same method as in Example 1. The experimental protocol and test results are shown in Table 1.

[0035] Table 1. Results of the experiment on optimizing the application rate of humic acid powder: As shown in Table 1, compared with the blank control, the concentrations ranged from 575 to 1725 g / m². 2 Basal application of humic acid powder significantly improved various root growth indicators of sweet potato seedlings. Specifically, 575 g / m³... 2 With 1150g / m 2 The differences in various indicators after treatment were small, 1725 g / m 2 All indicators decreased after treatment, and 575 g / m 2 The application rate is lower and the cost-effectiveness is higher. Therefore, the preferred application rate in this invention is 575 g / m³. 2 Humic acid powder is used as a base fertilizer for sweet potato cultivation.

[0036] Example 2: Optimization of the application concentration of naphthaleneacetic acid.

[0037] This embodiment focuses on screening and optimizing the application concentration of naphthaleneacetic acid (NAA). The specific experimental method is as follows: Sweet potato seedlings were immersed in a prepared NAA aqueous solution for 15 seconds (10-15 cm from the base of the stem), then removed and planted in soil. Three NAA concentrations were set: 50 mg / L, 100 mg / L, and 150 mg / L. A water treatment was used as a blank control. Ten sweet potato seedlings were planted for each treatment. On day 18 after planting, the roots were completely excavated, and root morphology indicators such as total root length, total projected area, total surface area, and total volume were analyzed using a root scanner. The roots were then placed in envelopes, dried in an oven to constant weight, and the dry weight of the roots was measured. The experimental scheme and test results are shown in Table 2.

[0038] Table 2 Results of the Optimization Experiment for Naphthaleneacetic Acid Concentration: As shown in Table 2, compared with the blank control, treatments with 50–150 mg / L naphthaleneacetic acid (NAA) all improved the root growth indicators of sweet potato seedlings to varying degrees. Among these, the 50 mg / L NAA treatment resulted in the highest total root length, total projected root area, total root surface area, and total root volume, indicating that soaking sweet potato seedling stem segments in a 50 mg / L NAA aqueous solution for 15 seconds is most beneficial for root elongation, increasing root surface area and root volume, and significantly improving the robustness of the sweet potato seedling root system. Therefore, this invention preferably uses a 50 mg / L NAA aqueous solution as the root dipping agent for sweet potato seedling cuttings.

[0039] Example 3: Optimization of fish protein application concentration.

[0040] This embodiment focuses on screening and optimizing the concentration of fish protein aqueous solution for root irrigation. The specific experimental method is as follows: 1000-fold concentrated fish protein slurry was diluted with pure water in a certain proportion to obtain fish protein aqueous solutions of different concentrations. Root irrigation treatment was performed on the 3rd, 8th, and 13th days after sweet potato seedling cuttings, with 50 ml applied to each seedling each time. Three treatment levels of fish protein aqueous solution were set: 1 g / L, 2 g / L, and 3 g / L. A blank control of root irrigation with plain water was also set up. Ten sweet potato seedlings were planted for each treatment. On the 18th day after planting, the plant roots were completely dug up, and root morphology indicators and root dry weight were detected using the same method as in Example 1. The experimental scheme and test results are shown in Table 3.

[0041] Table 3 Results of the experiment on optimizing fish protein concentration for root irrigation: As shown in Table 3, compared with the blank control, root irrigation treatments with 1–3 g / L fish protein aqueous solution significantly promoted the root growth of sweet potato seedlings. Specifically, the total root length, total projected root area, total root surface area, total root volume, and root dry weight of the 1 g / L fish protein treatment were significantly higher than those of the 2 g / L and 3 g / L treatments, indicating that root irrigation with 1 g / L fish protein aqueous solution was most beneficial for promoting rapid and robust root growth in sweet potato seedlings. Therefore, this invention preferentially uses 1 g / L fish protein aqueous solution as the root irrigation agent after sweet potato seedling planting.

[0042] Example 4: Verification of the synergistic effect of naphthaleneacetic acid, humic acid and fish protein.

[0043] This embodiment verifies the application effects of pairwise and compound combinations of naphthaleneacetic acid (NAA), humic acid, and fish protein, clarifying their synergistic effect. The specific experimental method is as follows: 75% humic acid powder was spread on the soil surface according to the set dosage, tilled and mixed, and then ridged. The base 10-15cm of sweet potato seedling stems were immersed in a 50mg / L NAA aqueous solution for 15s, removed and air-dried, and then planted in the ridges. On the 3rd, 8th, and 13th days after planting, the roots were irrigated with a 1g / L fish protein aqueous solution, with 50ml applied to each sweet potato seedling each time. The experiment set up 4 treatment groups: NAA + humic acid group, humic acid + fish protein group, NAA + fish protein group, and NAA + humic acid + fish protein group. A blank control group without the application of the three substances was also set up. The specific treatment parameters are shown in Table 4. Ten sweet potato seedlings were planted in each treatment. On the 15th day after planting, the roots of the plants were dug up completely, and the root morphology and root dry weight were tested using the same method as in Example 1. The experimental scheme and test results are shown in Table 4.

[0044] Table 4. Results of synergistic effect verification experiments for different combination methods: As shown in Table 4, compared with the blank control, the pairwise combinations of naphthaleneacetic acid, humic acid, and fish protein, as well as the combined combination of the three, significantly improved various root growth indicators of sweet potato seedlings. Among them, treatment 13, with the combined combination of the three, showed significantly higher total root length, total root projected area, total root surface area, total root volume, and root dry weight than the individual pairwise combinations, indicating that root dipping with 50 mg / L naphthaleneacetic acid and 575 g / m³ of fish protein significantly improved root growth indicators. 2 The combined application of humic acid as a base and 1g / L fish protein in multiple root irrigations has a significant synergistic effect, which can greatly accelerate the root development of sweet potato seedlings, significantly promote root elongation and expansion, and achieve the best root-promoting and seedling-strengthening effect.

[0045] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A compound preparation for promoting root growth in sweet potato seedlings, characterized in that, It consists of component one for soil basal application, component two for root dipping treatment of sweet potato seedlings, and component three for root irrigation treatment after planting of sweet potato seedlings; component one is humic acid powder with a humic acid content ≥75% by mass, and its field application dosage is 550g / m². 2 ~600g / m 2 Component 2 is an aqueous solution of naphthaleneacetic acid, wherein the concentration of naphthaleneacetic acid is 50 mg / L; Component 3 is an aqueous solution of fish protein, wherein the concentration of fish protein is 1 g / L, and the fish protein raw material for preparing the aqueous solution of fish protein is a 1000-fold concentrated slurry, wherein the total protein content of the concentrated slurry is ≥510 g / L and the amino acid mass content is ≥23%.

2. The sweet potato seedling root-promoting compound preparation according to claim 1, characterized in that, The dosage of the humic acid raw powder in component one is 575 g / m³. 2 .

3. The sweet potato seedling root-promoting compound preparation according to claim 1, characterized in that, The humic acid powder of component one can be applied alone to the soil surface, or mixed with conventional chemical fertilizers and then applied. After application, it can be thoroughly mixed with the soil by tilling.

4. The sweet potato seedling root-promoting compound preparation according to claim 1, characterized in that, The aqueous solution of naphthaleneacetic acid of component two is prepared by the following steps: Weigh naphthaleneacetic acid with a purity of 99%, dissolve it completely with a small amount of anhydrous ethanol, and then add pure water to dilute and bring the volume to obtain an aqueous solution with a naphthaleneacetic acid concentration of 50 mg / L.

5. The sweet potato seedling root-promoting compound preparation according to claim 1, characterized in that, The fish protein aqueous solution of component three is prepared by mixing and diluting the 1000-fold concentrated fish protein slurry with pure water at a mass ratio of 1:1000.

6. A method of using the sweet potato seedling root-promoting compound preparation according to claim 1, characterized in that, Includes the following steps: Step 1: Apply the components one by one to the target field, plow to mix them thoroughly with the soil, then rid the field with soil and set aside. Step 2: After soaking the base of the sweet potato seedling stems in component two, remove them, air dry them, and then plant them in the field treated in step 1. Step 3: After the sweet potato seedlings are planted, the roots of the sweet potato seedlings are irrigated with the following three components in three separate applications.

7. The method of using the sweet potato seedling root-promoting compound preparation according to claim 6, characterized in that, In step 2, the base of the sweet potato seedlings in the second soaking group should be 10cm to 15cm long, and the soaking time should be 15 seconds. After soaking, place them in a well-ventilated and shady place to air dry naturally for 5 to 10 minutes before planting.

8. The method of using the compound preparation for promoting root growth in sweet potato seedlings according to claim 6, characterized in that, In step 3, the root irrigation is carried out on the 3rd, 8th and 13th day after the sweet potato seedlings are planted, for a total of three irrigations.

9. The method of using the sweet potato seedling root-promoting compound preparation according to claim 8, characterized in that, In step 3, the dosage of the three components for each root irrigation is 150L per acre of field.

10. The method of using the sweet potato seedling root-promoting compound preparation according to claim 6, characterized in that, In step 3, the root irrigation is carried out by drip irrigation. During drip irrigation, water is dripped for 20 to 30 minutes first, and then the three components are introduced for drip application. After the drip application is completed, water continues to drip for 20 to 30 minutes.

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