A treatment method for improving the germination performance of watermelon seeds

Abstract

The application discloses a treatment method for improving the germination performance of watermelon seeds and belongs to the technical field of watermelon seed pretreatment. The application provides two optional treatment processes, one of which is that watermelon seeds are soaked in 0.1% anhydrous calcium sulfate suspension for 4h, and then are washed and dried; the other of which is that a cellulase and pectinase compound solution is used to carry out constant-temperature enzymolysis treatment of watermelon seeds according to the thousand-grain weight of the watermelon seeds, under the condition of 45 DEG C, and by matching the differentiated enzyme concentration and soaking time. The application can weaken the constraint of the watermelon seed shell from the source, and solve the problem of seedling emergence with shell. Experiments show that the calcium sulfate treatment can reduce the seedling emergence rate of small-grain seeds with shell to 20%-25%; the differentiated enzyme treatment can reduce the seedling emergence rates of large-grain seeds, medium-grain seeds and small-grain seeds with shell to 0-2%, 6%-8% and 2%-5% respectively, can shorten the seedling cycle by 7-10d, can air-dry the seeds for mechanical sowing and does not affect the storage performance, effectively reduces the seedling cost, and improves the seedling quality.

Description

Technical Field

[0001] This invention relates to the field of watermelon seed treatment technology, and in particular to a treatment method for improving the germination performance of watermelon seeds. Background Technology

[0002] During the cultivation of greenhouse vegetable seedlings, the phenomenon of seeds emerging with their seed coats intact is common, especially among watermelon seedlings, where the rate can reach 70%-85%. When the cotyledons emerge, the seed coat remains attached. If this is not removed promptly, the seedlings are prone to becoming tall and weak, and in severe cases, this can lead to yellowing, stunted growth, and negatively impact later plant development. This problem has plagued many watermelon farmers for years, and the mainstream solution used by seedling nurseries across the country remains manual seed removal. Currently, seedling nurseries generally employ mechanical sowing and tray seedling cultivation. Large-scale nurseries can cultivate tens of thousands to hundreds of thousands of watermelon seedlings at a time. Relying entirely on manual seed removal would consume a significant amount of manpower and resources, resulting in extremely high production costs.

[0003] Research indicates that over 80% of seedling nurseries still rely on manual seed hulling. Conventional pre-sowing water soaking only slightly improves seed emergence with the hull still attached, with very limited effect. Furthermore, mechanical sowing requires extremely dry seeds; they must be dry and loose before sowing to prevent problems such as seed absorption difficulties, seed breakage, and missed sowing. A few nurseries use nighttime mulching after emergence to assist hulling, but nighttime is a critical period for seed rooting, and mulching raises the seedbed temperature, easily inducing tall, weak seedlings. This method is only suitable for winter seedling cultivation at low temperatures and cannot be used in spring and autumn. Additionally, using high substrate humidity to assist hulling easily leads to seed rot, root rot, and a significant drop in germination rate, resulting in high seedling risk and poor stability.

[0004] Watermelon seeds have a seed coat rich in mucilage germination inhibitors, and the seed coat is dense and hard, which is the core internal factor leading to slow germination, uneven germination, inconsistent seedling emergence, and a high rate of seedlings emerging with the seed coat intact. Existing production processes mostly use methods such as soaking seeds in water, soaking seeds in conventional chemicals, and enzymatic hydrolysis treatment with uniform parameters to pretreat seeds, which generally have defects such as poor specificity, unstable treatment effects, and weak adaptability.

[0005] In existing technologies, calcium salts are mostly used for soil fertilization, soil improvement, and foliar spraying, and are rarely specifically used for watermelon seed coat softening, mucilage removal, and pre-treatment for dehulling. Conventional enzyme treatment processes all use uniform and fixed enzyme concentrations and soaking times, without differentiating parameters for different thousand-seed weights of watermelon seeds (large, medium, and small). This easily leads to problems such as hard seed coats, incomplete treatment, and poor dehulling in large seeds, and over-enzymatic hydrolysis and embryo damage in small seeds, making them unsuitable for the needs of large-scale, standardized mechanized seedling production. In summary, there is an urgent need for a simple seed pretreatment method that is adaptable to different sizes of watermelon seeds, provides stable dehulling results, and is suitable for mechanized sowing. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide two independently usable watermelon seed pretreatment processes to solve the problem of watermelon seeds emerging with their shells intact, reduce waste of inferior seedlings, improve seedling quality, shorten the seedling cycle, and reduce costs while increasing efficiency. The anhydrous calcium sulfate suspension soaking process is simple to operate, uses readily available raw materials, and is inexpensive, making it suitable for large-scale mass production. The compound enzyme constant-temperature soaking process uses differentiated enzymatic hydrolysis based on the thousand-seed weight of watermelon seeds, specifically breaking down the seed coat's gelatinous texture and hard seed shell barriers. It precisely matches the seed shell thickness and germination tolerance characteristics of different seed sizes, fundamentally reducing the rate of seeds emerging with their shells intact, improving seed germination rate and uniformity, and is fully compatible with large-scale mechanized tray seedling production.

[0007] The odd-numbered solution of the present invention is: a treatment method for improving the germination performance of watermelon seeds, comprising any one of the following treatment methods; Method 1: Soaking treatment with anhydrous calcium sulfate suspension, comprising the following steps: adding anhydrous calcium sulfate to distilled water at a mass ratio of anhydrous calcium sulfate: distilled water = 1:1000, stirring evenly to prepare an anhydrous calcium sulfate suspension with a mass concentration of 0.1%; placing watermelon seeds in the suspension, ensuring the suspension completely submerges the seeds, and soaking for 4 hours; after soaking, removing the seeds, rinsing thoroughly with water to remove the mucus from the seed surface, and placing them in a cool place to dry; Method 2: Constant temperature soaking treatment with compound enzyme solution, including the following steps: Weigh pectinase and cellulase separately, add acetate-sodium acetate buffer to prepare enzyme solutions with a mass concentration of 0.2%-1.6% and 0.25%-2% respectively, and perform compound enzyme soaking treatment on watermelon seeds. The soaking time for pectinase solution is between 20 min and 40 min, and the soaking time for cellulase solution is between 50 min and 3 h. Adjust the soaking time according to the thousand-seed weight of watermelon seeds. The soaking order of the two solutions is not important. Furthermore, in Method 1, the dried seeds and in Method 2, the soaked seeds can be used directly for sowing or dried and stored for later use; the dried seeds meet the drying requirements for mechanical tray sowing. Furthermore, in Method Two, watermelon seeds are treated according to their thousand-seed weight: Large watermelon seeds with a thousand-seed weight greater than 80g: soaked in a 0.7%-0.9% pectinase solution for 25-35 minutes and a 0.4%-0.6% cellulase solution for 50-70 minutes, respectively; Small watermelon seeds with a thousand-seed weight less than 30g: soaked in a 0.4%-0.6% cellulase solution for 2.5-3 hours and a 0.7%-0.9% pectinase solution for 25-40 minutes, respectively; Medium watermelon seeds with a thousand-seed weight between 30g and 80g: soaked in a 0.9%-1.2% cellulase solution for 1.5-2.5 hours and a 0.2%-0.25% pectinase solution for 25-35 minutes, respectively. Furthermore, in Method 2, the acetate-sodium acetate buffer solution is used to adjust the pH of the enzyme solution, maintain the suitable working pH range of the enzyme, keep the pH value between 4.5 and 4.8, and ensure stable enzyme activity.

[0008] The beneficial effects of this invention are as follows: 1. This invention provides two independently selectable seed pretreatment processes. The anhydrous calcium sulfate suspension soaking process uses readily available raw materials, is extremely simple to operate, and has very low cost, making it suitable for large-scale batch processing in seedling nurseries. It can effectively weaken the hard seed coat binding of watermelon seeds, degrade surface germination inhibitors, and significantly reduce the rate of seedlings emerging with their shells intact. Experimental verification shows that after soaking small watermelon seeds in a 0.1% anhydrous calcium sulfate suspension for 4 hours, the rate of seedlings emerging with their shells intact decreased from 70%–80% to 20%–25%. Compared to soaking in water for the same duration, the shell removal and quality improvement effect is increased by 35%, significantly reducing tall, weak, yellow, and deformed seedlings, and reducing seedling losses. 2. This invention improves the seed coat structure and removes germination barriers through pre-sowing pretreatment, effectively accelerating seed germination speed and shortening the overall seedling cycle by 7–10 days, precisely matching the needs of facility-based seedling production. The treated seeds have stable physicochemical properties and do not affect long-term storage performance at room temperature. At the same time, it completely avoids the drawbacks of traditional manual dehulling, film-coating to promote dehulling, and high-humidity substrate to promote dehulling, eliminating problems such as tall seedlings, rotten seeds, and rotten roots from the source, and significantly improving seedling stability; 3. The compound enzyme treatment process of this invention innovatively adopts the "differentiated enzymatic hydrolysis according to seed size" scheme. It matches specific enzyme concentrations and soaking times to the differences in seed coat thickness, density, and tolerance of large, medium, and small watermelon seeds, completely solving the defects of traditional uniform parameter treatment, such as incomplete treatment of large seeds and damage to the embryo by enzymatic hydrolysis of small seeds; it precisely degrades seed coat colloid and softens seed shell, with strong treatment targeting and stable effect. Experiments have verified that: after differentiated enzymatic hydrolysis treatment, the seed husk-in-soil emergence rate of large-grain watermelon seeds is reduced to 0-2%, medium-grain watermelon seeds to 6-8%, and small-grain watermelon seeds to 2-5%, demonstrating extremely excellent husk removal and quality improvement effects; 4. The seeds treated by this invention are dry and loose after air drying, making them perfectly compatible with fully automatic tray sowing machinery, eliminating the need for manual husk removal in the later stages, saving a significant amount of labor costs, greatly improving seedling efficiency, and adapting to modern, large-scale, and standardized seedling production models, resulting in high industrial value; 5. The two processes can be flexibly selected according to the scale of seedling production, material conditions, and seasonal environment, with a wide range of applications, low operating threshold, and strong promotion potential, making them suitable for use by various seedling bases and large-scale growers. Detailed Implementation

[0009] The technical solution of the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. The present invention sets up two sets of pretreatment processes, namely, Method 1: soaking treatment with anhydrous calcium sulfate suspension and Method 2: stepwise compound enzymatic hydrolysis soaking treatment. Among them, the anhydrous calcium sulfate suspension process is simple to operate, low in cost, and high in safety, and is suitable for large-scale simple pretreatment; the compound enzymatic hydrolysis process has strong targeting and excellent quality improvement effect, and can accurately break dormancy for watermelon seeds of different grain types. The following are examples according to the process methods. All examples have the same cultivation conditions, the same sampling quantity, and the same culture environment, and use seed germination rate, germination potential, seed coat integrity, and seedling uniformity as core evaluation indicators. In the following examples of Method 2, the pH of the enzyme solution is adjusted by using an acetate-sodium acetate buffer solution to maintain the pH value between 4.5 and 4.8 to ensure stable enzyme activity.

[0010] Method 1: Immersion Treatment with Anhydrous Calcium Sulfate Suspension. This method uses a 0.1% anhydrous calcium sulfate suspension to immerse watermelon seeds at a constant temperature. By gently modifying the microporous structure of the seed coat and supplementing trace mineral elements, it breaks the shallow dormancy of the seeds, enhances seed germination vitality, and causes no seed coat corrosion or embryo damage. It is suitable for all sizes of watermelon seeds.

[0011] Example 1 (General Standard Process | Suitable for All Sizes of Watermelon Seeds) Select plump, mold-free, and undamaged watermelon seeds. Rinse with clean water to remove surface dust and impurities, and allow to drain naturally. Add anhydrous calcium sulfate to distilled water at a mass ratio of 1:1000, and stir continuously at a uniform speed for 15 minutes. After stirring evenly, prepare a 0.1% anhydrous calcium sulfate suspension. Completely immerse the drained watermelon seeds in the suspension and soak at a constant temperature for 4 hours. After soaking, remove the seeds and rinse thoroughly with running water to remove any remaining suspension mucus and residual powder from the seed surface. Place in a ventilated, cool place to air dry naturally. After drying, proceed with conventional constant temperature germination and seedling cultivation.

[0012] Experimental Results: Anhydrous calcium sulfate suspension can gently modify the microstructure of watermelon seed coat, moderately increase the porosity of the seed coat surface, reduce the mechanical germination resistance of the seed coat, and effectively break the shallow dormancy of seeds. Simultaneously, it can supplement trace amounts of calcium and sulfur nutrients, activate the activity of antioxidant enzymes in the seeds, and enhance seed cell vitality and stress resistance. After treatment with this process, the seed emergence rate with seed coat decreased from 80% to 24%, the watermelon seed germination rate reached 83.6%, the germination potential was 75.2%, the seed coat was clean and free of residue and corrosion damage, and the seedling uniformity was significantly better than the blank control group. Seedlings had well-developed root systems and vigorous growth, effectively improving problems such as delayed seed germination, uneven emergence, and a high incidence of weak seedlings. The process is simple and easy to operate, suitable for large-scale, simplified pretreatment.

[0013] Example 2 (Large Watermelon Seeds | 1000-Seed Weight > 80g) Large watermelon seeds with a 1000-seed weight greater than 80g, plump and free from damage or mold were selected. The seeds were rinsed with clean water to remove surface impurities and allowed to drain naturally. A 0.1% anhydrous calcium sulfate suspension was prepared, and the large seeds were completely immersed in the suspension and soaked at a constant temperature for 4 hours. After soaking, the seeds were removed, rinsed repeatedly with running water to remove any residual powder, and then placed in a cool, ventilated place to dry. Conventional germination and seedling cultivation were then carried out.

[0014] Experimental Results: Large-grained watermelon seeds have thick, dense fibrous coats with small pores and poor water and air permeability, resulting in high resistance to natural germination and slow emergence. This process gently opens up the micropores in the seed coat, softens the hard fibrous structure of the surface, effectively reduces the germination resistance of large-grained seeds, and alleviates the problems of delayed emergence and difficulty in breaking through the soil. The entire treatment is gentle and non-irritating, causing no mechanical or chemical damage to the seeds, making it extremely safe. After treatment, the seed germination rate reached 85.1%, the germination vigor was 77.3%, and the seed emergence rate with the seed coat remaining decreased from 76% to 25%. Emergence was uniform, and seedlings grew evenly and vigorously. This process is suitable for low-cost, large-scale, and simple quality improvement pretreatment of high-quality large-grained watermelon seeds.

[0015] Example 3 (Small Watermelon Seeds | 1000-Seed Weight <30g) Small watermelon seeds with a 1000-seed weight of less than 30g, plump and free from shriveling, damage, or mold were selected. The seeds were rinsed thoroughly with clean water and allowed to drain naturally. They were then completely submerged in a prepared 0.1% anhydrous calcium sulfate suspension and soaked at a constant temperature for 4 hours. After soaking, the seeds were removed, rinsed thoroughly with running water to remove any residual suspension, and allowed to air dry naturally in a cool place. They were then subjected to conventional constant-temperature germination and seedling cultivation.

[0016] Experimental Results: Small watermelon seeds have thin skins, delicate embryos, and weak resistance to adverse conditions. Conventional strong-stimulation pretreatment easily causes seed rot and embryo damage. Anhydrous calcium sulfate treatment, a gentle method, does not erode the thin, delicate seed coat and embryo of small seeds. Under absolutely safe conditions, it optimizes the air and water permeability of the seed coat, effectively activating the endogenous germination vitality of weak seeds. After treatment, the seed germination rate reached 82.4%, the germination potential was 73.9%, and the seed emergence rate with seed coat decreased from 78% to 22%. This significantly reduces problems such as seed rot, stunted seedlings, and failure to germinate in small seeds, greatly improving the field seedling survival rate. The process is widely adaptable, low-cost, and has a high safety factor.

[0017] Example 4 (Medium-sized watermelon seeds | 30g-80g) Select medium-sized watermelon seeds with a thousand-seed weight between 30g and 80g, plump and undamaged, free from mold and pests. Rinse with clean water to remove surface dirt and allow to drain naturally. Prepare a 0.1% anhydrous calcium sulfate suspension and completely immerse the seeds in it, soaking at a constant temperature for 4 hours. After soaking, remove the seeds, rinse thoroughly with running water, and air dry in a cool, ventilated place. Then proceed with conventional germination and seedling cultivation.

[0018] Experimental Results: Medium-sized watermelon seeds exhibit moderate dormancy and uniform seed coat structure. This process can stably break the shallow physiological dormancy of seeds, moderately improve the water and air permeability of the seed coat, and uniformly enhance seed germination vigor. The treatment is non-irritating, residue-free, and does not damage the seed embryo, exhibiting extremely high batch stability. After treatment, the seed germination rate reached 84.5%, the germination vigor was 76.8%, and the seed emergence rate with seed coat decreased from 76% to 25%. Seedlings emerged uniformly and steadily, with stable growth. Compared to enzymatic hydrolysis, this process is simpler to operate and has lower production costs, making it suitable for large-scale, high-volume watermelon seed pretreatment for quality improvement.

[0019] Method 2: Stepwise Compound Enzymatic Hydrolysis and Soaking Treatment. This method employs a stepwise compound enzymatic hydrolysis process involving soaking pectinase and cellulase sequentially. Based on the differences in thousand-seed weight of watermelon seeds, different enzyme concentrations, soaking times, and treatment sequences are specifically matched to precisely degrade the seed coat pectin and dense fiber barriers, deeply breaking seed dormancy. The quality improvement effect is significantly better than single treatment, suitable for precise and high-quality pretreatment of watermelon seeds of different seed sizes. It should be noted that the soaking order of pectinase solution and cellulase solution in this process has no significant difference in seed treatment effect, germination index, and seedling quality. Both soaking sequences can achieve the same dormancy-breaking and quality improvement effect, offering high process flexibility and a wider range of applications.

[0020] Example 5 (General basic lower limit process: pectinase 0.2%, 20 min; cellulase 0.25%, 50 min) Pectinase and cellulase were weighed separately and added to acetate-sodium acetate buffer to prepare a 0.2% pectinase solution and a 0.25% cellulase solution. Plump, mold-free watermelon seeds were selected, and the surface moisture was drained. The watermelon seeds were soaked in the pectinase solution for 20 min. After that, they were taken out and rinsed briefly with clean water, and then soaked in the cellulase solution for 50 min. After the treatment, the seeds were taken out, rinsed with clean water, and then germinated and cultivated at a constant temperature according to conventional methods.

[0021] Experimental Results: This group employed a low-concentration, short-duration, and extremely mild process. The enzymatic hydrolysis was gentle, resulting in no seed corrosion or embryo damage. Seed germination rate reached 87.2%, germination vigor 78.5%, and the seed coat remained intact without cracking, browning, or damage. Seedling uniformity was moderate. Only the surface structure of the seed coat was slightly softened, and the dormancy-breaking effect was gentle, making it suitable for mild pretreatment of sensitive watermelon varieties that are intolerant of high-intensity treatments.

[0022] Example 6: Pectinase and cellulase were weighed separately and added to acetate-sodium acetate buffer to prepare a 1.0% pectinase solution and a 0.6% cellulase solution. Watermelon seeds were soaked in the pectinase solution for 40 minutes. After briefly rinsing with clean water, the seeds were soaked in the cellulase solution for 3 hours. After the treatment was completed, the seeds were rinsed with clean water and then germinated and raised as seedlings.

[0023] Experimental Results: Using the upper limit parameters of the process, the compound enzyme fully degraded the outer pectin and dense fiber layer of the seed coat, significantly improving the air and water permeability of the seed coat. The seed germination rate reached 96.8%, the germination potential was 92.3%, and the seedling emergence uniformity was excellent. The emergence cycle was shortened by 4-7 days compared with the control group. The seeds showed no excessive corrosion or endosperm damage, and the breakage rate was less than 0.5%. It can effectively break deep dormancy and is the optimal general process of this invention.

[0024] Example 7 (Cross-extreme process: pectinase 0.2%, 40 min; cellulase 2%, 50 min) Pectinase and cellulase were weighed separately and added to acetate-sodium acetate buffer to prepare a 0.2% pectinase solution and a 2% cellulase solution. Watermelon seeds were soaked in the pectinase solution for 40 min. After rinsing, they were soaked in the cellulase solution for 50 min. After rinsing with clean water, they were cultured as usual.

[0025] Experimental results: Low-concentration pectinase gently softens the surface pectin over a long period, while high-concentration cellulase rapidly cleaves the fibrous structure in a short time, balancing safety and processing efficiency. Seed germination rate was 92.5%, germination vigor was 86.7%, seedling emergence was rapid, seed coat integrity was high with no damage defects, making it suitable for quality improvement pretreatment of mid-maturing watermelon varieties.

[0026] Example 8 (Cross-extreme process: pectinase 1.6%, 20 min; cellulase 0.25%, 3 h) Pectinase and cellulase were weighed separately and added to acetate-sodium acetate buffer to prepare a 1.6% pectinase solution and a 0.25% cellulase solution. Watermelon seeds were soaked in the pectinase solution for 20 min; after rinsing, they were soaked in the cellulase solution for 3 h; after rinsing, they were cultured.

[0027] Experimental results: High-concentration pectinase quickly and rapidly clears the clogging of seed coat gums, while low-concentration cellulase gradually loosens deep fibers over a long period, deeply optimizing the aeration and water permeability channels of the seed coat. The seed germination rate was 93.1%, the germination vigor was 88.2%, and the seedling emergence was uniform. The effect on repairing and improving the quality of old and weak watermelon seeds was particularly outstanding.

[0028] Example 9 (General Intermediate Equilibrium Process): Pectinase and cellulase were weighed separately and added to acetate-sodium acetate buffer to prepare a 0.9% pectinase solution and a 1.1% cellulase solution by mass concentration. Watermelon seeds were soaked in the pectinase solution for 30 minutes, rinsed, and then soaked in the cellulase solution for 2.25 hours. After rinsing, the seeds were then germinated and raised as seedlings using conventional methods.

[0029] Experimental results: The intermediate parameters of the process are moderate in intensity, highly stable, and have a high tolerance for error. The seed germination rate is 90.4%, the germination potential is 83.5%, the seedlings emerge uniformly and grow steadily, with no risk of seed damage. It offers the best cost performance and is suitable for large-scale production pretreatment.

[0030] Example 10 (High-concentration short-time combined process: pectinase 1.6%, 20 min; cellulase 2%, 50 min) Pectinase and cellulase were weighed separately and added to acetate-sodium acetate buffer to prepare a 1.6% pectinase solution and a 2% cellulase solution by mass concentration; watermelon seeds were soaked in pectinase solution for 20 min; after rinsing, they were soaked in cellulase solution for 50 min; then they were taken out, rinsed and cultured.

[0031] Experimental Results: The dual high-concentration, short-time treatment resulted in high operational efficiency and a short cycle. Seed germination rate was 94.2%, germination potential was 89.6%, and seedling emergence was rapid, significantly reducing pretreatment time. Seed coat integrity was good, with no excessive corrosion, making it suitable for rapid batch processing in the seed industry.

[0032] Example 11 (Low-concentration, long-term, mild process: pectinase 0.2%, 40 min; cellulase 0.25%, 3 h) Pectinase and cellulase were weighed separately and added to acetate-sodium acetate buffer to prepare 0.2% pectinase solution and 0.25% cellulase solution by mass concentration; watermelon seeds were soaked in pectinase solution for 40 min; after rinsing, they were soaked in cellulase solution for 3 h; after rinsing, they were taken out and cultured.

[0033] Experimental results: The dual low-concentration, long-term, gentle enzymatic hydrolysis resulted in uniform action and excellent safety. Seed germination rate was 89.7%, germination potential was 81.3%, seed coat integrity rate was 100%, with no corrosive or pesticide damage. Suitable for rare watermelon varieties with thin skin and weak resistance.

[0034] Example 12 (Large seeds | 1000-seed weight > 80g | Lower limit values: pectinase 0.7%, 25min; cellulase 0.4%, 50min) Select plump, large watermelon seeds with a 1000-seed weight greater than 80g, rinse and drain; prepare 0.7% pectinase solution and 0.4% cellulase solution; first soak in pectinase for 25min, rinse and then soak in cellulase for 50min, rinse and then cultivate as usual.

[0035] Experimental results: It is mildly adapted to the structure of large, thick seed coats, and targets and softens the dense surface tissue without the risk of overtreatment. The seed germination rate is 91.2%, the germination potential is 83.7%, and the seed emergence rate with shell is reduced from 78% to 2%, effectively improving the problems of difficult emergence and delayed seedling emergence of large seeds, with stable and safe quality improvement effects.

[0036] Example 13 (Large seeds | 1000-seed weight > 80g | Upper limit: pectinase 0.9%, 35min; cellulase 0.6%, 70min) Select large seeds with a 1000-seed weight greater than 80g, rinse and drain; prepare 0.9% pectinase and 0.6% cellulase solutions; soak in the solutions for 35min and 70min in stages, rinse and dry before sowing.

[0037] Experimental results: Deeply degrades the thick seed coat's deep fiber and pectin barrier, completely breaking deep dormancy. Seed germination rate is 95.4%, germination potential is 90.5%, emergence cycle is shortened by 4-7 days, seed emergence rate with seed coat reduced from 78% to 1.6%, and seedlings are robust and uniform, representing the optimal process for this specification.

[0038] Example 14 (Large seeds | 1000-seed weight > 80g | Intermediate values: pectinase 0.8%, 30min; cellulase 0.5%, 60min) Select large watermelon seeds, rinse and drain; prepare 0.8% pectinase and 0.5% cellulase solutions, soak them in the solutions for 30min and 60min respectively, and then cultivate them in a conventional manner.

[0039] Experimental results: The seed exhibits balanced strength, strong stability, and suitability for mass production. The seed germination rate is 93.5%, the germination potential is 87.9%, and the seed emergence rate with husk has decreased from 78% to 0.5%, achieving both quality improvement and seed safety, demonstrating excellent industrial adaptability.

[0040] Example 15 (Small seeds | 1000-seed weight <30g | Lower limit values: cellulase 0.4%, 2.5h; pectinase 0.7%, 25min) Small seeds with a 1000-seed weight <30g were selected. A 0.4% cellulase and 0.7% pectinase solution was prepared using a reverse process of cellulase followed by pectinase. The seeds were soaked in the solution for 2.5h and 25min in stages, followed by rinsing and seedling cultivation.

[0041] Experimental results: Perfectly adapted to the delicate structure of thin seed coats, breaking dormancy with zero damage. Seed germination rate was 90.1%, germination vigor was 82.3%, and the seed emergence rate with seed coat was reduced from 80% to 5%, significantly improving the problems of weak emergence, scattered seedlings, and low seedling survival rate of small seeds.

[0042] Example 16 (Small seeds | 1000-seed weight <30g | Upper limit: cellulase 0.6%, 3h; pectinase 0.9%, 40min) Small seeds were soaked in 0.6% cellulase for 3h and 0.9% pectinase for 40min, rinsed and dried, and then cultured in a conventional manner.

[0043] Experimental results: Long-lasting, mild, gradient enzymatic hydrolysis maximizes seed viability. Seed germination rate was 93.8%, germination potential was 87.2%, and the rate of seed emergence with shell was reduced from 80% to 3.4%. Seedlings developed strong root systems and grew uniformly, completely solving the problem of weak seedlings caused by small seeds.

[0044] Example 17 (Small seeds | 1000-seed weight <30g | Intermediate values: cellulase 0.5%, 3h; pectinase 0.8%, 32min) Small seeds were treated with 0.5% cellulase for 3h and 0.8% pectinase for 32min before seedling cultivation.

[0045] Experimental results: Compatible with most commercial small-grain varieties, with good consistency in batch processing. Seed germination rate was 92.2%, germination potential was 85.1%, and the seed emergence rate with husk was reduced from 80% to 2%, demonstrating safety, stability, and balanced quality improvement.

[0046] Example 18 (Medium-grained seeds | 30-80g | Lower limit values: cellulase 0.9%, 1.5h; pectinase 0.2%, 25min) Medium-grained seeds were first soaked in 0.9% cellulase for 1.5h, then soaked in 0.2% pectinase for 25min, rinsed and cultured.

[0047] Experimental results: Precisely adapted to the medium dormancy characteristics of medium-sized seeds, gently breaking dormancy and improving germination rate. Seed germination rate was 92.7%, germination vigor was 86.4%, and the seed emergence rate with seed coat decreased from 75% to 8%, with uniform and stable seedling emergence.

[0048] Example 19 (Medium-grained seeds | 30-80g | Upper limit: cellulase 1.2%, 2.5h; pectinase 0.25%, 35min) Medium-grained seeds were treated stepwise by soaking in 1.2% cellulase for 2.5h and 0.25% pectinase for 35min.

[0049] Experimental results: Deeply opened the aeration channels of the seed coat, completely breaking physiological dormancy. The seed germination rate was 93.2%, the germination vigor was 88.1%, and the seed emergence rate with seed coat was reduced from 75% to 7.4%. The seedlings emerged quickly, with high uniformity and strong resistance to adverse conditions.

[0050] Example 20 (Medium-grained seeds | 30-80g | Intermediate values: cellulase 1.05%, 2h; pectinase 0.2%, 30min) Medium-grained seeds were treated by soaking in 1.05% cellulase for 2h and 0.2% pectinase for 30min.

[0051] Experimental results: Highest tolerance for error and strongest applicability. Seed germination rate was 94.6%, germination vigor was 89.8%, and the rate of seeds emerging with their husks was reduced from 75% to 6%. The overall quality improvement effect was balanced, making it suitable for large-scale industrial application.

[0052] The watermelon seeds processed in all the above embodiments can be dried and can be directly used for mechanical sowing, or dried and stored for subsequent mechanical sowing, which can save a lot of manpower, material resources and financial resources.

[0053] Comparative Example 1 (Blank Control Group): Watermelon seeds were soaked in an equal amount of acetic acid-sodium acetate buffer solution without the addition of pectinase and cellulase. The soaking times were 20 min, 30 min, 40 min, 50 min, 1 h, 1.3 h, 1.5 h, 2 h, 2.3 h, 2.5 h, and 3 h, respectively. The germination and seedling environment was completely consistent with all examples.

[0054] Experimental results: The blank group seeds had dense seed coats, significant dormancy, and poor air and water permeability. The germination rate was only 75.3%, the germination potential was 62.8%, and the seed emergence rate with seed coat was between 60% and 75%. The seedling emergence was uneven and the cycle was long. Stunted seedlings, weak seedlings, and failure to emerge were common. The overall seed vigor was significantly lower than that of all treatment examples of this invention.

[0055] Comparative Example 2 (Water Soaking Control Group): Watermelon seeds were treated by soaking in water only, without using acetate-sodium acetate buffer, and without adding pectinase or cellulase. Soaking times were 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, and 4h. The germination and seedling environment was completely consistent with all examples.

[0056] Experimental results: The control group seeds had dense seed coats, significant dormancy, and poor air and water permeability, with a germination rate of only 74%, a germination vigor of 61.1%, and a seed emergence rate with seed coat between 60% and 73%. Compared with all embodiments of the present invention, the seedling emergence was uneven, the cycle was long, and stunted, weak, or non-emerging seedlings were more common. The overall seed vigor was significantly lower than that of all treatment embodiments of the present invention.

Claims

1. A treatment method for improving the germination performance of watermelon seeds, characterized in that, The following are all possible treatment methods: Method 1: Soaking treatment with anhydrous calcium sulfate suspension, including the following steps: Add anhydrous calcium sulfate to distilled water at a mass ratio of anhydrous calcium sulfate: distilled water = 1:1000, stir evenly to prepare an anhydrous calcium sulfate suspension with a mass concentration of 0.1%; put watermelon seeds into the suspension, ensuring the suspension completely submerges the seeds, and soak for 4 hours; after soaking, remove the seeds, rinse thoroughly with water to remove the mucus on the seed surface, and place in a cool place to dry; Method 2: Constant temperature soaking treatment with compound enzyme solution, including the following steps: Weigh pectinase and cellulase separately, add acetate-sodium acetate buffer to prepare enzyme solutions with a mass concentration of 0.2%-1.6% and 0.25%-2% respectively. Soak watermelon seeds in the compound enzyme solution in stages. The soaking time for pectinase solution is between 20 min and 40 min, and the soaking time for cellulase solution is between 50 min and 3 h. Adjust the soaking time according to the thousand-seed weight of watermelon seeds. The soaking order of the two solutions is not important.

2. The method for improving the germination performance of watermelon seeds according to claim 1, characterized in that, In Method 1, the dried seeds and in Method 2, the soaked seeds can be used directly for sowing or dried and stored for later use; the dried seeds meet the drying requirements for mechanical tray sowing.

3. The method for improving the germination performance of watermelon seeds according to claim 1, characterized in that, In Method Two, watermelon seeds are treated according to their thousand-seed weight: Large watermelon seeds (thousand-seed weight > 80g): soaked in a 0.7%-0.9% pectinase solution for 25-35 minutes and a 0.4%-0.6% cellulase solution for 50-70 minutes; Small watermelon seeds (thousand-seed weight < 30g): soaked in a 0.4%-0.6% cellulase solution for 2.5-3 hours and a 0.7%-0.9% pectinase solution for 25-40 minutes; Medium watermelon seeds (thousand-seed weight between 30g and 80g): soaked in a 0.9%-1.2% cellulase solution for 1.5-2.5 hours and a 0.2%-0.25% pectinase solution for 25-35 minutes.

4. The method for improving the germination performance of watermelon seeds according to claim 1, characterized in that, In Method 2, the acetate-sodium acetate buffer is used to adjust the pH of the enzyme solution, maintain the suitable working pH range of the enzyme, keep the pH value between 4.5 and 4.8, and ensure stable enzyme activity.