A method to improve the adaptability of water chestnut to rapid water level changes

Abstract

This invention relates to the field of biotechnology, and more particularly to a method for enhancing the adaptability of *Trapa natans* to rapid water level changes. The invention provides a method to improve the adaptability of *Trapa natans* to rapid water level changes by controlling surface water level regulation, fertilization, and stake fixing during its growth stages. This method enables in-situ plant protection, complies with relevant national laws and regulations, and is scientifically sound. Furthermore, compared to a control group, the method of this invention effectively enhances the stem extension and fruiting of floating-leaved plants, effectively improving their ability to adapt to rapidly changing water levels.

Description

Technical Field

[0001] This invention relates to the field of biotechnology, and in particular to a method for improving the adaptability of *Trapa natans* to rapid changes in water level. Background Technology

[0002] Wild plants and other biological genetic resources are an important component of biodiversity, providing the material basis for genetic breeding and biotechnology research and development in my country, and are a vital strategic resource for national sustainable development. Plant resources not only provide food for humans but also raw materials such as medicinal herbs and spices, and are closely related to human life and industrial and agricultural production. Protecting wild plant resources is of great significance for improving the quality of forestry and agricultural products, maintaining biodiversity and ecological balance, and is a cornerstone of national security. To strengthen the effective protection of plant resources, my country released a revised "National Key Protected Wild Plant List" in 2021, which includes wild populations of important crops and closely related species with genetic value, as well as species of significant economic value that have experienced a sharp decline in wild resources and are threatened or severely threatened in their survival due to overexploitation.

[0003] Due to climate change and human activities, extreme precipitation events are becoming more frequent, leading to rapid increases in wetland water levels. These drastic environmental changes pose even greater threats to plants that are already sensitive to environmental conditions. The Sanjiang Plain is an important area of ​​concentrated freshwater wetlands in my country, rich in wild plant resources, including nationally protected wild plants such as *Aldrovanda vesiculosa*, *Trapa incisa*, and *Sagittaria natans*. In recent years, the main rivers in the region, especially the middle and lower reaches, have experienced frequent floods, with rare flood events causing rapid increases in water levels. *Trapa incisa*, a national second-class protected wild plant, although a floating-leaved plant, is also ill-suited to adapting to rapid water level increases, leading to plant death or being washed away by the current. Currently, there are no reports on methods to improve the ability of *Trapa incisa* to adapt to rapid water level changes. Therefore, developing a new method to enhance its adaptability is urgently needed for the protection of *Trapa incisa* wild plant resources in this region. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a method for improving the adaptability of water chestnut to rapid changes in water level.

[0005] This invention provides a method for improving the ability of floating-leaved plants to adapt to rapid changes in water level, comprising:

[0006] During the seed dormancy period of floating-leaved plants, the surface water depth should be controlled at 10-90cm, and during the seed germination period, the surface water depth should be controlled at 20-45cm. Fertilizer should be applied during the seedling stage, and the rise in surface water level should be controlled during the rapid growth period, and the plants should be fixed with supports.

[0007] Furthermore, the rate of rise in the surface water level is 3 cm / day.

[0008] The fertilization includes the application of nitrogen fertilizer and / or phosphorus fertilizer.

[0009] The application rate of the nitrogen fertilizer is 6 g / m³. 2 ~12g / m 2 .

[0010] The application rate of the phosphate fertilizer is 3g / m³. 2 .

[0011] The surface water depth during the seed dormancy period is controlled to be 55-65 cm.

[0012] The surface water level is controlled at 25-35cm during the seed germination period.

[0013] The fertilizer should be applied 10-15cm away from the seedling.

[0014] The depth of fertilization during the seedling stage is 8-10 cm below the soil surface.

[0015] The fixed spacing is 50cm.

[0016] The floating-leaved plants include water caltrop, water lily, giant water lily, water lily, water chestnut, water caltrop, water snowflake and / or water chestnut.

[0017] In a specific embodiment of the present invention, the floating-leaved plant is *Trapa natans*.

[0018] The method described in this invention, prior to its establishment, involves conducting a routine investigation of the habitat of floating-leaved plants, a step typically taken by those skilled in the art. This investigation includes, but is not limited to, assessing species population size, associated species, surface water depth, and / or aquatic environmental conditions. The method described in this invention can be implemented in conjunction with specific habitat conditions or used for individual breeding; this invention does not limit its application in this regard.

[0019] Furthermore, the method of the present invention includes the following steps:

[0020] Step 1: In the distribution area of ​​*Trapa natans*, conduct a field survey during the growing season to investigate the population size, associated species, surface water depth and / or aquatic environment of this species.

[0021] Step 2: During the seed dormancy period, control the surface water depth to 10-90cm;

[0022] Step 3: During the seed germination period, control the surface water depth to 20-45cm;

[0023] Step 4: Apply nitrogen and phosphorus fertilizers during the seedling stage.

[0024] Step 5: During the rapid growth period, control the surface water level rise to 1-5cm and use supports to fix the *Trapa natans* plants at 50cm intervals.

[0025] This invention provides a method to improve the ability of *Trapa natans* to adapt to rapid changes in water level by controlling surface water level regulation, fertilization, and stake fixing during the growth stages of the plant. The method enables in-situ protection of the plant, complies with relevant national laws and regulations, and is scientifically sound. Compared with the control group, the method of this invention can effectively enhance the stem extension and fruiting of the floating-leaved plant, thus significantly improving its ability to adapt to rapidly changing water levels. Attached Figure Description

[0026] Figure 1 This study demonstrates the effect of different experimental treatments on the number of discs on *Trapa natans*.

[0027] Figure 2 The effect of different experimental treatments on the diameter of the disc of *Trapa natans* is shown.

[0028] Figure 3 This study demonstrates the effect of different experimental treatments on the number of water chestnuts in the small-fruited water chestnut.

[0029] Figure 4 This shows the dynamic changes in surface water level in the experimental area throughout the year. Detailed Implementation

[0030] This invention provides a method for improving the adaptability of *Trapa natans* to rapid water level changes. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The method and application of this invention have been described through preferred embodiments. Those skilled in the art can obviously make modifications or appropriate alterations and combinations to the method and application described herein without departing from the content, spirit, and scope of this invention to implement and apply the technology of this invention.

[0031] The main growth stages of *Trapa natans* include: seed dormancy, seed germination (around May of the following year), seedling stage (lasting 1-2 months), vigorous growth stage (around June-July of the following year), flowering stage (around July-August of the following year), and fruiting stage (around August-September of the following year).

[0032] The test materials used in this invention are all common commercially available products. The invention is further illustrated below with reference to embodiments:

[0033] Example 1: A method to enhance the ability of *Trapa natans* to adapt to rapidly changing water levels

[0034] I. Methods to enhance the ability of *Trapa natans* to adapt to rapid changes in water level

[0035] From 2022 to 2023, in the Sanjiang National Wetland Nature Reserve in Heilongjiang Province, the method of this invention was used to enhance the ability of *Trapa natans* to adapt to rapidly changing water levels. The process was implemented according to the following steps:

[0036] 1. Habitat survey

[0037] In 2022, during the growing season (July-August), a field survey was conducted in the distribution area of ​​*Trapa natans* (E134.614748, N48.154519). 96 *Trapa natans* plants were found. The main associated species were *Zizania latifolia*, *Nymphaeatetragona*, and *Nymphoides peltata*. The surface water depth was 20-150 cm, and the water environment was as follows: total nitrogen 0.591 mg / L, total phosphorus 0.149 mg / L, total organic carbon 9.18 mg / L, and salinity 67.67 mg / L. The water quality was relatively good.

[0038] 2. Water level management

[0039] Before the winter freezes and the growing season ends, maintain an average surface water depth of 60cm in the distribution area described in step one. Freezing the seeds of the fine-fruited wild water chestnut in winter not only protects the seeds from damage and breaks seed dormancy, but also provides water for germination in the following spring.

[0040] 3. Seedling management

[0041] After the ice and snow thawed in the spring of 2023 and before the seedlings emerged (late April to early June), maintain an average water depth of 30cm on the ground surface. When the seedlings reach an average height of 20cm, insert a bamboo pole near each seedling, ensuring that the pole is upright, firm, and protrudes at least 1.5m above the ground. Apply a certain amount of fertilizer 10-15cm away from the plant to promote plant growth and fruiting. When fertilizing, make more than 10 holes (about 10cm deep) with a hollow tube, carefully apply the fertilizer into the holes, and immediately seal the holes with soil. The fertilizer used should be slow-release fertilizer.

[0042] 4. Plant Training

[0043] As temperatures rise, plants begin to grow rapidly, and irrigation measures are used to continuously increase the water depth in the distribution area (from mid-June to the end of July, a total of 45 days).

[0044] 5. Plant anchoring

[0045] In step four, during the rapid growth stage of the plant, the plant stem is fixed to the bamboo pole described in step three with ropes at heights of 50cm, 100cm, and 150cm respectively.

[0046] 6. Effect monitoring

[0047] After a large amount of floodwater begins to enter (in August), closely monitor water level changes and plant growth. After the flood recedes, untie the ropes above the water surface and observe the number, diameter, and number of horns of the surviving *Trapa natans* plants. This will help improve the *Trapa natans*' ability to adapt to rapid changes in water level.

[0048] II. Establishment and effectiveness verification of methods to improve the adaptability of *Trapa natans* to rapidly changing water levels.

[0049] The effectiveness of the method described in this embodiment for improving the adaptation of *Trapa natans* to rapidly changing water levels was verified by setting up experimental and control groups.

[0050] Experimental group: The experiment was conducted by changing the rate of water level rise in step 4 and the type and amount of fertilizer applied in step 3 in this embodiment.

[0051] Control group: Unlike the experimental group, no fertilizer was applied in step 3, but the other treatments were the same as the experimental group.

[0052] The experimental results are shown in Table 1 and Figures 1-3 As shown, Figures 1-3 The effect of fertilization treatment on the growth and fruit setting of *Trapa natans* when the water level rises at a rate of 3 cm / d was investigated. Figure 1 , Figure 2 and Figure 3 The numbers represent the number of discs, disc diameter, and number of horns of *Trapa natans*, respectively (Note: different lowercase letters indicate that the difference reached the significance level, P < 0.05). Figure 4 This shows the dynamic changes in surface water level in the experimental area throughout the year.

[0053] Table 1. Effects of different experimental treatments on the growth and fruit set of *Trapa natans*.

[0054]

[0055] In Table 1, CK represents no fertilization, N represents 6g of nutrients (as N) added per square meter, 2N represents 12g of nutrients (as N) added per square meter, and NP represents 6g of nutrients (as N) and 3g of nutrients (as P) added per square meter. Different lowercase letters in the same column indicate that the difference reached the significance level (P < 0.05).

[0056] Statistical analysis showed that water level raising training significantly affected the number of water chestnut discs (F=20.963, P=0.001), disc diameter (F=11.2, P<0.01), and number of horns (F=34.146, P<0.001) of *Trapa natans* after flooding. During the training phase, when the water level rose at an average rate of 1-3 cm per day, the stem elongation of the plants kept pace with the rise in water level; however, when the water level rose at a rate of 5 cm / day, the stem elongation rate was lower than the water level rise rate, and no plants reached above the water surface at the end of the training, and the plants below the water surface eventually died (Table 1). After experiencing a flood event (maximum water depth exceeding 1.5 m), Figure 4 In the treatment where the water level rose by an average of 1 cm per day, the number of water chestnut discs eventually reached zero, indicating that the rapidly rising floodwaters inhibited the survival of *Trapa natans*. The rapid rise in water level submerged the plants, making it difficult for them to perform normal physiological activities such as photosynthesis, ultimately leading to their death. In the treatment where the water level rose by an average of 3 cm per day, water chestnut discs floated on the surface after the flood receded, indicating that during the training period, an average daily water level rise of about 3 cm helped *Trapa natans* adapt to the flood events in the area and survive. Both excessively slow and rapid water level rises during the training period were detrimental to its adaptation to rapidly rising water levels.

[0057] Nitrogen (N) and phosphorus (P) are essential nutrients for plant growth, promoting plant growth and fruit production. (See Table 1 and...) Figures 1-3 It can be seen that when the water level rise rate is 3 cm / d, different fertilization treatments have a significant impact on the number, size, and number of water chestnuts in *Trapa natans* after flooding. Compared with no fertilization, the number and diameter of water chestnuts increased by 92%–169% and 13%–18%, respectively, after fertilization, with little difference among different fertilization treatments. *Trapa natans* is an annual floating-leaved plant, and flowering and fruiting are crucial for population maintenance, especially under the influence of flood events. This experiment found that compared with no fertilization, the number of water chestnuts increased slightly with nitrogen fertilizer alone, and the increase in N did not significantly promote water chestnut formation; however, with the simultaneous addition of N and P, the number of water chestnuts increased significantly by 2.1–4.0 times compared with nitrogen fertilizer alone, indicating that the simultaneous addition of N and P plays an important role in the adaptation of *Trapa natans* to flood events and the maintenance of population stability. Therefore, it is evident that by continuously increasing the water level (approximately 3 cm / day) before a flood, and simultaneously adding an appropriate amount of fertilizer, the goal of protecting wild populations of *Trapa natans* in their native habitat can be achieved.

[0058] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for enhancing the ability of floating-leaved plants to adapt to rapid changes in water level, characterized in that, include: During the seed dormancy period of floating-leaved plants, the surface water depth is controlled at 60cm, and during the seed germination period, the surface water depth is controlled at 30cm. Fertilizer is applied during the seedling stage, and during the rapid growth period, the rise in surface water level is controlled and the plants are fixed with supports. The rate of rise in the surface water level is 3 cm / day; The fertilization includes the application of nitrogen fertilizer and / or phosphorus fertilizer; The application rate of the nitrogen fertilizer is 6 g / m³. 2 ~12g / m 2 ; The application rate of the phosphate fertilizer is 3g / m³. 2 ; The floating-leaved plants include the fine-fruited water chestnut.

2. The method according to claim 1, characterized in that, The fertilizer should be applied 10-15cm away from the seedling.

3. The method according to claim 2, characterized in that, The depth of fertilization during the seedling stage is 8-10 cm below the soil surface.

4. The method according to claim 3, characterized in that, The spacing between the supports is 50cm.

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