A planting method for increasing the starch content of elephant ear

Abstract

This invention discloses a planting method for increasing the starch content of water chestnuts, comprising the following steps: (1) germination, seedling raising, and transplanting; (2) fertilization management: applying a total amount of nitrogen fertilizer of 100-400 kg / hm. ‑2 Fertilizer is applied in multiple applications. During the planting process, base fertilizer, seedling fertilizer, tillering fertilizer and swelling fertilizer are applied. The amount of nitrogen fertilizer added to the base fertilizer accounts for 1 / 3 to 2 / 3 of the total nitrogen fertilizer, the amount of nitrogen fertilizer added to the seedling fertilizer accounts for 1 / 6 to 2 / 3 of the total nitrogen fertilizer, the amount of nitrogen fertilizer added to the tillering fertilizer accounts for 0 to 1 / 3 of the total nitrogen fertilizer, and the amount of nitrogen fertilizer added to the swelling fertilizer accounts for 0 to 1 / 3 of the total nitrogen fertilizer; (3) Field management and harvesting. Using the method of the present invention to plant water chestnuts can improve the starch content and yield of water chestnuts and improve the quality of water chestnuts.

Description

Technical Field

[0001] This invention relates to the field of water chestnut cultivation technology, and in particular to a cultivation method for increasing the starch content of water chestnuts. Background Technology

[0002] Water chestnuts, also known as horse hooves, belong to the genus *Echinochloa* in the family Cyperaceae. They are perennial aquatic rhizomatous herbaceous plants. Their corms are rich in nutrients and can be used as vegetables or fruits, or to produce starch. Processed water chestnuts primarily produce starch, used to make various water chestnut pastries. Water chestnut powder has the effects of clearing heat and promoting body fluid production, relieving sore throat and swelling, resolving phlegm and relieving cough, and promoting diuresis and reducing swelling. It is a natural health product and is loved by consumers. Water chestnuts are one of Guangxi's advantageous and distinctive industries, with an annual planting area of ​​20,000 hectares. 2 This region accounts for over 50% of the national water chestnut sales. However, due to a lack of specialized water chestnut varieties and outdated cultivation techniques, there is a severe shortage of raw materials for water chestnut powder processing, resulting in high processing costs and seriously hindering the development of the water chestnut industry. In production, farmers, in pursuit of higher yields, blindly and excessively apply chemical fertilizers, leading not only to resource waste but also to serious environmental pollution. Therefore, exploring suitable fertilization programs to effectively increase water chestnut yield and starch content is of great significance for the sustainable and healthy development of the water chestnut industry.

[0003] Starch is a crucial component of water chestnut corms, and the corm enlargement process is also a starch accumulation process. Numerous studies have shown that starch accumulation is primarily influenced by starch-synthesizing enzymes, with nitrogen being the most active factor affecting starch content. Applying nitrogen fertilizer can significantly impact the activity of key starch-synthesizing enzymes. Currently, improper fertilization is a common problem in water chestnut cultivation. Inappropriate nitrogen fertilizer application leads to excessive vegetative growth of the above-ground parts of the water chestnut, affecting its quality and yield. Therefore, proper fertilization is vital for water chestnut growth. Determining which fertilizer to apply at which stage and how to use fertilizer to improve water chestnut quality, and how to rationally apply nitrogen fertilizer to increase the starch content of water chestnuts, urgently needs to be addressed.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a cultivation method that increases the starch content of water chestnuts, thereby overcoming the disadvantage of low starch content in water chestnuts grown using existing methods.

[0006] To achieve the above objectives, the present invention provides a method for increasing the starch content of water chestnuts, comprising the following steps:

[0007] (1) Germination, seedling cultivation and transplanting;

[0008] (2) Fertilizer management: The total amount of nitrogen fertilizer applied is 100-400 kg / hm. -2 Fertilizer should be applied in multiple applications. During the planting process, base fertilizer, seedling fertilizer, tillering fertilizer, and fruit enlargement fertilizer should be applied. The amount of nitrogen fertilizer added to the base fertilizer should account for 1 / 3 to 2 / 3 of the total nitrogen fertilizer, the amount of nitrogen fertilizer added to the seedling fertilizer should account for 1 / 6 to 2 / 3 of the total nitrogen fertilizer, the amount of nitrogen fertilizer added to the tillering fertilizer should account for 0 to 1 / 3 of the total nitrogen fertilizer, and the amount of nitrogen fertilizer added to the fruit enlargement fertilizer should account for 0 to 1 / 3 of the total nitrogen fertilizer.

[0009] (3) Field management and harvesting.

[0010] Preferably, in the above technical solution, the total amount of nitrogen fertilizer applied in step (2) is 120-360 kg / hm. -2 The preferred value is 200-250 kg / hm. -2 .

[0011] Preferably, in the above technical solution, in step (2), nitrogen fertilizer is applied in four applications, with nitrogen fertilizer added to the base fertilizer, seedling fertilizer, tillering fertilizer and expansion fertilizer respectively. The amount of nitrogen fertilizer added to the base fertilizer accounts for 1 / 3 to 1 / 2 of the total amount of nitrogen fertilizer, the amount of nitrogen fertilizer added to the seedling fertilizer accounts for 1 / 6 to 1 / 4 of the total amount of nitrogen fertilizer, the amount of nitrogen fertilizer added to the tillering fertilizer accounts for 1 / 6 to 1 / 4 of the total amount of nitrogen fertilizer, and the amount of nitrogen fertilizer added to the expansion fertilizer accounts for 1 / 6 to 1 / 4 of the total amount of nitrogen fertilizer.

[0012] Preferably, in the above technical solution, phosphate fertilizer and potassium fertilizer are added to the base fertilizer, tillering fertilizer and fruit enlargement fertilizer; during the planting process, the total amount of phosphate fertilizer applied is 40-80 kg / 667㎡, and the total amount of potassium fertilizer applied is 15-50 kg / 667㎡.

[0013] Preferably, in the above technical solution, the base fertilizer includes organic fertilizer, phosphate fertilizer, and potassium fertilizer. The amount of organic fertilizer applied is 1000-1500 kg / 667㎡, and the amount of phosphate fertilizer added to the base fertilizer accounts for 1 / 3-2 / 3 of the total amount of phosphate fertilizer. The tillering fertilizer includes phosphate fertilizer and potassium fertilizer. The amount of phosphate fertilizer in the tillering fertilizer accounts for 1 / 5-1 / 3 of the total amount of phosphate fertilizer, and the amount of potassium fertilizer accounts for 1 / 5-1 / 3 of the total amount of potassium fertilizer. The fruit enlargement fertilizer includes phosphate fertilizer and potassium fertilizer. The amount of phosphate fertilizer in the fruit enlargement fertilizer accounts for 1 / 5-1 / 3 of the total amount of phosphate fertilizer, and the amount of potassium fertilizer accounts for 1 / 5-1 / 3 of the total amount of potassium fertilizer.

[0014] Preferably, in the above technical solution, the nitrogen fertilizer is urea or ammonia nitrogen, the phosphate fertilizer is superphosphate, and the potassium fertilizer is potassium chloride.

[0015] Preferably, in the above technical solution, step (1) planting involves selecting healthy plants in July and planting them in the field with a plant spacing of 50-70cm, a row spacing of 50-70cm, and a planting density of 2400-3000 plants / 667㎡.

[0016] Preferably, in the above technical solution, step (3) field management includes applying seedling fertilizer in mid-August, applying tillering fertilizer in mid-September, and applying growth fertilizer in mid-October.

[0017] Preferably, in the above technical solution, step (3) field management includes: after planting, maintaining a water layer of 5-10cm on the soil surface to flood the field, and maintaining a water layer of 3-5cm on the soil surface until the early tillering stage, for 28-35 days; then deepening the water layer to 10-15cm for 12-18 days, and letting the field dry naturally; then continuing to deepen the water layer to 10-15cm for 12-18 days, and letting the field dry naturally; then continuing to deepen the water layer to 5-10cm for 7 days, and letting the field dry naturally, maintaining a water layer of 3-5cm until the early harvest stage; and carrying out pest and disease control during the growth period.

[0018] Compared with existing technologies, the present invention has the following beneficial effects: The planting method of the present invention for increasing the starch content of water chestnuts adjusts the application level and method of nitrogen fertilizer. Increased nitrogen fertilizer application can increase the starch accumulation, starch synthase activity, and starch accumulation rate in water chestnut corms. The starch accumulation rate is significantly positively correlated with the activities of key starch synthesis enzymes AGPASE, GBSS, SSS, and SBE. This significantly improves the starch content of water chestnuts. Therefore, planting water chestnuts using the method of the present invention can increase the starch content and yield of water chestnuts, and improve their quality. Attached Figure Description

[0019] Figure 1 This is a graph showing the accumulation rate of amylose in water chestnuts under different nitrogen fertilizer treatments according to the planting method of the present invention;

[0020] Figure 2 This is a graph showing the accumulation rate of amylopectin in water chestnuts under different nitrogen fertilizer treatments according to the planting method of the present invention;

[0021] Figure 3 This is a graph showing the total starch accumulation rate of water chestnuts under different nitrogen fertilizer treatments according to the planting method of the present invention;

[0022] Figure 4 This is a graph showing the AGPASE enzyme activity of water chestnut under different nitrogen fertilizer treatments according to the planting method of the present invention;

[0023] Figure 5 This is a graph showing the GBSS enzyme activity of water chestnut under different nitrogen fertilizer treatments according to the planting method of the present invention;

[0024] Figure 6 This is a graph showing the SSS enzyme activity of water chestnut under different nitrogen fertilizer treatments according to the planting method of the present invention;

[0025] Figure 7 This is a graph showing the SBE enzyme activity of water chestnuts under different nitrogen fertilizer treatments according to the planting method of the present invention. Detailed Implementation

[0026] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0027] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0028] A method for increasing the starch content of water chestnuts includes the following steps:

[0029] (1) Germination, seedling cultivation and transplanting;

[0030] Germinate and cultivate seedlings. In mid-July, select healthy plants and transplant them into the field with a plant spacing of 50-70cm and a row spacing of 50-70cm, resulting in a planting density of 2400-3000 plants / 667㎡.

[0031] (2) Fertilizer management:

[0032] The total amount of nitrogen fertilizer applied is 100-400 kg / hm. -2 The preferred total nitrogen fertilizer amount is 120-360 kg / hm. -2 More preferably 200-250 kg / hm -2 Nitrogen fertilizer is either urea or ammonia nitrogen, with urea being the preferred choice. Fertilizer is applied multiple times during the planting process: basal fertilizer, seedling fertilizer, tillering fertilizer, and fruit enlargement fertilizer. The amount of nitrogen fertilizer added to the basal fertilizer should be 1 / 3-2 / 3 of the total nitrogen fertilizer; the amount added to the seedling fertilizer should be 1 / 6-2 / 3 of the total nitrogen fertilizer; the amount added to the tillering fertilizer should be 0-1 / 3 of the total nitrogen fertilizer; and the amount added to the fruit enlargement fertilizer should be 0-1 / 3 of the total nitrogen fertilizer.

[0033] (3) Field management and harvesting.

[0034] Apply seedling fertilizer in mid-August, tillering fertilizer in mid-September, and fruit enlargement fertilizer in mid-October. From transplanting to canopy closure, control weed growth and maintain a water layer of 5-10cm. After canopy closure, water management should follow the principle of alternating between dry and wet conditions to keep the soil moist. Drain the field water in early December and wait for harvesting. Control pests and diseases during the growing season.

[0035] Preferably, in the above technical solution, in step (2), nitrogen fertilizer is applied in four applications, with nitrogen fertilizer added to the base fertilizer, seedling fertilizer, tillering fertilizer and expansion fertilizer respectively. The amount of nitrogen fertilizer added to the base fertilizer accounts for 1 / 3 to 1 / 2 of the total amount of nitrogen fertilizer, the amount of nitrogen fertilizer added to the seedling fertilizer accounts for 1 / 6 to 1 / 4 of the total amount of nitrogen fertilizer, the amount of nitrogen fertilizer added to the tillering fertilizer accounts for 1 / 6 to 1 / 4 of the total amount of nitrogen fertilizer, and the amount of nitrogen fertilizer added to the expansion fertilizer accounts for 1 / 6 to 1 / 4 of the total amount of nitrogen fertilizer.

[0036] Preferably, in the above technical solution, phosphate fertilizer and potassium fertilizer are added to the base fertilizer, tillering fertilizer, and fruit enlargement fertilizer; the phosphate fertilizer is superphosphate, and the potassium fertilizer is potassium chloride. During the planting process, the total amount of phosphate fertilizer applied is 40-80 kg / 667㎡, and the total amount of potassium fertilizer applied is 15-50 kg / 667㎡.

[0037] Preferably, in the above technical solution, the base fertilizer includes organic fertilizer, phosphate fertilizer, and potassium fertilizer. The amount of organic fertilizer applied is 1000-1500 kg / 667㎡, and the amount of phosphate fertilizer added to the base fertilizer accounts for 1 / 3-2 / 3 of the total amount of phosphate fertilizer. The tillering fertilizer includes phosphate fertilizer and potassium fertilizer. The amount of phosphate fertilizer in the tillering fertilizer accounts for 1 / 5-1 / 3 of the total amount of phosphate fertilizer, and the amount of potassium fertilizer accounts for 1 / 5-1 / 3 of the total amount of potassium fertilizer. The fruit enlargement fertilizer includes phosphate fertilizer and potassium fertilizer. The amount of phosphate fertilizer in the fruit enlargement fertilizer accounts for 1 / 5-1 / 3 of the total amount of phosphate fertilizer, and the amount of potassium fertilizer accounts for 1 / 5-1 / 3 of the total amount of potassium fertilizer.

[0038] Effects of different nitrogen fertilizer treatments on water chestnut growth

[0039] I. Materials and Methods

[0040] 1. Test materials

[0041] This experiment was conducted in 2022 at the Pingluo County Agricultural Research Institute in Guilin City, Guangxi Province. Pingluo County is located in the mid-subtropical monsoon climate zone, with moderate annual rainfall, an average annual temperature of 19.9℃, long hours of sunshine, and a very short frost period in winter, with 310 frost-free days per year. The soil physicochemical properties of the experimental plot were as follows: pH 6.4, organic matter 34.6 g / kg, hydrolyzable nitrogen 118.7 mg / kg, available phosphorus 1.12 mg / kg, and available potassium 79.2 mg / kg.

[0042] The tested fertilizers were urea (containing 46% N, produced by Henan Xinlianxin Fertilizer Co., Ltd.), superphosphate (containing 16% P2O5, produced by Guizhou Fuquan Phosphate Fertilizer Co., Ltd.), and potassium chloride (containing 60% K2O, produced by the manufacturer). The tested material was the main cultivated variety of starch-processing water chestnut, 'Guifenti No. 1'.

[0043] 2. Test methods

[0044] The experiment employed a randomized block design, setting four levels of nitrogen application: no nitrogen fertilizer (CK), 120 kg / hm², and 120 kg / hm². -2 (N1), 240 kg.hm -2 (N2) and 360 kg.hm -2(N3) Three nitrogen application methods are used: 1 / 2 basal fertilizer + 1 / 2 seedling fertilizer (T1); 1 / 2 basal fertilizer + 1 / 4 seedling fertilizer + 1 / 4 tillering fertilizer (T2); 1 / 2 basal fertilizer + 1 / 6 seedling fertilizer + 1 / 6 tillering fertilizer + 1 / 6 bulb enlargement fertilizer (T3). Specific application times and amounts for each stage are shown in Table 1. Phosphate and potassium fertilizers are applied in three stages, with basal fertilizer and topdressing each accounting for 50%. Topdressing is applied during the tillering and bulb enlargement stages, with each application being 25% of the total amount. The total amount of phosphate fertilizer applied is 60 kg / 667 m², and the total amount of potassium fertilizer applied is 30 kg / 667 m². Basal fertilizer includes organic fertilizer, phosphate fertilizer, and potassium fertilizer, with an organic fertilizer application rate of 1300 kg / 667 m². Tillering fertilizer includes phosphate fertilizer and potassium fertilizer, and bulb enlargement fertilizer includes phosphate fertilizer and potassium fertilizer.

[0045] Topdressing was applied on August 15 (seedling stage), September 15 (tillering stage), and October 15 (early fruit enlargement stage) in 2022. The experimental plots were 30 square meters in size, with a plant spacing of 50 x 50 cm. Each fertilization plot was randomly assigned to a block design with three replicates. The planting density was 2700 plants / 667 square meters, with three replicates in total, resulting in 30 plots. The experiment was conducted in the same experimental field. Seedlings were transplanted to the field on July 25, 2022, and harvested on November 30, 2022. Other field management practices were implemented according to the requirements for high-quality and high-yield cultivation.

[0046] Table 1. Nitrogen fertilizer application rate (kg.hm) for different nitrogen level treatments -2 )

[0047]

[0048] 3. Measurement Items and Methods

[0049] (1) Material collection: Sample collection began on October 15th, the early stage of bulb enlargement. Underground enlarged bulbs were collected in the field every 15 days for a total of 4 collections. The bulb development stage was divided into 4 stages, namely (80, 95, 110, 125) days after the plant was planted. After measuring the agronomic traits, the samples were marked, quick-frozen in liquid nitrogen, and stored at -80℃ to measure the relevant enzyme activities.

[0050] (2) Agronomic traits determination: Plant height and number of tillers were measured at the early stage of water chestnut expansion (80 days after transplanting). After the above-ground parts dried and were harvested, the weight of a single fruit was measured. After all the tubers in each plot were dug up and washed, the total yield was calculated based on the yield per unit area.

[0051] (3) Dry matter content: Wash some of the bulb samples, blanch them at 105℃ for 30 minutes, dry them at 75℃ until constant weight, and then weigh them.

[0052] (4) Starch accumulation and synthase determination: The content of linear, branched, and total starch and the enzyme activities of key starch synthesis enzymes (AGPase, GBSS, SSS and SBE) were determined by an enzymatic kit (Suzhou Greens Biotechnology Co., Ltd.).

[0053] Among them are adenosine diphosphate glucose pyrophosphorylase (AGPASE), soluble starch synthase (SSS), bound starch synthase (GBSS), and starch branching enzyme (SBE).

[0054] II. Results and Analysis

[0055] 1. Effects of different nitrogen fertilizer treatments on the agronomic traits of water chestnut plants

[0056] When water chestnuts are cultivated using the method of this invention, different nitrogen fertilizer treatments have different effects on the agronomic morphology of water chestnut plants, as shown in Table 2.

[0057] Table 2 Effects of different nitrogen fertilizer treatments on agronomic traits and yield of water chestnut plants

[0058]

[0059] Different letters indicate that the difference reached a significant level (P<0.05), and the same applies below.

[0060] Table 2 shows that nitrogen application rate significantly affected the yield and its components of water chestnuts. Under nitrogen-application treatments, plant height, number of tillers, single fruit weight, and yield were all significantly higher than in the control (CK) treatment without nitrogen application. With increasing nitrogen application rate, plant height and number of tillers showed a continuous increasing trend during the early expansion stage (80 days after transplanting), reaching their maximum values ​​at the N3 level. However, at the N2 and N3 levels, there were no significant differences in plant height and average single fruit weight. Yield initially increased and then decreased with increasing nitrogen application rate. At the same nitrogen application level, the yield of water chestnuts differed significantly under different application methods and ratios (T1, T2, and T3), while plant height and average single fruit weight did not differ significantly. Specifically, at the N2T3 level, the number of tillers and yield reached their maximum values ​​compared to other levels. This indicates that within a certain range, increasing nitrogen fertilizer application has a significant promoting effect on the growth and development of water chestnuts, while high nitrogen application actually reduces yield.

[0061] 2. Effects of different nitrogen fertilizer treatments on starch accumulation and accumulation rate during water chestnut corm enlargement.

[0062] The effects of different nitrogen fertilizer treatments on starch accumulation and accumulation rate during the corm enlargement process of water chestnuts cultivated using the method of this invention are shown in Table 3 and... Figure 1-3 As shown.

[0063] Table 3. Effects of different nitrogen fertilizer treatments on the accumulation of amylose, amylopectin, and total starch during the expansion of water chestnut corms.

[0064]

[0065] Table 3 shows that nitrogen fertilizer application significantly increased the amylose, amylopectin, and total starch content in water chestnut corms during corm enlargement. The amylose and amylopectin contents in the control group (CK) were relatively low. Under different nitrogen fertilizer levels, N2 showed the most significant increase in starch content, with amylose reaching its maximum in the early stage of corm enlargement, while amylopectin and total starch contents reached their maximum in the later stage. Under the high-nitrogen N3 treatment, the amylose, amylopectin, and total starch contents in water chestnut corms were lower than those under N1 and N2, indicating that excessive nitrogen fertilizer application leads to a decrease in these contents. At the same nitrogen fertilizer level, the amylose, amylopectin, and total starch contents of water chestnut corms differed significantly between the T1, T2, and T3 treatments. As nitrogen fertilizer application was delayed, the amylose content showed a trend of first increasing and then decreasing, while the amylopectin and total starch content showed a continuous upward trend. Among them, the N2T2 treatment had the highest amylose content at 13.6%, while the N2T3 treatment had the highest amylopectin and total starch content at 54.2% and 65.4%, respectively.

[0066] like Figure 1-3 As shown, with the advancement of water chestnut corm enlargement, the amylose accumulation rate in all nitrogen fertilizer treatments showed a trend of first decreasing and then increasing, while the amylopectin and total starch accumulation rates showed a trend of first increasing and then decreasing. Under different nitrogen fertilizer levels, with the increase of nitrogen application, the accumulation rates of amylose, amylopectin, and total starch all showed a trend of first increasing and then decreasing, but had little effect on the timing of the peak accumulation rates. Specifically, the peak accumulation rate of amylose occurred at 125 days after transplanting, while the peak accumulation rates of amylopectin and total starch occurred at 110 days after transplanting. Under the same nitrogen application level, with the later application of nitrogen fertilizer, the amylose accumulation rate showed a trend of first increasing and then decreasing, while the accumulation rates of amylopectin and total starch both showed a continuous upward trend.

[0067] 3. Effects of different nitrogen fertilizer treatments on the activity of starch synthase during the expansion of water chestnut corms

[0068] like Figure 4-7As shown, with the progression of water chestnut corm enlargement, GBSS enzyme activity showed a trend of first decreasing and then increasing, while AGPASE, SSS, and SBE enzyme activities all showed a trend of first increasing and then decreasing. Nitrogen helped increase the activities of AGPASE, GBSS, SSS, and SBE enzymes, significantly higher than the control (CK). With increasing nitrogen application, the activities of AGPASE, GBSS, SSS, and SBE enzymes all showed a trend of first increasing and then decreasing, reaching a peak at the N2 level. However, under the high-nitrogen N3 treatment, the activities of AGPASE, SSS, and SBE enzymes in water chestnut corms actually decreased, indicating that excessive nitrogen fertilizer application leads to a decrease in the activities of AGPASE, SSS, and SBE enzymes. At the same nitrogen fertilizer level, with the delay in nitrogen fertilizer application, the activities of GBSS, AGPASE, SSS, and SBE enzymes all showed a continuous upward trend, with the highest values ​​for AGPASE, SSS, and SBE enzymes under the N2T3 method. Nitrogen fertilizer management had little effect on the timing of peak AGPASE, SSS, and SBE enzyme activities, all of which occurred in the mid-stage of fruit enlargement (110 days after transplanting), while peak GBSS enzyme activities occurred in the early stage of fruit enlargement (80 days after transplanting).

[0069] The correlation analysis between starch accumulation rate and starch synthase activity showed (Table 4) that, under nitrogen fertilizer management, starch accumulation rate was significantly or extremely significantly positively correlated with the activities of AGPASE, GBSS, SSS and SBE enzymes.

[0070] Table 4. Correlation analysis of starch accumulation rate and enzyme activity in water chestnuts under different nitrogen fertilizer treatments.

[0071]

[0072] * and ** indicate that the correlation probability between enzyme activity and starch accumulation rate is significant at levels of 0.05 and 0.01, respectively.

[0073] The effect of different water management on starch accumulation during the expansion of water chestnut corms was investigated. Based on the results of previous nitrogen fertilizer experiments, the N2T3 nitrogen fertilizer treatment method was selected. Combined with two different water management methods for cultivating water chestnuts, the effects of different water management on the amount of starch accumulation in water chestnuts were observed.

[0074] The water management approach is as follows: Water management methods W1 and W2 are adopted.

[0075] W1: After transplanting, keep the soil surface submerged with a 5-10cm water layer until harvest.

[0076] W2: After planting, (1) keep the soil surface 5-10cm of water to flood the field, and keep the soil surface 3-5cm of water for 30 days until the early tillering stage. (2) Then deepen the water layer to 10-15cm for 15 days, and let the field dry naturally. Then continue to deepen the water layer to 10-15cm for 15 days, and let the field dry naturally. (3) Then continue to deepen the water layer to 5-10cm for 7 days, and let the field dry naturally. Keep the water layer 3-5cm until the early harvest stage.

[0077] This experiment was conducted in 2023 at the Pingluo County Agricultural Research Institute in Guilin City, Guangxi Province. Topdressing was applied on August 15 (seedling stage), September 15 (tillering stage), and October 15 (early fruit enlargement stage), 2023. The experimental plots were 100 m², with a plant spacing of 50 x 50 cm. Fertilization management followed the N2T3 nitrogen fertilizer treatment method. The planting density was 2700 plants / 667 m², with three replicates, for a total of six plots. The experiment was conducted in the same experimental field, and seedlings were transplanted to the field on July 25, 2023, and harvested on November 30, 2023. The planting results under different water management conditions are shown in Tables 4 and 5.

[0078] Table 5. Effects of different water management methods on the number of effective tillers and yield during the tuber enlargement process of water chestnuts.

[0079] deal with Plant height (cm) Number of effective tillers (number of tillers) Average weight of a single fruit (g) <![CDATA[Yield (kg / 667m 2 )]]> W1 85.7±2.4 9.8±0.9 16.7±0.8 2263.0±52 W2 81.4±1.8 12.1±1.1 17.2±0.5 2305.0±47

[0080] As shown in Table 4, W2 water management reduces ineffective tillers and increases the average weight of a single fruit during the water chestnut corm enlargement process, which helps to increase the total yield of water chestnuts.

[0081] Table 6. Effects of different water management methods on the accumulation of amylose, amylopectin, and total starch during the expansion of water chestnut corms.

[0082] deal with Amylose (%) Branched-chain starch (%) Total starch (%) W1 10.4 50.6 61 W2 9.8 56.3 68.1

[0083] As shown in Table 5, W2 moisture management significantly increased the accumulation of amylopectin and total starch.

[0084] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for increasing the starch content of water chestnuts, characterized in that, Includes the following steps: (1) Germination, seedling raising and transplanting; (2) Fertilizer management: The total amount of nitrogen fertilizer applied is 240 kg / hm. -2 Nitrogen fertilizer is applied in four applications: basal fertilizer, seedling fertilizer, tillering fertilizer, and fruit enlargement fertilizer. The amount of nitrogen fertilizer added to the basal fertilizer accounts for 1 / 3 to 1 / 2 of the total nitrogen fertilizer, the amount of nitrogen fertilizer added to the seedling fertilizer accounts for 1 / 6 to 1 / 4 of the total nitrogen fertilizer, the amount of nitrogen fertilizer added to the tillering fertilizer accounts for 1 / 6 to 1 / 4 of the total nitrogen fertilizer, and the amount of nitrogen fertilizer added to the fruit enlargement fertilizer accounts for 1 / 6 to 1 / 4 of the total nitrogen fertilizer. (3) Field management and harvesting; Step (3) Field management includes maintaining a 5-10 cm water layer on the soil surface after transplanting, and maintaining a 3-5 cm water layer on the soil surface until the early tillering stage for 28-35 days; then deepening the water layer to 10-15 cm for 12-18 days, and letting the field dry naturally; then deepening the water layer to 10-15 cm for 12-18 days, and letting the field dry naturally; then deepening the water layer to 5-10 cm for 7 days, and letting the field dry naturally until the early harvest stage, maintaining a 3-5 cm water layer; and controlling pests and diseases during the growing season.

2. The planting method for increasing the starch content of water chestnuts according to claim 1, characterized in that, Phosphate and potassium fertilizers are added to the base fertilizer, tillering fertilizer, and fruit enlargement fertilizer; during the planting process, the total amount of phosphate fertilizer applied is 40-80 kg / 667㎡, and the total amount of potassium fertilizer applied is 15-50 kg / 667㎡.

3. The planting method for increasing the starch content of water chestnuts according to claim 2, characterized in that, Base fertilizer includes organic fertilizer, phosphate fertilizer and potash fertilizer. The amount of organic fertilizer applied is 1000-1500 kg / 667㎡. The amount of phosphate fertilizer added to the base fertilizer accounts for 1 / 3-2 / 3 of the total amount of phosphate fertilizer. Tillering fertilizer includes phosphate fertilizer and potassium fertilizer. The amount of phosphate fertilizer in tillering fertilizer accounts for 1 / 5 to 1 / 3 of the total phosphate fertilizer, and the amount of potassium fertilizer accounts for 1 / 5 to 1 / 3 of the total potassium fertilizer. Enlargement fertilizer includes phosphate fertilizer and potassium fertilizer. Phosphate fertilizer accounts for 1 / 5 to 1 / 3 of the total amount of phosphate fertilizer, and potassium fertilizer accounts for 1 / 5 to 1 / 3 of the total amount of potassium fertilizer.

4. The planting method for increasing the starch content of water chestnuts according to claim 3, characterized in that, The nitrogen fertilizer is urea or ammonia nitrogen, the phosphate fertilizer is superphosphate, and the potassium fertilizer is potassium chloride.

5. The planting method for increasing the starch content of water chestnuts according to claim 1, characterized in that, Step (1) Planting: Select healthy plants in July and plant them in the field with a plant spacing of 50-70cm and a row spacing of 50-70cm. The planting density is 2400-3000 plants / 667㎡.

6. The planting method for increasing the starch content of water chestnuts according to claim 1, characterized in that, Step (3) Field management includes applying seedling fertilizer in mid-August, tillering fertilizer in mid-September, and growth fertilizer in mid-October.

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