Water culture method for tea trees

Abstract

The invention relates to the technical field of tea seedling cultivation, in particular to a water planting method for tea trees. According to the method, tap water is selected for culturing tea seedlings, or pure water is selected for culturing tea seedlings, root growth and nutrition metabolism of tea trees are controlled by adjusting the pH value of the tap water or the pH value of the pure water, and during culture, the illumination intensity of a water culture environment is controlled to be 2000lx, the illumination time is 14 hours per day, the environment temperature is 22-25 DEG C, and the humidity is 70%; the water culture method for the tea trees can effectively promote the growth of tea seedlings and improve the quality of tea leaves, and has the advantages of precise regulation and control and high efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tea seedling cultivation, in particular to a water culture method of tea tree. BACKGROUND

[0002] In traditional agriculture, the planting of tea trees mainly relies on soil environment. With the continuous advancement of agricultural modernization, planting techniques are also constantly updated and iterated. As an efficient, environmentally friendly and controllable planting method, water culture technology has been widely used in the cultivation of various crops, and the construction of tea tree water culture system has also been increasingly concerned.

[0003] The growth and development of tea trees are closely related to the substrate environment, especially for water-cultured tea trees, pH value is one of the key factors affecting their growth physiology and metabolic characteristics. pH value plays an important role in the physiological function of plant roots, nutrient absorption and overall growth trend, and deeply affects the yield and quality of tea. According to existing records, the optimal pH range for tea tree growth is between 4.5 and 5.5. Within this pH range, various elements in the growth environment exist in ionic forms that are beneficial to tea tree absorption, and also provide a suitable living environment for rhizosphere beneficial microorganisms, promoting the absorption and utilization of nutrients by tea trees and the positive interaction with rhizosphere microorganisms. In addition, pH value also has an important influence on the synthesis of secondary metabolites of tea trees, such as tea polyphenols, caffeine and theanine, thereby ensuring the normal growth and development of tea trees and becoming a dominant factor in determining tea quality.

[0004] However, the existing technology only focuses on the influence of pH value on the culture environment, and does not consider the interaction between pH and the culture environment, so it cannot precisely adjust the growth of tea trees through pH. This limitation limits the optimization of the growth environment of water-cultured tea trees and the improvement of tea quality. SUMMARY

[0005] The purpose of the present application is to avoid the shortcomings of the prior art and provide a water culture method of tea tree, which can effectively promote the growth of tea seedlings and improve the quality of tea, and has the advantages of precise control and high efficiency.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] The water culture method of tea tree is provided, and tap water or pure water is selected to culture tea seedlings,

[0008] The pH value of tap water or pure water is adjusted to control the root growth of tea trees and the nutritional metabolism of tea trees,

[0009] During the culture, the light intensity of the water culture environment is controlled to be 2000lx, the light time is 14 hours per day, the environmental temperature is 22℃-25℃, and the humidity is 70%.

[0010] In some embodiments, when tap water is selected to cultivate tea seedlings, the pH of the tap water is controlled to be 5.0-5.5, so as to increase the root surface area and root projection area of the tea tree.

[0011] In some embodiments, when pure water is selected to cultivate tea seedlings, the pH of the pure water is controlled to be 4.5-5.5, so as to increase the root volume and average diameter of the tea tree.

[0012] In some embodiments, when tap water is selected to cultivate tea seedlings, the pH of the tap water is controlled to be 5.0, so as to balance the nitrate nitrogen-phosphorus absorption and carbon sulfur metabolism of the tea tree, and promote the nutritional metabolism of the tea tree.

[0013] In some embodiments, when tap water is selected to cultivate tea seedlings, the pH of the tap water is controlled to be 5.0, so as to increase the SOD activity and POD activity, and promote the absorption of ammonium nitrogen, iron ions and aluminum ions by the tea tree.

[0014] In some embodiments, when tap water is selected to cultivate tea seedlings, the pH of the tap water is controlled to be 5.5, so as to promote the accumulation of caffeine in the tea tree and strengthen the bitterness threshold of tea.

[0015] In some embodiments, when pure water is selected to cultivate tea seedlings, the pH of the pure water is controlled to be 5.0, so as to promote the accumulation of GCG and ECG in the tea tree and increase the antioxidant properties of tea.

[0016] In some embodiments, when tap water is selected to cultivate tea seedlings, the pH of the tap water is controlled to be 5.0, so as to promote the content of theanine in the tea tree and strengthen the freshness of tea.

[0017] In some embodiments, when tap water is selected to cultivate tea seedlings,

[0018] The pH of the tap water is controlled to be 5.0, so as to promote the synthesis of terpenoids, increase the content of chemical defense substances in the tea tree, and resist external invasion;

[0019] The pH of the tap water is controlled to be 5.0, so as to promote nucleotide metabolism and accelerate the synthesis of caffeine, while inhibiting the synthesis of theaflavins A.

[0020] In some embodiments, the tap water or pure water is added with a nutrient solution, and the formula of the nutrient solution is shown in the following table:

[0021]

[0022]

[0023] The water cultivation method for tea trees has the following advantages:

[0024] The present application discovers the significant response relationship of water quality (tap water and pure water) and pH value to the physiological metabolism of tea trees, adopts differentiated pH regulation strategies for different water sources, realizes the precise management of tea seedling growth, and effectively improves the survival rate and growth quality of water-cultured tea trees. By scientifically regulating the pH value of the water-cultured environment, the root development and nutrient absorption efficiency of tea trees can be significantly promoted, the stress resistance of tea trees can be improved, and the growth obstacles caused by unsuitable water quality can be reduced. Compared with the traditional method, the present application provides a clear pH regulation strategy, which can be quickly and stably adjusted according to the water quality characteristics of tap water and pure water, reduces the difficulty of manual intervention, and improves the operability and stability of the water-cultured system. The present application provides a theoretical basis and practical technical solution for tea tree water-cultured cultivation, fills the gap of precise water-cultured management of tea trees, promotes the innovative application of soilless cultivation technology in the field of tea tree planting, and has important scientific value and industrial significance. At the same time, precise regulation reduces the waste of nutrient solution, reduces production cost, is suitable for large-scale and intensive tea tree cultivation, and has significant economic benefits and environmental friendliness. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a tea seedling morphology diagram in the specific embodiment.

[0026] Figure 2 is a tea tree root morphology diagram in the specific embodiment.

[0027] Figure 3 is a water quality element absorption diagram in the specific embodiment.

[0028] Figure 4 is a tea tree root enzyme activity diagram in the specific embodiment.

[0029] Figure 5 is a tea tree leaf element analysis diagram in the specific embodiment.

[0030] Figure 6 is a tea tree root element analysis diagram in the specific embodiment.

[0031] Figure 7 is a tea tree leaf internal substance diagram in the specific embodiment.

[0032] Figure 8 is a tea tree metabolite difference comparison and intersection analysis diagram based on VIP and Log2 (FoldChange) in the specific embodiment, note: diagrams A, B, and C are the difference metabolite volcano diagrams under ZG5.0 VS ZG4.5, ZG5.5 VS ZG4.5, and ZG5.5 VS ZG5.0, respectively; diagram D is a wein diagram of ZG5.0 VS ZG4.5, ZG5.5 VS ZG4.5, and ZG5.5 VS ZG5.0.

[0033] Figure 9Figure A, B, C and D are respectively the volcano plot of the differential metabolites under CG5.0 VS CG4.5, CG5.5 VS CG4.5, CG5.5 VS CG5.0, and the Venn diagram of CG5.0 VS CG4.5, CG5.5 VS CG4.5, CG5.5 VS CG5.0. DETAILED DESCRIPTION

[0034] Preferred embodiments of the present application will be described in more detail below. Although preferred embodiments of the present application are shown, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present application will be thorough and complete, and will fully convey the scope of the present application to those skilled in the art.

[0035] Example 1

[0036] Test materials and treatment

[0037] In this example, 300 one-year-old tea seedlings (height 40-50 cm, purchased from Gaoxiang Tea Seedling Planting Professional Cooperative in Xintang Town, Raoping County) of "Lingtou Dancong" were used as test materials. After the tea seedlings were washed and disinfected, they were placed in a hydroponic box for adaptive culture: first, they were acclimated to pure water for 5 days, then they were acclimated to 1 / 8, 1 / 4, and 1 / 2 concentrations of the basic nutrient solution (as shown in Table 1) for 5 days each, and finally they were cultured with full-strength nutrient solution until a large number of white new roots were formed (a total of 75 days). The formal experiment used a two-factor cross design, with three pH gradients of 4.5, 5.0, and 5.5 and two water quality treatments of pure water and tap water, for a total of 12 groups (23 plants per group, double repeats). The hydroponic environment was controlled at a light intensity of 2000 lx (14 h / d), a temperature of 22-25°C, and a humidity of 70%. Oxygen was continuously supplied by an air pump. The treatment period was 3 weeks, and the environmental conditions were controlled throughout the hydroponic experiment. The light intensity in the hydroponic room was controlled at 2000 lx, the light time was 14 hours per day, the temperature was maintained at 22-25°C, and the relative humidity was maintained at 70%, to ensure the stability of the environmental factors and exclude the interference of environmental fluctuations on the experimental results. The experimental period was arranged as follows: after the 75-day pre-culture period, the water quality and pH value treatments were initiated. After 22 days of treatment, the experimental materials were selected for testing of various indicators.

[0038] Table 1: Tea Nutrient Solution Formulation

[0039]

[0040]

[0041] Effect of water quality and pH treatment on tea tree phenotype

[0042] Tea tree morphological analysis

[0043] Figure 1 The figure shows tea plants treated with tap water (Z) and pure water (C) at different pH values ​​(4.5, 5.0, 5.5). Overall, the tea plant roots had more fibrous roots under each treatment. Figure 1 A) The roots are light brown and relatively densely distributed; as the pH value rises to 5.0, the roots of ZC5.0 (Figure B) are still light brown, but more evenly distributed; when the pH value reaches 5.5, the roots of ZC5.5 (Figure Figure 1 C) The root system color becomes darker brown and the distribution becomes relatively loose. When treated with pure water, CC4.5 ( Figure 1 D) The root system is lighter in color, ranging from white to light brown, and is relatively compact; CC5.0 ( Figure 1 E) fibrous roots are not only more numerous but also thicker and their color is mostly light brown; CC5.5( Figure 1 F) The root system is light brown in color and is also relatively compact.

[0044] Among them, when the pH value is 5.0, whether it is ZC5.0 ( Figure 1 B), or CC5.0 for pure water treatment ( Figure 1 E), the tea tree root system is relatively developed. The former has an evenly distributed root system, while the latter has many and thick fibrous roots, indicating that this pH value is relatively suitable for the growth and development of the tea tree root system.

[0045] Analysis of Root Morphological Indexes of Tea Trees

[0046] like Figure 2 As shown, in the tap water treatment group, the root volume content of ZG5.0 was 171% higher than that of ZG5.5, indicating that root volume indicators of tea plants developed better under tap water treatment at pH 5.0, while the corresponding indicators of ZG5.5 were inhibited. In the pure water treatment group, the root volume content of CG5.0 was 90% higher than that of CG4.5, indicating that pure water treatment at pH 5.0 had a greater advantage in root volume growth. A comparison of water quality revealed that, except for pH 4.5, the root surface area and projected area content of tea plants under tap water treatment were higher than those under pure water treatment at pH 5.0 and 5.5. In terms of root volume and average diameter, pure water treatment had higher content at pH 4.5 and 5.5, with tap water treatment having a superior effect at pH 5.0. Water quality and pH value significantly affected each indicator, with interactive effects. Overall, the contents of various indicators in the roots of tea trees at pH 4.5 are generally lower than those at pH 5.0 and 5.5, indicating that pH 5.0 and 5.5 are more suitable for the growth and development of tea tree roots.

[0047] Study on ion absorption law of tea tree under different water quality and pH treatment

[0048] As Figure 3 shown, in the control group, the content of partial ions (such as ammonium nitrogen, nitrate nitrogen, calcium ion) in ZLS+D (CK) and CS+D (CK) groups added with nutrient solution was significantly higher than that in groups without adding nutrient solution, and the content of ammonium nitrogen in ZLS (CK) group was significantly lower than that in groups added with nutrient solution. In the experimental group, the content of ammonium nitrogen in CS group was higher than that in ZLS group as a whole, and CS▲5.0 was significantly higher than ZLS▲5.0; the content of nitrate nitrogen in ZLS group was higher than that in CS group, and ZLS▲4.5 was significantly higher than CS▲4.5; the content of phosphorus ion in ZLS group was higher than that in CS group, and ZLS▲5.0 was significantly higher than CS▲5.0; the content of potassium ion in CS group was higher than that in ZLS group, and CS▲4.5 was significantly higher than ZLS▲4.5; the content of calcium ion in CS group was significantly higher than that in ZLS group, and CS▲5.5 was significantly higher than CS▲4.5; the content of aluminum ion in ZLS▲5.0 was significantly higher than that in CS▲5.0.

[0049] Overall, in terms of ion absorption, the absorption amount of ammonium nitrogen, potassium, calcium, magnesium and iron ions in the pure water group was higher than that in the tap water group, and the absorption of nitrate nitrogen, water-soluble phosphorus and aluminum ions in the tap water group was more advantageous. Under the influence of pH value, the absorption amount of different ions was significantly different, and under the condition of tap water treatment and pH 5.0, tea tree had more advantages in the absorption of various nutrients.

[0050] Note:▲is the content difference of tea tree absorbed elements, which is obtained by subtracting the content of nutrient solution after one cycle of tea tree cultivation from the content of nutrient solution added in the control group. The control group is divided into tap water group (ZLS (CK)) and pure water group (CS (CK)) without adding nutrient solution, and tap water group (ZLS+D (CK)) and pure water group (CS+D (CK)) added with nutrient solution; tap water: ZLS▲4.5, ZLS▲5.0, ZLS▲5.5, pure water: CS▲4.5, CS▲5.0, CS▲5.5).

[0051] Comparative analysis of antioxidant enzyme characteristics of tea tree roots under water quality and pH treatment

[0052] As Figure 4As shown, statistical analysis showed that all indicators in both groups increased with pH values ​​between 4.5 and 5.0, and decreased between 5.0 and 5.5. At pH 4.5, the levels or activities of relevant indicators in the tap water group were higher than those in the purified water group (SOD activity was 15.95% higher, POD content was 15.95% higher). The opposite was true at pH 5.5 (e.g., SOD activity and POD content were 26.50% lower, and CAT content dropped sharply by 93.01%). Specifically, both SOD and POD activities peaked at pH 5.0, and the fluctuations in activity across different pH values ​​in the tap water group were greater than those in the purified water group (SOD peak value was 64.15% higher than the minimum value in the tap water group, while it was 45.14% higher in the purified water group; POD content was 54.68% lower than the peak value in the tap water group, while it was 13.25% lower in the purified water group). CAT activity was severely affected in the tap water group at pH 5.5. The tap water group had higher MDA levels than the pure water group at all pH values, indicating a higher degree of cell membrane lipid peroxidation and a greater impact of pH fluctuations (peak MDA in the tap water group was 24.59% higher than the minimum, while in the pure water group it was 21.07% higher). At pH 4.5 and 5.0, antioxidant enzyme activity was relatively high in the tap water group, while MDA content was low in the pure water group. However, overall antioxidant enzyme activity was not as good as in the tap water group at optimal pH values.

[0053] Effect analysis of water quality and pH treatment on tea tree elements

[0054] Analysis of the effects of water quality and pH value treatment on elements in tea leaves

[0055] like Figure 5 As shown, nitrogen content in leaves was significantly higher in the tap water group than in the pure water group, reaching a peak at pH 5.0 and exceeding the minimum by 4.55%. Nitrogen content in the pure water group peaked at pH 4.5, initially decreasing and then increasing in the pH range of 5.0-5.5, a trend opposite to that of the tap water group. Furthermore, at pH 5.0, the peak content in the pure water group was 9.10% lower than that in the tap water group. Carbon content was higher in the pure water group than in the tap water group, with its peak and minimum values ​​occurring in the opposite order to those of nitrogen. Hydrogen content remained stable at 7.28%-7.36%, showing minimal influence from water quality and pH. Sulfur content in leaves increased with increasing pH in both the tap water and pure water groups, reaching a peak value of 21.73% and a peak value of 17.08%, respectively, exceeding the minimum value. The carbon-to-nitrogen ratio in leaves showed opposite trends with increasing pH, with the pure water group showing a higher carbon-to-nitrogen ratio, similar to the nitrogen ratio. There was no significant difference in the carbon-hydrogen ratio among the groups, which remained stable at 6.70%-6.81%.

[0056] Analysis of the effects of water quality and pH value treatment on elements in tea tree roots

[0057] like Figure 6As shown, in the root aspect, the nitrogen content of the tap water group was significantly higher than that of the pure water group in the pH 4.5-5.0 interval; in the tap water group, the nitrogen content decreased sharply when the pH value rose to 5.5, which was 47.07% lower than the peak value, while there was no significant difference among the pH values in the pure water group, and there was also no difference compared with the tap water group at pH 5.5. In the tap water group and the pure water group, the carbon content of the root increased first and then decreased with the increase of pH value, and the peak value of the tap water group was 2.56% higher than the minimum value, and the carbon content of the tap water group was significantly higher than that of the pure water group at pH 4.5. The change trend of hydrogen element was similar to that of carbon element, and the hydrogen content of the tap water group was higher than that of the pure water group in the pH 4.5-5.0 interval, but there was no significant difference between the two groups. In the pH 4.5-5.0 interval, the sulfur content of the tap water group was significantly higher than that of the pure water group. The carbon-nitrogen ratio in the pH 4.5-5.0 interval was significantly higher in the pure water group than in the tap water group, and in the tap water group, there was a significant difference between pH 5.5 and pH 4.5, 5.0, and the peak value was 30.17% higher than the minimum value, while there was no significant difference in the pure water group. At pH 4.5, the carbon-hydrogen ratio of the pure water group was significantly higher than that of the tap water group, and there was no significant difference in the tap water group, while in the pure water group, it was higher at pH 4.5 than at pH 5.5.

[0058] Compared with leaves and roots, the absorption of each element and the related ratio were affected by water quality and pH value in different ways. Overall, different water quality and pH value significantly affected the nutrient absorption and metabolism of tea trees. When treated with tap water and pH 5.0, the absorption of nitrogen element by tea leaves reached the peak value, and the balance among the elements at this time contributed to the growth and metabolism of the leaves; for the roots, although the nitrogen content decreased at pH 5.5, the absorption of nitrogen, carbon, sulfur and other elements was superior when treated with tap water in the pH 4.5-5.0 interval. Therefore, this condition was relatively more conducive to the growth and development of tea trees, which could meet the growth needs of leaves and also ensure the nutrient absorption and metabolic balance of roots to a certain extent.

[0059] Effect of water quality and pH treatment on tea tree internal substances

[0060] Analysis of the effect of water quality and pH value treatment on tea catechins

[0061] As shown in Table 2, the total catechin content of the tap water group was significantly higher than that of the pure water group, and the difference was significant at the 0.05 level. The total catechin content of the pure water group was significantly higher than that of the tap water group at pH 4.5, and the difference was significant at the 0.05 level. The total catechin content of the pure water group was significantly higher than that of the tap water group at pH 5.0, and the difference was significant at the 0.05 level. The total catechin content of the pure water group was significantly higher than that of the tap water group at pH 5.5, and the difference was significant at the 0.05 level. Figure 7As shown in AF, in terms of catechins, at pH 4.5-5.0, the GC content in the pure water group was higher than that in the tap water group, but there was no significant difference; in terms of the changes in the contents of ECG, C, EC, and EGCG, the pure water group increased at pH 4.5-5.0 and decreased at 5.0-5.5, while the tap water group decreased with increasing pH, and the ECG in the pure water group reached a peak at pH 5.0, which was 33.38% higher than the lowest value; GCG was affected by both water quality and pH value, and the pure water group reached a peak at pH 5.0, which was 59.07% higher than that of the tap water group at the same pH value; the CG change trends in the two groups were opposite, and at pH 4.5, the tap water group had the lowest point and the pure water group had the highest point, respectively, and the highest value was 44.59% higher than the lowest point.

[0062] Analysis of the effects of water quality and pH value treatment on caffeine in tea trees

[0063] like Figure 7 As shown in Figure G, caffeine content varied significantly depending on water quality. In the tap water group, caffeine content generally increased with increasing pH, reaching a peak at pH 5.5 (ZY5.5). In the purified water group, caffeine content peaked at pH 4.5 (CY4.5), then decreased between 4.5 and 5.0, and then increased again between 5.0 and 5.5. At pH 5.5, a significant difference was observed between the tap water and purified water groups, with ZY5.5 26.34% higher than CY5.5.

[0064] Effects of water quality and pH value treatment on theanine in tea trees

[0065] like Figure 7 As shown in Figure 3, theanine content in the tap water group was higher than that in the pure water group across the pH gradient. The tap water group's content increased between pH 4.5 and 5.0, then decreased between pH 5.0 and 5.5, reaching its highest point at pH 5.0 (ZY5.0), 41.06% higher than its lowest point (ZY5.5). Theanine content in the pure water group decreased with increasing pH, reaching its highest point (CY4.5) 30.86% higher than its lowest point (CY5.5).

[0066] Different water qualities and pH values ​​significantly affect the substances contained in tea leaves. Pure water at a pH of 5.0 favors the accumulation of various catechins, tap water at a pH of 5.5 has a higher caffeine content, and treated tap water at a pH of 5.0 has a higher theanine content.

[0067] The composition of tea tree root metabolites under the same water quality level: In the tap water treatment group, at pH 4.5-5.0, amino acids and their derivatives (20.68%) and organic acids (15.23%) accounted for the majority of 440 differential metabolites, terpenes accounted for 5.00%, and the number of up-regulation and down-regulation was balanced (219 VS 221), reflecting the dynamic balance of metabolic pathways, and terpenes may be involved in defense response; at pH 4.5-5.5, among 1617 differential metabolites, amino acids and their derivatives accounted for 22.89%, organic acids accounted for 14.40%, and terpenes accounted for 4.17%, with significantly more down-regulation than up-regulation (1509 VS 575), indicating that alkaline environment inhibits metabolite synthesis, and the defense mechanism involving terpenes may be weakened; at pH 5.0-5.5, among 2156 differential metabolites, amino acids and their derivatives accounted for 23.67%, organic acids accounted for 14.57%, and terpenes accounted for 4.13%, with significantly more down-regulation than up-regulation (1522 VS 630), indicating that metabolic pathways are significantly inhibited by alkaline environment, and terpene synthesis may shift to basic maintenance. Wayne plot analysis showed that there were 197 core differential metabolites in the three groups, which may be involved in the universal adaptation mechanism of tea tree to pH changes; ZG5.5 VS ZG4.5 and ZG5.5 VS ZG5.0 shared 1652 metabolites, reflecting the continuity of metabolic response when pH≥5.0; the unique differential metabolites of each group (82, 161, and 219) revealed specific adaptation strategies in specific pH intervals. The study showed that amino acid metabolism dominated under different pH gradients, while organic acids and terpenes played key roles in pH 4.5-5.0 and pH 5.0-5.5 regulation, respectively. The former maintained metabolic stability through dynamic balance, and the latter adjusted defense and growth strategies through content changes, together constituting the core metabolic pathway of tea tree roots in response to pH changes. Figure 8

[0068] ​In the pure water treatment group, at pH 5.0-4.5, 1176 kinds of differential metabolites, including amino acids and their derivatives accounted for 24.38%, organic acids accounted for 15.89%, the number of up-regulation was significantly more than that of down-regulation (847 VS 330), and terpenes accounted for 3.31% may be involved in defense response; at pH 5.5-5.0, 976 kinds of differential metabolites, including amino acids and their derivatives accounted for 23.16%, organic acids accounted for 14.34%, the number of down-regulation was more than that of up-regulation (583 VS 393), and terpenes accounted for 5.33% may turn to basic defense; at pH 5.5-4.5, 633 kinds of differential metabolites, including amino acids and their derivatives accounted for 22.12%, organic acids accounted for 16.11%, the number of up-regulation was more than that of down-regulation (426 VS 207), and terpenes accounted for 4.90% were involved in specific adaptive regulation. The analysis of the Venn diagram showed that there were 117 core differential metabolites in the three groups, 492 metabolites were shared by CG5.0-4.5 and CG5.5-5.0, and the unique differential metabolites (322, 155, and 226) of each group revealed specific adaptive strategies. The study showed that amino acid metabolism was dominant at different pH gradients, and organic acids and terpenes played a key role in the regulation at pH 5.0-4.5 and pH 5.5-5.0, respectively. The former maintained metabolic stability through dynamic balance, and the latter adjusted the defense strategy through content change, which together constituted the core metabolic pathway of tea tree roots in response to pH changes. Figure 9

[0069] It can be seen that water quality and pH value have significant effects on tea tree roots and there is an interaction between them. In the tap water treatment group at pH 5.0, it becomes the best condition for the hydroponic tea tree system, which is specifically manifested as follows: the tap water treatment at pH 5.0 significantly promotes the expansion of tea tree roots, promotes nutrient absorption, enhances antioxidant capacity, and improves tea quality.

[0070] Under the synergistic treatment of tap water and pH 5.0, the regulation of ion absorption and element distribution can significantly promote tea tree nutrient metabolism. It is manifested as follows: the nitrogen content in leaves reaches the peak value (4.55% higher than the minimum value), which drives the enhancement of photosynthetic carbon fixation; the carbon-nitrogen ratio (C / N) in roots is 17.8% higher than that in the pure water group, combined with the increase of sulfur content by 21.73%, which strengthens the antioxidant defense and expansion capacity of roots. Under this condition, nitrate nitrogen promotes nitrogen metabolism by up-regulating nitrate reductase activity, and phosphorus improves carbon fixation efficiency by enhancing acid phosphatase (ACP) activity, both of which optimize organ-specific element distribution by reducing leaf C / N ratio (9.1% higher than that in the pure water group) and increasing root C / N ratio. Calcium and magnesium ions indirectly affect nitrogen metabolism by regulating ion balance: the increase of calcium absorption significantly increases the nitrogen and sulfur content in roots, while excessive magnesium inhibits nitrogen accumulation. This synergistic effect enables tea trees to achieve high nitrogen and low C / N ratio in leaves at pH 5.0 to drive photosynthetic efficiency, high C / N ratio and sulfur accumulation in roots to support stress resistance, ultimately coordinating the overall growth and development of tea trees and metabolic balance. ​

[0071] The establishment of tea root morphology was synergistically regulated by water quality ion composition and pH value. The root surface area, projected area and root volume of tea root morphology were significantly higher in tap water treatment group than in pure water treatment group at pH 5.0 and 5.5, which was closely related to ion absorption characteristics. In ZC5.0 group, the efficient absorption of calcium, magnesium and iron ions at pH 5.0 activated the cell wall synthesis related signal pathway, promoted the cell proliferation of root tip meristem and the cell expansion of elongation zone, and formed morphological advantages such as larger root surface area and root volume. In ZC5.5 group, high pH value caused ion stress, which inhibited root diameter development. Therefore, the availability of ions in pH 5.0 and 5.5 environment is beneficial to the growth and morphological establishment of tea root, which provides experimental basis for revealing the molecular mechanism of water quality and pH regulating plant root morphology.

[0072] The activities of SOD and POD were significantly improved by 64.15% and 54.68% in tap water and pH 5.0 interaction treatment, and the stress resistance was best in pH 4.5-5.0 interval. The mechanism is that copper and zinc ions absorbed in tap water act as SOD cofactors to enhance the efficiency of free radical scavenging, and aluminum ions bind to the active center of SOD to improve antioxidant capacity. When the pH rises to 5.5, the precipitation of metal ions leads to a sharp decrease in enzyme activity and aggravates oxidative damage. Although the MDA content of pure water treatment group is low, it lacks 74 essential trace elements, and the overall enzyme activity is lower than that of tap water group at pH 4.5-5.0. In summary, tap water at pH 4.5-5.0 activates the antioxidant enzyme system, synergistically promotes ion absorption and stress resistance, and provides protection for the healthy development of tea root.

[0073] The absorption of nitrate nitrogen reached the peak at pH 5.0 in tap water, which drove the accumulation of theanine (41.06% higher than the minimum value) and inhibited the synthesis of catechins, forming a high fresh and refreshing characteristic. Pure water at pH 5.0 promoted the accumulation of ECG and other catechins (peak value 33.38% higher), and improved the antioxidant properties. The synthesis of caffeine was improved at pH 5.5 in tap water (26.34% higher than that in pure water group), which strengthened the bitter taste threshold. Under the interaction of tap water at pH 5.0, a fresh and refreshing tea quality model was formed.

[0074] From a metabolic perspective, water quality and pH have a central and crucial influence on the composition of tea plant metabolites and metabolic pathways. Differential metabolites in tea plant roots are significantly affected by water quality and pH. Under tap water treatment at a pH of 5.0, the synthesis of amino acids and their derivatives is significantly promoted, while inhibition of the synthesis of the terpenoid Picfeltarraenin IA may be lifted. The activation of these pathways is crucial for tea plant material and energy metabolism, directly linked to normal growth and development. Under pure water treatment at a pH of 5.0, some organic acids and terpenoid metabolites exhibit distinct expression patterns, favoring terpenoid accumulation. Simultaneously, pathways such as folate-mediated one-carbon metabolism and folate biosynthesis are enriched to meet the needs of cell division and growth. The root metabolic differences in tea plants under different pH values ​​stem from water composition, pH itself, and the interaction between the two. Specifically, during the pH increase from 4.5 to 5.5, tap water and purified water exhibited different effects on tea plant root metabolites.

[0075] Particularly at a pH of 5.0, tap water treatment revealed a relatively balanced and favorable trend in tea plant root metabolites. High levels of amino acid derivatives such as N-(3-Indolylacetyl)-L-isoleucine and Prolyl-leucyl-glycine were observed, contributing to the maintenance of acid-base balance and metabolic homeostasis within tea plant cells. Furthermore, while the levels of metabolites such as Taurocyamine, Tetrahydrofolicacid, and Vialinin A decreased, the decrease was relatively small. Overall, tap water and a pH of 5.0 are optimal conditions for tea plants, maintaining normal physiological functions and high metabolic activity, thereby promoting growth and stress resistance, and improving yield and quality.

[0076] The correlation analysis system reveals the synergistic regulation mechanism of tea root morphology development, ion absorption and antioxidant system: the expansion of root surface area, projected area and root volume enhances the antioxidant capacity by increasing the activities of POD, SOD and CAT, and the positive correlation between CAT and root diameter proves that CAT is involved in the process of lignification. The ion regulation path shows significant specificity: ammonium nitrogen accelerates H2O2 decomposition by activating CAT, iron element cooperatively activates POD and CAT to form a double antioxidant barrier, nitrate nitrogen inhibits CAT activity, and magnesium negatively regulates POD / MDA. In terms of metabolic response, magnesium inhibits 8 metabolites to interfere with basic metabolism, aluminum promotes 7 metabolites to activate stress response, and nitrate nitrogen specifically promotes tetrahydrofolic acid (one-carbon metabolism marker); VialininA, Glu-Val-Phe and Arg-Arg are positively correlated with root surface area as growth signal molecules, and Tetrahydrofolic acid negatively regulates root diameter to inhibit cell elongation. The element distribution mechanism shows that nitrate nitrogen promotes protein synthesis by increasing N / C / S content and reducing C / N ratio, aluminum reshapes carbon and nitrogen distribution by increasing C / N ratio, and magnesium significantly reduces N / C content to limit basic metabolism.

[0077] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for hydroponically growing tea trees, characterized in that: Choose tap water or pure water to cultivate tea seedlings. By adjusting the pH value of tap water or pure water, the root growth and nutritional metabolism of tea trees can be controlled. The light intensity of the hydroponic environment was controlled to be 2000 lx, the light duration was 14 hours per day, the ambient temperature was 22°C to 25°C, and the humidity was 70%.

2. The hydroponic method for tea plants according to claim 1, wherein: When using tap water to cultivate tea seedlings, control the pH of the tap water to 5.0-5.5 to increase the root surface area and root projection area of ​​the tea tree.

3. The hydroponic method for tea plants according to claim 1, wherein: When using pure water to cultivate tea seedlings, control the pH of the pure water to 4.5-5.5 to increase the root volume and average root diameter of the tea trees.

4. The hydroponic method for tea plants according to claim 1, wherein: When using tap water to cultivate tea seedlings, control the pH of the tap water to 5.0 to balance the nitrate nitrogen-phosphorus absorption and carbon and sulfur metabolism of the tea trees, thereby promoting the nutritional metabolism of the tea trees.

5. The hydroponic method for tea plants according to claim 1, wherein: When using tap water to cultivate tea seedlings, control the pH of the tap water to 5.0 to enhance SOD and POD activity and promote the tea trees to absorb ammonium nitrogen, iron ions, and aluminum ions.

6. The hydroponic method for tea plants according to claim 1, wherein: When using tap water to cultivate tea seedlings, control the pH of the tap water to 5.5 to promote the accumulation of caffeine in the tea trees and enhance the bitterness threshold of the tea leaves.

7. The hydroponic method for tea plants according to claim 1, wherein: When using pure water to cultivate tea seedlings, control the pH of the pure water to 5.0 to promote the accumulation of GCG and ECG in the tea trees and enhance the antioxidant properties of the tea leaves.

8. The hydroponic method for tea plants according to claim 1, characterized in that: When using tap water to cultivate tea seedlings, control the pH of the tap water to 5.0 to promote theanine content of the tea tree and enhance the freshness of the tea leaves.

9. The hydroponic method for tea plants according to claim 1, wherein: When using tap water to cultivate tea seedlings, Control the pH of tap water to 5.0 to promote the synthesis of terpenoid compounds, increase the content of chemical defense substances in tea trees, and resist external damage; The pH of tap water was controlled at 5.0 to promote nucleotide metabolism and thus accelerate caffeine synthesis, while inhibiting vilalin A synthesis.

10. The hydroponic method for tea plants according to claim 1, characterized in that: The tap water or pure water is added with a nutrient solution, the formula of which is shown in the following table:

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