Method for improving quality of mesona aculeata in plant factory by using red light and application thereof

Abstract

The application belongs to the field of crop cultivation and relates to the culture of mesona chinensis, in particular to a method for improving the quality of mesona chinensis in a plant factory by using red light and application. The LED lamp plate is adjusted to pure red light, the illumination intensity of the pure red light is 50-200 μmol / (m 2 ·s), and the illumination cycle is long / short light cycle 12 h / 12 h-20 h / 4 h. The subject group takes the current-year healthy and disease-free branch with a terminal bud of mesona chinensis as the material, carries out the influence of different light quality, light intensity and illumination time on the growth and total pectin and soluble sugar content accumulation of mesona chinensis in the plant factory, so as to provide a theoretical basis for the light regulation of mesona chinensis growth and functional component production application.

Description

Technical Field

[0001] This invention belongs to the field of crop cultivation and relates to the cultivation of Mesona chinensis, specifically to the method and application of using red light to improve the quality of Mesona chinensis in plant factories. Background Technology

[0002] Mesona chinensis ( Platostomapalustre Grass jelly (Ligustrum lucidum) is a herbaceous plant belonging to the genus Ligustrum in the Lamiaceae family. Also known as fairy grass or fairy jelly, it is an important plant used for both medicinal and edible purposes, possessing high nutritional value and potential health benefits. Grass jelly mainly contains polysaccharides, flavonoids, and terpenes, and is primarily used to process products such as grass jelly, tortoise jelly, Wanglaoji herbal tea, Jiaduobao herbal tea, Heqizheng herbal tea, and grass jelly dessert, showing broad prospects for product development and utilization.

[0003] Although some studies have reported on the cultivation techniques, germplasm screening and identification, tissue culture, chemical composition, and medicinal mechanisms of *Mesona chinensis*, the overall research foundation for *Mesona chinensis* remains relatively weak, requiring strengthened research on germplasm resource innovation, the breeding of superior cultivars, and key supporting technologies. Plant factories are highly efficient plant production systems with intelligent control of environmental conditions such as artificial light. They possess the advantage of not relying on natural conditions such as sunlight and soil, and suitable light formulations can precisely regulate the yield and quality of plants or target organs. Application CN110249833A discloses a method for improving the yield and quality of leafy vegetables in plant factories using low-dose long-wave ultraviolet light. This application improves the yield and quality of leafy vegetables by adding low-dose long-wave ultraviolet light to an LED light source; however, the applicant's application of this method to *Mesona chinensis* did not achieve the expected experimental results. Light, as one of the basic elements of plant growth and development, has a significant impact on plant growth and development due to factors such as light quality, light intensity, and light duration. To further explore the impact of light sources on the quality of grass jelly, the applicant conducted in-depth research, using LED lights for precise cultivation and targeted enrichment studies of grass jelly, which has a positive effect on promoting the development of the grass jelly industry. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a method and application for improving the quality of grass jelly in plant factories using red light.

[0005] The technical solution of this invention is implemented as follows:

[0006] A method to improve the quality of grass jelly in a plant factory by using red light involves adjusting the LED light panel to pure red light.

[0007] The intensity of the pure red light mentioned above is 50-200 μmol / (m²). 2 ·s).

[0008] Preferably, the intensity of the pure red light is 50-150 μmol / (m²). 2·s). Light intensity 50-150 μmol / (m 2 •s), long / short photoperiods of 20h / 4h are conducive to the accumulation of chlorophyll a, chlorophyll b, carotenoids, and total chlorophyll. Increased photoperiod and light intensity are beneficial to the root growth of *Mesona chinensis*.

[0009] Preferably, the intensity of the pure red light is 100-200 μmol / (m²). 2 ·s). 100-200 μmol / (m 2 •s) Light intensity and 8h / 16h photoperiod treatment help accumulate total pectin and soluble sugar content.

[0010] More preferably, the intensity of the pure red light is 150 μmol / (m²). 2 ·s). (150 μmol / (m 2 The light intensity and 20h / 4h photoperiod are more suitable for the industrialized cultivation and high-quality production of grass jelly.

[0011] The above illumination cycles are long / short light cycles of 12h / 12h-20h / 4h.

[0012] Preferably, the illumination period is a long / short light period of 20h / 4h.

[0013] The indoor temperature of the plant factory was 25 ℃, the air humidity was 65%, and the CO2 concentration was 400 μmol / mol.

[0014] The above-mentioned methods for improving the quality of grass jelly are selected from any of the following:

[0015] ① Increase the content of chlorophyll a, chlorophyll b, carotenoids and total chlorophyll;

[0016] ②Improving the quality of grass jelly includes increasing the total amount of pectin and the content of soluble sugars.

[0017] Application of the above-mentioned herbaceous grass cultivated using the above method in the preparation of health food.

[0018] The present invention has the following beneficial effects:

[0019] 1. Using healthy, disease-free branches with terminal buds from the current year as material, our research group conducted studies in a plant factory on the effects of different light qualities, light intensities, and light durations on the growth of *Mesona chinensis* and the accumulation of total pectin and soluble sugar content, aiming to provide a theoretical basis for light-regulated growth of *Mesona chinensis* and the production and application of its functional components.

[0020] 2. Compared to blue light, treatment with red light is more beneficial to the growth of *Mesona chinensis* plants. Increasing the intensity and duration of red light exposure can, to some extent, increase the overall weight and stem diameter of *Mesona chinensis*, while increasing the duration of light exposure is beneficial for increasing leaf area. Light intensity: 50-150 μmol / (m²) 2 • (s), long / short photoperiods of 20h / 4h are favorable for the accumulation of chlorophyll a, chlorophyll b, carotenoids, and total chlorophyll. Increased photoperiod and light intensity are beneficial for the root growth of *Mesona chinensis*. 100-200 μmol / (m 2 •s) Light intensity and 8h / 16h photoperiod treatment contribute to the accumulation of total pectin and soluble sugar content. Finally, membership function and principal component analysis results indicate that the T12 treatment (150 μmol / (m 2 The optimal light intensity (20h / 4h photoperiod) and light cycle (20h / 4h) are more suitable for the industrialized cultivation and high-quality production of *Mesona chinensis*. This study provides scientific data for large-scale cultivation and planting of *Mesona chinensis* in plant factories or indoors. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A comparison of the fresh weight of Mesona chinensis plants under different light quality conditions.

[0023] Figure 2 The values ​​represent growth indicators under different red light intensities and photoperiods; where (AE) represent plant height, total plant weight, number of leaves, stem diameter, and leaf area under different red light intensities and photoperiods, respectively; different letters indicate significant differences at the 0.05 level.

[0024] Figure 3 The graph shows the changes in chlorophyll content (a), chlorophyll b, carotenoids, and total chlorophyll under different red light intensities and photoperiods. (AD) represents the changes in chlorophyll a, chlorophyll b, carotenoids, and total chlorophyll content under different red light intensities and photoperiods. Different letters indicate significant differences at the 0.05 level.

[0025] Figure 4 The changes in root weight, root length, root volume, root surface area, and average root diameter under different red light intensities and photoperiods are shown. (AE) represents root weight, root length, root volume, root surface area, and average root diameter under different red light intensities and photoperiods. Different letters indicate significant differences at the 0.05 level.

[0026] Figure 5 The graph shows the changes in total pectin content and soluble sugar content. (A) shows the total pectin content under different light intensities and photoperiods; (B) shows the soluble sugar content under different light intensities and photoperiods.

[0027] Figure 6 The growth of *Mesona chinensis* plants under 16 different red light intensities and photoperiods in Experiment 2 was studied. Detailed Implementation

[0028] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Example

[0029] Experimental materials involved in this application:

[0030] 1. Experimental Site

[0031] The cutting propagation experiment was conducted in the plant factory of the Key Laboratory of Conservation and Genetic Improvement of Medicinal Resources in Guangxi Zhuang Autonomous Region Medicinal Botanical Garden. The indoor temperature of the plant factory was 25 ℃, the air humidity was 65%, and the CO2 concentration was 400 μmol / mol.

[0032] Experimental setup

[0033] Experiment 1:

[0034] Using 10-15cm tall *Mesona chinensis* cuttings as research material, they were transplanted into a plant factory for hydroponics. Different light quality ratios (red light R, blue light B, red-blue light ratios of 1:1, 3:1, 5:1, 7:1, and 9:1) and a light intensity of 200 μmol / (m²) were employed. 2 ·s).

[0035] Depend on Figure 1 It is evident that the fresh weight of individual plants was significantly higher in the pure red light and red-blue light treatments with ratios of 1:1, 3:1, 5:1, 7:1, and 9:1 than in the blue light treatment, while there was no significant difference in fresh weight among the red light treatments. Compared to blue light, the red light treatment was more beneficial to the growth of *Mesona chinensis* plants. Therefore, considering practical applications in production, we will next use red light to study the effects of light intensity and photoperiod on *Mesona chinensis*.

[0036] Experiment 2:

[0037] The experimental material was taken from the mother plant of *Mesona chinensis* at the Guangxi Zhuang Autonomous Region Medicinal Botanical Garden Research Base. On the day of propagation, healthy, disease-free branches with terminal buds, approximately 10 cm long, were taken from the mother plant. The terminal bud was retained at the top, and the bottom was cut at a smooth 45° angle, leaving 4-6 leaves and one bud. The cuttings were secured with planting cotton and placed in a 30 cm long, 23 cm wide, 20-hole floating board. The floating board was then placed in a plastic box for hydroponics. Before rooting, the cuttings were cultured in tap water. After 3 days, when roots appeared, they were cultured in half of the garden's experimental nutrient solution.

[0038] The light intensity can be adjusted to 50, 100, 150, and 200 μmol / (m²). 2 •s) 4 levels, photoperiod 8 L / 16D, 12 L / 12D, 16 L / 8D and 20 L / 4D 4 levels, a total of 16 treatments with 2 factors and 4 levels, as detailed in Table 1. 20 cuttings were taken from each treatment, for a total of 320 cuttings.

[0039] Table 1. Complete combination of photoperiod and light intensity processing

[0040] ;

[0041] The effects of different red light intensities and photoperiods on the growth of the upper parts of the grass: Figure 2 -A shows that 100 μmol / (m 2 •s) Light intensity 12 L / 12 D photoperiod and 200 μmol / (m 2 • Under photoperiods of 12 L / 12 D and 16 L / 8 D, plant height was significantly higher than in other treatments, while plant height showed no significant difference in other treatments. Figure 2 -B shows that, under the same light intensity, increasing the photoperiod and, under the same photoperiod, increasing the light intensity leads to an increasing trend in total plant weight, specifically at 100, 150, and 200 μmol / (m²). 2 •s) Light intensity, under a photoperiod of 20 L / 4 D, showed no significant difference in total plant weight, but was significantly higher than other treatments. Figure 2 -C shows that, under the same light intensity, the number of leaves first increases and then decreases with the increase of photoperiod, reaching its highest point at a photoperiod of 16 L / 8 D, and at 150 μmol / (m 2 •s) The number of leaves is highest under a light intensity of 16 L / 8 D photoperiod. The quality of *Mesona chinensis* is mainly determined by the number of leaves and its growth rate, while pale green leaves (more young leaves) indicate a higher growth rate. Figure 6 It can be seen that T9-T16 had more tender leaves, indicating that the growth rate of the grass was higher in this treatment. The T12 and T16 treatments showed the most obvious results, and T12 grew more evenly and was more energy efficient than T16.

[0042] Depend on Figure 2 -D shows that, under the same light intensity, stem diameter increases with increasing photoperiod, reaching 200 μmol / (m 2 • Under a light intensity of 20 L / 4 D photoperiod, the stem diameter was the thickest, significantly higher than other treatments. Figure 2 -E shows that, under the same light intensity, leaf area increases with increasing photoperiod; however, under the same photoperiod, leaf area first increases and then decreases with increasing light intensity. 100 μmol / (m 2 The leaf area is largest under a light intensity of 20 L / 4 D photoperiod.

[0043] Sample and data acquisition and measurement methods

[0044] Experiment 1:

[0045] One month after the grass plants were grown, the fresh weight of each grass plant under different treatments was measured.

[0046] Experiment 2:

[0047] Physiological index measurements: 1) Aboveground parts: 30 days after cutting, 10 cuttings with uniform growth were selected. Plant height and stem diameter were measured with calipers, total plant weight was measured with a 0.1% electronic balance, and single leaf area was measured with a leaf area meter. 2) Underground parts: 5 cuttings with uniform root growth were selected. The roots were cut from the cuttings, dried, and root weight was measured with a 0.1% electronic balance. Root length, average root diameter, root surface area, and root volume were measured using a plant image analysis system.

[0048] Leaf collection and preservation: Select the 3rd to 4th pairs of fresh leaves from the terminal bud from cuttings with uniform growth, put them into centrifuge tubes and flash-freeze them in liquid nitrogen at -196℃, then store them in an ultra-low temperature freezer at -80℃ for later use.

[0049] Photosynthetic pigment content determination: The 95% ethanol extraction method was used for determination. Two leaves were taken from different plants, the third pair of fresh leaves from the terminal bud, using a φ6mm punch. These leaves were quickly placed into centrifuge tubes containing 5ml of 95% ethanol, the caps were tightly closed, and this process was repeated five times. The tubes were then placed in the dark for 24 hours. After the leaves had completely turned white, multi-wavelength measurements were performed at 665, 649, and 470 nm using a UV spectrophotometer. The absorbance value A was recorded, and the contents of chlorophyll a, chlorophyll b, carotenoids (T), and total chlorophyll (T) were calculated using the formulas. a+b .

[0050] Total pectin content determination: Take 0.1g of frozen leaf samples and determine the total pectin content using the carbazole colorimetric method, with 5 replicates. Refer to the instructions for the Total Pectin Content Reagent Kit from Suzhou Greens Biotechnology Co., Ltd. for details.

[0051] Soluble sugar content determination: Take 0.1g of frozen leaf samples and determine the soluble sugar content using the anthrone colorimetric method, with 5 replicates. Refer to the instructions for the soluble sugar content reagent kit from Suzhou Gres Biotechnology Co., Ltd. for details.

[0052] Calculation formula

[0053] Chlorophyll a concentration C a (mg·L) -1 =13.95×A 665 -6.88×A 649 ;

[0054] Chlorophyll b concentration C b (mg·L) -1 = 24.96 × A 649 -7.32×A 665 ;

[0055] Carotenoid concentration C x.c (mg·L) -1 ) = (1000 × A 470 -2.05×C a -114.8×C b )÷245;

[0056] Photosynthetic pigment content T (mg / mm 2 =C×V T ÷(S×1000);

[0057] Total chlorophyll content T a+b =T a +T b ;

[0058] Total pectin content (mg / g) = 0.37 × (A determination - A blank + 0.0141) ÷ W;

[0059] Soluble sugar content (mg / g) = 0.41 × (A determination - A blank - 0.0203) ÷ W;

[0060] V T S represents the total volume of the extract (ml), and S represents the leaf area (mm²). 2 A represents the absorbance value, and W represents the sample weight in g.

[0061] Data Analysis

[0062] Office software was used for data organization, SPSS 13.0 software was used for analysis of variance, and GraphPad Prism5 software was used for graphing.

[0063] Effects of different light intensities and photoperiods on photosynthetic pigments in Mesona chinensis: Figure 3It can be seen that 50, 100, and 150 μmol / (m 2 Under light intensity ·s), chlorophyll a ( Figure 3 -A), chlorophyll b ( Figure 3 -B), carotenoids ( Figure 3 -C) and total chlorophyll ( Figure 3 The -D content showed no significant difference at photoperiods of 8 L / 16 D, 12 L / 12 D, and 16 L / 8 D, but was significantly lower than that at a photoperiod of 20 L / 4 D. 200 μmol / (m 2 Under light intensity ·s, the contents of chlorophyll a, chlorophyll b, carotenoids, and total chlorophyll did not differ significantly across the four photoperiods, but were significantly lower than those at 50, 100, and 150 μmol / (m²). 2 •s) Light intensity 20 L / 4 D photoperiod. This indicates that under low to medium light intensity, longer photoperiods can significantly increase the photosynthetic pigment content in *Mesona chinensis* leaves. Conversely, low to medium light intensity combined with shorter photoperiods and high light intensity are detrimental to the accumulation of photosynthetic pigments in *Mesona chinensis* leaves. The chlorophyll a / b ratio of *Mesona chinensis* under different light intensities and photoperiods ranged from 1.09 to 2.25, all below 3, indicating that *Mesona chinensis* is a shade-tolerant medicinal plant.

[0064] The effects of different light intensities and photoperiods on the roots of Mesona chinensis: such as Figure 4 As shown, under the same light intensity, increasing the light exposure time results in a decrease in root weight ( Figure 4 -A), root length ( Figure 4 -B), root surface area ( Figure 4 -C), root volume ( Figure 4 -D) and root average diameter ( Figure 4 -E) shows an increasing trend. Under the same photoperiod, increasing light intensity leads to an increasing trend in root weight, root length, root surface area, root volume, and average root diameter. 150 μmol / (m 2 ·s) and 200 μmol / (m 2 Under a light intensity of 20 L / 4 D photoperiod, root weight and root length were significantly higher than in other treatments (200 μmol / (m²)). 2 • Under a light intensity of 20 L / 4 D photoperiod, the root surface area was significantly higher than that under other treatments, 100 μmol / (m²) 2 •s) Light intensities of 12 L / 12 D, 16 L / 8 D, and 20 L / 4 D at photoperiods of 200 μmol / (m 2 ·s) Under a light intensity of 20 L / 4 D photoperiod, the root volume was significantly higher than that under other treatments, 100 μmol / (m 2• Under a light intensity of 20 L / 4 D photoperiod, the average root diameter was significantly higher than that under other treatments. This indicates that medium to high light intensity and long photoperiods are conducive to the formation of Mesona chinensis roots, while low light intensity and short photoperiods are not conducive to the formation of Mesona chinensis roots.

[0065] Effects of different light intensities and photoperiods on the total pectin and soluble sugar content of *Mesona chinensis*: Figure 5 It can be seen that 50 μmol / (m 2 ·s) Total pectin of Mesona chinensis under different light intensities and photoperiods ( Figure 5 -A) and soluble sugars ( Figure 5 -B) The content of these treatments did not differ significantly and was significantly lower than that of other treatments. (100, 150, and 200 μmol / (m)) 2 Total pectin (s) under a light intensity of 8 L / 16 D photoperiod Figure 5 -A) content was high, and significantly higher than other treatments. 100, 150 and 200 μmol / (m 2 ·s) Soluble sugars under light intensity ( Figure 5 -B) content tends to decrease with increasing photoperiod, 150 μmol / (m 2 •s) The soluble sugar content was highest under a light intensity of 12 L / 12 D photoperiod, and significantly higher than other treatments. This indicates that low light intensity and long photoperiod are not conducive to the accumulation of total pectin and soluble sugar content in *Mesona chinensis*, while shortening the photoperiod under medium to high light intensity is beneficial to the accumulation of total pectin and soluble sugar content in *Mesona chinensis*.

[0066] Correlation analysis of growth and content of *Gnaphalium affine* under different light intensities and photoperiods: Table 2 shows that light intensity is positively correlated with plant height, total plant weight, number of leaves, stem diameter, leaf area, carotenoid content, root weight, root length, root volume, root surface area, average root diameter, total pectin content, and soluble sugar content. Except for leaf area, carotenoid content, and total pectin content, the correlations are all highly significant. Light intensity is negatively correlated with chlorophyll a content, chlorophyll b content, and total chlorophyll content.

[0067] Photoperiod was positively correlated with total plant weight, number of leaves, stem diameter, leaf area, chlorophyll a content, chlorophyll b content, carotenoid content, total chlorophyll, root weight, root length, root volume, root surface area, average root diameter, total pectin content, and soluble sugar content, and all correlations except for average root diameter were highly significant. Photoperiod was significantly negatively correlated with plant height, total pectin content, and soluble sugar content.

[0068] This experiment shows that the stronger the light intensity, the better the aboveground growth and root development of *Gnaphalium affine*; the lower the chlorophyll content; and the higher the pectin content and soluble sugar content. The longer the photoperiod, the better the aboveground growth and root development of *Gnaphalium affine*; the lower the photosynthetic pigment content; and the lower the plant height, pectin content, and soluble sugar content.

[0069] Table 2. Correlation analysis of growth and content of *Mesona chinensis* under different light intensities and photoperiods.

[0070]

[0071] **:Correlation is significant at the 0.01 level.

[0072] *:Correlation is significant at the 0.05level.

[0073] Implementation effect analysis

[0074] We further calculated the D value for each treatment using membership functions of 16 indicators. A higher D value indicates a better treatment effect. The membership function and principal component analysis results are shown in Table 3.

[0075] Table 3. Overall Evaluation of Different Treatments

[0076]

[0077] As can be seen from Table 3, the T12 treatment (150 μmol / (m2·s) light intensity and 20h / 4h L / D photoperiod) has the largest D value, indicating that T12 is more suitable for the growth and quality formation of grass jelly compared with other treatments.

[0078] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for improving the quality of *Gnaphalium affine* in plant factories using red light, characterized by: Adjust the LED light panel to pure red light; The method is selected from any of the following: ① Use a light intensity of 50-150 μmol / (m 2 •s), red light with a photoperiod of 20h / 4h, is used to increase the content of chlorophyll a, chlorophyll b, carotenoids and total chlorophyll; ②Use 100-200 μmol / (m 2 •s) Red light with light intensity and an 8h / 16h photoperiod is used to increase total pectin and soluble sugar content; The indoor temperature of the plant factory is 25 ℃, the air humidity is 65%, and the CO2 concentration is 400 μmol / mol.

2. The application of the herb *Gnaphalium affine* cultivated using the method described in claim 1 in the preparation of health food products.

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