A method for supplemental lighting in greenhouse-grown bayberry

Abstract

This invention belongs to the field of agricultural biotechnology, specifically disclosing a method for supplemental lighting in greenhouse-grown bayberries. The method involves supplementing the greenhouse-grown bayberries with red light during the daytime hours from the beginning of flower bud differentiation to the end of flowering, while omitting supplemental lighting at night. This method promotes the growth and development of bayberry flower buds, thereby advancing flowering and increasing the number of flowers, which is beneficial for increasing the yield of bayberry fruit.

Description

Technical Field

[0001] This invention belongs to the field of agricultural biotechnology, specifically relating to a method for supplemental lighting in greenhouse-grown bayberry. Background Technology

[0002] The Chinese bayberry (Myrica rubra Sieb Zucc.) is an evergreen tree belonging to the Myricaceae family and the Myrica genus. It is a characteristic fruit tree of my country. The fruit of the Chinese bayberry can be eaten fresh or processed, is rich in nutrients, and has high economic value. The Chinese bayberry is dioecious, with female flowers forming catkins. When flowering, the catkins open gradually from the top to the base. The flower buds of the Chinese bayberry differentiate from the axillary buds at the top. The flower bud differentiation period begins at the end of July and is basically completed by the end of November. In early February of the following year, the flower buds begin to sprout and swell, and enter the peak flowering period in March. The number of flower buds differentiated on each fruiting branch is affected by a variety of factors. Among them, the number of flower buds can reach more than 25 when there are many. The number of flower buds of the female flowers determines the number of female flower inflorescences in that year, which has a significant impact on the yield of Chinese bayberries [Lu Shaoquan, Yao Heying. Flowering, fruiting and flower bud differentiation habits of Chinese bayberry [J]. Modern Rural Science and Technology, 2016(14):37-37.]. The process of flower bud differentiation and development is closely related to flowering quality and fruit harvesting period. It takes a long time for the waxberry to go from flower bud differentiation to full bloom. Therefore, studying the growth and development process of waxberry flower buds and exploring the influencing factors of flower bud germination is of great significance for guiding production.

[0003] Light is crucial for plant growth, and the flowering process of most plants is affected by light. For example, light intensity and light quality are the determining factors for gladiolus flower bud development. When there is insufficient light in the greenhouse during winter, most gladiolus flower buds fail to develop, resulting in a very low flowering rate [Zhang Xiaoping. The effect of light intensity on gladiolus flower bud development [J]. Journal of Nanjing Agricultural University, 1990, 13(4):35-38.]. In addition, supplemental lighting is an effective way to improve light conditions and influence plant growth. For example, studies have shown that LED supplemental lighting can significantly improve the fruit quality of blueberries [Wang Jiaqi, He Yingyu, Wei Xiaotong, Li Yongqiang, Yang Li, Chen Wenrong, Liao Fanglei, Guo Weidong. The effect of LED supplemental lighting combination on the growth and development of blueberries in greenhouse [J]. Journal of Horticulture, 2020, 47(6):1183-1193.]. In particular, greenhouse cultivation of bayberries allows for better control of growth conditions and yields higher-quality fruit. However, greenhouse cultivation often alters the photosynthetic characteristics of bayberries and also presents the problem of insufficient light within the greenhouse. Currently, there is limited research on supplemental lighting for bayberries, and even less research on supplemental lighting for greenhouse-grown bayberries. Furthermore, there are no reports on the effects of supplemental lighting on flower bud development or flowering processes in greenhouse-grown bayberries. Summary of the Invention

[0004] In order to improve the growth of flower buds and increase fruit yield in greenhouse-grown bayberries, this invention discloses a method for supplemental lighting in greenhouse-grown bayberries.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A method for supplemental lighting of greenhouse-grown bayberry, wherein red light is applied to the bayberry plants during the period from the beginning of flower bud differentiation to the end of flowering.

[0007] The inventors of this application studied the effects of different light quality supplemental lighting treatments on flower bud differentiation and growth development of greenhouse-grown bayberries. They discovered that supplemental red light can better promote flower bud development, including increasing the number of flower buds, making them larger and stronger, and accelerating their development. Simultaneously, the inventors found that supplemental red light can reduce the chlorophyll content of bayberry leaves, which may be detrimental to the growth of the bayberry tree. Therefore, supplementing bayberry trees with red light only during normal daylight hours (generally from 5 am to 7 pm) from the beginning of flower bud differentiation to the end of flowering, while refraining from lighting during normal dark hours (generally from 7 pm to 5 am), can promote better flower bud development, leading to earlier fruiting and increased yield, while avoiding the potential adverse effects of long-term red light supplementation on the growth of the bayberry tree, and also reducing supplemental lighting costs.

[0008] In one embodiment of this application, the flower bud differentiation of the greenhouse-grown bayberry begins in July of each year and the flowering ends in April of the following year. However, the timing of flower bud differentiation or flowering may vary slightly depending on the facility conditions or the variety of bayberry.

[0009] In some methods, the specific process of supplementing red light irradiation includes setting a light intensity threshold in seven stages between 5 a.m. and 7 p.m. each day. When the natural light intensity irradiating the bayberry plant is insufficient to meet the light intensity threshold, red light irradiation is increased.

[0010] Furthermore, the seven stages and their corresponding light intensity thresholds are as follows: 5-7 points, light intensity threshold 80 μmol / s / m²; 7-9 points, light intensity threshold 160 μmol / s / m²; 9-11 points, light intensity threshold 320 μmol / s / m²; 11-13 points, light intensity threshold 400 μmol / s / m²; 13-15 points, light intensity threshold 320 μmol / s / m². 2 From 3 PM to 5 PM, the light intensity threshold is 160 μmol / s / m²; from 5 PM to 7 PM, the light intensity threshold is 80 μmol / s / m².

[0011] It should be noted that the above seven stages and their light intensity thresholds were set based on natural light conditions and the light response characteristics of the bayberry. The photosynthetic rate of the bayberry is influenced by the cultivation environment, exhibiting both "single-peak" and "double-peak" phenomena. The light compensation point is between 25 and 53 μmol / s / m², and the light saturation point is between 335.05 and 700.09 μmol / s / m². 2 Between. Such supplemental lighting settings can enable the greenhouse-grown bayberry plants to make better use of light, while avoiding the adverse effects of excessive supplemental lighting at a certain point in time or improper artificial supplemental lighting.

[0012] In some embodiments, the light quality composition of the red light includes 400-500nm blue light, 500-600nm green light, 600-700nm red light, and 700-780nm far-red light, with the proportions of 400-500nm blue light, 500-600nm green light, 600-700nm red light, and 700-780nm far-red light being 12%, 10%, 58%, and 19%, respectively.

[0013] In some embodiments, the red light is provided by an LED red light lamp, which is 25W.

[0014] In some arrangements, the bayberry trees in the facility are arranged in parallel, with the center point of the canopy of adjacent trees in the same row being 0.7m apart and the center point of the canopy of two adjacent rows of trees being 1m apart. Two rows of LED red lights are installed in parallel at the top of each row of trees, 0.3m above the top. These two rows of LED red lights are located on both sides of the center point of the canopy and are spaced 0.4m apart. An LED red light is also suspended between adjacent trees in the same row, with the bottom of the LED red light 0.5m from the ground.

[0015] In some embodiments, the greenhouse-grown bayberry is a 7-year-old water chestnut bayberry grown in greenhouses.

[0016] The advantages of this invention are as follows: By studying the effects of different light quality supplemental lighting treatments on the differentiation and growth of bayberry flower buds, the inventors of this invention discovered that supplementing bayberry with red light can more effectively promote the differentiation and growth of bayberry flower buds, thereby leading to earlier flowering, ensuring flowering quality, and improving the economic benefits of fruit farmers. Attached Figure Description

[0017] Figure 1 Schematic diagram of supplemental lighting installation within the facility;

[0018] Figure 2 Light quality analysis spectra of two different LED lights;

[0019] Figure 3 The impact of different treatments on the light environment within the facility;

[0020] Figure 4 Effects of different treatments on chlorophyll content;

[0021] Figure 5 The effect of different treatments on the number of flower buds;

[0022] Figure 6 The effect of different treatments on flower bud size;

[0023] Figure 7 The effects of different treatments on flower bud germination;

[0024] Figure 8 Microscopic structural observation of flower bud development under different treatments. Detailed Implementation

[0025] The present invention will be further described in detail below through specific embodiments.

[0026] The differentiation and development of flower buds in fruit trees is a highly complex physiological, biochemical, and morphological process that determines the amount and timing of flowering, thereby affecting fruit yield and ripening time. Therefore, studying the development process of fruit tree flower buds is of paramount importance. The inventors of this application investigated the effects of different supplemental light qualities and conditions on the development of flower buds in *Myrica rubra* (Chinese bayberry).

[0027] By comparing the development of bayberry flower buds under LED white light (providing white light), LED red light (providing red light), and no supplemental lighting, it was found that under LED red light, the number of flower buds differentiated was the highest, and the flower buds were the largest and developed the fastest at the same time, which is conducive to advancing the flowering period. Simultaneously, the inventors conducted comparative studies on light quality and light intensity, and the results showed that using red light under the following conditions had the best effect on the growth and development of bayberry flower buds in greenhouse cultivation:

[0028] Red light irradiation was used to cultivate bayberries during the period from the onset of flower bud differentiation to the end of flowering. Light intensity thresholds were set in seven stages between 5:00 AM and 7:00 PM daily. When the natural light intensity irradiating the bayberry plants was insufficient to reach the light intensity threshold, red light irradiation was increased. The seven stages and their corresponding light intensity thresholds were as follows: 5:00 AM to 7:00 AM, with a light intensity threshold of 80 μmol / s / m². 2 From 7:00 to 9:00, the light intensity threshold is 160 μmol / s / m. 2 From 9:00 to 11:00, the light intensity threshold is 320 μmol / s / m. 2 From 11:00 AM to 1:00 PM, the light intensity threshold is 400 μmol / s / m. 2 From 1 PM to 3 PM, the light intensity threshold is 320 μmol / s / m. 2 From 3 PM to 5 PM, the light intensity threshold is 160 μmol / s / m. 2 From 5 PM to 7 PM, the light intensity threshold is 80 μmol / s / m.2 The red light is provided by LED red lights. The LED red lights are 25W, and their light composition includes 400-500nm blue light, 500-600nm green light, 600-700nm red light, and 700-780nm far-red light, with proportions of 12%, 10%, 58%, and 19%, respectively. The bayberry trees within the facility are arranged in parallel rows, with the center point of the canopy of adjacent trees in the same row 0.7m apart, and the center point of the canopy of two adjacent rows of trees 1m apart. Two rows of LED red lights are installed parallel to each other at 0.3m from the top of each row of trees, located on either side of the center point of the canopy, with a spacing of 0.4m. An LED red light is suspended between adjacent trees in the same row, with its bottom 0.5m from the ground.

[0029] It should be emphasized that the spacing and location of the bayberry plants, as well as the number and location of the supplementary lights, were adjusted and optimized by the inventor based on the growth of 7-year-old water chestnut bayberry plants in the facility. Under these conditions, air circulation can be guaranteed, the bayberry plants can receive sufficient natural sunlight, daily management can be facilitated, and the supplementary light can be evenly distributed on the tree.

[0030] Example 1

[0031] Under the same conditions, LED lights with different light qualities were used for supplemental lighting. Optical analysis was conducted, and the light intensity, leaf chlorophyll content, number of flower buds, and longitudinal and transverse diameters of flower buds at the same time were compared under different treatments. The germination and internal development of flower buds were also observed through external morphology and section microscopy to study the effects of different light quality supplemental lighting treatments on the growth of bayberry flower buds. The details are as follows:

[0032] 1. Experimental materials and supplemental lighting methods

[0033] The experiment was conducted in a glass greenhouse at the Zhejiang Academy of Agricultural Sciences experimental base in Hangzhou, Zhejiang Province. The test material was healthy 7-year-old potted bayberry 'Biji' variety. Each treatment had 10 replicates. Except for the supplemental lighting treatment, the other facility environment was the same, and watering and fertilization were uniformly managed. At the same time, a control group (ZK) was set up without supplemental lighting, and all other aspects were the same.

[0034] Two types of LED lights with different light qualities (white LED lights and red LED lights) were used for supplemental lighting from both the top and sides of the tree. The arrangement of the lamps and the duration of the supplemental lighting were exactly the same for both treatments, and they were named the white light (WL) treatment and the red light (RL) treatment based on their color temperature. The supplemental lighting treatment began from the differentiation of the waxberry flower buds (July) and continued until the end of flowering (April of the following year). The light intensity in the greenhouse was divided into seven periods each day, and a light intensity threshold was set for each period, as shown in Table 1. Supplemental lighting was automatically activated when the light intensity was insufficient. The division and setting of these seven periods and their light intensity thresholds were based on natural light conditions. This allows the waxberry plants to make better use of light while avoiding the adverse effects of excessive or improper artificial supplemental lighting.

[0035] Specifically, the LED white light (brand 4D BIOS, model SLD-015TDSSB-XJ) is 16W, and the LED red light (brand iGrowtek, model STP-EU-25-1200L) is 25W. The bayberry trees within the facility are arranged in parallel rows, with the center point of the canopy of adjacent trees in the same row 0.7m apart, and the center point of the canopy of two adjacent rows 1m apart. Two rows of LED red lights are installed parallel to each other at 0.3m from the top of each row of trees, positioned on either side of the center point of the canopy, with a spacing of 0.4m. An LED red light is suspended between adjacent trees in the same row, with its bottom 0.5m from the ground. Figure 1 ).

[0036] Table 1 Light Intensity Thresholds for Automatic Complementary Lighting

[0037]

[0038] 2. Detection and Analysis Methods

[0039] (1) Optical Analysis

[0040] The two types of lamps were placed in a spectrometer (Haas Suite, EVERFINE) and kept lit for 15 minutes. After the lamps were preheated and stabilized, they were tested every 30 minutes. The test scanning wavelength was 380nm-780nm.

[0041] (2) Greenhouse light environment measurement

[0042] The light intensity in the greenhouse was measured at four different locations on each tree using a handheld digital illuminance meter (Himar, AS813), and the results were statistically analyzed.

[0043] (3) Determination of the number and size of flower buds

[0044] Select current-year branches from the four directions (east, south, west, and north) of each plant, count the number of flower buds, and then take the flower buds for microscopic observation and photography using a super depth-of-field stereomicroscope (Keyence, Japan, VHX-950F) under the same parameters. Use ImageJ software to measure the longitudinal and transverse diameters of the photographed flower buds.

[0045] (4) Determination of chlorophyll content in leaves

[0046] Twelve leaves from each plant were selected from four directions (north, south, east, and west) and the chlorophyll mass fraction (SPAD value) of the living leaves was measured using a SPAD-502Plus chlorophyll meter (Minolta Corporation, Japan).

[0047] (5) Observation of the anatomical structure of flower buds

[0048] Fresh flower buds were fixed with 50% FAA fixative, then embedded in paraffin and sectioned. They were stained with safranin and fast green and observed and photographed under a microscope.

[0049] (6) Data processing

[0050] All data were statistically analyzed using SPSS 25.0 software. All data obtained in the experiment are expressed as mean ± standard deviation. The significance of differences between the means of different treatments was compared using the Turkey method. For the same indicator, different lowercase letters indicated significant differences (p < 0.05).

[0051] 3. Experimental Results

[0052] (1) Analysis of LED light quality with different light qualities and its effects on greenhouse light environment and chlorophyll content

[0053] Because these two types of supplemental lighting tubes have significant color differences, light quality analysis was conducted to analyze their light wavelength composition. The results show ( Figure 2 The color temperature of the white light treatment (LED white light) is 3329K, and the color temperature of the red light treatment (LED red light) is 1531K.

[0054] From the perspective of light composition (Table 2), there are significant differences between the two treatments. In the white light treatment, the ratio of 400-500nm blue light, 500-600nm green light, 600-700nm red light, and 700-780nm far-red light is 18:28:48:5; while in the red light treatment, the ratio is 12:10:58:19. The proportion of blue and green light (cool light) is higher in the white light treatment, approximately 46%, significantly higher than the 22% in the red light treatment; while the proportion of red and far-red light (warm light) is higher in the red light treatment, accounting for approximately 76% of all light components, much higher than the 53% in the white light treatment. Furthermore, the red-blue light ratios of the two light sources differed significantly. The red-blue light ratio for the white light treatment was 2.6, while that for the red light treatment was as high as 4.7, approximately twice that of the white light. Although their peak wavelengths were similar, the white light exhibited a higher photosynthetic irradiance, indicating that the effective radiation from the LED white light was greatest within a specific range for plant photosynthesis.

[0055] Table 2 Light quality analysis parameters of different supplementary lights

[0056]

[0057] Both supplemental lighting treatments significantly improved the light environment inside the greenhouse. Actual photos of the supplemental lighting setup and its effects are shown below. Figure 3 As shown, the results indicate that different light qualities have a significant impact on increasing the light intensity around the tree. The white light treatment resulted in the highest light intensity, while the red light treatment also significantly increased the light intensity around the tree, but its light intensity was weaker than that of the white LED light.

[0058] Light affects plant photosynthesis and chlorophyll content. To investigate this, the inventors measured the chlorophyll content of bayberry leaves under different treatments, and the results showed... Figure 4 Compared with the supplemental lighting treatment, the control group had a higher SPAD value, indicating that both types of supplemental lighting resulted in a decrease in the chlorophyll content of the leaves.

[0059] (2) Effects of different light qualities on the number and size of flower buds

[0060] Both supplemental lighting treatments with different light qualities were beneficial to the differentiation of female flower buds. Under the supplemental lighting treatment, the number of flower buds on fruiting branches was significantly increased compared to the control group. Figure 5 The number of flower buds was highest under LED red light supplemental lighting, indicating that LED red light supplemental lighting has the most significant effect on promoting flower bud differentiation.

[0061] Supplemental lighting treatment increased the number of flower buds and significantly improved their size. Microscopic observation and longitudinal and transverse diameter measurements were performed on flower buds at the same stage under different supplemental lighting treatments. Figure 6The results showed that the flower buds treated with red light had the longest longitudinal diameter and the clearest fish-scale stripes, followed by those treated with white light. The supplemental lighting also significantly increased the transverse diameter of the flower buds, but there was no significant difference in transverse diameter between the two different lighting treatments. The results indicated that the control group differentiated the fewest flower buds, and the longitudinal and transverse diameters of the flower buds were also the smallest at the same time point, indicating the slowest flower bud growth rate.

[0062] (3) The effect of supplemental lighting of different light qualities on flower bud germination

[0063] Both types of supplemental lighting significantly accelerated the flower bud germination process. In the flowering process of female bayberry flowers, the stigmas of the small flowers at the upper part of the inflorescence typically appear first, followed by the gradual unfolding of stigmas from other parts of the inflorescence. The exposed stigmas continuously extend outwards, and their color gradually deepens to a dark red. Phenological observations were conducted on the flower bud germination of bayberry under different treatments at the same time. Figure 7 As can be seen, the bracts of the bayberry flower buds under both different light quality supplemental lighting treatments had unfolded. Under red light treatment, the Y-shaped stigma elongated and became exposed, turning a bright red color, indicating a flowering trend. Under white light treatment, the flower buds loosened, and the small stigma at the tip was exposed, but the stigma color remained light pink. In contrast, the flower bud bracts in the control group remained closed and did not sprout, indicating delayed flower development. Accelerated flower bud germination is beneficial for advancing the flowering period; the flowering period was advanced by 6-8 days under red light treatment and by 3-5 days under white light treatment, indicating that supplemental lighting is beneficial for flower bud development and promotes earlier flowering.

[0064] To more accurately observe the developmental status of bayberry flower buds, we conducted anatomical microscopic observations of bayberry flower buds under three different treatments at the same stage. Figure 8 This study aimed to analyze the developmental process within flower buds. The flower of *Myrica rubra* is a catkin inflorescence. Besides the terminal floret primordium, small floret primordia also develop in the axils. Each small floret primordium can develop into a small flower, and each small flower contains an ovary. After fertilization, a *Myrica rubra* fruit can be formed. This study showed that, in the control group, the development of the lower female floret primordia remained stagnant. However, in the flower buds treated with supplemental light, the terminal floret primordium continuously grew and swelled, while multiple small floret primordia had also formed in the lower axils (indicated by black arrows). The red light treatment resulted in the largest number of small floret primordia, indicating that a higher proportion of red and far-red light had the most significant promoting effect on the growth and development of small floret primordia.

[0065] In summary, compared with the control (CK), supplemental lighting with LED white light and LED red light during the period from the onset of flower bud differentiation (July) to the end of flowering (April of the following year) effectively improved the quantity and quality of flower buds in greenhouse-grown bayberries, accelerated flower bud germination, and advanced the flowering period. Furthermore, the effect of LED red light was significantly better than that of LED white light. It is worth noting that while LED white light has lower power than LED red light, its light intensity, irradiance, and effective radiation are all higher, yet the effect of LED white light on promoting flower bud development is lower. This result indicates that the growth of flower buds in greenhouse-grown bayberries is less related to light intensity and effective radiation, and more closely related to light quality. The light quality composition of LED red light is more conducive to the growth of flower buds in greenhouse-grown bayberries. Furthermore, when using LED white and LED red lights for supplemental lighting in greenhouse-grown bayberries, the chlorophyll content of the bayberry leaves decreased. This may be due to the increased light intensity causing photo-oxidation and destruction of chlorophyll; the specific reasons require further investigation. Therefore, when greenhouse-grown bayberries receive insufficient light, simply increasing photosynthetic irradiance or light duration is insufficient. Instead, a comprehensive consideration of the combined effects of light duration, photosynthetic irradiance, and light quality is necessary for a more scientific and reasonable supplemental lighting approach. In particular, using the LED red lights described in this example, supplemental lighting according to the above method, has shown excellent effects on the growth of flower buds, subsequent fruit yield, and overall tree health in greenhouse-grown bayberries.

[0066] Comparative Example 1

[0067] LED red lights were used for supplemental lighting from 5 a.m. to 7 p.m., and other aspects were the same as in Example 1.

[0068] The results showed that the number of flower buds in greenhouse-grown bayberries not only did not increase, but decreased, and the bayberry plants exhibited leaf wrinkling and falling, which may be due to excessive supplemental lighting leading to poor growth and development of bayberries.

[0069] Comparative Example 2

[0070] LED seedling lamps (the light quality consists of red and blue light in a 2:1 ratio, 25W, Shanghai Heming Lighting & Electric Co., Ltd.) were used, and other aspects were the same as in Example 1.

[0071] The results showed that the flower bud growth of the greenhouse-grown bayberry was better than that of the control group, and similar to the results of the LED white light lamp.

[0072] Comparative Example 3

[0073] Fluorescent seedling lamp (light quality composed of red and blue light in a 1:4 ratio, 25W, Shanghai Heming Lighting & Electric Co., Ltd.), other features are the same as in Example 1.

[0074] The results showed that the flower bud growth of the greenhouse-grown bayberry was better than that of the control group, but worse than that of the LED white light group.

[0075] The number of flower buds, transverse diameter of flower buds, and longitudinal diameter of flower buds (all average values) on the current year's branches of Yangmei cultivated in protected environments under the conditions of Examples 1 to Comparative Examples 1-3 are shown in the table below.

[0076] Table 3. Number and condition of flower buds on current-year branches of Yangmei trees in each group under protected cultivation.

[0077]

[0078]

[0079] The data in the table shows that the number of flower buds on the current year branches of the greenhouse-grown bayberry under the LED red light treatment in Example 1 was the highest and the flower buds were more robust, which was significantly better than other groups. This result proves that the LED red light and supplemental lighting conditions in Example 1 are most conducive to the growth and development of flower buds in greenhouse-grown bayberry, and thus conducive to increasing the yield of bayberry fruit.

[0080] It should be understood that the specific embodiments described above are merely illustrative of the present invention and are not intended to limit the invention. Any modifications made based on the technical concept and solutions of the present invention are within the scope of protection of the present invention. Unless otherwise specified, all materials and reagents used in the present invention are commercially available.

Claims

1. A method for supplemental lighting in greenhouse-grown bayberry to increase the number of flower buds, the transverse diameter of flower buds, and the longitudinal diameter of flower buds on current-year branches, characterized in that, During the daytime hours from the onset of flower bud differentiation to the end of flowering, the bayberry trees were irradiated with red light, while no supplemental lighting was provided at night. The specific process involved setting seven light intensity thresholds between 5 AM and 7 PM daily. When the natural light intensity within the facility was insufficient to meet the threshold, red light was applied. The red light consisted of 400-500nm blue light, 500-600nm green light, 600-700nm red light, and 700-780nm far-red light, with proportions of 12%, 10%, 58%, and 19%, respectively. The red-blue light ratio was 4.

7. The red light was provided by LED red lights. The seven stages and their corresponding light intensity thresholds were: 5 AM to 7 AM, with a light intensity threshold of 80 μmol / s / m². 2 From 7:00 to 9:00, the light intensity threshold is 160 μmol / s / m. 2 From 9:00 to 11:00, the light intensity threshold is 320 μmol / s / m. 2 From 11:00 AM to 1:00 PM, the light intensity threshold is 400 μmol / s / m. 2 From 1 PM to 3 PM, the light intensity threshold is 320 μmol / s / m. 2 From 3 PM to 5 PM, the light intensity threshold is 160 μmol / s / m. 2 From 5 PM to 7 PM, the light intensity threshold is 80 μmol / s / m. 2 The LED red light is 25W with a color temperature of 1531K; the bayberry plants in the facility are arranged in parallel, with the distance between the center points of the canopies of adjacent trees in the same row being 0.7m, and the distance between the center points of the canopies of two adjacent rows of trees being 1m; two rows of LED red lights are set in parallel at 0.3m above the top of each row of trees, and these two rows of LED red lights are located on both sides of the center point of the canopy, with a spacing of 0.4m; and an LED red light is suspended between adjacent trees in the same row, with the bottom of the LED red light 0.5m from the ground; the bayberry planted in the facility is a 7-year-old water chestnut bayberry; the number of flower buds on the current year's branches is 9, the transverse diameter of the flower bud is 1712μm, and the longitudinal diameter of the flower bud is 3384μm.

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