A method for regulating the growth of citrus seedlings by light supplementation

Abstract

The present application belongs to the technical field of plant light environment regulation, and particularly relates to a method for regulating growth of citrus seedlings by light supplement. 432 The above-mentioned method can significantly improve the above-ground indexes such as plant height and leaf number, and promote the increase of root system related parameters; the CL3 can significantly increase the total root length, root surface area and root tip number, and has a prominent promoting effect on the development of the underground part, and can improve the morphology of the above-ground part.

Description

Technical Field

[0001] This invention belongs to the field of plant light environment regulation technology, specifically relating to a method for regulating the growth of citrus seedlings through supplemental lighting. Background Technology

[0002] Citrus is an important economic fruit tree, and the quality of its seedling cultivation directly determines the success rate of orchard establishment, tree vigor, and the timing of fruiting. Cultivating high-quality seedlings with well-developed root systems, robust stems, and healthy leaves is fundamental to the efficient development of the citrus industry. Among the many environmental factors affecting seedling growth, light conditions play a central role—not only providing energy for photosynthesis but also acting as a signaling factor in seedling morphogenesis, carbon and nitrogen metabolism, and stress resistance regulation.

[0003] Artificial lighting has become an indispensable regulatory method in modern citrus seedling cultivation. Existing lighting technologies mostly employ high-pressure sodium lamps or LED lamps with fixed light quality ratios, extending the photoperiod by maintaining constant light intensity and timed switching. However, the current lighting technologies have not yet achieved the desired effect on promoting citrus seedling growth. How to precisely and efficiently regulate citrus seedling growth is a pressing technical problem that needs to be solved in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a method for regulating the growth of citrus seedlings through supplemental lighting. The method provided by this invention can not only regulate above-ground indicators such as plant height and number of leaves in terms of morphology, but also promote the increase of root-related parameters.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for regulating the growth of citrus seedlings through supplemental lighting. The method includes providing supplemental lighting to the citrus seedlings at night, wherein the light quality of the supplemental lighting is chlorophyll a monochromatic light (L). 432 ), chlorophyll a monochromatic light (L 665 ), chlorophyll b monochromatic light (L 465 ), chlorophyll b monochromatic light (L 650 ), Lutein monochromatic light (L 445 ), β-carotene monochromatic light (L 454 ), chlorophyll a complex light (CL1), chlorophyll b complex light (CL2), chlorophyll a and b complex light (CL3), chlorophyll a, b and carotenoid complex light (CL4), and yellow-green light (L 550 ), green light (L) 520 One or more of the following: white light (W).

[0007] Preferably, regulating the growth of citrus seedlings involves: increasing plant height and leaf number, promoting above-ground growth, or increasing the fresh and dry weight of roots, stems, and leaves; the light quality of the nighttime supplemental lighting is: L 432 .

[0008] Preferably, regulating the growth of citrus seedlings involves: increasing plant height and leaf number, promoting above-ground growth, increasing root length, or increasing dry matter accumulation; the light quality of the nighttime supplemental lighting is: L 454 .

[0009] Preferably, regulating the growth of citrus seedlings involves increasing leaf width and thickness, inhibiting plant height, or enhancing dry matter accumulation; the light quality of the nighttime supplemental lighting is: L 650 .

[0010] Preferably, the regulation of citrus seedling growth involves: inhibiting stem thickening and promoting root elongation; the light quality of the nighttime supplemental lighting is: L 520 .

[0011] Preferably, the regulation of citrus seedling growth involves: overall suppression of the above-ground parts; the light quality of the nighttime supplemental lighting is: L 550 .

[0012] Preferably, the regulation of citrus seedling growth is achieved by increasing total root length, root surface area, and number of root tips, or by promoting aboveground growth, or by promoting biomass accumulation; the light quality of the nighttime supplemental lighting is CL3.

[0013] Preferably, the regulation of citrus seedling growth is achieved by promoting root material distribution or increasing the root-to-shoot ratio; the light quality of the nighttime supplemental lighting is CL2.

[0014] Preferably, the duration of the nighttime supplemental lighting is 4 hours, preferably from 0:00 at night to 4:00 in the morning.

[0015] Preferably, the citrus seedling is a sweet orange seedling, and more preferably a 1-month-old sweet orange seedling.

[0016] Preferably, the citrus seedlings are cultured at a temperature of 25 ± 2 ℃, a photoperiod of 12 h / 12 ​​h, and a light intensity of 100 μmol m⁻²·s. -1 .

[0017] Beneficial effects:

[0018] (1) This invention regulates the morphogenesis, material accumulation, and distribution of citrus seedlings through nighttime supplemental lighting. In terms of morphology, L... 432 It can significantly improve aboveground indicators such as plant height and leaf number, while also promoting the increase of root-related parameters, resulting in optimal overall performance; L 454 L 445 It can effectively promote plant height and leaf development, L 650It is beneficial for thickening and widening the leaves, L 520 It can significantly promote root elongation but inhibit stem thickening, L 550 L 665 The overall promoting effect is relatively weak. Regarding material accumulation, L... 432 It can significantly improve the fresh and dry weight of roots, stems, and leaves, and has the strongest ability to accumulate substances; L 454 L 650 White light can significantly increase dry matter accumulation, while L... 520 L 550 It has an inhibitory effect on biomass accumulation. Correlation and principal component analysis showed a high positive correlation between aboveground indicators, with root growth significantly driving aboveground development. 432 The overall score was much higher than other treatments, making it the best monochromatic light for promoting the overall growth of orange seedlings.

[0019] (2) In terms of morphogenesis, CL3 significantly increases total root length, root surface area, and number of root tips, and has a prominent promoting effect on underground development. It also improves the morphology of the aboveground parts, showing the best overall performance. CL2 increases the number and thickness of leaves, CL1 has no significant promoting effect on the morphology of the aboveground parts, and CL4 increases leaf thickness but inhibits root elongation. In terms of material accumulation and distribution, CL3 significantly increases the biomass of stems, leaves, and the whole plant, CL2 is beneficial to root material accumulation and increases the root-to-shoot ratio, and CL1 and CL4 have a certain promoting effect on dry matter accumulation. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments 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.

[0021] Figure 1 The UV-Vis absorption spectra of chlorophyll a, chlorophyll b, xanthophyll, and β-carotene are shown.

[0022] Figure 2 The spectrum of different LED light qualities.

[0023] Figure 3 The changes in the aboveground morphology of orange seedlings under nighttime interrupted supplemental lighting with different light qualities.

[0024] Figure 4 Changes in the morphology of the underground parts of orange seedlings under nighttime interrupted supplemental lighting of different light qualities

[0025] Figure 5 Changes in biomass of orange seedlings under nighttime interrupted supplemental lighting of different light qualities 1.

[0026] Figure 6 Changes in biomass of orange seedlings under different light qualities and nighttime interrupted supplemental lighting. Detailed Implementation

[0027] This invention provides a method for regulating the growth of citrus seedlings through supplemental lighting. To further illustrate this invention, the technical solution provided by this invention will be described in detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of this invention.

[0028] Unless otherwise specified, the production processes, experimental methods, or testing methods involved in the embodiments of this invention are all conventional methods in the prior art, and their names and / or abbreviations are all conventional names in the field, which are very clear and distinct in the relevant application areas. Those skilled in the art can understand the conventional process steps based on the names and apply the corresponding equipment, and implement them according to conventional conditions or the conditions recommended by the manufacturer.

[0029] The various instruments, equipment, raw materials or reagents used in the embodiments of this invention are not subject to any special restrictions on their source. They are all conventional products that can be purchased through regular commercial channels and can be prepared according to conventional methods known to those skilled in the art.

[0030] Test materials used in the embodiments of this invention:

[0031] This invention was conducted in the cultivation and physiology laboratory of the Citrus Research Institute of Southwest University. The tested variety was sweet orange (Citrus × junos Siebold ex Tanaka). Mature fruits of sweet orange were collected from Baihelin, Citrus Research Institute of Southwest University. The seeds were disinfected, and the inner and outer seed coats were removed before germination. When the sweet orange roots reached about 1 cm in length, they were transplanted into a hydroponic incubator (48 cm × 35.5 cm). The light conditions were 12 h light / 12 h dark, and the temperature in the culture room was 25 ± 2 ℃. The modified Hogland solution was rotated every week. After one month of cultivation, seedlings with uniform growth were selected for light quality testing.

[0032] The formula for the improved Hogrange nutrient solution described in this invention is shown in the table below:

[0033] Table 1 Improved Hogland Nutrient Solution Formula

[0034]

[0035] Example 1

[0036] The experiment used white LED lights as a control (CK), with a photoperiod of 12 / 12 h and illumination time from 8:00 AM to 6:00 PM. Nighttime supplemental lighting was set based on the absorption spectra of photosynthetic pigments (chlorophyll a, chlorophyll b, xanthophyll, β-carotene). Figure 1 The design simulates the light quality of 10 LED photosynthetic pigments, including two chlorophyll a monochromatic lights (L...). 432 L 665 ), chlorophyll b monochromatic light (L 465 L 650 ) and one type of lutein monochromatic light (L 445 ), β-carotene monochromatic light (L 454 ), chlorophyll a complex light (CL1), chlorophyll b complex light (CL2), chlorophyll a and b complex light (CL3), chlorophyll a, b and carotenoid complex light (CL4), and yellow-green light (L 550 ), green light (L) 520 There are 13 types of LED light, including white light (W) (spectral diagrams of different LED light qualities are shown in the figure). Figure 2 As shown in the figure, the duration of each LED supplemental lighting was set to 4 hours (0:00 AM to 4:00 AM). There were a total of 14 treatment groups, each isolated in a separate chamber. The LED light switching was individually controlled, and the lamp panel was placed on top of the chamber with adjustable height. The temperature of the incubation chamber was 25 ± 2 ℃, the photoperiod was 12 h / 12 ​​h, and the light intensity was 100 μmol m². -2 ·s -1 .

[0037] Seventy one-month-old sweet orange seedlings with uniform growth were selected from each treatment group for light quality treatment. Two months after the light quality treatment, the following indicators were measured on the seedlings.

[0038] Example 2, Apparent Index Measurement

[0039] Two months after the light quality treatment, eight orange trees were selected from each treatment group, with single-tree replication. The tree height, leaf length and width of the third-to-last mature leaf were measured with a ruler, and the leaf thickness and stem diameter at the lower end of the leaf were measured with a micrometer. The number of leaves per tree was also recorded. Two months after the light quality treatment, the total root length of the orange seedlings was measured using the Win RHIZO software system (Regent Instruments Canada INC., Canada).

[0040] Morphological changes in sweet orange seedlings, and analysis of the results:

[0041] Changes in the above-ground morphology of orange seedlings; changes in plant height: from Figure 3 It can be seen that, compared with the control, L 432The seedling height in the treatment group was significantly increased, 42.6% higher than that in the control group (p<0.05); L 445 L 454 Plant height also increased to varying degrees in the L, W, and CL4 treatment groups, with increases of 13.6%, 21.7%, 16.1%, and 7.1%, respectively. 445 L 454 The differences were significant in the W treatment (p<0.05), but not significant in the CL4 treatment (p>0.05); L 465 L 550 L 665 L 520 The CL3 treatment group and the control group showed similar results, with no significant differences (p>0.05); while L 650 The seedling height of the CL1 and CL2 treatment groups was inhibited, and was 8.6%, 6.4%, and 2.9% lower than that of the control, respectively, with no significant difference (p>0.05).

[0042] Stem diameter changes: from Figure 3 It can be seen that, compared with the control (CK, 1.38±0.13 mm), L 432 L 445 The stem diameter of seedlings in the CL2 treatment group increased slightly, by 4.3%, 4.3%, and 4.3% respectively compared with the control, but the differences were not significant (p>0.05); L 454 L 465 L 550 L 665 L 650 The stem diameters of the CL1, W, CL2, and CL4 treatment groups were similar to or inhibited compared to the control group, with no significant differences (p>0.05); L 520 The stem diameter of the treatment group was significantly inhibited, and was 9.4% lower than that of the control (p<0.05).

[0043] Changes in leaf number: from Figure 3 It can be seen that, compared with the control, L 432 The number of leaves in the treatment group seedlings increased significantly, by 28.7% compared to the control (p<0.05); L 445 L 454 L 650 The number of leaves in the CL1, CL2, CL3, and CL4 treatment groups also increased to varying degrees, with increases of 6.8%, 11.8%, 6.8%, 6.8%, 13.6%, 18.6%, and 3.4%, respectively. The differences in CL2 and CL3 treatments were significant (p<0.05), while the differences in the other treatments were not significant (p>0.05). 465 L 550 L 665 W, L 520 The treatment group and the control group were similar, and the differences were not significant (p>0.05).

[0044] Leaf length changes: from Figure 3 It was found that, compared with the control, the leaf length of seedlings in the W treatment group was significantly increased, exceeding the control by 30.8% (p<0.05); L 432 L 445 L 454 L 650 Leaf length also increased to varying degrees in the CL4 treatment groups, with increases of 19.5%, 14.5%, 13.8%, 12.3%, and 8.8%, respectively. Among these, L432, L445, L454, and L... 650 No significant differences were observed in treatments (p>0.05), and no significant differences were observed in CL4 treatments (p>0.05); L465, L550, L 665 L 520 Leaf length was inhibited in the CL1, CL2, and CL3 treatment groups, and was 3.8%, 14.8%, 16.5%, 3.0%, 11.5%, 1.8%, and 1.8% lower than the control, respectively. The differences in the CL2 and CL3 treatments were significant (p<0.05), while the differences in the other treatments were not significant (p>0.05).

[0045] Leaf width variation: from Figure 3 It can be seen that, compared with the control, L 650 The leaf width of seedlings in the W and L treatment groups increased significantly, by 28.6% and 31.4% respectively compared with the control (p<0.05); 432 L 445 Leaf width also increased to varying degrees in the CL4 treatment group, with increases of 16.4%, 17.1%, and 9.3%, respectively. Among them, L... 432 L 445 The differences in treatment were significant (p<0.05), while the differences in CL4 treatment were not significant (p>0.05); L 454 L 465 L 550 L 665 L 520 The leaf widths of the CL1, CL2, and CL3 treatment groups were similar to or inhibited compared to the control group, with no significant differences (p>0.05).

[0046] Leaf thickness variation: from Figure 3 It can be seen that, compared with the control, L 650 The leaf thickness of seedlings in the CL2 and CL4 treatment groups was significantly increased, by 25.0%, 25.0%, and 25.0% respectively compared with the control (p<0.05); L 454 L 465 L 550Leaf thickness also increased to varying degrees in the CL1 and CL3 treatment groups, with increases of 8.3%, 8.3%, 8.3%, 16.7%, and 16.7%, respectively. The differences in CL1 and CL3 treatments were significant (p<0.05), while the differences in the other treatments were not significant (p>0.05). 432 L 445 L 665 W, L 520 The treatment group and the control group were similar, and the differences were not significant (p>0.05).

[0047] Morphological changes in the underground parts of orange seedlings: Changes in total root length: from Figure 4 It was found that, compared with the control, the total root length of seedlings in the W and CL3 treatment groups was significantly increased, by 24.2% and 76.5% respectively (p<0.05); CL2 and L 432 L 650 L 454 The total root length of the treatment groups also increased to varying degrees, with increases of 55.9%, 88.0%, 40.2%, and 48.1%, respectively. Among them, L... 432 The differences were significant in the CL2 treatment (p<0.05), while the differences in the other treatments were not significant (p>0.05); L 445 L 465 L 520 L 550 L 665 The total root length of the CL1 and CL4 treatment groups was inhibited, decreasing by 9.2%, 14.5%, 11.0%, 6.0%, 17.7%, 22.6%, and 10.9% respectively compared to the control. Among these, L... 465 L 520 L 665 There were no significant differences in treatments CL1 and CL4 (p>0.05).

[0048] Changes in projected area: from Figure 4 It can be seen that, compared with the control, W and L 432 The projected area of ​​seedlings in the CL3 treatment group was significantly increased, by 33.1%, 77.8%, and 68.7% respectively compared with the control (p<0.05); CL2 and L 650 L 454 The projected area of ​​the CL1 treatment group also increased to varying degrees, with increases of 57.7%, 28.8%, 26.8%, and 8.1%, respectively. The difference was significant in the CL2 treatment (p<0.05), while the differences in the other treatments were not significant (p>0.05). 445 L 465 L 520 L 550 L 665The projected area of ​​the CL4 treatment group was suppressed, decreasing by 5.3%, 37.0%, 37.1%, 2.0%, 16.6%, and 17.0% compared to the control, respectively. Among these, L... 465 L 520 The differences were significant in the CL4 treatment (p<0.05), while the differences in the other treatments were not significant (p>0.05).

[0049] Changes in root surface area: from Figure 4 It can be seen that, compared with the control, W and L 432 The root surface area of ​​seedlings in the CL3 treatment group was significantly increased, by 33.1%, 78.0%, and 23.0% respectively compared with the control (p<0.05); CL2 and L 650 L 454 The root surface area of ​​the CL2 and L1 treatment groups also increased to varying degrees, with increases of 28.7%, 28.9%, 26.8%, and 7.9%, respectively. 650 The differences were significant in the first treatment (p<0.05), while the differences in the other treatments were not significant (p>0.05); L 445 L 465 L 520 L 550 L 665 The root surface area of ​​the CL4 treatment groups was suppressed, decreasing by 5.2%, 11.2%, 25.8%, 1.9%, 12.3%, and 21.5% compared to the control, respectively. Among these, L... 465 L 520 The differences were significant in the CL4 treatment (p<0.05), while the differences in the other treatments were not significant (p>0.05).

[0050] Mean diameter variation: from Figure 4 It can be seen that, compared with the control, W and L 432 The average root diameter of seedlings in the CL3 treatment group was significantly increased, by 43.3%, 68.4%, and 62.1% respectively compared with the control (p<0.05); CL2 and L 650 L 454 The average root diameter of the CL1 and CL4 treatment groups also increased to varying degrees, with increases of 12.6%, 20.2%, 8.6%, -5.2%, and 21.2%, respectively. The differences between the CL2 and CL4 treatments were not significant (p>0.05). 445 L 465 L 520 L 550 L 665 The average root diameter in the treatment groups was suppressed, decreasing by 0.2%, 29.0%, 37.4%, 8.9%, and 14.3%** compared to the control, respectively. Among these, L... 465 L 520The differences in treatment were significant (p<0.05), while the differences in other treatments were not significant (p>0.05).

[0051] Changes in the number of root tips: from Figure 4 It was found that, compared with the control, the number of root tips in the CL3 and CL4 treatment groups was significantly increased, by 61.2% and 39.1% respectively (p<0.05); W, L 432 CL2, L 454 L 650 L 665 The number of root tips also increased to varying degrees in the CL1 treatment groups, with increases of 43.7%, 54.6%, 39.7%, 44.3%, 31.7%, 34.0%, and 16.0%, respectively. Among these, W and L... 432 CL2, L 454 The differences were significant in the first treatment (p<0.05), while the differences in the other treatments were not significant (p>0.05); L 445 L 465 L 520 L 550 The number of root tips in the treatment groups was suppressed, decreasing by 1.6%, 38.1%, -6.8%, and 0.7% compared to the control, respectively. Among these, L... 465 The differences in treatment were significant (p<0.05), while the differences in other treatments were not significant (p>0.05).

[0052] Example 3, Biomass Measurement

[0053] Two months after light quality treatment, five orange trees from each treatment group were selected to determine biomass, with single-tree replicates. Fresh weight was measured by washing the plants, allowing them to air dry, and then weighing them using an electronic balance (accuracy 0.0001 g). The fresh weights of the seedling roots, stems, and leaves were measured separately. Then, the plants were blanched at 105 ℃ for 30 min, dried at 75 ℃ for 24 h, and weighed again using an electronic balance (accuracy 0.0001 g). The dry-to-fresh weight, dry-to-fresh weight ratio, and root-to-shoot ratio of the plants were calculated using the following methods:

[0054] Dry to Fresh Weight Ratio = Dry Weight / Fresh Weight

[0055] Root-to-shoot ratio = Dry mass of underground part / Dry mass of aboveground part

[0056] Interrupting supplemental lighting at night with different light qualities not only significantly affects the growth and development of orange seedlings, but also further regulates their biomass accumulation process.

[0057] Changes in fresh stem weight: from Figure 5 It can be seen that, compared with the control, L 432 The fresh weight of seedling stems in the treatment group increased significantly, by 92.3% compared to the control (p<0.05); L 454The fresh weight of stems in the W, CL3, and CL4 treatment groups also increased to varying degrees, with increases of 46.2%, 46.2%, 46.2%, and 46.2%, respectively, all with significant differences (p<0.05); L 445 L 465 L 550 L 665 L 650 The fresh stem weight of the CL1 and CL2 treatment groups was similar to or slightly higher than that of the control group, with no significant difference (p>0.05); L 520 The fresh weight of stems in the treatment group was exactly the same as that in the control group, with no significant difference (p>0.05).

[0058] Changes in stem mass: from Figure 5 It can be seen that, compared with the control, L 432 L 454 L 650 The stem dry weight of seedlings in the CL1, W, and CL3 treatment groups increased significantly, by 100.0%, 75.0%, 50.0%, 50.0%, 50.0%, and 50.0% respectively compared with the control (p<0.05); L 445 L 465 L 550 L 665 The stem dry weights of the CL2 and CL4 treatment groups were similar to those of the control group, with no significant differences (p>0.05); L 520 The stem weight of the treatment group was exactly the same as that of the control group, and the difference was not significant (p>0.05).

[0059] Changes in leaf fresh quality: from Figure 5 It can be seen that, compared with the control, L 432 The fresh weight of seedling leaves in the treatment group increased significantly, by 91.7% compared to the control (p<0.05); L 445 L 650 The fresh leaf weight of the L, W, and CL3 treatment groups also increased to varying degrees, with increases of 30.6%, 36.1%, 33.3%, and 27.8%, respectively. 445 L 650 The differences were significant in the W treatment (p<0.05), but not significant in the CL3 treatment (p>0.05); L 454 L 465 L 550 L 665 CL1, CL2, L 520 The fresh weight of leaves in the CL4 treatment group was similar to or inhibited compared with the control group, and the difference was not significant (p>0.05).

[0060] Changes in leaf dry weight: from Figure 5 It was found that, compared with the control, the leaf dry weight of seedlings in the L432 treatment group increased significantly, by 150.0% (p<0.05); L454 L 650 Leaf dry weight also increased to varying degrees in the L, W, CL3, and CL4 treatment groups, with increases of 75.0%, 100.0%, 87.5%, 62.5%, and 62.5%, respectively. 454 L 650 The differences between the W and L treatments were significant (p<0.05), while the differences between the CL3 and CL4 treatments were not significant (p>0.05); L 445 L 465 L 550 L 665 CL1, CL2, L 520 The leaf dry weight in the treatment group was similar to or inhibited compared to the control group, with no significant difference (p>0.05).

[0061] Changes in fresh root quality: from Figure 5 It can be seen that, compared with the control, L 432 The fresh weight of seedling roots in the CL2 and CL3 treatment groups increased significantly, by 34.4%, 21.9%, and 21.9% respectively compared with the control (p<0.05); L 454 L 665 The root fresh weights of the CL1, W, and CL4 treatment groups were similar to those of the control group, with no significant differences (p>0.05); L 445 L 465 L 550 L 650 L 520 The root fresh weight of the treatment groups was suppressed, and was 15.6%, 15.6%, 12.5%, 25.0%, and 28.1% lower than that of the control, respectively, with no significant differences (p>0.05).

[0062] Changes in root-stem quality: from Figure 5 It can be seen that, compared with the control, L 432 L 454 L 650 The root dry weight of seedlings in the W treatment group increased significantly, by 42.9%, 28.6%, 42.9%, and 42.9% respectively compared with the control (p<0.05); L 465 L 550 L 665 The root dry weights of the CL1, CL2, CL3, and CL4 treatment groups were similar to those of the control group, with no significant differences (p>0.05); L 445 L 520 The root dry weight of the treatment group was exactly the same as that of the control group, and the difference was not significant (p>0.05).

[0063] Changes in fresh plant quality: from Figure 6 It can be seen that, compared with the control, L 432The wet weight of seedlings in the CL4, L, and W treatment groups increased significantly, by 69.1%, 29.6%, and 27.2% respectively compared to the control (p<0.05); CL4 and L 445 L 454 L 465 L 665 L 650 The wet weight of plants in the CL1 and CL2 treatment groups was similar to or slightly higher than that in the control group, with no significant difference (p>0.05); L 550 L 520 The wet weight of the plants in the treatment groups was suppressed, and was 2.5% and 8.6% lower than that in the control group, respectively, with no significant difference (p>0.05).

[0064] Changes in stem mass: from Figure 6 It can be seen that, compared with the control, L 432 The dry weight of seedlings in the treatment group increased significantly, by 100.0% compared to the control (p<0.05); L 650 W, CL4, L 454 CL3, L 445 L 465 L665, CL1, CL2, L 550 L 520 The dry weight of plants in the treatment groups also increased to varying degrees, with increases of 68.4%, 63.2%, 47.4%, 63.2%, 42.1%, 31.6%, 31.6%, 31.6%, 36.8%, 26.3%, 15.8%, and 10.5%, respectively. Among these, L... 650 W, CL4, L 454 The differences in treatment were significant (p<0.05), while the differences in other treatments were not significant (p>0.05).

[0065] Changes in the fresh weight of the above-ground parts: from Figure 6 It can be seen that, compared with the control, L 432 The fresh weight of the aboveground parts of the seedlings in the treatment group increased significantly, by 91.8% compared to the control (p<0.05); L 650 W, L 445 CL3, CL4, L 454 L 465 CL1, CL2, L 665 L 550 L 520 The fresh weight of the aboveground parts of the treatment groups also increased to varying degrees, with increases of 36.7%, 36.7%, 32.7%, 30.6%, 26.5%, 28.6%, 18.4%, 22.4%, 6.1%, 8.2%, 4.1%, and 4.1%, respectively. Among them, the L650 and W treatments showed significant differences (p<0.05), while the other treatments did not show significant differences (p>0.05).

[0066] Changes in the ratio of plant to fresh weight: from Figure 6 It can be seen that, compared with the control, L 432 L 454 L 465 L 550 L 665 L 650 CL1, W, L 520 The dry-to-fresh weight ratio of seedlings in the CL4 treatment group was significantly increased, exceeding the control by 16.7%, 45.8%, 20.8%, 16.7%, 16.7%, 50.0%, 20.8%, 29.2%, 20.8%, and 25.0%, respectively (p<0.05); L 445 The dry-to-fresh weight ratios of the CL2 and CL3 treatment groups were similar to those of the control group, with no significant differences (p>0.05).

[0067] Changes in the dry mass of the aboveground parts: from Figure 6 It can be seen that, compared with the control, L 432 The aboveground dry weight of seedlings in the treatment group increased significantly, by 133.3% compared to the control (p<0.05); L 650 W, L 454 CL4, L 445 CL3, L 465 L 665 CL1, CL2, L 550 L 520 The aboveground dry weight of the treated groups also increased to varying degrees, with increases of 83.3%, 83.3%, 75.0%, 58.3%, 50.0%, 50.0%, 41.7%, 33.3%, 50.0%, 25.0%, 25.0%, and 16.7%, respectively. Among these, L... 650 W, L 454 The differences in treatment were significant (p<0.05), while the differences in other treatments were not significant (p>0.05).

[0068] Changes in root-to-shoot ratio: from Figure 6 It was found that, compared with the control, the root-to-shoot ratio of seedlings in the CL2 treatment group was significantly increased, 3.3% higher than that of the control (p<0.05); L 465 L 550 L 665 CL1, L 520 The root-to-shoot ratios of the CL3 and CL4 treatment groups were similar to or slightly higher than those of the control group, with no significant differences (p>0.05); L 432 L445, L 454 L 650 The root-to-shoot ratio in the L and W treatment groups was suppressed, decreasing by 41.0%, 34.4%, 27.9%, 26.2%, and 24.6% compared to the control, respectively. 432 L445 The differences in treatment were significant (p<0.05), while the differences in other treatments were not significant (p>0.05).

[0069] Example 4: Data Statistics and Analysis

[0070] Microsoft Excel 2021 was used for data preparation, R language was used for descriptive statistics, one-way ANOVA, and correlation analysis, RStudio 4.5.2 was used for plotting, and Adobe Illustrator 2022 was used for data enhancement.

[0071] Comprehensive analysis of growth and development indicators: Correlation analysis of growth and development indicators.

[0072] Correlation analysis was performed on 18 growth and development indicators of sweet orange seedlings, and the results are shown in Tables 2-1 and 2-2. A highly synergistic growth relationship was observed among the aboveground growth indicators: plant height was significantly positively correlated with leaf fresh weight, leaf dry weight, stem fresh weight, and stem dry weight (r=0.884, 0.838, 0.861, 0.860, P<0.01); leaf length was significantly positively correlated with leaf width (r=0.775, P<0.01); and the number of leaves was significantly or significantly positively correlated with stem and leaf biomass, indicating that the morphogenesis of sweet orange seedling stems and leaves and the process of biomass accumulation are highly synchronized. There is a broad and close correlation between underground part indicators and whole plant growth indicators: total root length is significantly positively correlated with leaf number, leaf thickness, stem diameter, stem fresh weight, root fresh weight, and root dry weight (r=0.909, 0.722, 0.669, 0.747, 0.660, 0.756, P<0.01), indicating that root elongation can effectively drive aboveground leaf differentiation, stem thickening, and whole plant material accumulation; stem diameter is significantly positively correlated with root fresh weight and root dry weight (r=0.793, 0.694, P<0.01), reflecting a significant linkage effect between stem development and root biomass accumulation; root projected area is significantly positively correlated with root surface area and average diameter (r=1.000, 0.972, P<0.01), indicating a high degree of collinearity among various root morphological parameters.

[0073] Overall, the growth and development indicators showed significant or highly significant positive correlations, with only root tip number showing a negative correlation with most biomass indicators. No trade-off between aboveground and belowground growth was observed. This indicates that under nighttime interrupted supplemental lighting, orange seedlings exhibited a synergistic growth pattern across the entire plant, with root development having a significant positive promoting effect on aboveground growth.

[0074] Table 2-1

[0075]

[0076] Table 2-2

[0077]

[0078] Note: * indicates P < 0.05; ** indicates P < 0.01. The same applies below.

[0079] Principal component analysis of growth and development indicators:

[0080] Principal component analysis (PCA) was performed on the growth and development indicators of sweet orange seedlings. The results showed that four principal components were extracted, with eigenvalues ​​of 8.067, 3.21, 1.50, and 1.048, respectively. The cumulative variance contribution rate reached 86.407%, which can fully represent the core information of plant growth and development. From the loading matrix, principal component 1 (PC1) had a variance contribution rate of 50.421%, with loading values ​​ranging from 0.779 to 0.932. It mainly included indicators such as leaf dry weight, plant height, leaf length, leaf fresh weight, stem fresh weight, and stem dry weight, all of which were positive loadings, primarily reflecting the comprehensive level of aboveground morphogenesis and total plant biomass accumulation. Principal component 2 (PC2) had a variance contribution rate of 20.06%, with loading values ​​ranging from 0.429 to 0.980. It mainly covered indicators such as total root length, number of leaves, projected area, root surface area, and average diameter, all of which were positive loadings, primarily reflecting the expansion of underground root morphology and leaf number differentiation. Principal component 3 (PC3) contributed 9.374% of the variance, with loadings ranging from 0.644 to 0.850. It mainly included indicators such as stem diameter, total root length, fresh root weight, and dry root weight, all of which were positive loadings, primarily reflecting stem development and root biomass accumulation. Principal component 4 (PC4) contributed 6.553% of the variance, with loadings ranging from 0.338 to 0.951. It mainly included indicators such as root volume and root tip number, all of which were positive loadings, primarily reflecting the fine structure and volume development characteristics of the root system.

[0081] The comprehensive score was calculated and ranked using the proportion of each principal component eigenvalue as the weight. The results show that: L 432 The treatment with the highest overall score (5.50636) was significantly better than the control (CK) (0.71834) and other treatments, ranking first; CL3 (4.06253), white light W (3.26374), L 454 (2.64044) ranked 2nd, 3rd, and 4th respectively; L 520 The treatment had the lowest overall score (0.31779), ranking 14th, and its growth performance was weaker than the control.

[0082] Table 3 Principal component score coefficients and contribution rates

[0083]

[0084] Table 4. Principal component factor coefficients and comprehensive scores for different light quality treatments during nighttime interrupted supplemental lighting.

[0085]

[0086] The effects of interrupted nighttime supplemental lighting on the morphology of orange seedlings:

[0087] Nighttime interrupted supplemental lighting is an important measure for regulating plant photoperiod and morphogenesis, and light quality and duration of supplemental lighting are key factors affecting the development of roots, stems, and leaves. The regulatory effect of nighttime interrupted monochromatic light on the morphology of orange seedlings exhibits significant wavelength differences. 432 L 454 Monochromatic blue light can significantly increase plant height and leaf number, and promote above-ground growth, among which L 454 It can significantly increase root length; L 650 It can optimize leaf width and thickness, but inhibit plant height; L 520 While green light inhibits stem thickening, it significantly promotes root elongation; L 550 Yellow-green light has an inhibitory effect on the above-ground parts of the plant. Therefore, monochromatic blue light has the best effect on the formation of the above-ground morphology of oranges, while green light has a unique promoting effect on root elongation. Different monochromatic lights shape the overall plant structure by synergistically regulating the development of the above-ground and underground parts.

[0088] Regarding composite light, red-blue composite light only promotes stem elongation, inhibiting stem diameter and root development, and its regulatory effect is weaker than that of monochromatic blue light. The effect of composite light weakens with time, and overall it is inferior to monochromatic blue light. This invention further verifies this rule, showing significant differences in the effects of different composite lights: CL3 can simultaneously promote root morphology and aboveground growth, exhibiting the best overall performance; CL2 and CL4 can only improve some indicators, while CL1 has no significant promoting effect on overall morphology. The results indicate that most composite lights are unable to achieve synergistic optimization between aboveground and belowground parts, and their regulatory effect is significantly weaker than that of high-quality monochromatic blue light.

[0089] The effects of interrupted nighttime supplemental lighting on nutrient accumulation and distribution in orange seedlings:

[0090] Light quality is a core signal regulating the accumulation and distribution of plant matter. Interrupting supplemental lighting at night can alter the patterns of biomass accumulation and translocation through differences in light quality. Previous studies have shown that 4 hours of blue or red light supplementation significantly promotes material accumulation more effectively than 2 hours, significantly improving the fresh and dry weight of roots, stems, and leaves, and facilitating the distribution of photosynthetic products to the aboveground parts; while green and yellow-green light comprehensively inhibit material accumulation. 432 It has a highly significant promoting effect on both fresh and dry weight of roots, stems, and leaves, making it the optimal monochromatic light treatment; L 454 L 650 White light can significantly increase dry matter accumulation; L 520 L 550This manifests as an inhibitory effect. In terms of distribution, monochromatic blue light treatment significantly increases the dry-to-fresh weight ratio and decreases the root-to-shoot ratio, promoting the transport of more photosynthetic products to the aboveground parts, which is more conducive to the efficient accumulation and distribution of substances in orange seedlings.

[0091] In composite light, short-duration red-blue composite light is more conducive to the accumulation of aboveground substances, but its overall effect is weaker than that of monochromatic blue light. In this invention, the effects of composite light show significant differentiation: CL3 significantly promotes the accumulation of whole-plant biomass, CL2 is more conducive to root substance distribution and increasing the root-to-shoot ratio, while CL1 and CL4 only improve the dry weight of some organs. In summary, the effect of nighttime interrupted composite light supplementation on the regulation of substance accumulation and distribution is limited, and its overall performance is inferior to that of monochromatic blue light, which is consistent with existing research results.

[0092] As shown in the above examples, by simulating the photosynthetic pigment spectrum of orange leaves, the effects of different nighttime interruptions in supplemental lighting on the growth of orange seedlings were investigated, and the results are as follows:

[0093] (1) Nighttime interruption of monochromatic light significantly regulates the morphogenesis, material accumulation, and distribution of orange seedlings, and the effects of different wavelengths of monochromatic light differ significantly. In terms of morphology, L... 432 It can significantly improve aboveground indicators such as plant height and leaf number, while also promoting the increase of root-related parameters, resulting in optimal overall performance; L 454 L 445 It can effectively promote plant height and leaf development, L 650 It is beneficial for thickening and widening the leaves, L 520 It can significantly promote root elongation but inhibit stem thickening, L 550 L 665 The overall promoting effect is relatively weak. Regarding material accumulation, L... 432 It can significantly improve the fresh and dry weight of roots, stems, and leaves, and has the strongest ability to accumulate substances; L 454 L 650 White light can significantly increase dry matter accumulation, while L... 520 L 550 It has an inhibitory effect on biomass accumulation. Correlation and principal component analysis showed a high positive correlation between aboveground indicators, with root growth significantly driving aboveground development. 432 The overall score was much higher than other treatments, making it the best monochromatic light for promoting the overall growth of orange seedlings.

[0094] (2) The regulatory effect of nighttime interrupted composite light on the growth of orange seedlings was weaker than that of high-quality monochromatic blue light, and the effects of different composite light treatments were significantly differentiated. In terms of morphogenesis, CL3 significantly increased total root length, root surface area, and number of root tips, and had a prominent promoting effect on underground development. It also improved the aboveground morphology, showing the best overall performance. CL2 increased the number and thickness of leaves, CL1 had no significant promoting effect on aboveground morphology, and CL4 increased leaf thickness but inhibited root elongation. In terms of material accumulation and distribution, CL3 significantly increased the biomass of stems, leaves, and the whole plant, CL2 was beneficial to root material accumulation and increased the root-to-shoot ratio, and CL1 and CL4 had a certain promoting effect on dry matter accumulation.

[0095] Overall, among the composite light sources, only CL3 achieved coordinated growth of both aboveground and belowground parts. Other composite light sources generally exhibited limited promotion range and suppressed certain indicators, resulting in a lower overall growth effect compared to L. 432 Monochrome blue light processing.

[0096] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for regulating the growth of citrus seedlings by supplemental lighting, characterized in that, The method includes providing supplemental lighting to citrus seedlings at night, wherein the light quality of the supplemental lighting is chlorophyll a monochromatic light (L). 432 ), chlorophyll a monochromatic light (L 665 ), chlorophyll b monochromatic light (L 465 ), chlorophyll b monochromatic light (L 650 ), Lutein monochromatic light (L 445 ), β-carotene monochromatic light (L 454 ), chlorophyll a complex light (CL1), chlorophyll b complex light (CL2), chlorophyll a and b complex light (CL3), chlorophyll a, b and carotenoid complex light (CL4), and yellow-green light (L 550 ), green light (L) 520 One or more of the following: white light (W).

2. The method according to claim 1, characterized in that, The regulation of citrus seedling growth is achieved by increasing plant height and leaf number, promoting above-ground growth, or increasing the fresh and dry weight of roots, stems, and leaves; the light quality of the nighttime supplemental lighting is: L 432 .

3. The method according to claim 1, characterized in that, The regulation of citrus seedling growth is achieved by increasing plant height and leaf number, promoting above-ground growth, increasing root length, or increasing dry matter accumulation; the light quality of the nighttime supplemental lighting is: L 454 .

4. The method according to claim 1, characterized in that, The regulation of citrus seedling growth is achieved by increasing leaf width and thickness, inhibiting plant height, or enhancing dry matter accumulation; the light quality of the nighttime supplemental lighting is: L 650 .

5. The method according to claim 1, characterized in that, The regulation of citrus seedling growth is achieved by inhibiting stem thickening and promoting root elongation; the light quality of the nighttime supplemental lighting is: L 520 .

6. The method according to claim 1, characterized in that, The regulation of citrus seedling growth is achieved by: overall inhibition of the above-ground parts; the light quality of the nighttime supplemental lighting is: L 550 .

7. The method according to claim 1, characterized in that, The regulation of citrus seedling growth is achieved by increasing total root length, root surface area, and number of root tips, or by promoting aboveground growth, or by promoting biomass accumulation; the light quality of the nighttime supplemental lighting is CL3.

8. The method according to claim 1, characterized in that, The regulation of citrus seedling growth is achieved by promoting root nutrient distribution or increasing the root-to-shoot ratio; the light quality of the nighttime supplemental lighting is CL2.

9. The method according to claim 1, characterized in that, The duration of the nighttime supplemental lighting is 4 hours.

10. The method according to claim 1, characterized in that, The citrus seedlings were cultured at a temperature of 25 ± 2 ℃, with a photoperiod of 12 h / 12 ​​h and a light intensity of 100 μmol m⁻²·s⁻¹. -1 .

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