Method for promoting growth and development of rice based on illumination and nitrogen implementation

Abstract

The invention belongs to the technical field of agriculture, and particularly relates to a method for promoting growth and development of rice based on illumination and nitrogen. One of the purposes of the invention is to provide a method for promoting growth and development of rice based on illumination and nitrogen. The method comprises the following steps: providing cultivation conditions of illumination intensity of 600-800 [mu] mol.m <-2 >. S <-1 > and nitrogen concentration of 5.51-8.11 mM for rice in a tillering stage of the rice. By accurately applying a specific combination of illumination intensity and nitrogen concentration in the tillering stage of rice, efficient loading and long-distance transportation of photosynthetic products (especially cane sugar and the like) in phloem are promoted, and the photosynthetic products are guided to be more effectively and directionally distributed to developed library organs (such as fruits, grains or root systems); therefore, the transfer and circulation efficiency of carbon-nitrogen substances in plants is improved synergistically on the whole, the waste phenomenon of nitrogen redundancy or local lack and ineffective accumulation of photosynthetic products is reduced, and finally, an important physiological regulation basis is provided for remarkably improving the yield and quality of crops.

Description

Technical Field

[0001] The invention belongs to the technical field of agriculture, and in particular relates to a method for promoting rice growth and development based on light and nitrogen. Background Art

[0002] Plant growth and development rely on the precise coordination of numerous environmental factors and internal physiological processes. Among these, nitrogen (N), a core element constituting macromolecules such as proteins, nucleic acids, and chlorophyll, is crucial for plant growth and yield formation. Early research focused on the impact of soil nitrogen supply on overall plant growth. With the advancement of biochemistry and plant physiology, researchers have gradually uncovered the diverse forms of nitrogen in plants (such as nitrate, ammonium, and amino acids) and their metabolic pathways. They have also recognized that nitrogen transport between different plant organs and tissues (primarily through the xylem and phloem) is a key factor in determining nitrogen use efficiency and plant performance. In particular, leaves, as the primary site of nitrogen assimilation and photosynthesis, have a direct impact on photosynthetic capacity due to their nitrogen status. Stems, on the other hand, serve as transport pathways connecting nitrogen sources (leaves) with sinks (such as fruits and roots), and their nitrogen status can influence transport efficiency.

[0003] At the same time, as the fundamental source of plant energy and carbon skeleton, the impact of light intensity, quality and duration on plant physiology has a long history of research. The elucidation of the mechanism of photosynthesis has revealed how light energy drives carbon dioxide fixation and carbohydrate synthesis. Studies have shown that light not only directly affects the photosynthetic rate and the production of carbon assimilation products, but also profoundly affects plant morphology, metabolic pathways and nutrient distribution patterns by regulating a series of light receptor signaling pathways. For example, light intensity affects the synthesis rate of photosynthetic products, while light quality can regulate the transport direction of photosynthetic products.

[0004] It's worth noting that these two key factors, nitrogen and light, do not act independently on plants. Studies have confirmed significant interactions between them. On the one hand, sufficient light promotes nitrogen absorption and assimilation, which in turn facilitates chlorophyll synthesis and the establishment of photosynthetic machinery, thereby enhancing light energy utilization efficiency. On the other hand, changes in light conditions can significantly affect nitrogen distribution patterns within plants, for example, preferentially allocating nitrogen to leaves with sufficient light to maximize photosynthetic benefits. Similarly, nitrogen levels also profoundly influence the accumulation and distribution strategies of photosynthetic products.

[0005] However, despite a fairly in-depth understanding of the respective roles of nitrogen and light, as well as some of their interactions, existing research still suffers from significant limitations and technical deficiencies. A prominent issue is that most studies tend to examine nitrogen transport or photosynthate transport as relatively independent processes, or focus solely on changes in total nitrogen or carbon assimilates at the plant level. There is a lack of systematic and in-depth research into the potential differences in nitrogen transport dynamics among different plant parts (particularly leaves and stems, which have distinct functions) under specific light-nitrogen interaction conditions, as well as the dynamic regulatory mechanisms by which light-nitrogen interactions affect the allocation of carbon and nitrogen metabolites (sucrose, starch, nitrate, and protein) and the carbon-nitrogen ratio in rice. This lack of understanding limits our ability to accurately predict and optimize plant biomass production and distribution efficiency in complex environments (such as artificial light environments combined with precision fertilization in protected agriculture) and also hinders agricultural technology innovation aimed at simultaneously improving nitrogen and light energy use efficiency. Summary of the Invention

[0006] In order to overcome the shortcomings of the existing technology, the present invention analyzes the influence of light-nitrogen interaction on the growth phenotype of rice during the tillering period, explores the synergistic effect threshold of light intensity and nitrogen, and proposes a light intensity and nitrogen combination scheme that is suitable for rice production in plant factories.

[0007] One of the objectives of the present invention is to provide a method for promoting rice growth and development based on light and nitrogen, the method comprising the following steps: providing the rice with a light intensity of 600-800 μmol·m-2·s-1 and a cultivation condition of a nitrogen concentration of 5.51-8.11 mM during the rice tillering stage.

[0008] According to a preferred embodiment, the length of the rice tillering period is the total number of leaves on the main stem minus the number of elongated internodes.

[0009] According to a preferred embodiment, the cultivation conditions further include hydroponic rice cultivation.

[0010] According to a preferred embodiment, the cultivation conditions further include: temperature of 30±2°C; relative humidity of 55±2%; and carbon dioxide of 450±30 ppm.

[0011] According to a preferred embodiment, the cultivation conditions are 700 μmol·m-2·s-1 and 6.48 mM nitrogen concentration.

[0012] One of the purposes of the present invention is to provide a method for promoting rice growth and development based on the above-mentioned light and nitrogen, which is used to increase the number of rice tillers, reduce rice plant height, promote rice root growth, and increase rice dry matter accumulation.

[0013] One of the purposes of the present invention is to provide a plant factory control system, which includes a lighting module, a nutrient solution module, and a data control module wirelessly connected to the lighting module and the nutrient solution module.

[0014] The data control module is configured as follows: When the rice is in the tillering stage, the light module is controlled to provide 600-800 μmol·m -2 ·s -1 The light intensity is controlled; the nutrient solution module is controlled to provide nutrient substances with a nitrogen concentration of 5.51~8.11 mM to the rice.

[0015] According to a preferred embodiment, the plant factory control system further includes an image acquisition module, wherein the data control module is configured to: Based on the image feature of the rice picture collected by the image acquisition module showing the base leaf axils extending out, it is confirmed that the rice has entered the tillering stage.

[0016] According to a preferred embodiment, the plant factory control system is further provided with a temperature control module, a humidity control module and a carbon dioxide control module, and the data control module is configured as follows: The temperature control module provides a temperature condition of 30±2℃ to the rice; The humidity control module provides 55±2% relative humidity conditions to the rice; The carbon dioxide control module provides 450±30 ppm carbon dioxide conditions to the rice.

[0017] According to a preferred embodiment, the data control module is configured to: When the rice is in the tillering stage, the light module is controlled to provide 700 μmol·m -2 ·s -1 The light intensity was controlled; the nutrient solution module provided nutrient with a nitrogen concentration of 6.48 mM to the rice.

[0018] Beneficial effects of this technical solution: By precisely applying a specific combination of light intensity and nitrogen concentration during the rice tillering period, the light-nitrogen interaction effect was significantly optimized, and the physiological processes of nitrogen absorption, transport, and photosynthetic product synthesis and distribution in leaves (source organs) and stems (transport organs) were effectively and synergistically regulated. While improving nitrogen utilization efficiency, it promoted the efficient loading and long-distance transport of photosynthetic products (especially sucrose, etc.) in the phloem, and guided their more effective directional distribution to developing sink organs (such as fruits, grains or roots). This synergistically improved the overall transport and circulation efficiency of carbon-nitrogen substances in the plant body, reduced nitrogen redundancy or local deficiency, and the waste of ineffective accumulation of photosynthetic products, and ultimately provided an important physiological regulation basis for significantly improving crop yield and quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the cultivation condition diagram, where A is the spectrum diagram and B is the environmental parameters; Figure 2 This is a diagram showing the effects of different light intensities and nitrogen concentrations on the morphological characteristics of rice plants during the tillering stage; Figure 3 The figure shows the effects of different light intensities on various positions of rice plants at different nitrogen concentrations, where A is the dry weight of plant roots, B is the dry weight of aboveground parts, and C is the total dry weight. Figure 4 The figure shows the effects of different light intensities on rice plants at the tillering stage under different nitrogen concentrations, where A is plant height, B is tiller number, and C is root length; Figure 5 This is a diagram showing the effects of different light intensities on the total nitrogen and total carbon content of rice plants at various nitrogen concentrations. A is the total carbon content; B is the total nitrogen content; Figure 6 The effects of different light intensities on the nitrogen absorption and carbon conversion capabilities of rice plant roots at various nitrogen concentrations, A represents the nitrogen absorption capacity; B represents the carbon conversion capacity; Figure 7 The effects of different nitrogen concentrations on the nitrogen absorption capacity of rice roots and the carbon assimilation capacity of rice leaves at the tillering stage under different light intensities are shown in Figure 2. A represents the nitrogen absorption capacity; B represents the carbon assimilation capacity; Figure 8 The effects of different nitrogen concentrations on the morphological characteristics of rice plants at the tillering stage under different light intensities; Figure 9 Figure 3 shows the effects of different nitrogen concentrations on various positions of rice plants during the tillering period under different light intensities, where A is the root dry weight, B is the aboveground dry weight, and C is the total dry weight. Figure 10 The effect of different nitrogen concentrations on rice plants at the tillering stage under different light intensities, where A is plant height, B is tiller number, and C is root length; Figure 11 is the response of the carbon-nitrogen ratio of rice plants to different nitrogen concentrations and light intensities, where A is the nitrogen concentration and B is the light intensity; Figure 12 is the Pearson correlation coefficient between rice growth traits and carbon and nitrogen related parameters; Figure 13 Correlation analysis of rice growth parameters with light intensity and nitrogen concentration. The correlation coefficient is shown for each parameter, A is total dry weight, B is number of tillers, C is root dry weight, D is stem dry weight, and E is leaf dry weight; Figure 14 The effects of light intensity and nitrogen supply on the distribution of nitrogen in various organs of rice, A is sucrose, B is starch; Figure 15 This is the effect of light intensity and nitrogen supply on photosynthesis in rice leaves. A is the net photosynthetic rate, and B is the light response curve. DETAILED DESCRIPTION

[0020] In the description of the present invention, terms are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly indicate the number of technical features indicated. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0021] The raw materials used in the following examples were all commercially available or homemade; unless otherwise specified, their mass percentages are indicated.

[0022] This study used 'CP511' rice as the material, set up four light intensities and five nitrogen concentrations in a plant factory, studied the synergistic effect of light intensity and nitrogen supply on rice growth during the tillering period, constructed a fitting equation for the interaction between light and nitrogen on the total dry weight and tiller number of rice plants, and proposed the optimal combination range of light intensity and nitrogen that is beneficial to rice production in plant factories; by measuring physiological indicators such as sucrose, starch, carbon and nitrogen concentrations, nitrate, and ammonium salts in various organs of rice plants, the effects of light intensity and nitrogen concentration on the accumulation and distribution of dry matter and C and N metabolites in various rice organs (roots, stems, and leaves) were explored.

[0023] Example 1 1 Materials and Methods 1.1 Materials The experiment used the rice variety 'CP511' as the experimental material. It was conducted in July 2024 at the Plant Breeding Accelerator of the Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences. Full and uniform rice seeds were selected for germination and then transplanted into seedling boxes. -2 ·s −1 The seedlings were grown under white light for 10 days, and the spectrum was as follows Figure 1 As shown in A. After the seedlings were grown, rice seedlings with the same growth were selected and planted in custom-made cultivation boxes of the same specifications. -2 ·s −1 After 6 days of seedling acclimatization in 1 / 2 concentration Hoagland nutrient solution (commercial), the seedlings were cultured under 4 different light intensities and 5 different nitrogen concentrations. The light intensity was set at 150±10 μmol·m -2 ·s −1 , recorded as L150; 300±10 μmol·m -2 ·s −1 , recorded as L300; 500±10 μmol·m -2 ·s −1, recorded as L500; 700±10 μmol·m -2 ·s −1 , denoted as L700. Nitrogen concentrations were set at 0 mM, 0.54 mM, 1.62 mM, 6.48 mM, and 12.96 mM (Kimura B nutrient solution is formulated by scaling ammonium and nitrate in equal proportions, with the EC value maintained relatively constant by adding CaCl2). Each treatment consisted of three pots, with 12 plants per pot.

[0024] During the experiment, the photoperiod was 10 h. Figure 1 As shown in B, the relative humidity was maintained at 55 ± 2%, the CO2 concentration was maintained at 450 ± 30 ppm, and the temperature was 30 ± 2 ° C. The treatment time was 25 days.

[0025] 1.2 Detection Method 1.2.1 Determination of morphological indicators After the experimental treatment, 18 rice plants with uniform growth were selected from each treatment for morphological index determination.

[0026] Tiller number: the total number of tillers growing on all main stems.

[0027] Dry weight of roots, stems and leaves: Fresh samples were inactivated at 110 °C and then dried in an oven at 70 °C for 3 days to constant weight to obtain dry matter weight.

[0028] Plant height (cm): Measure the distance from the leaf tip to the base of the pseudostem of the rice plant using a ruler.

[0029] Root length (cm): Measure the distance from the base of the pseudostem to the root tip of the rice plant using a ruler.

[0030] 1.2.2 Determination of carbon and nitrogen concentrations The C concentrations in rice roots, stems and leaves were determined by combustion method (mg·g −1 The N concentrations in rice roots, stems, and leaves were determined by acid digestion (mg·g −1 ).

[0031] 1.2.3 Determination of the Light Response Curve and Net Photosynthetic Rate of Rice Leaves The light response curve of the second fully expanded leaf from the top was measured using a portable photosynthesis system (Li-6800, Li-Cor). The measurement was performed using an LED light source, with 10% blue light and 90% red light, at a CO2 concentration of 400 μmol·mol −1 The initial light intensity was set at 2000 μmol·m -2 ·s −1, and then decreased to 1800, 1500, 1200, 900, 700, 500, 300, 150, 100, 50, 20 and 0 μmol·m -2 ·s −1 Determine the net photosynthetic rate of the leaves at each corresponding light intensity condition.

[0032] 1.2.4 Data Analysis One-way ANOVA was performed, and the significant differences among treatments were analyzed using Duncan test. The standard of significant difference was p < 0.05.

[0033] 1.3 Results 1.3.1 Effects of light intensity on rice growth during the tillering stage under different nitrogen concentrations Figure 2 These are morphological characteristics of rice plants during the tillering stage under different nitrogen concentrations and light intensities. As light intensity increases, rice plant height decreases at all nitrogen concentrations. Compared to 0 mM nitrogen, increasing light intensity at other nitrogen concentrations promotes an increase in rice tiller number.

[0034] like Figure 3 As shown in Figure A, at 0 mM nitrogen, light intensity had no significant effect on the underground dry weight of rice. However, at other nitrogen concentrations, the underground dry weight of rice showed an upward trend with increasing light intensity. At 0.54 mM nitrogen, the underground dry weight of L300, L500, and L700 increased by 102.4%-157.6% compared to the L150 treatment; at 1.62 mM nitrogen, the increase was 152.2%-352.5%; at 6.48 mM nitrogen, the increase was 167.3%-594.8%; and at 12.96 mM nitrogen, the increase was 101.2%-429.2%. The underground dry weight of rice plants reached its maximum at a nitrogen concentration of 6.48 mM and a light intensity of L700.

[0035] like Figure 3 As shown in Figure B, compared to 0 mM nitrogen, the aboveground dry weight of rice increased with increasing light intensity at other nitrogen concentrations. At 0.54 mM nitrogen, the aboveground dry weight of L300, L500, and L700 increased by 49.2%-57.1% compared to the L150 treatment; at 1.62 mM nitrogen, the aboveground dry weight increased by 90.2%-159.9%; at 6.48 mM nitrogen, the aboveground dry weight increased by 124.7%-261.7%; and at 12.96 mM nitrogen, the aboveground dry weight increased by 90.7%-219.9%.

[0036] like Figure 3As shown in Figure C, compared to 0 mM nitrogen, the dry weight of rice plants increased with increasing light intensity at other nitrogen concentrations. At 0.54 mM nitrogen, the dry weight of rice plants in the L300, L500, and L700 treatments increased by 58.8%-75.3% compared to the L150 treatment; at 1.62 mM nitrogen, the dry weight increased by 98.4%-185.6%; at 6.48 mM nitrogen, the dry weight increased by 129.6%-299.5%; and at 12.96 mM nitrogen, the dry weight of rice plants reached its maximum at a nitrogen concentration of 6.48 mM and a light intensity of L700.

[0037] like Figure 4 Figure A shows the effects of different light intensities on rice plant height under various nitrogen concentrations. As can be seen from the figure, under various nitrogen concentrations, rice plant height decreased with increasing light intensity. At 0 mM nitrogen, plant height decreased by 12.6%-18.8% in the L300, L500, and L700 treatments compared to the L150 treatment; at 0.54 mM nitrogen, plant height decreased by 17.6%-37.7%; at 1.62 mM nitrogen, plant height decreased by 14.9%-33.4%; at 6.48 mM nitrogen, plant height decreased by 3.4%-27.6%; and at 12.96 mM nitrogen, plant height decreased by 1.8%-18.2%.

[0038] like Figure 4 Figure B shows the effect of different light intensities on rice tiller number under various nitrogen concentrations. As can be seen, compared to 0 mM nitrogen, the tiller number of rice plants increased significantly with increasing light intensity at other nitrogen concentrations. At 0.54 mM nitrogen, the tiller number of rice plants under the L300, L500, and L700 treatments increased by 125.6%-284.6% compared to the L150 treatment; at 1.62 mM nitrogen, the tiller number increased by 181.3%-345.8%; at 6.48 mM nitrogen, the tiller number increased by 112.3%-276.9%; and at 12.96 mM nitrogen, the tiller number increased by 106.2%-286.2%.

[0039] like Figure 4 Figure C shows the effects of different light intensities on rice root length at various nitrogen concentrations. As can be seen from the figure, at 0.54 mM nitrogen, rice root length significantly increased with increasing light intensity. At other nitrogen concentrations, root length initially decreased and then increased with increasing light intensity.

[0040] 1.3.2 Effects of light intensity on total nitrogen and carbon content in rice under different nitrogen concentrations like Figure 5 Figure A shows the effect of light intensity on total nitrogen content in rice plants under various nitrogen concentrations. At 0 mM nitrogen, increasing light intensity had no significant effect on total carbon content in rice plants. At other nitrogen concentrations, total nitrogen content in rice plants showed an upward trend with increasing light intensity. At 0.54 mM nitrogen, total carbon content in rice plants increased by 60.7%–77.8% under light intensities of L300, L500, and L700 compared to L150. At 1.62 mM nitrogen, total carbon content increased by 104.8%–198.7%, at 6.48 mM nitrogen, by 131.8%–329.3%, and at 12.96 mM nitrogen, by 99.2%–270.2%.

[0041] like Figure 5 Figure B shows the effect of light intensity on the total nitrogen content of rice plants under various nitrogen concentrations. As shown in the figure, under low nitrogen conditions (0 mM, 0.54 mM, and 1.62 mM), light intensity had no significant effect on the total nitrogen content of rice plants. However, under high nitrogen conditions (6.48 mM and 12.96 mM), the total nitrogen content of rice plants showed an upward trend with increasing light intensity. At a nitrogen concentration of 6.48 mM, the total nitrogen content of rice plants increased by 119.2% to 200.4% under light intensities of L300, L500, and L700 compared to L150. At a nitrogen concentration of 12.96 mM, the total nitrogen content increased by 86.5% to 228.2%.

[0042] 1.3.3 Effect of light intensity on root nitrogen absorption under different nitrogen concentrations Depend on Figure 6 As shown in Figure A, the ability of rice roots to absorb nitrogen decreased with increasing light intensity under various nitrogen concentrations. At 0 mM nitrogen, compared to light intensity L150, the ability of rice roots to absorb nitrogen decreased by 24.7% to 43.9% at L300, L500, and L700. At 0.54 mM nitrogen, the ability decreased by 47.8% to 63.6%; at 1.62 mM nitrogen, the ability decreased by 53.7% to 74.5%; at 6.48 mM nitrogen, the ability decreased by 19.2% to 57.6%; and at 12.96 mM nitrogen, the ability decreased by 7.7% to 39.1%.

[0043] Figure 6Figure B reflects the effect of light intensity on the carbon assimilation capacity of rice leaves under various nitrogen concentrations. Under various nitrogen concentrations, the carbon assimilation capacity of rice leaves showed an upward trend with increasing light intensity. At 0 mM nitrogen, compared to L150, the carbon assimilation capacity of rice leaves increased by 16.9%–27.6% under light intensities of L300, L500, and L700. At 0.54 mM nitrogen, the carbon assimilation capacity increased by 41.4%–54.6%, at 1.62 mM nitrogen, by 47.2%–96.2%, at 6.48 mM nitrogen, by 40.0%–88.5%, and at 12.96 mM nitrogen, by 6.5%–33.9%.

[0044] Depend on Figure 7 As shown in Figure 1, under various light intensities, the ability of rice roots to absorb nitrogen concentration increased with increasing nitrogen concentration. Under a light intensity of L150, the ability of rice roots to absorb nitrogen increased by 90.1% to 507.0% at nitrogen concentrations of 0.54 mM, 1.62 mM, 6.48 mM, and 12.96 mM compared to the 0 mM treatment. Under a light intensity of L300, the ability increased by 31.8% to 643.9%; under a light intensity of L500, the ability increased by 19.0% to 495.5%; and under a light intensity of L700, the ability increased by 25.2% and 100.8% to 566.6%.

[0045] Depend on Figure 7 Figure B shows the effect of nitrogen concentration on the carbon assimilation capacity of rice leaves during the tillering stage under various light intensities. Under various light intensity treatments, as nitrogen concentration increased, the carbon assimilation capacity of rice leaves showed a downward trend at lower light intensities (L150 and L300), and an initial increase followed by a decrease at higher light intensities (L500 and L700). Under L150 light intensity conditions, the ability of rice leaves to assimilate carbon decreased by 19.5%~41.8% at nitrogen concentrations of 0.54 mM, 1.62 mM, 6.48 mM, and 12.96 mM compared with the 0 mM treatment; under L300 light intensity conditions, it decreased by 10.2%~51.1%; under L500 light intensity conditions, compared with 0 mM nitrogen concentration, there was no significant difference in the ability of rice leaves to assimilate carbon at 0.54 mM nitrogen concentration, but it decreased by 11.9%~40.5% at nitrogen concentrations of 1.62 mM, 6.48 mM, and 12.96 mM; under L700 light intensity conditions, it first increased by 6.5% and 1.2%, and then decreased by 19.3% and 33.4%.

[0046] 1.3.4 Effects of nitrogen concentration on rice growth under different light intensities Figure 8 These are morphological characteristics of rice plants during the tillering stage under various light intensities and nitrogen concentrations. As nitrogen concentration increases, rice plant height increases across all light intensity treatments. Furthermore, under all light intensities, the number of tillers also increases significantly with increasing nitrogen concentration, while root length decreases.

[0047] like Figure 9 Figure A shows the effect of nitrogen concentration on the underground dry weight of rice plants under various light intensities. The results showed that, under various light intensities, the underground dry weight of rice plants initially increased and then decreased with increasing nitrogen concentration. Under a light intensity of L150, compared to the 0 mM nitrogen treatment, the underground dry weight of the rice plants increased by 39.9%–85.0% at treatments with 0.54 mM, 1.62 mM, 6.48 mM, and 12.96 mM nitrogen concentrations. Under a light intensity of L300, the underground dry weight increased by 133.8%–262.8%; under a light intensity of L500, the underground dry weight increased by 254.3%–543.8%; and under a light intensity of L700, the underground dry weight increased by 204.8%–521.7%.

[0048] like Figure 9 Figure B shows the effect of nitrogen concentration on the aboveground dry weight of rice plants under various light intensities. As shown in the figure, under various light intensities, the aboveground dry weight of rice plants initially increased and then decreased with increasing nitrogen concentration. Under a light intensity of L150, compared to the 0 mM nitrogen treatment, the aboveground dry weight increased by 101.0%–185.1% at treatments with 0.54 mM, 1.62 mM, 6.48 mM, and 12.96 mM nitrogen concentrations. Under a light intensity of L300, the aboveground dry weight increased by 152.0%–396.9%; under a light intensity of L500, the aboveground dry weight increased by 215.7%–757.3%; and under a light intensity of L700, the aboveground dry weight increased by 190.3%–775.0%.

[0049] like Figure 9Figure C shows the effect of nitrogen concentration on the total dry weight of rice plants under various light intensities. The results showed that under various light intensities, the total dry weight of rice plants initially increased and then decreased with increasing nitrogen concentration. Under a light intensity of L150, compared to the 0 mM nitrogen treatment, the total dry weight of plants treated with nitrogen concentrations of 0.54 mM, 1.62 mM, 6.48 mM, and 12.96 mM increased by 97.9%–165.1%. Under a light intensity of L300, the total dry weight increased by 161.0%–355.9%. Under a light intensity of L500, the total dry weight increased by 224.7%–707.6%. Under a light intensity of L700, the total dry weight increased by 194.0%–709.8%.

[0050] like Figure 10 Figure A shows the effect of nitrogen concentration on rice plant height under various light intensities. The results showed that under various light intensities, rice plant height increased with increasing nitrogen concentration. Under a light intensity of L150, plant height increased by 31.6% to 57.6% in treatments with 0 mM nitrogen concentration, compared to the 0 mM nitrogen concentration. Under a light intensity of L300, plant height increased by 24.0% to 74.8%, under a light intensity of L500, plant height increased by 18.9% to 75.0%, and under a light intensity of L700, plant height increased by 1.0% to 56.6%.

[0051] like Figure 10 Figure B shows the effect of nitrogen concentration on tiller number under various light intensities. Under all light intensities, tiller number increased with increasing nitrogen concentration. Under a light intensity of L150, total dry weight increased by 34.5%–124.1% for treatments with 0 mM nitrogen concentration, 1.62 mM, 6.48 mM, and 12.96 mM nitrogen concentrations compared to the 0 mM treatment. Under a light intensity of L300, total dry weight increased by 166.7%–318.2%, under a light intensity of L500, total dry weight increased by 351.9%–755.6%, and under a light intensity of L700, total dry weight increased by 417.2%–765.5%.

[0052] like Figure 10 Figure C shows the effect of nitrogen concentration on rice root length under various light intensities. Under the L150 light intensity treatment, rice root length reached its maximum at 0 mM nitrogen, with no significant differences among the other groups. Under the L300, L500, and L700 light intensities, rice root length reached its maximum at 0.54 mM nitrogen and then decreased with increasing nitrogen concentration.

[0053] 1.3.5 Response of Rice Plant Carbon-Nitrogen Ratio (C / N) to Different Nitrogen Concentrations and Light Intensities like Figure 11 As shown in Figure 2, the C:N ratio is inversely proportional to the increase in N concentration and decreases significantly as the N concentration increases from 0 mM to 12.96 mM. -2 ·s −1 and 700 μmol·m -2 ·s −1 Under high light conditions, the fitted equation and its corresponding R² value fit the experimental data well, indicating that the effect of N on reducing the C / N ratio is more pronounced under high light conditions. The C:N ratio increases with increasing light intensity. This suggests that as light intensity increases, plants tend to allocate more C relative to N. At a N concentration of 0.54 mM, R² ² The highest value (0.9999) indicates a high accuracy of the fitting. This trend suggests that although N availability is crucial for plant growth, higher light intensity may lead to the accumulation of C relative to N, affecting the nutritional quality of plants.

[0054] 1.3.6 Correlation Analysis between Carbon-Nitrogen Ratio and Growth Indicators The correlation coefficients between growth indexes and C and N ratio related parameters were analyzed by Pearson correlation analysis. Figure 12 Total dry weight (TDW) showed extremely significant positive correlations with tiller number (TN), root dry weight (RDW), stem dry weight (SDW), and leaf dry weight (LDW), with correlation coefficients exceeding 0.9. Plant height (PH) and root length (RL) showed weaker correlations with TDW and its components. C and N concentrations in various plant organs also showed extremely significant correlations with growth. Stem and leaf C concentrations showed moderate positive correlations with total biomass and weaker correlations with N concentration. The C:N ratio of roots, stems, and leaves showed significant negative correlations with TDW and biomass-related traits, indicating that a lower C:N ratio (associated with higher N content) is beneficial for rice growth. This was particularly evident in the root C:N ratio, which was negatively correlated with most growth traits. In summary, high N allocation (reflected in a lower C:N ratio) plays a key role in promoting biomass accumulation.

[0055] Total dry weight analysis showed that the light intensity (0.23 *** ) and N (0.28 *** ) showed a moderate correlation with total biomass, indicating that both factors contributed significantly to total biomass, with N having a slightly stronger effect ( Figure 13 ). Correlation between tiller number and light intensity (0.33 *** ) is higher than the correlation with N (0.23 ***), indicating that the improvement of light utilization efficiency has a greater impact on tillering, which is crucial to the overall productivity of plants. Root and stem dry weights were significantly positively correlated with light intensity, but weakly correlated with nitrogen content. Leaf dry weight was extremely significantly correlated with nitrogen content (0.54 *** ), and is very weakly correlated with light intensity (0.09 *** ).

[0056] Based on the above research findings, at N concentrations of 1.62–12.96 mM, 537–611 μmol·m −2 ·s −1 The light intensity of 300~700 μmol·m −2 ·s −1 Under the light conditions of , 5.51~8.11 mM N concentration is more conducive to rice growth and tillering.

[0057] Example 2 1 Materials and Methods 1.1 Materials The experiment used 'CP511' rice as the experimental material. It was carried out in the Plant Factory Breeding Accelerator of the Institute of Urban Agriculture, Chinese Academy of Agricultural Sciences in July 2024. The seedling raising process was the same as the above steps. After the seedling raising was completed, rice seedlings with consistent growth were selected and randomly planted in four sets of identical hydroponic systems. Light intensity and nitrogen fertilizer treatments were started after 5 days of seedling acclimatization. A total of four treatments were set up in the experiment, namely high light and high nitrogen treatment, and the light intensity of the treatment conditions was set to 700±10 μmol·m -2 ·s −1 , the nitrogen concentration was set to 6.48 mM, recorded as HLHN; the high light and low nitrogen treatment, the light intensity of the treatment conditions was set to 700±10 μmol·m -2 ·s −1 , the nitrogen concentration was set to 0.54 mM, recorded as HLLN; low light and high nitrogen treatment, the light intensity of the treatment conditions was set to 150±10 μmol·m -2 ·s −1 , the nitrogen concentration was set to 6.48 mM, recorded as LLHN; low light and low nitrogen treatment, the light intensity of the treatment conditions was set to 150±10 μmol·m -2 ·s −1 , the nitrogen concentration was set to 0.54 mM, denoted as LLLN.

[0058] The cultivation environment was the same as that in Example 1.

[0059] 1.2 Detection Method Sugar and starch content in rice roots, stems, and leaves were measured using a sucrose-glucose-fructose content assay kit (hexokinase method) and an enzymatic starch assay kit, respectively. Each treatment was replicated three times. The assay kits were purchased from Suzhou Gress Biotechnology Co., Ltd. Specific procedures are described in the manufacturer's instructions.

[0060] 1.3 Results 1.3.1 Nutrient distribution like Figure 14 Figure A reflects the effects of light intensity and nitrogen supply on sucrose distribution in rice roots. The results showed that under both LL and HL conditions, sucrose distribution to leaves increased significantly under HN compared to LN, while distribution to stems and roots decreased significantly. Under LL, the proportion of sucrose in rice leaves increased from 43.7% to 74.2% under HN, and from 33.3% to 61.5% under HL.

[0061] Under LN conditions, sucrose allocation to leaves was significantly reduced under HL conditions compared to LL conditions, while allocation to roots was significantly increased. Allocation to stems was not significantly affected. Compared to LL conditions, sucrose allocation to leaves decreased from 43.7% to 33.3% under HL conditions, while allocation to roots increased from 7.7% to 16.7%. Under HN conditions, sucrose allocation to leaves and roots decreased significantly under HL compared to LL conditions, while allocation to stems increased significantly. Compared to LL conditions, sucrose allocation to leaves decreased from 74.2% to 61.5%, allocation to roots decreased from 4.6% to 3.2%, and allocation to stems increased from 21.2% to 35.3% under HL conditions.

[0062] like Figure 14 Figure B shows the effects of light intensity and nitrogen supply on starch distribution in rice plants. Under LL and HL conditions, starch distribution to leaves and roots significantly increased under HN compared to LN, while distribution to stems significantly decreased. Under LL, starch distribution to leaves increased from 4.9% to 37.3%, while distribution to stems decreased from 94.0% to 57.3%. Distribution to roots increased from 1.1% to 5.4%.

[0063] Under LN conditions, light intensity had little effect on the distribution of starch among roots, stems, and leaves in rice plants, but had a greater effect under HN conditions. Under HN conditions, HL conditions significantly reduced the distribution of starch in leaves and roots, and significantly increased the distribution of starch in stems. Compared with LL conditions, starch distribution in leaves decreased from 37.3% to 6.7% and in roots from 5.4% to 0.6% under HL, while starch distribution in stems increased from 57.3% to 92.6%.

[0064] 1.3.2 Effects of light intensity and nitrogen supply on photosynthesis in rice leaves like Figure 15 Figure A reflects the net photosynthetic rate (Pn) of rice under each treatment condition. The results show that under all light intensities, the net photosynthetic rate of rice significantly increased with increasing nitrogen concentration, increasing by 71.9% under LL conditions and 93.8% under HL conditions. The net photosynthetic rate of rice leaves also significantly increased with increasing light intensity under each nitrogen concentration, increasing by 247.0% under LN conditions and 291.1% under HN conditions.

[0065] like Figure 15 As shown in Figure B, it reflects the light response curve of rice leaves under various treatment conditions. The results show that increasing light intensity and nitrogen supply level can significantly improve the photosynthetic capacity of rice.

[0066] This study systematically revealed the key mechanisms by which light intensity and nitrogen supply regulate rice carbon and nitrogen metabolism in a plant factory environment. -2 ·s -1 ) synergistically with high nitrogen (6.48 mM) significantly improved the distribution efficiency of photosynthetic products to the aboveground parts, with leaf sucrose concentration increasing by 143.3% and stem starch accumulation surging by 1144.4%, while also optimizing nitrogen use efficiency. Light intensity affects nitrogen use efficiency by regulating the distribution of carbon metabolites, while nitrogen concentration regulates carbon metabolic balance by altering the nitrate assimilation pathway. Especially under high-light conditions, increased nitrogen fertilizer application can make the stem a key organ for both carbon and nitrogen storage, providing new ideas for regulating plant architecture in rice cultivation in plant factories.

Claims

1. A method for promoting rice growth and development based on light and nitrogen, characterized in that: The method comprises the following steps: providing 600-800 μmol·m -2 ·s -1 The cultivation conditions were light intensity and nitrogen concentration of 5.51~8.11 mM.

2. The method for promoting rice growth and development based on light and nitrogen according to claim 1, characterized in that: The length of the rice tillering period is the total number of leaves on the main stem minus the number of elongated internodes.

3. The method for promoting rice growth and development based on light and nitrogen according to claim 1, characterized in that: The cultivation conditions also include hydroponic rice.

4. The method for promoting rice growth and development based on light and nitrogen according to claim 1, characterized in that: The cultivation conditions also include: Temperature is 30±2℃; Relative humidity is 55 ± 2%; Carbon dioxide is 450±30 ppm.

5. The method for promoting rice growth and development based on light and nitrogen according to claim 1, wherein: The incubation conditions were 700 μmol·m -2 ·s -1 , 6.48 mM nitrogen concentration.

6. A method for promoting rice growth and development based on light and nitrogen to increase the number of rice tillers, reduce rice plant height, promote rice root growth, and increase rice dry matter accumulation, characterized in that: The method for promoting rice growth and development based on light and nitrogen is the method for promoting rice growth and development based on light and nitrogen as claimed in any one of claims 1 to 5.

7. A plant factory control system, characterized in that: It includes a lighting module, a nutrient solution module, and a data control module that is wirelessly connected to the lighting module and the nutrient solution module. The data control module is configured to: When the rice is in the tillering stage, the light module is controlled to provide 600-800 μmol·m -2 ·s -1 The light intensity is controlled; the nutrient solution module is controlled to provide nutrient substances with a nitrogen concentration of 5.51~8.11 mM to the rice.

8. The plant factory control system according to claim 7, characterized in that: The plant factory control system further includes an image acquisition module, wherein the data control module is configured to: Based on the image feature of the rice picture collected by the image acquisition module showing the base leaf axils extending out, it is confirmed that the rice has entered the tillering stage.

9. The plant factory control system according to claim 7, characterized in that: The plant factory control system is further provided with a temperature control module, a humidity control module and a carbon dioxide control module, and the data control module is configured as follows: The temperature control module provides a temperature condition of 30±2℃ to the rice; The humidity control module provides 55±2% relative humidity conditions to the rice; The carbon dioxide control module provides 450±30 ppm carbon dioxide conditions to the rice.

10. The plant factory control system according to claim 7, characterized in that: The data control module is configured to: When the rice is in the tillering stage, the light module is controlled to provide 700 μmol·m -2 ·s -1 The light intensity was controlled; the nutrient solution module provided nutrient with a nitrogen concentration of 6.48 mM to the rice.

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