Plant factory cultivation method for shortening rice growth period based on carbon and nitrogen nutrition regulation

Abstract

The application belongs to the technical field of rice cultivation and relates to a plant factory cultivation method for shortening the growth period of rice based on carbon and nitrogen nutrition regulation. In view of the technical problem that the existing plant factory rice cultivation method has a long growth period and is difficult to meet the rapid cultivation demand, the method comprises seed soaking, germination, seedling raising, post-transplanting management and harvesting, and the core is to transplant rice seedlings to a plant factory water culture system, and synchronous control of cultivation conditions is used to promote early flowering: maintaining CO2 concentration of 400-1600 ppm, using full-spectrum artificial light source, using basic nutrient solution with total nitrogen of 1.2-3.2 mM, molar ratio of ammonium nitrogen to nitrate nitrogen of 2:1-4:1 and pH of 5.5-6.5, and adding L-carnitine and aconitic acid metabolism promoters with a molar ratio of 1.2:1-2.2:1 at the tillering peak stage. The method is mainly used for rapid cultivation of rice in a plant factory, and the cultivation efficiency is improved by shortening the growth period.

Description

Technical Field

[0001] This invention relates to the field of plant factory crop cultivation technology. More specifically, this invention relates to a method for cultivating rice in a plant factory based on carbon and nitrogen nutrition regulation to shorten the growth period. Background Technology

[0002] Plant factories, as a highly efficient crop cultivation model under controlled environments, demonstrate significant advantages in the large-scale, standardized cultivation of rice due to their precise control over conditions such as temperature, light, and nutrients. They are particularly suitable for shortening cultivation cycles and ensuring stable yields. However, from a carbon source supply perspective, the carbon dioxide concentration within plant factories is typically maintained at natural atmospheric levels or a lower, artificially controlled range. This insufficient carbon source support for rice photosynthesis hinders the accumulation of photosynthetic products and delays growth and development. Regarding nitrogen nutrient regulation, existing nutrient solutions often use conventional soil cultivation or general hydroponic standards for total nitrogen concentration and ammonium to nitrate nitrogen ratios, failing to optimize for the physiological needs of early flowering in rice. This mismatch between nitrogen form and concentration can lead to excessive vegetative growth and delayed reproductive growth. Therefore, there is an urgent need for a plant factory cultivation method based on carbon and nitrogen nutrient regulation to shorten the rice growth period. Summary of the Invention

[0003] To achieve these objectives and other advantages according to the present invention, a plant factory cultivation method for shortening the growth period of rice based on carbon and nitrogen nutrition regulation is provided, including seed soaking, germination, seedling raising, post-transplanting management, and harvesting, wherein rice seedlings are transplanted into a hydroponic system in the plant factory, and the following cultivation conditions are simultaneously controlled to promote early flowering of rice:

[0004] Maintain the carbon dioxide concentration in the plant factory environment at 400-1600 ppm;

[0005] Basic illumination is provided using a full-spectrum artificial light source, with a light cycle of 10-12 hours per day and a photosynthetically active radiation intensity of 250-350 μmol m². -2 s -1 ;

[0006] Rice was cultivated using a basic nutrient solution, wherein the total nitrogen concentration in the basic nutrient solution was 1.2-3.2 mM, the molar ratio of ammonium nitrogen to nitrate nitrogen in the basic nutrient solution was 2:1-4:1, and the pH value of the basic nutrient solution was 5.5-6.5.

[0007] During rice cultivation, a metabolism promoter is added to the basal nutrient solution. This promoter comprises L-carnitine and aconitine in a molar ratio of 1.2:1 to 2.2:1. The method for adding the metabolism promoter is as follows:

[0008] S1. When the leaf age index of the main stem reaches 55%-65%, add a metabolism promoter to the basic nutrient solution until the L-carnitine concentration in the basic nutrient solution reaches 0.004-0.006 mM, and maintain it for 24-48 hours after the addition is completed.

[0009] S2. After maintenance, add a metabolic promoter to the basal nutrient solution again to raise the L-carnitine concentration to 0.01-0.018 mM, and maintain this concentration for 2-4 days. After maintenance, continue to use the basal nutrient solution for cultivation.

[0010] Preferably, the method for preparing the metabolism promoter includes the following steps:

[0011] A1. Mix L-carnitine and aconitine, dissolve them in 2-(N-morpholino)ethanesulfonic acid buffer solution with pH 6.0±0.1 to prepare a mixed stock solution with a total concentration of 10-15 mM; add the mixed stock solution dropwise to citrate-sodium citrate buffer solution with pH 4.0±0.2 while stirring at a rate of 1-2 mL / min, control the pH of the final mixed system to 5.2-5.6, and let it stand at 25℃ for 30 minutes to obtain the complex precursor dispersion;

[0012] A2. Under magnetic stirring, the complex precursor dispersion was mixed with an equal volume of chitosan hydrochloride solution with a concentration of 0.8-1.2 mg / mL, and then ultrasonically treated to obtain a nanocomposite suspension.

[0013] A3. While stirring, add sodium tripolyphosphate solution dropwise to the nanocomposite suspension. The final concentration of sodium tripolyphosphate is 0.05-0.15 w / v%. After the addition is complete, continue stirring for 30 minutes to obtain a nanogel suspension.

[0014] A4. Place the nanogel suspension at 4°C and treat it under a vacuum of -0.08 to -0.10 MPa for 10-15 minutes. Then restore it to normal pressure and store it at 4°C in the dark to obtain the metabolism promoter.

[0015] Preferably, in step A2, before mixing the complex precursor dispersion with the chitosan hydrochloride solution, the chitosan hydrochloride solution is first mixed with sodium chloride to make the final concentration of sodium chloride 0.01-0.03 mol / L, thereby obtaining the modified chitosan solution;

[0016] The complex precursor dispersion and the modified chitosan solution were then mixed in equal volumes at 28-32℃. After mixing, the system was allowed to stand for 25-35 minutes to obtain a nanoscale composite suspension.

[0017] Preferably, during the rice flowering period, the daytime temperature is maintained at 24-26°C and the nighttime temperature is controlled at 18-20°C.

[0018] On the first day of the flowering period, a gas and chemical synergistic regulation was implemented: 1-methylcyclopropene gas was released into the growing area during the nighttime temperature period at a concentration of 0.5-0.8 ppm for 1-2 hours; the day after the release of 1-methylcyclopropene gas, a targeted slow-release formulation was sprayed onto the spikelets of rice plants during the 4th-6th hour of light exposure. The targeted slow-release formulation contained melatonin at a concentration of 50-150 μmol / L and cationic guar gum at a concentration of 0.01-0.02 w / v%, and was sprayed onto the spikelets of rice plants.

[0019] Preferably, the targeted sustained-release formulation further contains pectin lyase at a concentration of 0.02-0.05 w / v%, wherein the pectin lyase is a chemically modified photoactivated pectin lyase; the photoactivated pectin lyase has a photocage protecting group covalently linked to an amino acid side chain at one allosteric site, and the photocage protecting group is 4,5-dimethoxy-2-nitrobenzyl.

[0020] Ten hours after spraying the targeted sustained-release formulation, the rice panicles were given supplemental lighting. The peak spectral density of the supplemental lighting was 350-370 nm (ultraviolet light), and the photon flux density was 20-40 μmol m. -2 s -1 Irradiate continuously for 15-30 minutes to specifically remove photocage protective groups and activate the activity of pectin lyase.

[0021] Preferably, the photoactivated pectin lyase is encapsulated in microcapsules, the capsule walls of which are formed by cross-linking polyvinyl alcohol with phenylboronic acid derivatives.

[0022] Preferably, starting from the early stage of rice panicle differentiation, boron supplementation is performed for two consecutive cycles, with each cycle lasting three days. The specific operation method for each cycle is as follows:

[0023] At the beginning of the first day of light exposure, add boric acid to the basal nutrient solution to make the boron concentration in the basal nutrient solution 0.05-0.09 mg / L, and maintain it for 4-6 hours.

[0024] Then continue to supplement boric acid into the basic nutrient solution until the concentration of boron element is 0.2-0.3 mg / L, and maintain this until the end of the light exposure.

[0025] After the light exposure ends, replace the nutrient solution with the basic nutrient solution.

[0026] Preferably, before continuing to supplement boric acid into the basal nutrient solution to a boron concentration of 0.2-0.3 mg / L, a synergist composed of calcium chloride, L-glutathione, and trehalose in a mass ratio of 1:(0.2-0.3):(0.05-0.1) is added to the basal nutrient solution to bring the L-glutathione concentration in the basal nutrient solution to 20-30 µM, maintain this concentration for 20-30 minutes, and then supplement boric acid to the target high concentration.

[0027] Preferably, the basic nutrient solution also includes phosphorus, potassium, calcium, magnesium, and trace elements. Phosphorus is provided in the form of dihydrogen phosphate at a concentration of 0.15-0.25 mM; potassium is provided in the form of potassium ions at a concentration of 1.0-1.4 mM; calcium is provided in the form of calcium ions at a concentration of 1.8-2.2 mM; and magnesium is provided in the form of magnesium ions at a concentration of 0.8-1.2 mM. The trace elements include iron, manganese, zinc, copper, and molybdenum. Iron is provided in the form of Fe-EDTA at a concentration of 20-30 μM; manganese is provided in the form of divalent manganese ions at a concentration of 10-15 μM; zinc is provided in the form of divalent zinc ions at a concentration of 2.0-4.0 μM; copper is provided in the form of divalent copper ions at a concentration of 0.5-1.0 μM; and molybdenum is provided in the form of heptamolybdate at a concentration of 0.05-0.15 μM.

[0028] The present invention has at least the following beneficial effects:

[0029] This invention significantly accelerates nitrogen metabolism and the tricarboxylic acid cycle in rice by increasing carbon dioxide concentration, precisely controlling light intensity, and synergistically combining carbon and nitrogen nutrition with a high ammonium nitrogen ratio, along with the phased addition of L-carnitine and aconitine metabolism promoters. This promotes the allocation of nutrients to reproductive organs, resulting in earlier flowering and a shorter growth period. Simultaneously, the synergistic regulation of various cultivation conditions ensures normal vegetative growth of rice, preventing plant weakness caused by premature reproductive growth. This provides reliable technical support for the rapid cultivation of rice in plant factories, improving cultivation efficiency and yield stability.

[0030] The metabolic promoter preparation method of this invention utilizes a multi-step synergistic effect to form a structurally compatible active system of L-carnitine and aconitic acid. The composite of chitosan hydrochloride and the cross-linking of sodium tripolyphosphate construct a highly efficient carrier. This synergistic effect enhances the combined action of the two components, ensuring efficient fatty acid transport and tricarboxylic acid cycle regulation in hydroponic systems. It deeply integrates with carbon and nitrogen nutrient regulation, accelerates the initiation of reproductive growth in rice, significantly shortens the growth period, and promotes the directional distribution of photosynthetic products to grains, greatly increasing seed yield. Furthermore, the preparation process is controllable and suitable for large-scale application.

[0031] This invention modifies chitosan hydrochloride solution with sodium chloride, increasing the charge density and hydrophilicity of chitosan molecules and enhancing their binding force with the complex precursor dispersion. The modified composite system can more efficiently load metabolism promoters, ensuring their synergistic regulatory role in rice cultivation, strengthening the precise control of rice metabolic processes, and further shortening the growth period. Simultaneously, it improves the efficiency of metabolism promoters, aiding in the accumulation and distribution of photosynthetic products, effectively increasing seed yield, and providing crucial support for optimizing cultivation results.

[0032] This invention provides suitable environmental conditions for rice pollination and fruit setting through precise temperature and humidity control during the flowering period, reducing the adverse effects of temperature fluctuations on floret development. 1-Methylcyclopropene gas effectively delays floret senescence and extends the pollination window. Combined with a targeted, sustained-release formulation containing melatonin and cationic guar gum, it significantly enhances pollen viability and floret fruit set rate. The synergistic regulation of the gas and chemical agents can shorten the growth period while ensuring fruit set rate, avoiding yield decline due to accelerated reproductive growth and improving the economic benefits of plant factory rice cultivation.

[0033] This invention modifies pectin lyase with a 4,5-dimethoxy-2-nitrobenzyl photocage protecting group, achieving precise photocontrolled activation of enzyme activity and preventing premature action of the enzyme at non-target sites. Precise irradiation with 350-370 nm ultraviolet light specifically removes the protecting group, activating enzyme activity and enabling it to efficiently degrade the pectin layer on the surface of the spikelet, thus improving melatonin absorption efficiency. The introduction of this photoactivation mechanism significantly improves the targeting and efficacy of the formulation, reduces enzyme waste, and avoids damage to other rice tissues, further optimizing the regulation of flowering time.

[0034] This invention utilizes polyvinyl alcohol-phenylboronic acid derivative microcapsules to encapsulate a photoactivated pectin lyase. The capsule wall effectively protects enzyme activity, preventing inactivation due to external environmental factors and significantly extending the enzyme's duration of action. Simultaneously, the capsule wall allows for the transmission of 350-370 nm ultraviolet light without affecting the photoactivation process, enabling sustained release and precise control of enzyme activity. The microcapsulated enzyme is slowly released from the floret, exerting a continuous effect and further enhancing pectin degradation and melatonin absorption efficiency, thus ensuring rice seed setting rate and yield, and strengthening the practicality of the technical solution.

[0035] This invention addresses the boron requirements of rice in the early stages of panicle differentiation by employing a phased, gradient boron supplementation strategy. First, a low concentration of boric acid is used to meet the basic needs during this initial stage. Then, a high concentration of boric acid is applied to ensure rapid panicle development, avoiding boron toxicity caused by a single high-concentration supplementation. Replacing the basal nutrient solution promptly after the end of daylight hours prevents excessive boron accumulation and ensures safe rice growth. Precise boron supplementation effectively promotes panicle differentiation, shortens the reproductive growth cycle, and increases the quantity and quality of spikelets, laying the foundation for high yields.

[0036] This invention utilizes a synergistic pretreatment agent composed of calcium chloride, L-glutathione, and trehalose to activate the absorption function of rice roots, enhance the efficiency of boron transport, alleviate the potential stress of high-concentration boron on roots, and maintain cell membrane stability. This synergistic pretreatment significantly improves the absorption efficiency of boron in rice, enhancing the effectiveness of boron supplementation, more fully meeting the nutritional needs of young panicle differentiation, further promoting panicle development, shortening the growth period, and improving the growth quality and yield of rice.

[0037] This invention clarifies the supply form and concentration of medium-level elements such as phosphorus, potassium, calcium, and magnesium in the basic nutrient solution, while optimizing the ratio of micro-elements such as iron, manganese, and zinc, thus constructing a comprehensive and balanced nutrient system. This ratio can meet the nutritional needs of rice at all stages of growth, avoid physiological disorders caused by element deficiency or imbalance, and ensure normal vegetative and reproductive growth of rice. The balanced nutrient supply lays a good foundation for the implementation of technologies such as carbon and nitrogen regulation and metabolic promoters, ensuring a shortened growth period while maintaining robust growth and high yield potential in rice plants.

[0038] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0040] According to one embodiment of the present invention, the present invention provides a plant factory cultivation method for shortening the growth period of rice based on carbon and nitrogen nutrition regulation, including seed soaking, germination, seedling raising, post-transplanting management and harvesting, transplanting rice seedlings into a hydroponic system in the plant factory, and simultaneously controlling the following cultivation conditions to promote early flowering of rice:

[0041] Maintain the carbon dioxide concentration in the plant factory environment at 400-1600 ppm;

[0042] Basic illumination is provided using a full-spectrum artificial light source, with a light cycle of 10-12 hours per day and a photosynthetically active radiation intensity of 250-350 μmol m². -2 s -1 ;

[0043] Rice was cultivated using a basic nutrient solution, wherein the total nitrogen concentration in the basic nutrient solution was 1.2-3.2 mM, the molar ratio of ammonium nitrogen to nitrate nitrogen in the basic nutrient solution was 2:1-4:1, and the pH value of the basic nutrient solution was 5.5-6.5.

[0044] During rice cultivation, a metabolism promoter is added to the basal nutrient solution. This promoter comprises L-carnitine and aconitine in a molar ratio of 1.2:1 to 2.2:1. The method for adding the metabolism promoter is as follows:

[0045] S1. When the leaf age index of the main stem reaches 55%-65%, add a metabolism promoter to the basic nutrient solution until the L-carnitine concentration in the basic nutrient solution reaches 0.004-0.006 mM, and maintain it for 24-48 hours after the addition is completed.

[0046] S2. After maintenance, add a metabolic promoter to the basal nutrient solution again to raise the L-carnitine concentration to 0.01-0.018 mM, and maintain this concentration for 2-4 days. After maintenance, continue to use the basal nutrient solution for cultivation. A high proportion of ammonium nitrogen promotes nitrogen metabolism in rice, synergizing with the fatty acid transport function of L-carnitine and the tricarboxylic acid cycle regulation function of aconitic acid, thus shortening the flowering period. Carbon dioxide control can be achieved using a carbon dioxide generator and an intelligent environmental monitor. The carbon dioxide generator can be installed at the top of the plant factory cultivation area, while the intelligent environmental monitor can be installed in the middle and top of the cultivation area to ensure comprehensive monitoring of concentration changes. A full-spectrum artificial light source can be a full-spectrum LED plant growth lamp, which can be installed at the top of the cultivation area and evenly distributed along the length of the hydroponic system. The EC value of the basal nutrient solution is 1.2-2.0 mS / cm. The basal nutrient solution does not contain boron. pH adjustment can be achieved using hydrochloric acid and sodium hydroxide solutions. Carbon dioxide concentrations can be selected as 400 ppm, 1000 ppm, or 1600 ppm. The photoperiod can be selected as 10 hours, 11 hours, or 12 hours (the photoperiod starts at 8:00 AM daily). The photosynthetically active radiation intensity can be selected as 250 μmol m... -2 s -1 300 μmol m -2 s -1 350 μmol m -2 s -1The concentrations of L-carnitine and aconitine in the metabolism promoter can be selected as follows: 1.2 mM, 1.6 mM, 3.2 mM; the molar ratio of ammonium nitrogen to nitrate nitrogen can be 2:1, 3:1, 4:1; the molar ratio of L-carnitine to aconitic acid in the metabolism promoter can be 1.2:1, 1.7:1, 2.2:1; the concentration of L-carnitine in step S1 can be 0.004 mM, 0.005 mM, 0.006 mM, and the maintenance time can be 24 hours, 36 hours, 48 ​​hours; the concentration of L-carnitine in step S2 can be 0.01 mM, 0.014 mM, 0.018 mM, and the maintenance time can be 2 days, 3 days, 4 days; when the leaf age index of the main stem reaches 55%, 60%, or 65%, the metabolism promoter is added in stages according to the steps; the leaf age index of the main stem (%) = (number of unfolded leaves on the main stem / total number of leaves on the main stem) ×100, the number of fully unfolded leaves on the main stem refers to the number of leaves that have fully unfolded on the main stem of the rice plant, counted from the first fully unfolded leaf. The total number of leaves on the main stem refers to the inherent total number of leaves on the main stem of the rice variety. This invention can promote earlier flowering of rice, shorten the growth period, and at the same time ensure the normal vegetative growth of rice, providing support for the rapid cultivation of rice in plant factories and improving cultivation efficiency.

[0047] According to another embodiment of the present invention, the method for preparing the metabolism promoter includes the following steps:

[0048] A1. Mix L-carnitine and aconitine, dissolve them in 2-(N-morpholino)ethanesulfonic acid buffer solution with pH 6.0±0.1 to prepare a mixed stock solution with a total concentration of 10-15 mM; add the mixed stock solution dropwise to citrate-sodium citrate buffer solution with pH 4.0±0.2 while stirring at a rate of 1-2 mL / min, control the pH of the final mixed system to 5.2-5.6, and let it stand at 25℃ for 30 minutes to obtain the complex precursor dispersion;

[0049] A2. Under magnetic stirring, the complex precursor dispersion was mixed with an equal volume of chitosan hydrochloride solution with a concentration of 0.8-1.2 mg / mL, and then ultrasonicated (ultrasonic power 100 W, ultrasonic time 20 minutes, frequency 40 kHz) to obtain a nanocomposite suspension.

[0050] A3. While stirring, add sodium tripolyphosphate solution dropwise to the nanocomposite suspension. The final concentration of sodium tripolyphosphate is 0.05-0.15 w / v%. After the addition is complete, continue stirring for 30 minutes to obtain a nanogel suspension.

[0051] A4. Place the nanogel suspension at 4℃ and treat it under a vacuum of -0.08 to -0.10 MPa for 10-15 minutes. Return to normal pressure and store at 4℃ in the dark to obtain the metabolism promoter. In the preparation of the complex precursor dispersion, the total concentration of the mixed mother liquor can be selected as 10 mM, 12 mM, or 15 mM; in the preparation of the nanocomposite suspension, the concentration of the chitosan hydrochloride solution can be selected as 0.8 mg / mL, 1.0 mg / mL, or 1.2 mg / mL; in the preparation of the nanogel suspension, the final concentration of sodium tripolyphosphate can be selected as 0.05 w / v%, 0.10 w / v%, or 0.15 w / v; the storage temperature of the metabolism promoter is fixed at 4℃, and the vacuum degree can be selected as -0.08 MPa, -0.09 MPa, or -0.10 MPa. The treatment time can be selected as 10 minutes, 12 minutes, or 15 minutes, and a vacuum drying oven can be used. The metabolic promoters prepared by this invention ensure that they play an effective role in rice cultivation and help shorten the growth period.

[0052] According to another embodiment of the present invention, in step A2, before mixing the complex precursor dispersion with the chitosan hydrochloride solution, the chitosan hydrochloride solution is first mixed with sodium chloride to make the final concentration of sodium chloride 0.01-0.03 mol / L, thereby obtaining a modified chitosan solution.

[0053] The complex precursor dispersion and the modified chitosan solution are then mixed in equal volumes at 28-32℃. After mixing, the system is allowed to stand for 25-35 minutes to obtain a nanoscale composite suspension. In the preparation of the modified chitosan solution, the final sodium chloride concentration can be selected as 0.01 mol / L, 0.02 mol / L, or 0.03 mol / L. A magnetic stirrer can be used to assist dissolution, and this device can be placed in the middle of the operating table. During the mixing process, the mixing temperature can be selected as 28℃, 30℃, or 32℃, the mixing volume ratio is fixed at equal volumes, and the standing time can be selected as 25 minutes, 30 minutes, or 35 minutes.

[0054] According to another embodiment of the present invention, during the flowering period of rice, the daytime temperature is maintained at 24-26°C and the nighttime temperature is controlled at 18-20°C;

[0055] On the first day of the flowering period (using the population flowering observation method: observe the rice population within the cultivation unit daily from 9-11 AM (peak flowering period). When a random sample observes that approximately 5% of the plants have flowering florets on their main stem panicles, that day is considered the first day of the flowering period), implement gas and chemical synergistic regulation: release 1-methylcyclopropene gas into the rice growing area within the plant factory during the nighttime temperature period at a concentration of 0.5-0.8 ppm for 1-2 hours; the day after the release of 1-methylcyclopropene gas, at the 4th-6th hour of the photoperiod (i.e., if the daily light start time is 8 AM, then the targeted corrosion inhibitor is sprayed at 12 PM, 1 PM, or 2 PM), spray a targeted slow-release formulation containing 50-150 μmol / L melatonin and 0.01-0.02 μmol / L of melatonin. Cationic guar gum (w / v%) is sprayed onto the spikelets of rice plants (0.5-1.0 mL per plant). Release occurs during nighttime when temperatures are high, and a small gas release device can be used, mounted on the top of the cultivation area. For the 1-methylcyclopropene gas release, the concentration can be selected as 0.5 ppm, 0.6 ppm, or 0.8 ppm, and the duration can be selected as 1 hour, 1.5 hours, or 2 hours. Melatonin concentrations can be selected as 50 μmol / L, 100 μmol / L, or 150 μmol / L, and cationic guar gum concentrations can be selected as 0.01 w / v%, 0.015 w / v%, or 0.02 w / v%. This invention ensures a stable growth environment for rice during the flowering period, promotes pollination and fruit setting of spikelets through synergistic regulation of gases and chemicals, and further shortens the overall growth period.

[0056] According to another embodiment of the present invention, the targeted sustained-release formulation further comprises pectin lyase at a concentration of 0.02-0.05 w / v%, wherein the pectin lyase is a chemically modified photoactivated pectin lyase; the photoactivated pectin lyase has a photocage protecting group covalently linked to an amino acid side chain at one allosteric site, and the photocage protecting group is 4,5-dimethoxy-2-nitrobenzyl.

[0057] Ten hours after spraying the targeted sustained-release formulation, the rice panicles were given supplemental light treatment. The peak spectral intensity of the supplemental light was 350-370 nm (ultraviolet light), and its photon flux density was 20-40 μmol m. -2 s -1The process involves continuous irradiation for 15-30 minutes to specifically remove photocage protective groups and activate pectin lyase activity. 1-Methylcyclopropene inhibits floret senescence, melatonin promotes pollen viability, and pectin lyase degrades the pectin layer on the floret surface to improve melatonin absorption efficiency. These three factors synergistically enhance the fruit set rate during flowering, preventing yield reduction caused by shortened growth period. The supplemental lighting in this invention uses 350-370 nm ultraviolet light, and its core function is to activate the deprotection reaction of photocage protective groups, rather than providing the energy required for photosynthesis. The photon flux density is 20-40 μmol / m². -2 s -1 This ensures efficient removal of photocage groups; the photocage protecting group is an o-nitrobenzyl derivative, such as, but not limited to, 4,5-dimethoxy-2-nitrobenzyl, 1-(2-nitrophenyl)ethyl, or 2-nitrobenzyl. The derivative is linked to the amino acid side chain via amide, ester, or carbamate bonds; the irradiation time is 10 hours after the targeted sustained-release formulation is sprayed, and a narrow-spectrum LED lamp can be used, mounted on top of the cultivation area, located to the side of the full-spectrum light source; the pectin lyase is a conventional agricultural enzyme preparation, chemically modified to obtain a photoactivated form. The modification process can utilize conventional chemical reaction equipment, such as a three-necked flask or a constant-temperature water bath, which can be placed on a laboratory workbench; in the photoactivated pectin lyase, the photocage protecting group covalently linked to the allosteric site amino acid side chain is 4,5-dimethoxy-2-nitrobenzyl (DMNB). This group is a classic photocage protecting group recognized in the art. It is covalently linked to the side chain of the amino acid (e.g., the ε-amino group of lysine) via a carbamate bond. For example, 4,5-dimethoxy-2-nitrobenzylchloroformate can be used to chemically modify pectin lyase to obtain the photoactivated pectin lyase. Under light irradiation at a wavelength of 350-370 nm, this DMNB protecting group can undergo a specific photolysis reaction and be removed. In the optimization of the targeted sustained-release formulation, the concentration of pectin lyase can be selected as 0.02 w / v%, 0.03 w / v%, or 0.05 w / v; the photon flux density can be selected as 20 μmol / m². -2 s -1 30 μmol m -2 s -1 40 μmol m -2 s -1 The irradiation time can be selected as 15 minutes, 20 minutes, or 30 minutes. This invention can precisely regulate the activity of pectin lyase through photoactivation, improve melatonin absorption efficiency, further optimize the regulation effect during the flowering period, and help shorten the growth period.

[0058] According to another embodiment of the present invention, a photoactivated pectin lyase is encapsulated in microcapsules, the capsule wall of which is formed by cross-linking polyvinyl alcohol and a phenylboronic acid derivative (transmissive to 350-370 nm ultraviolet light). This invention enables the sustained release of the photoactivated pectin lyase, prolonging its duration of action, enhancing the regulatory effect of targeted sustained-release formulations, and ensuring stable growth of rice during the flowering period.

[0059] According to another embodiment of the present invention, starting from the early stage of rice panicle differentiation, boron supplementation is performed for two consecutive cycles, with each cycle lasting three days. The specific operation method for each cycle is as follows:

[0060] At the beginning of the first day of light exposure, add boric acid to the basal nutrient solution to make the boron concentration in the basal nutrient solution 0.05-0.09 mg / L, and maintain it for 4-6 hours.

[0061] Then continue to supplement boric acid into the basic nutrient solution until the concentration of boron is 0.2-0.3 mg / L, and maintain this until the end of the light exposure (the EC value is still in the range of 1.2-2.0 mS / cm).

[0062] After the light exposure ends, the nutrient solution is replaced with a basic nutrient solution. Two conventional methods can be used to determine the early stage of panicle differentiation: one is conventional microscopic observation, where a microscope is placed on a laboratory observation table, and temporary sections are prepared by peeling off the growing point of the rice main stem to observe whether panicle primordia appear; the other is the leaf age remainder method, which involves checking the number of undeveloped leaves on the main stem (leaf age remainder). When the leaf age remainder on the rice main stem is 3-4 leaves, it indicates the early stage of panicle differentiation. During the first stage of boric acid supplementation, the boron concentration can be selected as 0.05 mg / L, 0.07 mg / L, or 0.09 mg / L, and the maintenance time can be selected as 4 hours, 5 hours, or 6 hours. During the second stage of boric acid supplementation, the boron concentration can be selected as 0.2 mg / L, 0.25 mg / L, or 0.3 mg / L, and maintained until the end of the light exposure. A nutrient solution circulation system can be used for nutrient solution replacement. This invention can accurately meet the boron requirements of rice during the panicle differentiation stage, promote panicle development, shorten the growth period, and improve the quality of rice growth.

[0063] According to another embodiment of the present invention, before continuing to supplement boric acid into the basic nutrient solution to a boron concentration of 0.2-0.3 mg / L, a synergist composed of calcium chloride, L-glutathione, and trehalose in a mass ratio of 1:(0.2-0.3):(0.05-0.1) is added to the basic nutrient solution to bring the L-glutathione concentration in the basic nutrient solution to 20-30 µM (micromoles per liter), and maintained for 20-30 minutes, before supplementing boric acid to the target high concentration; the mass ratio of calcium chloride, L-glutathione, and trehalose in the synergist can be selected as 1:0.2:0.05, 1:0.25:0.08, or 1:0.3:0.1, and the concentration of L-glutathione after addition can be selected as 20 µM, 25 µM, or 30 µM; the maintenance time can be selected as 20 minutes, 25 minutes, or 30 minutes. This invention can improve the absorption efficiency of boric acid in rice through synergists, enhance the boron supplementation effect, further promote the development of young panicles, and improve rice quality while ensuring a shorter growth period.

[0064] According to another embodiment of the present invention, the basic nutrient solution further includes phosphorus, potassium, calcium, magnesium, and trace elements, wherein phosphorus is provided in the form of dihydrogen phosphate at a concentration of 0.15-0.25 mM; potassium is provided in the form of potassium ions at a concentration of 1.0-1.4 mM; calcium is provided in the form of calcium ions at a concentration of 1.8-2.2 mM; magnesium is provided in the form of magnesium ions at a concentration of 0.8-1.2 mM; and the trace elements include iron, manganese, zinc, copper, and molybdenum, wherein iron is provided in the form of Fe-EDTA at a concentration of 20-30 μM; manganese is provided in the form of divalent manganese ions at a concentration of 10-15 μM; zinc is provided in the form of divalent zinc ions at a concentration of 2.0-4.0 μM; copper is provided in the form of divalent copper ions at a concentration of 0.5-1.0 μM; and molybdenum is provided in the form of heptamolybdate at a concentration of 0.05-0.15 μM. μM; the basic nutrient solution does not contain boron; for element regulation, phosphorus concentrations can be selected as 0.15 mM, 0.20 mM, or 0.25 mM, provided in the form of dihydrogen phosphate, and potassium dihydrogen phosphate can be used; potassium concentrations can be selected as 1.0 mM, 1.2 mM, or 1.4 mM, provided in the form of potassium ions, and potassium chloride or potassium nitrate can be used; calcium concentrations can be selected as 1.8 mM, 2.0 mM, or 2.2 mM, provided in the form of calcium ions, and calcium chloride can be used; magnesium concentrations can be selected as 0.8 mM, 1.0 mM, or 1.2 mM, provided in the form of magnesium ions, and magnesium sulfate can be used;

[0065] In the micronutrient regulation, the iron concentration can be selected at 20 μM, 25 μM, or 30 μM, provided in the form of Fe-EDTA; the manganese concentration can be selected at 10 μM, 12 μM, or 15 μM, provided in the form of divalent manganese ions, such as manganese sulfate; the zinc concentration can be selected at 2.0 μM, 3.0 μM, or 4.0 μM, provided in the form of divalent zinc ions, such as zinc sulfate; the copper concentration can be selected at 0.5 μM, 0.8 μM, or 1.0 μM, provided in the form of divalent copper ions, such as copper sulfate; and the molybdenum concentration can be selected at 0.05 μM, 0.10 μM, or 0.15 μM, provided in the form of heptamolybdate, such as ammonium molybdate. After preparation, the pH is maintained at 5.5-6 using a pH adjustment device. This invention can provide comprehensive and balanced nutrition for rice growth, ensuring normal growth and development, and laying a good nutritional foundation for carbon and nitrogen nutrition regulation and shortening the growth period.

[0066] The following examples and comparative examples illustrate the specific implementation:

[0067] <Example 1>

[0068] This invention provides a method for cultivating plant factories based on carbon and nitrogen nutrition regulation to shorten the growth period of rice. The specific implementation process is as follows:

[0069] Seed soaking, germination, and seedling raising: Select seeds of the Nipponbare rice variety, and after routine soaking and germination treatment, raise seedlings until they reach the 3-leaf, 1-heart seedling stage for later use.

[0070] Post-transplanting management: Transplant the rice seedlings to a hydroponic system in a plant factory, and simultaneously control the following cultivation conditions to promote early flowering of the rice:

[0071] Environmental control: Maintain the carbon dioxide concentration in the plant factory environment at 1000 ppm;

[0072] Light control: Basic illumination is provided using full-spectrum LED plant grow lights, with a light cycle of 11 hours per day, starting at 8:00 AM daily; the photosynthetically active radiation intensity is 300 μmol / m². -2 s -1 ;

[0073] Nutrient solution control: Rice was cultivated using a basic nutrient solution that did not contain boron; the total nitrogen concentration in the basic nutrient solution was 2.2 mM, and the molar ratio of ammonium nitrogen to nitrate nitrogen was 3:1; hydrochloric acid and sodium hydroxide solutions were used for pH adjustment.

[0074] Metabolic acid promoter addition: During rice cultivation, a metabolic acid promoter is added to the basal nutrient solution. The metabolic acid promoter consists of L-carnitine and aconitine in a molar ratio of 1.7:1 (mixed directly before use). The addition method is as follows:

[0075] S1. When the leaf age index of the main stem reaches 60%, add a metabolism promoter to the basic nutrient solution until the L-carnitine concentration in the basic nutrient solution reaches 0.005 mM, and maintain it for 36 hours after the addition is completed.

[0076] S2. After maintenance, add a metabolic promoter to the basal nutrient solution again to raise the L-carnitine concentration to 0.014mM, and maintain this concentration for 3 days. After maintenance, continue to use the basal nutrient solution for cultivation.

[0077] Harvesting: Harvest the rice after it has matured;

[0078] The basic nutrient solution also includes phosphorus, potassium, calcium, magnesium, and trace elements. Phosphorus is provided in the form of dihydrogen phosphate at a concentration of 0.20 mM; potassium in the form of potassium ions at a concentration of 1.2 mM; calcium in the form of calcium ions at a concentration of 2.0 mM; and magnesium in the form of magnesium ions at a concentration of 1.0 mM. The trace elements include iron, manganese, zinc, copper, and molybdenum. Iron is provided in the form of Fe-EDTA at a concentration of 25 μM; manganese in the form of divalent manganese ions at a concentration of 12 μM; zinc in the form of divalent zinc ions at a concentration of 3.0 μM; copper in the form of divalent copper ions at a concentration of 0.8 μM; and molybdenum in the form of heptamolybdate at a concentration of 0.10 μM.

[0079] <Example 2>

[0080] Rice cultivation was carried out using the method of Example 1, except that the preparation method of the metabolism promoter included the following steps:

[0081] A1. Mix L-carnitine and aconitine, dissolve them in 2-(N-morpholino)ethanesulfonic acid buffer solution with pH 6.0±0.1 to prepare a mixed stock solution with a total concentration of 12 mM; add the mixed stock solution dropwise to citrate-sodium citrate buffer solution with pH 4.0±0.2 while stirring at a rate of 1 mL / min, control the pH of the final mixed system to 5.4±0.1, and let it stand at 25℃ for 30 minutes to obtain the complex precursor dispersion;

[0082] A2. Under magnetic stirring, the complex precursor dispersion was mixed with an equal volume of chitosan hydrochloride solution with a concentration of 1.0 mg / mL, and then ultrasonicated (ultrasonic power 100 W, ultrasonic time 20 minutes, frequency 40 kHz) to obtain a nanocomposite suspension.

[0083] A3. While stirring, add sodium tripolyphosphate solution dropwise to the nanocomposite suspension. The final concentration of sodium tripolyphosphate is 0.10 w / v%. After the addition is complete, continue stirring for 30 minutes to obtain a nanogel suspension.

[0084] A4. The nanogel suspension was placed at 4°C and treated under a vacuum of -0.09 MPa for 12 minutes. After restoring to normal pressure, it was stored at 4°C in the dark to obtain the metabolism promoter.

[0085] <Example 3>

[0086] Rice cultivation was carried out using the method of Example 2, except that in step A2, before mixing the complex precursor dispersion with the chitosan hydrochloride solution, the chitosan hydrochloride solution was first mixed with sodium chloride to make the final concentration of sodium chloride 0.02 mol / L, thus obtaining the modified chitosan solution.

[0087] The complex precursor dispersion and the modified chitosan solution were then mixed in equal volumes at 30°C. After mixing, the system was allowed to stand for 30 minutes to obtain a nanoscale composite suspension.

[0088] <Example 4>

[0089] Rice was cultivated using the method of Example 3, except that during the rice flowering period, the daytime temperature was maintained at 24-26°C and the nighttime temperature was controlled at 18-20°C.

[0090] On the first day of the flowering period, a gas and chemical synergistic regulation was implemented: 1-methylcyclopropene gas was released into the growing area at a concentration of 0.6 ppm during the nighttime temperature period for 1.5 hours; the day after the release of 1-methylcyclopropene gas, at the 5th hour of light, a targeted slow-release formulation containing 100 μmol / L melatonin and 0.015 w / v% cationic guar gum was sprayed onto the spikelets of the rice plants.

[0091] <Example 5>

[0092] Rice was cultivated using the method of Example 4, except that 1-methylcyclopropene was not released.

[0093] <Example 6>

[0094] Rice was cultivated using the method of Example 4, except that the targeted sustained-release formulation did not contain melatonin, that is, the targeted sustained-release formulation contained cationic guar gum at a concentration of 0.015 w / v%.

[0095] <Example 7>

[0096] Rice was cultivated using the method described in Example 4, except that the targeted sustained-release formulation also contained pectin lyase at a concentration of 0.035 w / v%, wherein the pectin lyase was a chemically modified photoactivated pectin lyase; the photoactivated pectin lyase had a photocage protecting group covalently linked to the amino acid side chain at one of its allosteric sites, and the photocage protecting group was 4,5-dimethoxy-2-nitrobenzyl.

[0097] Ten hours after spraying the targeted sustained-release formulation, the rice panicles were given a supplemental light treatment. The peak spectral intensity of the supplemental light was 350-370 nm (ultraviolet light), and its photon flux density was 30 μmol m. -2 s -1 Irradiation was continued for 20 minutes to specifically remove photocage protective groups and activate the activity of pectin lyase.

[0098] Photoactivated pectin lyase is encapsulated in microcapsules, the capsule walls of which are formed by cross-linking polyvinyl alcohol with phenylboronic acid derivatives.

[0099] <Example 8>

[0100] Rice cultivation was carried out using the method described in Example 7, except that: starting from the early stage of rice panicle differentiation, boron supplementation was performed for two consecutive cycles, with each cycle lasting three days. The specific operation method for each cycle was as follows:

[0101] At the beginning of the first day of light exposure, boric acid was added to the basal nutrient solution to maintain a boron concentration of 0.07 mg / L for 5 hours.

[0102] Then, continue to supplement boric acid into the basic nutrient solution until the concentration of boron element is 0.25 mg / L, and maintain this level until the light exposure ends.

[0103] After the light exposure ends, replace the nutrient solution with the basic nutrient solution.

[0104] <Example 9>

[0105] Rice cultivation was carried out using the method of Example 8, except that before continuing to supplement boric acid into the basal nutrient solution to a boron concentration of 0.25 mg / L, a synergist composed of calcium chloride, L-glutathione, and trehalose in a mass ratio of 1:0.25:0.075 was first added to the basal nutrient solution to bring the L-glutathione concentration in the basal nutrient solution to 25 μM, which was maintained for 25 minutes, and then boric acid was supplemented to the target high concentration.

[0106] <Comparative Example 1>

[0107] Rice was cultivated based on the method described in Example 1. The cultivation method was as follows:

[0108] Soaking, germination, and seedling raising: Select seeds of the Japanese white rice variety, soak and germinate them according to conventional methods, and then raise and cultivate them into seedlings. The rice seedlings will be ready for use when they grow to the 3-leaf and 1-heart stage.

[0109] Post-transplanting management: Transplant the above-mentioned rice seedlings into the hydroponic system in the plant factory and control the following conventional cultivation conditions;

[0110] Environmental control: Maintain the carbon dioxide concentration in the plant factory environment at the natural atmospheric level (approximately 400 ppm).

[0111] Nutrient solution control: Rice was cultivated using conventional hydroponic nutrient solution, which did not contain boron; the total nitrogen concentration in the nutrient solution was 1.0 mM, and the molar ratio of ammonium nitrogen to nitrate nitrogen was 1:1; hydrochloric acid and sodium hydroxide solutions were used for pH adjustment.

[0112] Light control: Use full-spectrum LED plant growth lights for basic lighting, with a light cycle of 8 hours per day;

[0113] No metabolic promoters are added during the cultivation process; conventional hydroponic nutrient solution is used continuously for cultivation.

[0114] Harvesting: Harvest the rice after it has matured.

[0115] <Comparative Example 2>

[0116] Rice was cultivated using the method described in Example 1, except that the cultivation conditions were as follows:

[0117] Environmental control: Maintain the carbon dioxide concentration in the plant factory environment at the natural atmospheric level (approximately 400 ppm).

[0118] Nutrient solution control: Rice was cultivated using conventional hydroponic nutrient solution, which did not contain boron; the total nitrogen concentration in the nutrient solution was 1.0 mM, and the molar ratio of ammonium nitrogen to nitrate nitrogen was 1:1; hydrochloric acid and sodium hydroxide solutions were used for pH adjustment.

[0119] Light control: Use full-spectrum LED plant growth lights for basic lighting, with a light cycle of 8 hours per day;

[0120] Metabolic promoter addition: During rice cultivation, a metabolic promoter is added to the basic nutrient solution. The metabolic promoter includes L-carnitine and aconitine in a molar ratio of 1.7:1 (mixed directly before use).

[0121] <Comparative Example 3>

[0122] Rice was cultivated using the method of Example 1, except that L-carnitine was added as a control, replacing the metabolism promoter.

[0123] <Comparative Example 4>

[0124] Rice was cultivated using the method of Example 1, except that aconitine was added as a control, replacing the metabolism promoter.

[0125] <Experimental Characterization>

[0126] 1. Growth period and yield per plant

[0127] Growing period: Record the total number of days from the date of transplanting to the date of harvest.

[0128] Yield per plant: Total dry weight of all plump grains per plant (dried at 65℃ to constant weight);

[0129] The results are shown in Table 1;

[0130] Table 1 shows the number of days in the growing season and the yield per plant.

[0131]

[0132] Table 1 shows that the various embodiments of the plant factory cultivation method based on carbon and nitrogen nutrition regulation of the present invention exhibit significant advantages in both growth period and yield per plant compared to the comparative examples using conventional cultivation conditions or lacking key regulatory links. With the gradual integration and improvement of technical features such as optimized preparation of metabolic promoters, improved nutrient element ratios, synergistic regulation of flowering period, and precise boron supplementation in the cultivation method, the rice growth period shows a gradual shortening trend, while the yield per plant shows a continuous increasing trend. This fully demonstrates that the synergistic effect of the various technical means of the present invention can achieve both rapid rice cultivation and guaranteed yield improvement.

[0133] 2. Statistical analysis of the start of flowering time and flowering period.

[0134] Flowering start time: refers to the number of days from the date of transplanting to the opening of the first floret on the observed plant. Opening is defined as the observation of the anther emerging from the glumes. Record the specific number of days for each plant and calculate the average for the treatment groups; observations were conducted from 08:30 to 11:00 AM.

[0135] Flowering cycle: The number of days from the opening of the first flower to the opening of the last flower. The average flowering cycle of all observed plants in each treatment group was calculated. Observations were conducted from 08:30 to 11:00 in the morning.

[0136] The results are shown in Table 2;

[0137] Table 2 shows the flowering time and flowering period.

[0138]

[0139] As shown in Table 2, the embodiments using the optimized cultivation method of this invention exhibited significantly earlier flowering times and more concentrated flowering cycles compared to other groups. In particular, with the gradual integration of technologies such as improved metabolic promoter preparation processes, targeted regulation of flowering period, and the application of photoactivated enzyme preparations, the effect of advancing rice flowering has become increasingly significant. Simultaneously, the flowering period has been shortened, indicating that the cultivation conditions of this invention can precisely regulate the reproductive growth process of rice, promoting the efficient conversion of vegetative growth to reproductive growth, and providing crucial support for shortening the overall growth period.

[0140] <Microencapsulation Validation>

[0141] The following experiments were conducted on the microcapsules of photoactivated enzymes:

[0142] 1. Determine the light transmittance of the microcapsule wall.

[0143] Experimental group: microcapsule suspension containing photoactivated pectin lyase, enzyme concentration 0.02% w / v, basal nutrient solution;

[0144] Control group: Light-activated pectin lyase solution, enzyme concentration 0.02% w / v, basal nutrient solution;

[0145] Reference solution: basic nutrient solution;

[0146] Experimental equipment: UV-Vis spectrophotometer (available for purchase on the market), quartz cuvette (1 cm optical path), electronic balance, pipette, vortex mixer;

[0147] Transmittance and absorbance measurements: The UV-Vis spectrophotometer was turned on and preheated for 30 minutes. The measurement wavelength range was set to 350-370 nm, and detection points were set at 1 nm intervals. The reference solution was first added to a quartz cuvette and placed in the instrument for baseline calibration. After calibration, the microcapsule suspension of the experimental group and the free enzyme solution of the control group were added to the cuvettes respectively, and the transmittance and absorbance values ​​at each wavelength were measured in sequence.

[0148] Data processing: Each sample was measured three times in parallel at each wavelength point. The measured values ​​were recorded, and the average value and standard deviation were calculated to reduce experimental error.

[0149] Experimental results: The transmittance of the microcapsule suspension in the experimental group was greater than 85% across the entire wavelength range of 350-370 nm, and the difference in absorbance between the experimental group and the control group's free enzyme solution at the same wavelength did not exceed ±0.05. These data indicate that microencapsulation has minimal impact on light absorption and scattering in the target ultraviolet band of 350-370 nm. This demonstrates that the capsule wall material (polyvinyl alcohol-phenylboronic acid derivative) used in this embodiment is essentially transparent to activation light, ensuring that the activation light effectively penetrates the capsule wall to reach the photoactivated pectin lyase inside. This ensures the smooth occurrence of the specific deprotection reaction of the photocage protecting group, thereby achieving precise activation of enzyme activity and guaranteeing the regulatory effect of the targeted sustained-release formulation.

[0150] 2. Verify that light energy effectively activates enzymes within the capsules.

[0151] Experimental equipment: 350-370 nm narrow-spectrum LED illumination equipment (photon flux density 30 μmol m²) -2 s -1 ), UV-Vis spectrophotometer;

[0152] This experiment was set up with 3 experimental groups, each with 3 replicates in parallel, as follows;

[0153] Experimental group: microcapsule group treated with light;

[0154] Negative control group: Microcapsule group not exposed to light;

[0155] Positive control group: Free enzyme group treated with light;

[0156] Experimental methods:

[0157] Sample pretreatment: Equal volumes of microcapsule suspensions containing photoactivated pectin lyase were divided equally between the experimental group and the negative control group; a free photoactivated pectin lyase solution with the same enzyme content as the microcapsule suspension was added to the positive control group. All three groups of samples were adjusted to the same volume with blank basal nutrient solution and placed in a 25℃ constant temperature water bath for 30 minutes to ensure consistent initial temperature.

[0158] Illumination treatment: The 350-370 nm narrow-spectrum LED illumination device was turned on to illuminate the experimental group and the positive control group for 20 minutes. The sample temperature was maintained at 25°C during the illumination process. The negative control group was placed in the same environment but shielded from light and was not illuminated.

[0159] Enzyme activity assay: The DNS colorimetric method was used to determine the enzyme activity of each group. The specific steps are as follows: ① Take 1 mL of each group of treated samples, add 2 mL of buffer solution containing 1% pectin substrate (pH 5.5, consistent with the pH of the basic nutrient solution), and place in a 30℃ constant temperature water bath for 30 minutes; ② After the reaction, immediately add 3 mL of DNS reagent and heat in a boiling water bath for 5 minutes to terminate the reaction; ③ After cooling to room temperature, measure the absorbance value at a wavelength of 540 nm. The same operation was performed using blank basic nutrient solution instead of the sample as a blank control; ④ Calculate the amount of reducing sugar produced according to the glucose standard curve, and then calculate the enzyme activity (defined as the amount of reducing sugar produced by enzyme catalyzing pectin per unit mass per unit time).

[0160] Data processing: Record the absorbance values ​​of each group, calculate the mean and standard deviation of enzyme activity of each replicate in the positive control group, and compare the differences in enzyme activity among the groups using conventional analysis of variance.

[0161] Experimental results:

[0162] Experimental data showed that the enzyme activity in the experimental group (microcapsule group exposed to light) was significantly higher than that in the negative control group (microcapsule group without light exposure), with a marked increase in enzyme activity. Furthermore, there was no significant difference in enzyme activity between the experimental group and the positive control group (free enzyme group exposed to light), indicating comparable activation efficiency. These results directly demonstrate that activation light with a wavelength of 350-370 nm can effectively penetrate the microcapsule wall, successfully triggering the deprotection reaction of the photocage protecting group on the photoactivated pectin lyase within the capsule, thus effectively activating the enzyme activity. Simultaneously, it indicates that microencapsulation does not affect the photoactivation efficiency of the enzyme, ensuring that the encapsulated photoactivated pectin lyase can be precisely activated during actual cultivation, playing a role in degrading the pectin layer on the surface of the flower spike and enhancing melatonin absorption efficiency, thereby guaranteeing the regulatory effect of the targeted sustained-release formulation.

[0163] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A plant factory cultivation method for shortening the growth period of rice based on carbon and nitrogen nutrition regulation, including seed soaking, germination, seedling raising, post-transplanting management, and harvesting, characterized in that... Rice seedlings were transplanted into a hydroponic system in a plant factory, and the following cultivation conditions were controlled simultaneously to promote early flowering of rice: Maintain the carbon dioxide concentration in the plant factory environment at 400-1600 ppm; Basic illumination is provided using a full-spectrum artificial light source, with a light cycle of 10-12 hours per day and a photosynthetically active radiation intensity of 250-350 μmol m². -2 s -1 ; Rice was cultivated using a basic nutrient solution, wherein the total nitrogen concentration in the basic nutrient solution was 1.2-3.2 mM, the molar ratio of ammonium nitrogen to nitrate nitrogen in the basic nutrient solution was 2:1-4:1, and the pH value of the basic nutrient solution was 5.5-6.

5. During rice cultivation, a metabolism promoter is added to the basal nutrient solution. This promoter comprises L-carnitine and aconitine in a molar ratio of 1.2:1 to 2.2:

1. The method for adding the metabolism promoter is as follows: S1. When the leaf age index of the main stem reaches 55%-65%, add a metabolism promoter to the basic nutrient solution until the L-carnitine concentration in the basic nutrient solution reaches 0.004-0.006 mM, and maintain it for 24-48 hours after the addition is completed. S2. After maintenance, add a metabolism promoter to the basal nutrient solution again to raise the L-carnitine concentration to 0.01-0.018mM, and maintain this concentration for 2-4 days. After maintenance, continue to use the basal nutrient solution for cultivation. The preparation method of the metabolism promoter includes the following steps: A1. Mix L-carnitine and aconitine, dissolve them in 2-(N-morpholino)ethanesulfonic acid buffer solution with pH 6.0±0.1 to prepare a mixed stock solution with a total concentration of 10-15 mM; add the mixed stock solution dropwise to citrate-sodium citrate buffer solution with pH 4.0±0.2 while stirring at a rate of 1-2 mL / min, control the pH of the final mixed system to 5.2-5.6, and let it stand at 25℃ for 30 minutes to obtain the complex precursor dispersion; A2. Under magnetic stirring, the complex precursor dispersion was mixed with an equal volume of chitosan hydrochloride solution with a concentration of 0.8-1.2 mg / mL, and then ultrasonically treated to obtain a nanocomposite suspension. A3. While stirring, add sodium tripolyphosphate solution dropwise to the nanocomposite suspension. The final concentration of sodium tripolyphosphate is 0.05-0.15 w / v%. After the addition is complete, continue stirring for 30 minutes to obtain a nanogel suspension. A4. Place the nanogel suspension at 4°C and treat it under a vacuum of -0.08 to -0.10 MPa for 10-15 minutes. Then restore it to normal pressure and store it at 4°C in the dark to obtain the metabolism promoter.

2. The plant factory cultivation method for shortening the rice growth period based on carbon and nitrogen nutrition regulation as described in claim 1, characterized in that, In step A2, before mixing the complex precursor dispersion with the chitosan hydrochloride solution, the chitosan hydrochloride solution is first mixed with sodium chloride to make the final concentration of sodium chloride 0.01-0.03 mol / L, thus obtaining the modified chitosan solution; The complex precursor dispersion and the modified chitosan solution were then mixed in equal volumes at 28-32℃. After mixing, the system was allowed to stand for 25-35 minutes to obtain a nanoscale composite suspension.

3. The plant factory cultivation method for shortening the rice growth period based on carbon and nitrogen nutrition regulation as described in claim 1, characterized in that, During the rice flowering period, daytime temperatures should be maintained at 24-26°C, and nighttime temperatures should be controlled at 18-20°C. On the first day of the flowering period, a gas and chemical synergistic regulation was implemented: 1-methylcyclopropene gas was released into the growing area during the nighttime temperature period at a concentration of 0.5-0.8 ppm for 1-2 hours; the day after the release of 1-methylcyclopropene gas, a targeted slow-release formulation was sprayed onto the spikelets of rice plants during the 4th-6th hour of light exposure. The targeted slow-release formulation contained melatonin at a concentration of 50-150 μmol / L and cationic guar gum at a concentration of 0.01-0.02 w / v%, and was sprayed onto the spikelets of rice plants.

4. The plant factory cultivation method for shortening the rice growth period based on carbon and nitrogen nutrition regulation as described in claim 3, characterized in that, The targeted sustained-release formulation also contains pectin lyase at a concentration of 0.02-0.05 w / v%, wherein the pectin lyase is a chemically modified photoactivated pectin lyase; the photoactivated pectin lyase has a photocage protecting group covalently attached to the amino acid side chain at one allosteric site, and the photocage protecting group is 4,5-dimethoxy-2-nitrobenzyl. Ten hours after spraying the targeted sustained-release formulation, the rice panicles were given supplemental lighting. The peak spectral density of the supplemental lighting was 350-370 nm, and the photon flux density was 20-40 μmol m. -2 s -1 Irradiate continuously for 15-30 minutes to specifically remove photocage protective groups and activate the activity of pectin lyase.

5. The plant factory cultivation method for shortening the rice growth period based on carbon and nitrogen nutrition regulation as described in claim 4, characterized in that, Photoactivated pectin lyase is encapsulated in microcapsules, the capsule walls of which are formed by cross-linking polyvinyl alcohol with phenylboronic acid derivatives.

6. The plant factory cultivation method for shortening the rice growth period based on carbon and nitrogen nutrition regulation as described in claim 1, characterized in that, Starting from the early stage of rice panicle differentiation, boron supplementation was performed for two consecutive cycles, each lasting three days. The specific operation method for each cycle was as follows: At the beginning of the first day of light exposure, add boric acid to the basal nutrient solution to make the boron concentration in the basal nutrient solution 0.05-0.09 mg / L, and maintain it for 4-6 hours. Then continue to supplement boric acid into the basic nutrient solution until the concentration of boron element is 0.2-0.3 mg / L, and maintain this until the end of the light exposure. After the light exposure ends, replace the nutrient solution with the basic nutrient solution.

7. The plant factory cultivation method for shortening the rice growth period based on carbon and nitrogen nutrition regulation as described in claim 6, characterized in that, Before supplementing the basal nutrient solution with boric acid to a boron concentration of 0.2-0.3 mg / L, add a synergist made of calcium chloride, L-glutathione, and trehalose in a mass ratio of 1:(0.2-0.3):(0.05-0.1) to the basal nutrient solution to bring the L-glutathione concentration in the basal nutrient solution to 20-30 µM and maintain it for 20-30 minutes before supplementing with boric acid to the target high concentration.

8. The plant factory cultivation method for shortening the rice growth period based on carbon and nitrogen nutrition regulation as described in claim 1, characterized in that, The basic nutrient solution also includes phosphorus, potassium, calcium, magnesium, and trace elements. Phosphorus is provided in the form of dihydrogen phosphate at a concentration of 0.15-0.25 mM; potassium in the form of potassium ions at a concentration of 1.0-1.4 mM; calcium in the form of calcium ions at a concentration of 1.8-2.2 mM; and magnesium in the form of magnesium ions at a concentration of 0.8-1.2 mM. Trace elements include iron, manganese, zinc, copper, and molybdenum. Iron is provided in the form of Fe-EDTA at a concentration of 20-30 μM; manganese in the form of divalent manganese ions at a concentration of 10-15 μM; zinc in the form of divalent zinc ions at a concentration of 2.0-4.0 μM; copper in the form of divalent copper ions at a concentration of 0.5-1.0 μM; and molybdenum in the form of heptamolybdate at a concentration of 0.05-0.15 μM.

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