Aroma-enhancing and aroma-keeping cultivation method for upland rice

Abstract

The invention discloses an aroma-enhancing and aroma-keeping cultivation method for upland rice, which comprises the following steps: controlling the application amount of pure nitrogen to be 60-80kg / ha in a vegetative growth period, applying a base fertilizer and a tillering fertilizer in a ratio of 1: 1 for several times, and synchronously applying phosphoric dianhydride; stopping nitrogen fertilizer supply in the early reproductive stage, topdressing phosphoric dianhydride and potassium oxide, and maintaining the soil water content to be 60-70% of the field moisture capacity in the filling stage; the preparation method comprises the following steps: preparing a liquid medicine taking jasmine leaching liquid as a basic solvent, adding trehalose and tea saponin, and adjusting the pH value to 5.6-6.0; the pesticide liquid is uniformly sprayed on the front and back sides of the leaves at nightfall from the full heading stage to the early grouting stage, mild nitrogen stress is created through fertilizer and water regulation, aroma degradation is inhibited, and precursor accumulation is promoted; the liquid medicine formula synergistically activates aroma synthesis genes and promotes glycosylation conversion, so that the aroma stability is enhanced; the absorption efficiency is improved by combining spraying at nightfall and utilizing physiological characteristics, so that efficient induction and long-acting maintenance of aroma substances are realized, the problem that aroma of dry rice is easy to lose is effectively solved, and the quality and durability of the aroma of the rice are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of agricultural cultivation technology, and in particular to a method for enhancing and preserving the aroma of dryland rice. Background Technology

[0002] Upland rice is a type of rice that is highly adaptable, drought-resistant, and water-saving. However, compared to paddy rice, upland rice faces more complex challenges in improving and maintaining its aroma and quality.

[0003] However, existing aroma-enhancing technologies have significant shortcomings at the principle level. Although these methods can promote the synthesis of 2-AP in upland rice and achieve the initial accumulation of aroma substances, their focus is too concentrated on the generation stage of aroma substances, while insufficient attention is paid to how to effectively retain aroma substances in the harsh cultivation environment of high temperature and drought after generation. Upland rice often encounters the dual stress of high daytime temperature and soil drought during the grain-filling stage. Under such extreme conditions, the newly synthesized free 2-AP, as a small molecule volatile substance, has inherent instability and is easily lost physically due to thermal volatilization caused by high temperature, or chemically due to degradation by reactive oxygen species, resulting in the loss of a large amount of aroma substances before maturity. Ultimately, this leads to a low aroma retention rate in harvested rice, making it difficult to fully demonstrate the aroma-enhancing effect. This technical route that emphasizes synthesis over aroma preservation has become a deep contradiction that is difficult to overcome in the application of existing methods in upland rice, seriously restricting the stable improvement of aroma quality.

[0004] Therefore, it is necessary to provide a cultivation method for enhancing and preserving the aroma of dryland rice to solve the above-mentioned technical problems. Summary of the Invention

[0005] This invention overcomes the shortcomings of the prior art and provides a method for enhancing and preserving the fragrance of dryland rice.

[0006] To achieve the above objectives, the technical solution adopted by this invention is: a method for enhancing and preserving the aroma of dryland rice, comprising the following steps:

[0007] S1. During the vegetative growth period of upland rice, control the application of pure nitrogen to 60-80 kg per hectare, of which the base fertilizer and tillering fertilizer are applied in a 1:1 ratio in multiple applications, and simultaneously apply 35-45 kg of phosphate dianhydride per hectare as base fertilizer.

[0008] S2. Stop supplying nitrogen fertilizer in the early stage of reproductive growth, and apply 20-30 kg of phosphodianhydride and 60 kg of potassium oxide per hectare as top dressing. Maintain the soil moisture content at 60-70% of field capacity during the grain-filling stage.

[0009] S3. Prepare jasmine infusion as a base solvent, and add trehalose and plant-derived surfactant tea saponin, mix uniformly, adjust the pH value of the mixed solution to 5.6-6.0, form a liquid medicine, and the addition amount of trehalose is 1-3 g / L and the addition amount of tea saponin is 0.5-1.5 g / L based on the volume of jasmine infusion;

[0010] S4. Spraying is carried out in the evening during the heading stage to the early grain filling stage of upland rice;

[0011] S5. The liquid medicine is uniformly sprayed on the front and back of the upland rice leaf, and the droplet size and spraying amount are controlled.

[0012] In one preferred embodiment of the present application, in the S1, the pure nitrogen application amount of base fertilizer and tillering fertilizer is 30-40 kg per hectare, and the nitrogen fertilizer is selected from urea or ammonium sulfate; and the SPAD value of the leaf during the tillering stage is monitored to be 35-40.

[0013] In one preferred embodiment of the present application, in the S2, the phosphorus and potassium fertilizer is applied during the young ear differentiation stage, the water regulation is monitored by sensors arranged in the 0-30 cm and 30-60 cm soil layers, and an automatic irrigation system is used.

[0014] 2. In one preferred embodiment of the present application, in the S3, the preparation method of jasmine infusion includes the following steps:

[0015] S3.1 Fresh jasmine flowers are weighed and placed in water, the water temperature is maintained at 35-45℃, and the mixture is soaked for 22-26 hours to form a mixed solution;

[0016] S3.2 The mixed solution after soaking is filtered through a filter screen with a pore size of 180-200 μm to separate the flower residue and collect the jasmine infusion.

[0017] In one preferred embodiment of the present application, in the S3.1, the mass ratio of fresh jasmine flowers to water is 1:7-9, and the variety of fresh jasmine flowers is double-petal jasmine.

[0018] In one preferred embodiment of the present application, in the S3, the trehalose is D-(+)-trehalose, the purity of the trehalose is 99.8%, and the purity of the active ingredient tea saponin in the surfactant is 95%.

[0019] In one preferred embodiment of the present application, in the S4, the specific time point of spraying during the heading stage to the early grain filling stage of upland rice is within 7-14 days after the upland rice heading, and the specific time in the evening is 16:00-18:00 in the afternoon.

[0020] In a preferred embodiment of the present application, in the S5, the agricultural spraying device used in the spraying operation is a fan-shaped nozzle, which ensures a spraying angle of 100-120° and a coverage width of 1-2 m, and the spraying is carried out at a pressure of 0.1-0.3 MPa.

[0021] In a preferred embodiment of the present application, in the S5, the droplet size is controlled so that the atomized liquid forms droplets with an average particle size of 50-100 μm, and the spraying amount is controlled so that the leaves are evenly wetted but the liquid does not drip.

[0022] In a preferred embodiment of the present application, in the S5, the spraying amount is controlled to be 30-50 L of liquid per mu.

[0023] The present application solves the defects in the background art and has the following beneficial effects:

[0024] (1) The present application provides a dry rice aroma-enhancing and aroma-preserving cultivation method, which controls the fertilizer and water management, that is, reasonably controls the nitrogen fertilizer amount during the vegetative growth period and applies it in several times, stops the supply of nitrogen fertilizer during the reproductive growth period and increases the application of phosphorus and potassium fertilizer, and maintains the soil moisture in a suitable range. This creates a mild nitrogen stress environment, effectively inhibits the activity of aroma degradation genes, promotes the accumulation of aroma precursor substances, and provides sufficient energy and substrate for aroma synthesis, thereby significantly improving the synthesis efficiency of aroma substances in dry rice. Compared with the existing technology, which often causes aroma degradation due to excessive or improper application of nitrogen fertilizer, the present application balances the supply of fertilizer and water, avoids metabolic disorders, and can build a stable cell metabolic environment, so that the aroma substances are efficiently converted in the grain and stably exist for a long time, thereby enhancing the aroma persistence and overall quality of rice.

[0025] (2) The present application provides a dry rice aroma-enhancing and aroma-preserving cultivation method, which uses jasmine infusion as the base solvent, and combines trehalose and plant-derived surfactants, and adjusts the liquid to a slightly acidic condition. In this formula, the natural active ingredients contained in the jasmine infusion can simulate the endogenous signals of plants and effectively activate the expression of aroma synthesis genes. Trehalose acts as a glycosyl donor and a signal molecule, promoting the glycosylation reaction of aroma substances. The surfactant helps to improve the spreading and adhesion of the liquid on the leaf surface, and the slightly acidic environment optimizes the transmembrane absorption efficiency of the liquid. This can greatly improve the biosynthesis rate and stabilization degree of aroma substances, increase the instantaneous concentration of aroma, and through glycosylation conversion, make the aroma substances have the characteristics of high temperature resistance and oxidation resistance, so as to ensure that the aroma is completely preserved during the subsequent processing and storage of rice, and realize the efficient induction and long-term preservation of aroma.

[0026] (3) The application provides a dry rice flavoring and flavor preserving cultivation method, which selects a key growth stage of dry rice and combines with liquid medicine spraying at the end of each day, the physiological characteristics of open plant stomata caused by air temperature drop and air humidity rise in the evening are utilized, and the liquid medicine absorption is significantly promoted; meanwhile, the active ingredients in the liquid medicine are efficiently transported to the grains by means of the active material transportation system of the plant at night, in the spraying technology aspect, an optimized spraying mode is adopted, the liquid drop size and distribution are controlled, the liquid medicine is uniformly covered on the front and back surfaces of the leaves, so that the contact area of the liquid medicine and the leaves is maximized; the time intervention directly improves the absorption efficiency and utilization rate of the active ingredients in the liquid medicine, and also activates the aroma synthesis and storage mechanism in the grains, promotes the free aroma substances to be converted into non-volatile glycoside form, so that after the rice is harvested, even after processing, the rich aroma can be re-released through simple treatment, and the flavor preserving goal from production to consumption is realized. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0028] Figure 1 is a flowchart of the preferred embodiment of the present application; DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0030] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, therefore, the protection scope of the present application is not limited by the specific embodiments disclosed below.

[0031] As Figure 1 shown, the present application provides a dry rice flavoring and flavor preserving cultivation method, a dry rice flavoring and flavor preserving cultivation method, comprising the following steps:

[0032] S1. During the vegetative growth period of upland rice, the amount of pure nitrogen applied is controlled to be 60-80 kg per hectare, wherein the base fertilizer and the tillering fertilizer are applied in several times in a ratio of 1:1, and diphosphoric anhydride is applied synchronously as base fertilizer at 35-45 kg per hectare, the amount of pure nitrogen applied in the base fertilizer and the tillering fertilizer is 30-40 kg per hectare respectively, and the nitrogen fertilizer is selected from urea or ammonium sulfate; and by monitoring, the leaf SPAD value in the tillering period is controlled to be 35-40;

[0033] S2. The supply of nitrogen fertilizer is stopped in the early reproductive growth period, diphosphoric anhydride is applied at 20-30 kg per hectare, potassium oxide is applied at 60 kg per hectare, and the soil water content is maintained at 60-70% of the field water holding capacity during the grain filling period, the phosphorus and potassium fertilizers are applied during the young ear differentiation period, the water content is monitored through sensors arranged in the 0-30 cm and 30-60 cm soil layers, and an automatic irrigation system is used to realize the water content regulation;

[0034] S3. A jasmine extract solution is prepared as a base solvent, and trehalose and a plant-derived surfactant tea saponin are added, the mixture is uniformly mixed, and then the pH value of the mixture is adjusted to 5.6-6.0 to form a liquid medicine, wherein the amount of trehalose added is 1-3 g / L based on the volume of the jasmine extract solution, and the amount of tea saponin added is 0.5-1.5 g / L, the trehalose is D-(+)-trehalose, the purity of the trehalose is 99.8%, and the purity of the active ingredient tea saponin in the surfactant is 95%;

[0035] S4. The spraying is performed in the evening during the heading period to the early grain filling period of the upland rice, and the specific time point of the spraying during the heading period to the early grain filling period of the upland rice is within 7-14 days after the heading of the upland rice, and the specific time in the evening is 16:00-18:00 in the afternoon;

[0036] S5. The liquid medicine is uniformly sprayed on the front and back surfaces of the upland rice leaves, the droplet size and the spraying amount are controlled, the spraying amount is controlled to be 30-50 L of the liquid medicine per mu, the agricultural spraying equipment used in the spraying operation is a fan-shaped nozzle, the spraying angle is ensured to be 100-120°, the coverage width is 1-2 m, the spraying is performed at 0.1-0.3 MPa, the droplet size is controlled to be that the liquid medicine is atomized to form droplets with an average particle size of 50-100 μm, and the spraying amount is controlled to be that the leaves are uniformly wet but the liquid medicine does not drip.

[0037] In the following, each step will be described in detail.

[0038] In step S1, the amount of pure nitrogen applied is controlled to be 60-80 kg per hectare at a relatively low level, and the base fertilizer and the tillering fertilizer are applied in several times in a ratio of 1:1, which not only meets the growth demand of the plants, but also is a mild nitrogen stress physiological environment;

[0039] Under this environment, the expression of BADH2 gene responsible for the degradation of key aroma 2-AP in the body of upland rice will be significantly inhibited, at the same time, the conversion of aroma precursor-△1-pyrroline to other metabolic pathways will also be reduced, so that more precursor substances can be accumulated to prepare for the subsequent explosive synthesis of aroma;

[0040] At this stage, 35-45 kg of phosphoric acid dihydride per hectare is applied as a base fertilizer, and phosphorus element is not only necessary for the healthy development of upland rice root system and the establishment of early photosynthetic capacity, but also an important raw material for the synthesis of ATP, NADPH and UDP-glucose, a key sugar donor for the subsequent "sugar-based solidification of aroma".

[0041] Therefore, the application of phosphorus at this time is equivalent to reserving sufficient reaction substrates and structural components for the biochemical reaction of converting free aroma into stable form during the metabolism period, especially the grain filling period, and to ensure the effective implementation of nitrogen control measures, the application introduces a quantifiable monitoring index, that is, maintaining the leaf SPAD value at 35-40 during the tillering period.

[0042] SPAD value is a sensitive indicator of leaf nitrogen nutrition status, and stabilizing this value in a certain range is the key to achieving ideal mild nitrogen stress, which ensures that the plant will not be affected by nitrogen deficiency to affect normal growth and yield construction, and effectively activates the aforementioned nitrogen control aroma physiological mechanism to avoid the negative effects of excessive nitrogen on aroma synthesis.

[0043] In step S2, by different fertilizer and water regulation, nitrogen fertilizer supply is stopped while phosphorus and potassium nutrition is strengthened, and water management is implemented to synergistically promote the synthesis and conversion of aroma substances into stable form.

[0044] Specifically, nitrogen fertilizer supply must be completely stopped from the early reproductive growth period to the booting stage, which is to avoid the risk of overexpression of BADH2 gene induced by high nitrogen environment at the booting stage, so as to protect the aroma precursor substances that have been successfully accumulated during the vegetative growth period from being degraded;

[0045] At this stage, 20-30 kg of phosphoric acid dihydride per hectare and 60 kg of potassium oxide per hectare need to be applied, and the application should be carried out during the young ear differentiation period. The key role of applying phosphorus fertilizer is that it is an essential element for the synthesis of adenosine triphosphate, reduced coenzyme II, and an important sugar donor uridine diphosphate glucose.

[0046] High phosphorus environment can effectively activate glycolysis and pentose phosphate pathway to directly provide energy and sugar donor precursors for the subsequent glycosylation reaction of aroma substances, and the application of potassium element plays a role in maintaining osmotic pressure and activating the activity of various metabolic enzymes, which cooperates with phosphorus element to ensure smooth carbon metabolic flow.

[0047] After entering the grain-filling stage, water management becomes the core, and the soil water content needs to be maintained at 60-70% of the field water holding capacity through drip irrigation or micro-sprinkler irrigation systems. Water regulation is achieved by real-time monitoring of soil moisture sensors placed in the key root distribution soil layers of 0-30 cm and 30-60 cm, and connecting the automatic irrigation system.

[0048] Maintaining this specific water interval has a double physiological significance: first, it can avoid severe drought leading to the decline of glycosyltransferase activity responsible for the glycosylation of aroma substances, while preventing root hypoxia caused by over-wet soil; second, this mild water stress state itself can induce the activation of the jasmonic acid signaling pathway in the body of upland rice, which can produce a signal superposition effect with the subsequent foliar spraying of jasmine extract, and together enhance the activation of aroma synthesis genes;

[0049] Step S2 connects the previous and next steps, through a series of interventions such as stopping nitrogen to preserve precursors, increasing phosphorus and potassium to provide energy, and controlling water to stabilize enzyme activity, to create an optimal intracellular environment for the large amount of aroma substances synthesized during the grain-filling stage, which is the decisive link to achieve the goal of preserving aroma and overcome the problem of aroma loss caused by high temperature and drought.

[0050] In step S3, the preparation method of jasmine extract includes the following steps:

[0051] S3.1 Weigh fresh jasmine flowers and place them in water, maintain the water temperature at 35-45℃, soak for 22-26h, the mass ratio of fresh jasmine flowers to water is 1:7-9, the variety of fresh jasmine flowers is double-petal jasmine, and a mixed solution is formed;

[0052] S3.2 The mixed solution after soaking is filtered through a filter screen with a pore size of 180-200μm to separate the flower residue and collect the jasmine extract.

[0053] The extract is rich in natural active substances such as jasmonate, which is used as a precursor of jasmonic acid signal after being absorbed by the plant, activates the expression of genes related to the synthesis of 2-acetyl-1-pyrroline, and thus directly promotes the generation of aroma substances.

[0054] In the jasmine infusion, high-purity trehalose is added, and the added amount of trehalose is controlled at 1-3 g / L based on the volume of the jasmine infusion. The trehalose used is D-(+)-trehalose, and the purity is not less than 99.8%. As a stable non-reducing disaccharide, the core role of trehalose is not directly as a nutrient, but after being absorbed and hydrolyzed into glucose, on the one hand, it provides a sugar donor for the glycosylation reaction of aroma substances, and on the other hand, it itself as a signal molecule can activate the SnRK1 signal pathway, and then up-regulate the expression of the key glycosyltransferase UGT74H3, laying an enzymatic foundation for the conversion of free aroma substances into stable glycoside forms.

[0055] In order to improve the adhesion and absorption efficiency of the liquid medicine on the waxy leaves of upland rice, a plant-derived surfactant tea saponin is also added. The added amount of tea saponin is also controlled at 0.5 to 1.5 grams per liter based on the volume of the jasmine infusion, and the purity of the active ingredient tea saponin is not less than 95%. Tea saponin can significantly reduce the surface tension of the liquid medicine, so that it can spread uniformly on the leaf surface to form a liquid film, prevent the liquid medicine from gathering into beads and rolling off, and ensure that the active ingredients can fully contact with the leaf surface.

[0056] In step S3, an acidic adjusting agent such as citric acid is used to adjust the pH value of the mixed liquid medicine to a slightly acidic range of 5.6-6.0, which can help to reduce the charge repulsion between the liquid medicine and the negatively charged leaf surface, and to enhance the permeability of the cuticle layer of the leaf, thereby optimizing the transmembrane absorption efficiency of the active ingredients such as jasmonate and trehalose;

[0057] It is noted that no exogenous nitrogen, phosphorus, and potassium fertilizers are added during the entire preparation process, in order to avoid unnecessary interference with the metabolic homeostasis of the plants established in the front-end cultivation.

[0058] In step S4, it is emphasized that the spraying operation is carried out in the evening during the full heading to early grain filling period, and the specific time window is the core link to ensure that the composite aroma-fixing liquid medicine can play the maximum effect. The reason is that it is highly synergistic with the physiological rhythm of upland rice and the field microenvironment.

[0059] Specifically, the specific time point of spraying should be selected within 7 to 14 days after the upland rice heading, at which time the rice plant is in the key physiological stage of transition from full heading to early grain filling. The spraying is carried out in the evening, i.e. from 16:00 to 18:00, which is based on the consideration of multiple environmental and physiological factors;

[0060] At this time, the light intensity decreases, the air temperature gradually decreases, and the air humidity begins to rise. These changes together promote the stomata of the upland rice leaves to open moderately. The opening of the stomata provides an efficient channel for the active ingredients in the liquid medicine, such as jasmonate and trehalose, to enter the mesophyll cells. Compared with the daytime high temperature and strong light, the stomata tend to close to reduce water transpiration. The microenvironment in the evening greatly promotes the absorption efficiency of the liquid medicine.

[0061] The spraying timing of step S4 utilizes the substance transport rule of E. coracana itself. After photosynthesis during the day, the plant body accumulates sufficient photosynthetic products. The transport system from the leaf to the developing grain remains active at night;

[0062] Spraying in the evening means that the active substances absorbed by the leaves can be immediately integrated into the active photosynthetic product transport flow at night, and are efficiently transported to the target site of the grain. This ensures that the signal substances and precursor substances in the pesticide solution can quickly accumulate in the grain, which is the action site, to gain time for subsequent initiation of aroma synthesis and sugar-based aroma fixation reactions.

[0063] In step S5, i.e. the field spraying operation of the pesticide solution, by controlling the spraying technical parameters, it is ensured that the compound aroma fixation pesticide solution can be efficiently absorbed by the E. coracana leaves. Step S5 is the final execution link of the terminal intervention, and the core is to realize the optimal distribution and adhesion of the pesticide solution on the leaf surface, which is directly related to the final realization of all previous cultivation measures and the efficacy of the preparation.

[0064] Specifically, an agricultural spraying instrument with good atomization performance should be selected, and the type of the spray head should be a fan-shaped nozzle. During the spraying process, the spraying angle should be controlled at 100-120° to ensure that the pesticide solution covers a width of 1-2 m and achieves uniform spraying. At the same time, the spraying pressure should be stabilized within 0.1-0.3 MPa, so that the pesticide solution can form fine droplets with an average particle size of 50-100 μm after atomization;

[0065] The spraying operation ensures that the pesticide solution uniformly covers both sides of the E. coracana leaves, and special attention should be paid to the pesticide adhesion on the back of the leaves. This is because the stomata on the back of the E. coracana leaves are more densely distributed, and the cuticle layer is thinner, which is the main channel for the absorption of exogenous substances. The spraying amount should be controlled at 30 to 50 liters of pesticide solution per mu, and the final judgment standard is that the leaf surface is uniformly moist but the pesticide solution does not form droplets;

[0066] This can not only ensure that there is enough pesticide solution to contact the leaf surface to promote absorption, but also effectively avoid waste of pesticide solution and environmental pollution, thereby maximizing the effective contact area between the pesticide solution and the leaves, creating optimal conditions for the rapid absorption of key active ingredients such as jasmonate and trehalose and their efficient transport to the grain, and ultimately achieving the cultivation goal of aroma enhancement and aroma preservation.

[0067] Within 0-2h after the spray in the evening, jasmonate and trehalose in the liquid are efficiently absorbed into the leaf cells through the stomata on the back of the leaf. In this initial stage, the slightly acidic environment regulated by citric acid plays an important role, significantly promoting the transmembrane absorption efficiency of trehalose and jasmonate, ensuring that the active ingredients can quickly and adequately enter the plant body. The presence of tea saponin ensures the uniform spreading of the liquid on the hydrophobic leaf surface, maximizing the absorption contact area.

[0068] Within 2-12h after the spray (i.e. at night), the absorbed jasmonate is rapidly converted into bioactive jasmonic acid inside the grain of the upland rice. The jasmonic acid then binds to its specific receptor COI1, triggering a downstream signal cascade reaction, leading to the ubiquitination and degradation of JAZ protein. The degradation of JAZ protein releases its inhibition on the MYC2 transcription factor, allowing the MYC2 transcription factor to activate a series of genes related to 2-AP biosynthesis, prompting the synthesis of a large amount of Δ¹-pyrroline, the precursor of 2-AP, and finally converting it into free 2-AP.

[0069] At the same time, the trehalose absorbed by the leaf is efficiently transported to the developing grain through the phloem. In the aleurone cells of the grain, trehalose is hydrolyzed to glucose by endogenous trehalase. The increase in glucose concentration not only provides the carbon skeleton required for glycosylation, but more importantly, it activates the SnRK1 signaling pathway, which in turn upregulates the transcription and expression of the UGT74H3 gene.

[0070] UGT74H3 is a key glycosyltransferase, and its high expression provides an adequate enzymatic basis for the subsequent glycosylation of 2-AP. This process forms a high-efficiency synergy with the abundant UDP-glucose pool established by the high-phosphorus background in the front-end cultivation module, ensuring an adequate supply of glycosyl donors.

[0071] Within 12-72h after the spray (i.e. at the peak of grain filling), under the synergistic action of the abundant UDP-glucose donor provided by the front-end module and the high expression of UGT74H3 enzyme induced by the end module, the UGT74H3 enzyme begins to efficiently catalyze the glycosyl transfer reaction between the newly synthesized free 2-AP and UDP-glucose, generating non-volatile, heat-resistant 2-AP-β-D-glucoside (2-AP-G).

[0072] 2-AP-G is a bound form of 2-AP, which has the following significant properties: First, it is non-volatile and does not escape with the air in a continuous high-temperature environment, thereby avoiding the physical loss of aroma substances and significantly improving the retention rate of aroma in the grain. 2-AP-G has high resistance to oxidative stress and is not easily degraded by active oxygen in the plant body, thereby avoiding the chemical loss of aroma substances.

[0073] The combined state 2-AP-G can be re-released as free state 2-AP through hydrolysis during subsequent cooking processing, such as high-temperature cooking or under the action of β-glucosidase, thereby ensuring the rich burst and perception intensity of aroma during consumption.

[0074] The in-situ glycosylation of the aroma fixation arrangement, without introducing exogenous hormones, realizes the stable storage and on-demand release of aroma substances through the regulation and activation of the endogenous metabolic pathways of the upland rice.

[0075] Example 1:

[0076] S1. During the vegetative growth period of the upland rice, the pure nitrogen application amount is controlled to be 70 kg per hectare, wherein the pure nitrogen application amount of the base fertilizer is 35 kg per hectare, the pure nitrogen application amount of the tillering fertilizer is 35 kg per hectare, the nitrogen fertilizer is selected to be urea, and the phosphoric acid dihydride is simultaneously applied as base fertilizer at 40 kg per hectare, and the leaf SPAD value during the tillering period is maintained at 38 through monitoring;

[0077] S2. After entering the reproductive growth period, stop supplying nitrogen fertilizer during the young ear differentiation period, apply phosphoric acid dihydride at 25 kg per hectare and potassium oxide at 60 kg per hectare, and maintain the soil water content at 65% of the field water holding capacity through the automatic irrigation system by monitoring the sensors arranged in the 0-30 cm and 30-60 cm soil layers during the grain filling period;

[0078] S3. Fresh double-petal jasmine flowers are weighed, mixed with water maintained at 40°C at a mass ratio of 1:8, soaked for 24 h, and then filtered using a filter screen with a pore size of 190 μm to obtain a jasmine infusion. The infusion is used as the base solvent, 2 g / L of D-(+)-trehalose with a purity of 99.8% and 1 g / L of tea saponin with a purity of 95% are added, and the mixture is mixed uniformly and then adjusted to a pH value of 5.8;

[0079] S4. Then arrange for spraying, and select 17:00 in the afternoon within 10 days after the upland rice heading to spray;

[0080] S5. Use agricultural spraying equipment equipped with fan-shaped nozzles, set the spraying angle to be 110°, the coverage width to be 1.5 m, and the spraying pressure to be 0.2 MPa, uniformly spray the liquid to the front and back surfaces of the upland rice leaves, control the average droplet size to be 75 μm, and control the spraying amount to be 40 L of liquid per mu, so that the leaves are uniformly wet but the liquid does not drip.

[0081] Example 2:

[0082] The embodiment is basically the same as embodiment 1, the difference is that in the step of S3, fresh double-petal jasmine flowers are mixed with water maintained at 40℃ at a mass ratio of 1:8, soaked for 24h, then filtered with a filter screen with a pore size of 190μm to obtain jasmine infusion, and then 99.8% pure D-(+)-trehalose (added amount 1g / L) and 95% active ingredient pure tea saponin (added amount 1g / L) are added to the infusion as the base solvent, and the mixture is mixed uniformly and the pH value of the mixture is adjusted to 5.8.

[0083] Embodiment 3:

[0084] The embodiment is basically the same as embodiment 1, the difference is that in the step of S3, fresh double-petal jasmine flowers are mixed with water maintained at 40℃ at a mass ratio of 1:8, soaked for 24h, then filtered with a filter screen with a pore size of 190μm to obtain jasmine infusion, and then 99.8% pure D-(+)-trehalose (added amount 1g / L) and 95% active ingredient pure tea saponin (added amount 1g / L) are added to the infusion as the base solvent, and the mixture is mixed uniformly and the pH value of the mixture is adjusted to 5.8.

[0085] Embodiment 4:

[0086] The embodiment is basically the same as embodiment 1, the difference is that in the step of S3, fresh double-petal jasmine flowers are mixed with water maintained at 40℃ at a mass ratio of 1:8, soaked for 24h, then filtered with a filter screen with a pore size of 190μm to obtain jasmine infusion, and then 99.8% pure D-(+)-trehalose (added amount 1g / L) and 95% active ingredient pure tea saponin (added amount 1g / L) are added to the infusion as the base solvent, and the mixture is mixed uniformly and the pH value of the mixture is adjusted to 5.8.

[0087] Embodiment 5:

[0088] The embodiment is basically the same as embodiment 1, the difference is that in the step of S3, fresh double-petal jasmine flowers are mixed with water maintained at 40℃ at a mass ratio of 1:8, soaked for 24h, then filtered with a filter screen with a pore size of 190μm to obtain jasmine infusion, and then 99.8% pure D-(+)-trehalose (added amount 1g / L) and 95% active ingredient pure tea saponin (added amount 1g / L) are added to the infusion as the base solvent, and the mixture is mixed uniformly and the pH value of the mixture is adjusted to 5.8.

[0089] Embodiment 6:

[0090] The embodiment is basically the same as example 1, the difference is that in the step of S3, fresh double-petal jasmine flowers are mixed with water maintained at 40℃ at a mass ratio of 1:7, soaked for 24h, then filtered with a filter screen with a pore size of 190μm to obtain jasmine infusion, and then 99.8% pure D-(+)-trehalose (added amount 2g / L) and 95% pure tea saponin (added amount 1g / L) are added to the infusion as the base solvent, and the pH value of the mixture is adjusted to 5.8 after uniform mixing.

[0091] Example 7:

[0092] The embodiment is basically the same as example 1, the difference is that in the step of S3, fresh double-petal jasmine flowers are mixed with water maintained at 40℃ at a mass ratio of 1:7, soaked for 24h, then filtered with a filter screen with a pore size of 190μm to obtain jasmine infusion, and then 99.8% pure D-(+)-trehalose (added amount 2g / L) and 95% pure tea saponin (added amount 1g / L) are added to the infusion as the base solvent, and the pH value of the mixture is adjusted to 5.8 after uniform mixing.

[0093] Comparative Example 1:

[0094] The comparative example is basically the same as example 1, the difference is that in the step of S3, fresh double-petal jasmine flowers are mixed with water maintained at 40℃ at a mass ratio of 1:7, soaked for 24h, then filtered with a filter screen with a pore size of 190μm to obtain jasmine infusion, and then 95% pure tea saponin (added amount 1g / L) is added to the infusion as the base solvent, and the pH value of the mixture is adjusted to 5.8 after uniform mixing.

[0095] Comparative Example 2:

[0096] The comparative example is basically the same as example 1, the difference is that in the step of S3, fresh double-petal jasmine flowers are mixed with water maintained at 40℃ at a mass ratio of 1:7, soaked for 24h, then filtered with a filter screen with a pore size of 190μm to obtain jasmine infusion, and then 99.8% pure D-(+)-trehalose (added amount 2g / L) is added to the infusion as the base solvent, and the pH value of the mixture is adjusted to 5.8 after uniform mixing.

[0097] Comparative Example 3:

[0098] The comparative example is basically the same as example 1, the difference is that in the step of S5, S5. An agricultural spraying device equipped with a fan-shaped nozzle is used, the spraying angle is set to 110°, the coverage width is 1.5m, the spraying pressure is 0.2MPa, the pesticide solution is uniformly sprayed on the front of the upland rice leaves, the average droplet size is controlled to be 75μm, and the spraying amount is controlled to be 40L of pesticide solution per mu, and the leaves are uniformly wetted but the pesticide solution does not drip.

[0099] Experimental Example:

[0100] Objective: To verify the effects of the aroma-enhancing and preserving cultivation methods of Examples 1-7 and Comparative Examples 1-3 on the synthesis and retention of aroma substances in upland rice, by measuring the contents of 2-acetyl-1-pyrroline (2-AP) and its glycoside form (2-AP-G) in rice, to evaluate the aroma-enhancing and preserving effects of each method.

[0101] Experimental Method: A field randomized block design was used, with 11 treatment groups (corresponding to Examples 1-7 and Comparative Examples 1-3) and 3 replicates for each treatment group, totaling 33 plots. Each plot was 10 m2 in size and planted with the same upland rice variety (e.g., "Hanhang No. 1"). In addition to following the methods of each example and comparative example, other conditions (e.g., irrigation, pest control) were kept consistent. After harvesting, rice samples were taken for aroma substance analysis.

[0102] Experimental Steps

[0103] Test Setup: Select a uniform soil fertility upland field and divide it into 33 plots, randomly assigning the treatment groups.

[0104] Cultivation Treatment: Cultivate according to the detailed steps in Examples 1-7 and Comparative Examples 1-3 in the document. For example:

[0105] Sample Collection: At the mature stage of upland rice (one week before harvesting), randomly collect 10 rice panicles from each plot, and dehull to obtain rice grains. Dry, dehull, and mill the rice grains to obtain polished rice samples.

[0106] Aroma Substance Measurement: Use gas chromatography-mass spectrometry (GC-MS) to measure the contents of free 2-AP and bound 2-AP-G in polished rice. Specific steps:

[0107] Weigh 2.0 g of polished rice powder, add 10 mL of methanol, and ultrasonically extract for 30 min, then centrifuge and take the supernatant.

[0108] Use GC-MS analysis with the following conditions: chromatographic column DB-5MS, programmed temperature from 50°C (2 min hold) to 250°C (5 min hold) at 10°C / min, and quantification by standard curve.

[0109] Data Processing: Calculate the average 2-AP content, 2-AP-G content, and total aroma content (2-AP + 2-AP-G) for each treatment group. Statistical analysis uses one-way analysis of variance (ANOVA) to compare differences between groups.

[0110] Experimental Data: Show the aroma substance measurement results (average, n=3) for each treatment group.

[0111] Table One:

[0112] Group 2-AP content (mg / kg) 2-AP-G content (mg / kg) Total aroma content (mg / kg) Example 1 12.34 45.67 58.01 Example 2 11.25 43.21 54.46 Example 3 11.89 44.53 56.42 Example 4 10.75 42.18 52.93 Example 5 10.92 42.67 53.59 Example 6 11.05 43.05 54.10 Example 7 10.98 42.89 53.87 Comparative Example 1 8.90 35.67 44.57 Comparative Example 2 9.15 36.24 45.39 Comparative Example 3 9.38 37.01 46.39

[0113] From Table 1, it can be seen that:

[0114] The contents of 2-acetyl-1-pyrroline (2-AP) and its glycoside form (2-AP-G) in rice of each treatment group, as well as the total aroma content (2-AP+2-AP-G), and the base scheme of Example 1, show the highest 2-AP-G content and total aroma content, which indicates that its flavoring and aroma preservation effect is optimal, and other examples and comparative examples deviate in different parameters, resulting in aroma substance synthesis or retention effect not as good as Example 1.

[0115] Example 1 adopts the optimal parameter combination, including trehalose addition amount 2 g / L, tea saponin addition amount 1 g / L, mass ratio of jasmine flower to water 1:8, and comprehensive foliar spraying, and the success of Example 1 lies in the synergistic effect with the metabolic pathway of upland rice;

[0116] During the vegetative growth period, the nitrogen control measure (pure nitrogen 70 kg / ha) slightly inhibits the expression of BADH2 gene and accumulates aroma precursor Δ1-pyrroline; the nitrogen stop and the increase of phosphorus and potassium fertilizer (phosphoric acid diester 25 kg / ha, potassium oxide 60 kg / ha) during the reproductive growth period provide sufficient UDP-glucose and energy for glycosylation reaction; jasmonate in jasmine extract activates jasmonic acid signaling pathway and directly promotes 2-AP synthesis; trehalose as a signal molecule and glycosyl donor activates SnRK1 pathway and up-regulates UGT74H3 enzyme expression, promoting efficient conversion of free 2-AP to stable 2-AP-G; tea saponin ensures uniform spreading and absorption of the liquid on the leaves; spraying in the evening (17:00) promotes the transport of active ingredients to the grain by taking advantage of the open period of stomata, and this multi-link synergistic effect maximizes the synthesis of aroma substances and stabilizes them, so Example 1 performs best.

[0117] Example 2 and Example 3 adjust the trehalose addition amount to 1 g / L and 3 g / L respectively, and compared with Example 1, their 2-AP-G and total aroma contents are lower, and the internal principle lies in that the dosage of trehalose is crucial to the regulation of glycosylation process;

[0118] The trehalose addition amount of Example 2 is insufficient (1 g / L), which leads to less glucose produced by hydrolysis after being absorbed, and the SnRK1 signaling pathway cannot be fully activated, so that the UGT74H3 enzyme expression is not up-regulated enough, the glycosylation reaction is not sufficient, the efficiency of converting free 2-AP to 2-AP-G is reduced, and aroma substances are easy to volatilize and lose at high temperature;

[0119] The trehalose addition amount of Example 3 is too high (3 g / L), which may cause osmotic stress or feedback inhibition, interfere with the normal carbon metabolism of upland rice, overload the signal function of trehalose, and reduce the activity of UGT74H3 enzyme. At the same time, excessive sugar donors may cause metabolic redundancy and waste precursor substances, so the aroma synthesis effect is not as good as the balanced dose of Example 1.

[0120] Example 5 and Example 6 adjust the addition amount of tea saponin and the ratio of jasmine flowers to water respectively. Example 5 uses tea saponin 1.5 g / L (higher than 1 g / L in Example 1), and Example 6 uses the mass ratio of jasmine flowers to water 1:7 (higher than 1:8 in Example 1).

[0121] Table I shows that their aroma content has decreased compared with Example 1. Tea saponin as a surfactant, its addition amount needs to be moderate: the excessive tea saponin (1.5 g / L) in Example 5 may excessively reduce the surface tension of the solution, resulting in too thin or rapid evaporation of the leaf liquid film, thereby reducing the contact time of active ingredients with the leaf and affecting the absorption efficiency of jasmonate and trehalose;

[0122] At the same time, excessive tea saponin may cause slight damage to the wax layer of the leaf, introducing unnecessary stress. The high ratio of jasmine flowers (1:7) in Example 6 increases the concentration of jasmine extract, but the high concentration of jasmonate may excessively activate the jasmonic acid signaling pathway, causing downstream gene expression disorder, thereby inhibiting the stability of 2-AP synthesis genes. In addition, high-concentration extract may carry more impurities, interfering with the absorption and transport of trehalose, so the effect is not as good as the balanced ratio of Example 1.

[0123] Example 6 and Example 7 change the ratio of jasmine flowers to water, and Example 7 uses a ratio of 1:9 (lower than 1:8 in Example 1). Table I shows that the aroma content of Example 7 is also lower than that of Example 1. The concentration of jasmine extract directly affects the supply of jasmonate: the low ratio of jasmine flowers (1:9) in Example 7 results in insufficient extract concentration, reducing the content of jasmonate, which cannot fully activate the MYC2 transcription factor and downstream aroma synthesis genes, resulting in insufficient accumulation of 2-AP precursors.

[0124] At the same time, low-concentration extract may not produce a synergistic signal effect with trehalose, weakening the induction of UGT74H3 enzyme, and the glycosylation reaction is not complete, resulting in a decrease in the retention rate of aroma substances. The 1:8 ratio of Example 1 achieves the best balance between providing moderate signal stimulation and avoiding inhibition.

[0125] The comparative example 1 omits trehalose and only uses jasmine extract and tea saponin. Table 1 shows that the 2-AP-G content is extremely low, and the total aroma content is significantly lower than that of the example 1. The absence of trehalose seriously damages the glycosylation process. Without trehalose, the effective signal molecule in the body of the upland rice is lacking to activate the SnRK1 pathway, and the UGT74H3 enzyme expression is insufficient, resulting in that the free 2-AP cannot be efficiently converted into stable 2-AP-G; the amount of glucose provided by trehalose hydrolysis is reduced, which limits the expansion of the UDP-glucose pool, resulting in a shortage of glycosyl donors. Although the jasmine extract can promote the synthesis of 2-AP, the synthesized free aroma is easy to lose due to volatilization and cannot be stably retained during the grain filling period. Therefore, the aroma retention effect of the comparative example 1 is poor.

[0126] The comparative example 2 omits tea saponin and only uses jasmine extract and trehalose. Table 1 shows that the aroma content is low, especially the 2-AP absorption is insufficient. The absence of tea saponin leads to a decrease in the absorption efficiency of the solution. Without tea saponin as a surfactant, the solution cannot spread uniformly on the waxy leaves of the upland rice and is easy to gather into beads and roll off, reducing the contact area of the jasmonate and trehalose with the leaf surface; the repulsion effect of the leaf surface charge is enhanced, and the optimized absorption effect of the slightly acidic environment (pH 5.8) cannot be exerted, and the transmembrane absorption of active ingredients is hindered, especially the utilization rate of the stomatal absorption channel on the back of the leaf is low. Although the components of trehalose and jasmine extract are complete, the insufficient absorption makes them unable to be effectively transported to the grain, and the supply of aroma synthesis precursors is insufficient. Therefore, the effect is poor.

[0127] The comparative example 3 only sprays the front of the upland rice leaves, without covering the back. Table 1 shows that the aroma content is significantly lower than that of the example 1. The back of the leaf is the main absorption channel, and the stomata are more densely distributed on the back of the upland rice leaf, and the cuticle layer is thinner, which is the high-efficiency part of the absorption of exogenous substances. Spraying only the front of the leaf makes the solution unable to fully contact the stomata on the back, reducing the absorption amount of jasmonate and trehalose, and the uneven distribution of the solution reduces the transportation efficiency to the grain. The advantage of evening spraying cannot be maximized, and the integration of active ingredients in the nighttime transportation flow is insufficient, which limits the synthesis of 2-AP and the glycosylation reaction. Therefore, the one-sided spraying of the comparative example 3 destroys the comprehensiveness of the absorption of the solution, resulting in poor effect.

[0128] Based on the ideal embodiments of the present application, the above-described contents can be variously changed and modified without deviating from the technical concept of the present application. The technical scope of the present application is not limited to the contents described in the specification, and must be determined by the scope of the claims.

Claims

1. A method for flavoring and preserving the flavor of upland rice, characterized by, The method comprises the following steps: S1. During the vegetative growth period of upland rice, the pure nitrogen application amount is controlled to be 60-80 kg per mu, wherein the base fertilizer and the tillering fertilizer are applied in several times in a proportion of 1:1, and phosphoric acid dianhydride is synchronously applied as base fertilizer at 35-45 kg per mu; S2. The supply of nitrogen fertilizer is stopped at the early reproductive growth period, 20-30 kg of phosphoric acid dianhydride and 60 kg of potassium oxide are applied as topdressing, and the soil water content is maintained at 60-70% of the field water holding capacity during the grain filling period; S3. Jasmine infusion is prepared as a base solvent, and trehalose and tea saponin as a plant-derived surfactant are added, then the mixture is uniformly mixed, the pH value of the mixture is adjusted to 5.6-6.0 to form a liquid medicine, the addition amount of trehalose is 1-3 g / L based on the volume of jasmine infusion, and the addition amount of tea saponin is 0.5-1.5 g / L; S4. Spraying is carried out in the evening during the heading stage to the early grain filling stage of upland rice; S5. The liquid medicine is uniformly sprayed on the front and back of the leaves of upland rice, and the droplet size and spraying amount are controlled.

2. The method for flavoring and flavor-protecting cultivation of Oryza sativa L. according to claim 1, characterized by: In the S1, the pure nitrogen application amount of the base fertilizer and the tillering fertilizer is 30-40 kg per mu, and the nitrogen fertilizer is selected from urea or ammonium sulfate; and the SPAD value of the leaf during the tillering period is monitored to be 35-40.

3. The method for flavoring and flavor preserving cultivation of upland rice according to claim 1, characterized in that: In the S2, the phosphorus and potassium fertilizer topdressing is applied during the young ear differentiation period, the water regulation is monitored through sensors arranged in the 0-30 cm and 30-60 cm soil layers, and an automatic irrigation system is used.

4. The method for flavoring and flavor-protecting cultivation of Oryza sativa L. according to claim 1, characterized by: In the S3, the preparation method of jasmine infusion comprises the following steps: S3.1 Fresh jasmine flowers are weighed and placed in water, the water temperature is maintained at 35-45℃, and the mixture is soaked for 22-26 hours to form a mixture; S3.2 The mixture after soaking is filtered through a filter screen with a pore size of 180-200 μm to separate the flower residue and collect the jasmine infusion.

5. The method for flavoring and flavor preserving cultivation of Oryza sativa of claim 4, wherein: In the S3.1, the mass ratio of fresh jasmine flowers to water is 1:7-9, and the variety of fresh jasmine flowers is double-petal jasmine.

6. The method for flavoring and flavor preserving cultivation of Oryza sativa of claim 1, wherein: In the S3, the trehalose is D-(+)-trehalose, the purity of the trehalose is 99.8%, and the purity of the active ingredient tea saponin in the surfactant is 95%.

7. The method for flavoring and flavor preserving cultivation of Oryza sativa of claim 1, wherein: In the S4, the specific time point of spraying during the heading stage to the early grain filling stage of upland rice is within 7-14 days after the heading of upland rice, and the specific time in the evening is 16:00-18:00 in the afternoon.

8. The method for flavoring and flavor preserving cultivation of Oryza sativa of claim 1, wherein: In the S5, the agricultural spraying equipment used in the spraying operation is an agricultural sprayer, the type of the sprayer nozzle is a fan-shaped nozzle, the spraying angle is ensured to be 100-120°, the coverage width is 1-2 m, and the spraying is carried out at 0.1-0.3 MPa.

9. The method for flavoring and flavor preserving cultivation of upland rice according to claim 1, characterized by: In the S5, the droplet size is controlled to form droplets with an average particle size of 50-100 μm after atomization of the liquid medicine, and the spraying amount is controlled to be uniform wetting of the leaves without liquid dripping.

10. The method for flavoring and flavor preserving cultivation of upland rice according to claim 1, characterized in that: In the S5, the spraying amount is controlled to be 30-50 L of liquid medicine per mu.

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