Planting method for increasing anthocyanin content in purple rice grains

Abstract

The invention discloses a planting method for increasing the content of anthocyanin in purple rice grains, which comprises the following specific steps: sowing purple rice seeds from May 20th to May 30th every year, and setting the nitrogen application amount to be 24kg N / mu and the planting density to be 1.58-2.22 million holes / mu at the same time. According to the method, the sowing time, the nitrogen application amount and the planting density are precisely and cooperatively regulated and controlled, resource distribution in the key period of purple rice anthocyanin synthesis is directionally optimized, the content of paeoniflorin and cyanidin in grains is remarkably increased, meanwhile, yield stability and efficient resource utilization are both considered, and through cultivation technology innovation which is low in cost and easy to popularize, the yield of purple rice is increased. The multi-target of directional enhancement of functional components of purple rice, stable yield and high resource efficiency is achieved, a technical normal form is provided for green transformation of functional agriculture, remarkable economic, ecological and social benefits are achieved, and the important requirement for green and high-efficiency development of functional agriculture is met.

Description

Technical Field

[0001] The present invention belongs to the technical field of crop cultivation, and particularly relates to a planting method for increasing the anthocyanin content in purple rice grains. Background Art

[0002] Purple rice is one of the high-quality rice varieties, belonging to the Gramineae family and the Oryza genus. The grains of purple rice are wrapped by husks, and the color of the husks also varies depending on the variety. The milled rice after dehulling is dark purple. Purple rice grains are rich in a large amount of anthocyanins, such as active ingredients like peonidin and cyanidin. Therefore, it shows significant functional value in antioxidant, anti-inflammatory and prevention of chronic diseases, and has become a popular raw material in the field of health food. With the surging demand for nutritionally enhanced agricultural products in the consumer market, the demand for improving the quality and efficiency of purple rice planting and deep processing industries is becoming increasingly urgent. However, the stability and controllability of the anthocyanin content in purple rice still face major challenges, and the existing technical system is still difficult to balance the goals of high yield, high quality and enrichment of functional components.

[0003] Currently, the research on improving anthocyanin in purple rice mainly focuses on the field of genetic breeding, and the anthocyanin synthesis pathway is directionally improved through multi-generation hybridization or gene editing technology. However, such methods have problems such as long cycle (requiring several years to decades), high cost, and easy introduction of adverse traits (such as yield decline and weakened stress resistance). In addition, although genetic engineering means can precisely regulate anthocyanin-related genes, they are limited by technical complexity, gene expression stability (such as gene silencing and genetic background dependence) and regulatory risks, and are difficult to be rapidly promoted and applied. In contrast, cultivation regulation technology has become an important supplementary means due to its flexible operation, low cost and compliance with the concept of green agriculture. However, existing cultivation research mostly focuses on the yield and conventional quality regulation of ordinary rice, and the exploration of the targeted regulation mechanism of anthocyanin synthesis in purple rice grains is insufficient. For example, although key agronomic measures such as nitrogen application rate and density have been proven to affect the physiological metabolism of rice, their accumulation rules for specific anthocyanin components (such as peonidin and cyanidin) in purple rice grains are still unclear, especially the synergistic regulation mechanism of nitrogen fertilizer management and population structure during the key growth period (such as the peak period of anthocyanin synthesis) has not been systematically revealed.

[0004] Previous studies have shown that by regulating the nitrogen application rate and the ratio of inorganic to organic fertilizers, the yield and grain quality of purple rice can be improved, but no mention has been made of the impact on the anthocyanin content in the grains. Unreasonable planting density may indirectly affect the biosynthesis efficiency of anthocyanin precursors through microenvironmental factors such as light competition and ventilation conditions. However, traditional cultivation models often adopt a fixed nitrogen application rate and unified density management, failing to dynamically optimize during the critical period of anthocyanin synthesis, resulting in low resource utilization efficiency and limited improvement in anthocyanin content. In addition, in existing technologies, research on nitrogen fertilizer forms (such as the organic / inorganic ratio) or single agronomic measures, due to the lack of precise matching with growth stages, is difficult to achieve the coordinated improvement of anthocyanin content, yield, and stress resistance.

[0005] Therefore, developing a dynamic regulation technology for nitrogen application rate and density based on the critical period of anthocyanin synthesis, by analyzing the spatio-temporal interaction effects of nitrogen supply and population structure, and promoting the enrichment of peonidin and cyanidin in purple rice grains in a targeted manner, has become an important direction to break through the bottleneck of existing technologies. This technology is expected to avoid the limitations of genetic breeding while achieving the multi-objective coordination of increased anthocyanin content, stable yield, and efficient resource utilization, providing a popularizable solution for the functional cultivation of purple rice. Summary of the Invention

[0006] In view of the deficiencies of the existing technology, the present invention provides a planting method for increasing the anthocyanin content in purple rice grains. By planting purple rice with an appropriate sowing date, nitrogen application rate, and transplanting density, the content of peonidin and cyanidin in purple rice can be increased.

[0007] The present invention is achieved through the following technical solutions:

[0008] A planting method for increasing the anthocyanin content in purple rice grains, wherein purple rice seeds are sown from May 20th to 30th every year, and at the same time, the nitrogen application rate is set at 24 kg N / mu, and the transplanting density is 15,800 - 22,200 holes / mu. Sowing, seedling raising, transplanting, and field management are the same as those in conventional cultivation, without adding additional management measures.

[0009] Preferably, the anthocyanins are peonidin and cyanidin.

[0010] Preferably, the specific treatment method for the nitrogen application rate is as follows: applying base fertilizer, tillering fertilizer, flower-promoting fertilizer, and flower-preserving fertilizer in a ratio of 3:3:2:2.

[0011] Preferably, the specific treatment method for the transplanting density is as follows: planting according to a row spacing of 30×(10 - 14) cm and 4 seedlings per hole.

[0012] Preferably, the variety of purple rice is Yangzidao 6.

[0013] The beneficial effects of the present invention are as follows:

[0014] (1) Based on the experimental data of double sowing dates (S1, S2) and multi-factor combinations, the present invention has achieved a breakthrough increase in the anthocyanin content of purple rice grains for the first time. Under the normal sowing date (S1), the combination of N3&D3 (24 kg N / mu + 22,200 hills / mu) makes the contents of cyanidin and peonidin reach 1082.56 mg / kg and 477.33 mg / kg respectively, which are 441% and 400% higher than those of the lowest nitrogen density treatment (N0&D1). Under the postponed sowing date (S2), the combination of N3&D2 (24 kg N / mu + 18,500 hills / mu) achieves 1015.25 mg / kg of cyanidin and 433.29 mg / kg of peonidin, which are 192% and 193% higher than those of the lowest treatment (N0&D1) in the S2 sowing date. Moreover, through the optimization of light and temperature in the sowing date S2, the negative effects of high density (D3) are significantly reduced. Through the coordination of sowing date and nitrogen density, the present invention steadily increases the proportion of peonidin and cyanidin in the total anthocyanin, strengthens the antioxidant function of purple rice, and meets the development needs of high-value-added health products.

[0015] (2) The present invention reveals the non-linear interaction law of "sowing date - nitrogen application rate - density". The test results show that postponing the sowing date (S2) can significantly reduce the dependence on nitrogen fertilizer by optimizing the light and temperature conditions, reduce the nitrogen fertilizer application rate per unit area by 10% - 20%, improve the nitrogen utilization rate by 12.5%, and reduce the risk of non-point source pollution. For example, under the postponed sowing date (S2), the cyanidin content of the N0&D2 (no nitrogen application + medium density) combination reaches 463.89 mg / kg, which is 114.7% higher than that under the same treatment conditions in the normal sowing date (S1), proving that light and temperature resources can partially replace chemical fertilizer input. At the same time, the synergistic effect of nitrogen density is also found. For example, in the S1 sowing date, "high nitrogen and high density" (N3&D3) is required to maximize the anthocyanin content, while in the S2 sowing date, "high nitrogen and medium density" (N3&D2) is required to avoid population competition (the anthocyanin content of N3&D3 decreases by 4.6%) to maximize the anthocyanin content.

[0016] (3) The present invention constructs a "time and place specific" decision-making framework, and through a dynamic regulation model, it can be flexibly adapted to different ecological conditions. In the normal sowing date (S1), the "high nitrogen and high density" mode (N3&D3) is recommended to maximize the utilization of resources, and the anthocyanin content of purple rice can reach the leading level in the industry. In the postponed sowing date (S2), the "high nitrogen and medium density" mode (N3&D2) is adopted to avoid high temperature / oligophotic stress and achieve the coordinated improvement of anthocyanin content and yield. In low fertility / ecologically fragile areas, the combination of "S2 + N2&D2" (20 kg N / mu + 18,500 hills / mu) is selected to achieve 762.71 mg / kg of cyanidin and 318.16 mg / kg of peonidin with a relatively low input, and the nitrogen utilization rate is increased by more than 15%. Detailed implementation manners

[0017] The present invention will be further described in detail below in conjunction with specific embodiments.

[0018] Example 1

[0019] 1. Test conditions

[0020] The test area of this example is located at the Shatou Base of Yangzhou University in Guangling District, Yangzhou City. The test variety is Yangzidao 6, a newly bred purple rice variety with moderate plant height, thick stems, and strong lodging resistance; it is a mid-late maturing variety with a full growth period of about 140 - 150 days (suitable for single-season rice cultivation); the brown rice is purple-black (rich in anthocyanins), and the milled rice still retains some purple color; it is significantly higher than ordinary purple rice (the specific content varies depending on cultivation conditions); it has characteristics such as high anthocyanin content, good quality, and strong stress resistance.

[0021] 2. Test design

[0022] Split-plot design, with the sowing date as the main plot, the nitrogen application rate as the sub-plot, and the density as the sub-sub-plot. Plastic tray blanket seedling raising, with a seedling age of about 20 days. The plot area is about 10 - 12m 2 or so, with 3 replicates. Water management and pest and weed control are implemented uniformly according to local large-scale production, and the following tests are carried out, as shown in Table 1 specifically.

[0023] (1) Sowing date treatment: Divided into the normal sowing date (Group S1, around May 20th) and the normal sowing date postponed by 10 days (Group S2, around May 30th).

[0024] (2) Nitrogen application rate treatment: 0, 16, 20, 24 kg N / mu, where the basal fertilizer: tillering fertilizer: flower-promoting fertilizer: flower-preserving fertilizer = 3:3:2:2.

[0025] (3) Planting density treatment: 15,800 holes / mu (row spacing 30×14 cm), 18,500 holes / mu (row spacing 30×12 cm), 22,200 holes / mu (row spacing 30×10 cm), with 4 seedlings per hole.

[0026] Table 1 Test design

[0027]

[0028] 3. Measurement content: Anthocyanin content in purple rice grains at maturity

[0029] The test measurement results are shown in Tables 2 and 3. Table 2 shows the contents of peonidin and cyanidin under different nitrogen application rates and densities in the first sowing date (Group S1), and Table 3 shows the contents of peonidin and cyanidin under different nitrogen application rates and densities in the second sowing date (Group S2).

[0030] Table 2 Contents of cyanidin and peonidin in sowing date S1

[0031]

[0032]

[0033] Table 3 Contents of cyanidin and peonidin at sowing date S2

[0034]

[0035] 4. Analysis of measurement results

[0036] As can be seen from Table 2 and Table 3, the present invention significantly improves the contents of peonidin and cyanidin in purple rice grains through the coordinated regulation of sowing date, nitrogen application rate and density. The specific analysis is as follows:

[0037] (1) First, reveal the dynamic interaction effects of sowing date, nitrogen application rate and density on the anthocyanin content of purple rice

[0038] Traditional research mostly analyzes the effects of single agronomic measures (such as only applying nitrogen or only adjusting density) on anthocyanin content in isolation. However, through the cross experiment of two sowing dates (S1, S2) combined with multiple levels of nitrogen application rate (N0 - N3) and density (D1 - D3), the present invention first discovers that:

[0039] ① The regulation of sowing date on anthocyanin synthesis in purple rice has a critical threshold effect

[0040] Under S1 (normal sowing date), the anthocyanin content increases significantly with the increase of nitrogen application rate (N0 → N3) and density (D1 → D3) (Table 2), and the highest value appears at N3&D3 (cyanidin content 1082.56 mg / kg, peonidin content 477.33 mg / kg).

[0041] ② Under S2 (delayed sowing date), the anthocyanin accumulation pattern in purple rice changes significantly

[0042] The peak value is reached at N3&D2 (non - highest density) (cyanidin content 1015.25 mg / kg, peonidin content 433.29 mg / kg), and at D3 (highest density), the anthocyanin synthesis is inhibited due to population closure (for example, the cyanidin content at N1&D3 is only 510.06 mg / kg, significantly lower than N1&D1 / D2).

[0043] This result indicates that delaying the sowing date may change the response thresholds of plants to nitrogen and density by optimizing light and temperature conditions (such as avoiding high - temperature stress), providing a new direction for targeted regulation.

[0044] ③ There is a non - linear relationship between the synergistic effect of nitrogen application rate and density in purple rice

[0045] Under the S1 sowing period, high nitrogen (N3) must be combined with high density (D3) to maximize the anthocyanin content of purple rice (the cyanidin content of N3&D3 is 25.4% higher than that of N3&D1); while under the S2 sowing period, high nitrogen needs to be matched with medium density (D2) to avoid group competition, thereby increasing the anthocyanin content (the cyanidin content of N3&D2 is 4.6% higher than that of N3&D3).

[0046] This finding demonstrates that anthocyanin synthesis and accumulation require a precise match between nitrogen supply and population structure.

[0047] (2) Propose a method for optimizing resource allocation during the critical growth period of purple rice

[0048] The present invention finds through data comparison:

[0049] ① Delaying sowing time (S2) can significantly increase the anthocyanin content of purple rice under low nitrogen conditions

[0050] Under the N0 (no nitrogen application) level, the cyanidin content of the D2 treatment (density 18,500 holes / mu) in the S2 sowing period of purple rice was 463.89 mg / kg, which was 114.7% higher than that of the same treatment conditions in the S1 sowing period (216.14 mg / kg), indicating that the optimization of light and temperature conditions can partially replace nitrogen input, and is also beneficial to increase the anthocyanin content.

[0051] ② Purple rice needs to avoid "redundant growth" through density control under high nitrogen conditions

[0052] Under the S1 sowing period, the anthocyanin content of N3&D3 (highest nitrogen + highest density) reached a peak value, while under the S2 sowing period, the anthocyanin content of N3&D3 decreased due to group competition (the cyanidin content of N3&D3 was 971.04 mg / kg, lower than 1015.25 mg / kg of N3&D2), which proved that delaying the sowing period of purple rice required reducing the density, which was beneficial to the synthesis and accumulation of anthocyanins in purple rice.

[0053] (3) Establish a dynamic control model that is “based on time and place”

[0054] The present invention creatively constructs a decision-making framework of the trinity of "sowing date-nitrogen application amount-density":

[0055] ① Normal sowing period (S1) area: High nitrogen and high density (N3&D3) mode is recommended to make full use of growing season resources and maximize anthocyanin synthesis (for example, the cyanidin content of N3&D3 is increased by 441% compared with N0&D1).

[0056] ② Delayed sowing area (S2): The high nitrogen medium density (N3&D2) mode is recommended to reduce the demand for nitrogen fertilizer through light and temperature synergy while maintaining the anthocyanin content (the cyanidin content of N3&D2 is increased by 192% compared with N0&D1).

[0057] ③Low-fertility soil or ecologically fragile areas: The S2 sowing date + N2&D2 combination can be adopted to achieve efficient accumulation of anthocyanins with a relatively low nitrogen fertilizer (20 kg N / mu), with the content of cyanidin being 762.71 mg / kg and the content of peonidin being 318.16 mg / kg, taking into account environmental sustainability.

[0058] (4) Innovate high-quality cultivation techniques for purple rice to achieve multi-objective coordination

[0059] Existing research has mostly focused on the yield formation of common rice. However, this invention systematically analyzes for the first time the specific response laws of anthocyanins (especially peonidin and cyanidin) in purple rice to cultivation factors, innovates high-quality cultivation techniques for purple rice, and can provide technical support for the precise cultivation of functional rice.

[0060] ① Resolution of the yield-quality contradiction: Under the S1 sowing date, although the N3&D3 is the optimal combination for anthocyanins, it may lead to lodging risks due to dense planting; while the N3&D2 mode under the S2 sowing date reduces population competition through light and temperature optimization, synchronously improving the anthocyanin content and yield potential (reasonable panicle number and grain weight).

[0061] ② Improvement of resource efficiency: Compared with the N3&D3 mode under the S1 sowing date, the N3&D2 mode under the S2 sowing date increases the nitrogen utilization rate by 12.5% (the anthocyanin output per unit of nitrogen increases), and reduces the field management cost caused by dense planting.

[0062] In summary, by revealing the non-linear interaction laws of sowing date, nitrogen application rate, and density on anthocyanin synthesis in purple rice, this invention innovatively constructs a cultivation decision-making model of "optimized allocation of temporal and spatial resources", breaks through the dilemma of "high yield is difficult to achieve high quality, and high quality does not result in high yield" in traditional technologies, has both theoretical innovation and practical promotion value, and meets the major requirements of the green and efficient development of functional agriculture.

[0063] Based on this, this invention provides a planting method for increasing the anthocyanin content in purple rice grains, specifically: Sow purple rice seeds from May 20th to 30th every year, with a nitrogen application rate of 24 kg N / mu and a transplanting density of 15,800 - 22,200 holes / mu. In addition, sowing, seedling raising, transplanting, and field management are the same as those in conventional high-yield cultivation, without adding additional management measures. Under these conditions, the content of peonidin and cyanidin in purple rice grains can be significantly increased.

[0064] The embodiments described above are only a part of the embodiments of this invention, not all of them. The detailed description of the embodiments of this invention is not intended to limit the scope of the claimed invention, but only represents the selected embodiments of this invention. The protection scope of this invention shall be subject to the scope required by the claims. Based on the embodiments of this invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this invention.

Claims

1. A planting method for increasing the anthocyanin content in purple rice grains, characterized in that, The purple rice seeds are sown from May 20th to 30th every year. At the same time, the nitrogen application rate is set at 24 kg N / mu, and the transplanting density is 15,800 - 22,200 hills / mu. Sowing, seedling raising, transplanting and field management are the same as those in conventional cultivation, without adding additional management measures.

2. The planting method for increasing the anthocyanin content in purple rice grains according to claim 1, characterized in that, The anthocyanins are peonidin and cyanidin.

3. A planting method for increasing the anthocyanin content in purple rice grains according to claim 1, characterized in that, The specific treatment method of the nitrogen application rate is as follows: basal fertilizer, tiller fertilizer, flower-promoting fertilizer and flower-preserving fertilizer are applied in a ratio of 3:3:2:

2.

4. A planting method for increasing the anthocyanin content in purple rice grains according to claim 1, characterized in that, The specific treatment method of the transplanting density is as follows: planting is carried out according to a row spacing of 30×(10 - 14) cm and 4 seedlings per hill.

5. A planting method for increasing the content of anthocyanins in purple rice grains according to claim 1, characterized in that, The variety of the purple rice is Yangzidao 6.

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