A cultivation method for reducing the GI value of rice, a special spraying fertilizer therefor, and rice obtained by the method

Abstract

The application discloses a cultivation method for reducing the GI value of rice, a special spraying fertilizer for the method, and rice obtained by the method. The application is characterized by: a special leaf spraying fertilizer containing a secondary energy active component is prepared, and accurate spraying is performed on rice in the key growth period from the jointing stage to the grain filling stage, so that the grain nutrient metabolism path of the rice is directionally regulated, and the enrichment and accumulation of resistant starch and beta-glucan are greatly promoted. The rice obtained by the special process has a content of resistant starch and beta-glucan more than 10 times that of ordinary rice, significantly reduces the glycemic index of the rice, retains the original taste and flavor of the rice, and does not need to be modified in the later stage, is original, has no addition, and is high in safety. The application has the advantages of simple process, low cost, no influence on the yield of rice, and realization of large-scale production, effectively solves the pain points of traditional rice, such as fast sugar rise and low functional and nutritional components, and is suitable for daily use of people who need to control blood sugar and people who need to keep fit.

Description

Technical Field

[0001] This invention belongs to the field of functional rice cultivation and agricultural product quality improvement technology, specifically involving a low-glycemic, high-resistant starch, and high-β-glucan nutritious rice cultivated through targeted intervention with special functional fertilizers for the rice growth period, as well as a suitable special spray fertilizer and a rice quality improvement cultivation method. Background Technology

[0002] Starch content in ordinary rice typically accounts for 75%–90% of the dry weight of the grain. Based on the rate of small intestinal digestion, starch can be divided into three categories: rapidly digestible starch, slowly digestible starch, and resistant starch. Rapidly digestible starch is quickly broken down into glucose after ingestion, leading to a rapid rise in postprandial blood glucose. Resistant starch, due to its special crystalline structure or the formation of complexes with lipids and proteins, resists hydrolysis by intestinal amylases and is almost not digested or absorbed. After entering the colon, it is fermented and utilized by intestinal flora to produce short-chain fatty acids, thus playing a role in stabilizing postprandial blood glucose, improving insulin sensitivity, and promoting intestinal health. Beta-glucan, as a water-soluble dietary fiber, has high viscosity and can slow gastric emptying and glucose release rates in the small intestine, thereby lowering the glycemic index of the diet. However, the resistant starch content in ordinary rice is typically only 0.5%–2.5% (dry basis), and the beta-glucan content is even less than 0.1%, which is almost negligible. The nutritional structure of rice, characterized by a high proportion of rapidly digestible starch, low resistant starch, and low dietary fiber, determines that ordinary rice is a high-GI food (GI value is usually between 75 and 90). It has a significant postprandial blood sugar response and is not suitable for long-term, regular consumption by people with high blood sugar, type 2 diabetes patients, and people who want to lose weight and control their blood sugar.

[0003] To address the growing demand for low-GI diets, various technological approaches have emerged both domestically and internationally in recent years for the development of low-GI rice. One approach involves variety breeding and genetic engineering, which involves screening natural low-GI germplasm resources or using molecular marker-assisted selection and gene editing to alter the amylose-amylose ratio. However, this method has an extremely long breeding cycle (typically 8-15 years), limited regional adaptability, significant quality fluctuations, and limited improvement in resistant starch content for a single variety (usually only from 2% to 5%-8%), making it difficult to achieve a significant leap in yield. Furthermore, gene-edited products face challenges related to biosafety regulations and consumer acceptance. Another approach utilizes methods such as wet heat treatment, pressure heating, and microwave radiation to disrupt starch crystal structures or induce the formation of amylose-lipid complexes. However, this is a late-stage processing step, increasing production steps and energy costs. The processing also leads to rice protein denaturation, partial vitamin loss, and grain densification, resulting in hard, quickly hardened cooked rice. Additionally, the modified resistant starch exhibits poor stability and is prone to partial reversal during cooking, leading to a significant decrease in the actual post-meal benefits. Enzymatic modification utilizes amylase, pullulanase, and transglycosidase to perform targeted hydrolysis and branching reconstruction of rice starch. However, the process is complex, enzyme preparations are expensive, and industrial scale-up is difficult. Furthermore, enzymatic treatment deviates from rice's inherent characteristics as a natural whole grain, resulting in high grain breakage and reduced head rice yield, significantly diminishing its commercial value. The mixed grain compounding route involves blending rice with high-resistant starch or high-β-glucan raw materials, extruding and granulating, or compound cooking. However, this route alters the taste and flavor characteristics of pure rice, masking its aroma, and only achieves a physical dilution effect without fundamentally improving the functional nutritional components of the rice grains, thus facing significant market resistance. A few studies have also reported on improving the nutritional quality of rice by applying foliar fertilizers containing specific mineral elements or plant growth regulators during the rice growing season. However, the functional improvement of existing programs is extremely limited (the improvement rate of resistant starch is usually less than 30%-50%), which is far from enough to significantly change the GI value. Moreover, most programs focus on micronutrient enrichment rather than targeted intervention on starch component metabolic pathways, and have little effect on the core indicators of blood sugar reduction and control.

[0004] In summary, existing low-GI rice improvement technologies have shortcomings in various dimensions: variety breeding yields low improvement and is time-consuming; physical and enzymatic modifications destroy natural properties and are costly; blending with other grains alters the taste without improving the rice's nutritional value; and existing fertilizer methods offer minimal improvement. The core flaw in these technologies is that none can achieve a tenfold or greater increase in resistant starch and β-glucan content, and significantly reduce the GI value to the low-to-medium GI range, without altering the original rice cultivation system, adding post-processing steps, or affecting the rice's original taste and yield. This technological gap directly results in a lack of large-scale products on the market that both retain the natural properties of pure rice and possess clear blood sugar-lowering and blood sugar-controlling functions.

[0005] To address the shortcomings of existing technologies, this invention provides a novel technical solution: by developing a specialized functional fertilizer for foliar spraying during the rice's growth period, precise and repeated targeted spraying interventions are conducted during the critical growth window from the jointing stage to the grain-filling stage. Without altering conventional rice cultivation and management practices, affecting yield per acre, or increasing post-processing, this invention directionally regulates starch synthesis and nutrient metabolism pathways from the grain-filling stage, resulting in a simultaneous enrichment of resistant starch and β-glucan content in rice by more than 10 times. This significantly lowers the rice's glycemic index (GI) from the high GI range to the medium-low GI range, providing a truly natural staple rice with both edible and medicinal properties for people with abnormal blood sugar, those trying to lose weight, and those seeking health-conscious blood sugar control.

[0006] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0007] Purpose of the invention

[0008] To address the shortcomings of existing technologies, this invention provides a low-GI, high-nutrient rice, along with its dedicated spray fertilizer and planting method. Through a proprietary fertilizer formula and precise spraying technology during the growth period, a natural functional rice with resistant starch and β-glucan content more than 10 times that of ordinary rice and a significantly lower glycemic index is cultivated. It requires no post-processing or modification, is grown organically, has excellent taste, and can be mass-produced.

[0009] To address the shortcomings of existing technologies, this invention provides a cultivation method for reducing the GI value of rice, a special spray fertilizer thereof, and rice obtained by the method.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] A cultivation method for reducing the GI value of rice includes the following steps:

[0012] Based on conventional rice land preparation, seedling raising, transplanting, and field water and fertilizer management, apply special spray fertilizer 6-8 times during the rice jointing stage to the grain filling stage.

[0013] Through metabolic intervention during the growth period, the resistant starch content and β-glucan content of the harvested rice are more than 10 times that of ordinary rice of the same variety and from the same plot of land, and the glycemic index is lower than that of ordinary rice.

[0014] The special spray fertilizer is diluted with water, and 50-60 kg of diluted solution is sprayed per hectare at a time, with an interval of 7-10 days between sprayings.

[0015] Preferably, the special spray fertilizer, by weight, contains 8 parts of magnetic energy active functional component, 40 parts of photosynthetic bacteria nutrient solution, 40 parts of traditional Chinese medicine extract, and 1-2 parts of leaf penetration aid.

[0016] Furthermore, the magnetic energy active functional component is tourmaline-maifanite composite mineral powder, specifically including 4.8 parts tourmaline powder, 2.4 parts maifanite powder, and 0.8 parts neodymium iron boron permanent magnet powder, which are mixed and then treated with a 0.4T alternating magnetic field for 40 minutes.

[0017] The photosynthetic bacteria nutrient solution is a liquid culture of *Rhodopseudomonas capsulata* and / or *Rhodopseudomonas spheroides*, with an effective viable count ≥ 5 × 10⁻⁶. 8 CFU / m;

[0018] The Chinese herbal extracts are aqueous extracts of Astragalus membranaceus, Lycium barbarum, Glycyrrhiza uralensis, or mulberry leaves, with a solid content ≥20%.

[0019] The leaf surface penetration aid is a polyether-modified trisiloxane organosilicon surfactant.

[0020] The second aspect of the present invention provides a special spray fertilizer for the cultivation method described in the claim. The special spray fertilizer, by weight, comprises 8 parts of magnetic energy active functional component, 40 parts of photosynthetic bacteria nutrient solution, 40 parts of traditional Chinese medicine extract, and 1-2 parts of foliar penetration aid. The special spray fertilizer is used for foliar spraying of rice from the jointing to the grain-filling stage to directionally increase the content of resistant starch and β-glucan in rice and reduce the glycemic index.

[0021] Preferably, it should be diluted with water 20-800 times before use, and sprayed at the end of the rice jointing stage, the beginning of the grain filling stage, and the middle of the grain filling stage.

[0022] It is recommended to dilute it 300 times with water.

[0023] A third aspect of the present invention provides a low-GI rice obtained by the cultivation method, which, compared with ordinary rice of the same variety and conventionally cultivated in the same plot, has a resistant starch content of more than 10 times, a β-glucan content of more than 10 times, and a glycemic index of lower than that of ordinary rice.

[0024] Preferably, the rice is obtained from harvested rice through conventional processing such as hulling, milling, and screening, and has the characteristics of low glycemic index, high dietary fiber, and high resistant starch, while retaining the original taste and flavor of rice.

[0025] The preferred method does not alter the original rice water and fertilizer, pest and disease control, and field management system throughout the entire process, and is suitable for the cultivation of various conventional rice varieties, including indica and japonica rice.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] 1. Significant breakthrough in nutritional indicators: The rice of this invention has resistant starch and β-glucan content that are more than 10 times that of ordinary rice, far exceeding existing conventional improved rice, and the functional nutritional components have achieved an order-of-magnitude increase.

[0028] 2. Significant low-GI blood sugar control effect: The proportion of rapidly digestible starch in the grains is reduced, while the proportion of resistant starch is greatly increased. The starch digestion rate is slowed down, and postprandial blood sugar fluctuations are smooth, making it suitable for people with abnormal blood sugar and those who want to control their blood sugar.

[0029] 3. Original ecological and natural attributes: Improvement is achieved only through foliar spraying of natural functional fertilizers during the growth period. There are no artificial synthetic additives, no subsequent physical / chemical modifications, and no compounding of mixed grains, thus preserving the original taste, aroma, and edible texture of rice.

[0030] 4. Suitable for large-scale production: The process is simple, the cost is low, no modification of planting equipment is required, and it does not affect rice yield, so it can be widely promoted for planting.

[0031] 5. High safety: The fertilizer components are green and harmless, and there is no residue in the rice, which meets the national food safety standards. Detailed Implementation

[0032] The present invention will be further described below through specific embodiments. To make the inventive objectives, technical solutions, and beneficial technical effects of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the embodiments described in this specification are merely for explaining the present invention and are not intended to limit the present invention.

[0033] Unless otherwise stated, all instruments and reagents used in the examples are commercially available or synthesized using conventional methods and can be used directly without further processing, and all instruments used in the examples are commercially available.

[0034] Example 1:

[0035] A conventional japonica rice variety (Nanjing 9108) was selected and planted in separate plots within the same field, with a control group and an experimental group established. The control group received conventional rice fertilization and cultivation management throughout the entire process, without being sprayed with the functional fertilizer of this invention. The experimental group, in addition to conventional cultivation management, received the special spray fertilizer of this invention six times at three growth stages: late jointing, early grain filling, and mid-grain filling. Specifically, it was sprayed twice at late jointing, twice at early grain filling, and twice at mid-grain filling, with each spraying occurring 10 days apart.

[0036] The special spray fertilizer contains, by weight parts:

[0037] Eight parts of tourmaline-maifanite composite mineral powder (composed of 4.8 parts tourmaline powder, 2.4 parts maifanite powder, and 0.8 parts neodymium iron boron permanent magnet powder, with a particle size of 200-300 mesh, prepared by mixing and then treating with a 0.4T alternating magnetic field for 40 minutes).

[0038] 40 portions of photosynthetic bacteria nutrient solution (liquid culture of Rhodopseudomonas capsulatum, effective viable count 6×10⁻⁶) 8 (CFU / mL)

[0039] Forty portions of traditional Chinese medicine extracts (Astragalus membranaceus aqueous extract, solids content 25%).

[0040] One part of leaf penetration aid (polyether-modified trisiloxane organosilicon surfactant).

[0041] Dilute 20 times with water, and apply 50 kg of the diluted solution per hectare per single spray. All other field management procedures are identical to the control group. After maturity, harvest, hull, and grind the crops uniformly, and send them to a third-party CMA testing agency for analysis.

[0042] The results showed that the resistant starch content of the rice in the experimental group was 11.2 times that of the control group, the β-glucan content was 10.8 times that of the control group, and the GI value was 52.3, which was significantly lower than the 83.6 of the control group. The rice grains were plump and had a soft and glutinous texture. The yield per mu was not significantly different from that of the control group.

[0043] Example 2

[0044] A conventional japonica rice variety (Nanjing 9108) was selected and planted in separate plots within the same field, with a control group and an experimental group established. The control group received conventional rice fertilization and cultivation management throughout the entire process, without being sprayed with the functional fertilizer of this invention. The experimental group, in addition to conventional cultivation management, received the special spray fertilizer of this invention seven times at three growth stages: late jointing, early grain filling, and mid-grain filling. Specifically, it was sprayed twice at late jointing, three times at early grain filling, and twice at mid-grain filling, with each spraying occurring eight days apart.

[0045] The special spray fertilizer contains, by weight parts:

[0046] Eight parts of tourmaline-maifanite composite mineral powder (composed of 4.8 parts tourmaline powder, 2.4 parts maifanite powder, and 0.8 parts neodymium iron boron permanent magnet powder, with a particle size of 200-300 mesh, prepared by mixing and then treating with a 0.4T alternating magnetic field for 40 minutes).

[0047] 40 portions of photosynthetic bacteria nutrient solution (liquid culture of Rhodopseudomonas spheroidae, effective viable count 7 × 10⁻⁶) 8 (CFU / mL)

[0048] Forty portions of traditional Chinese medicine extracts (goji berry water extract, solid content 22%).

[0049] 1.5 parts of foliar penetration enhancer (alkyl glycoside);

[0050] Dilute the solution 300 times with water, and apply 55 kg of the diluted solution per hectare per single spray. All other field management procedures are identical to the control group. After maturity, harvest, hull, and grind the crops uniformly, and then send them to a third-party CMA testing agency for analysis.

[0051] The results showed that the resistant starch content of the rice in the experimental group was 13.5 times that of the control group, the β-glucan content was 12.1 times that of the control group, and the GI value was 48.7, which was significantly lower than the 83.6 of the control group. The rice grains were plump and had a soft and glutinous texture. The yield per mu was not significantly different from that of the control group.

[0052] Example 3

[0053] A conventional japonica rice variety (Nanjing 9108) was selected and planted in separate plots within the same field, with a control group and an experimental group established. The control group received conventional rice fertilization and cultivation management throughout the entire process, without being sprayed with the functional fertilizer of this invention. The experimental group received the special spray fertilizer of this invention eight times at three growth stages: late jointing, early grain filling, and mid-grain filling. Specifically, it was sprayed twice at the late jointing stage, three times at the early grain filling stage, and three times at the mid-grain filling stage, with each spraying occurring 7 days apart.

[0054] The special spray fertilizer contains, by weight parts:

[0055] Eight parts of tourmaline-maifanite composite mineral powder (composed of 4.8 parts tourmaline powder, 2.4 parts maifanite powder, and 0.8 parts neodymium iron boron permanent magnet powder, with a particle size of 200-300 mesh, prepared by mixing and then treating with a 0.4T alternating magnetic field for 40 minutes).

[0056] 40 portions of photosynthetic bacteria nutrient solution (mixed liquid culture of Rhodopseudomonas capsulatum and Rhodopseudomonas spheroidosa, mass ratio 1:1, total effective viable bacteria count 8×10⁻⁶) 8 (CFU / mL)

[0057] Forty portions of traditional Chinese medicine extracts (licorice water extract, solids content 28%).

[0058] Two parts of foliar penetration enhancer (fatty alcohol polyoxyethylene ether).

[0059] Dilute 800 times with water, and apply 60 kg of the diluted solution per hectare per single spray. All other field management procedures are identical to the control group. After maturity, harvest, hull, and grind the crops uniformly, and send them to a third-party CMA testing agency for analysis.

[0060] The results showed that the resistant starch content of the rice in the experimental group was 10.3 times that of the control group, the β-glucan content was 10.1 times that of the control group, and the GI value was 54.1, which was significantly lower than the 83.6 of the control group. The rice grains were plump and had a soft and glutinous texture. The yield per mu was not significantly different from that of the control group.

[0061] Example 4

[0062] A conventional indica rice variety (Fengliangyou 4) was selected and planted in separate plots within the same field, with a control group and an experimental group established. The control group received conventional rice fertilization and cultivation management throughout the entire process, without being sprayed with the functional fertilizer of this invention. The experimental group, in addition to conventional cultivation management, received the special spray fertilizer of this invention seven times at three growth stages: late jointing, early grain filling, and mid-grain filling. Specifically, it was sprayed twice at late jointing, three times at early grain filling, and twice at mid-grain filling, with each spraying occurring eight days apart.

[0063] The special spray fertilizer contains, by weight parts:

[0064] Eight parts of tourmaline-maifanite composite mineral powder (composed of 4.8 parts tourmaline powder, 2.4 parts maifanite powder, and 0.8 parts neodymium iron boron permanent magnet powder, with a particle size of 200-300 mesh, prepared by mixing and then treating with a 0.4T alternating magnetic field for 40 minutes).

[0065] 40 portions of photosynthetic bacteria nutrient solution (liquid culture of Rhodopseudomonas capsulatum, effective viable count 6×10⁻⁶) 8 (CFU / mL)

[0066] Forty portions of traditional Chinese medicine extracts (mulberry leaf water extract, solids content 24%).

[0067] 1.5 parts of leaf penetration enhancer (polyether-modified trisiloxane organosilicon surfactant);

[0068] Dilute the solution 300 times with water, and apply 55 kg of the diluted solution per hectare per single spray. All other field management procedures are identical to the control group. After maturity, harvest, hull, and grind the crops uniformly, and then send them to a third-party CMA testing agency for analysis.

[0069] The results showed that the resistant starch content of the rice in the experimental group was 12.8 times that of the control group, the β-glucan content was 11.5 times that of the control group, and the GI value was 49.2, which was significantly lower than the 81.4 of the control group. The rice grains were plump and had a soft and glutinous texture. The yield per mu was not significantly different from that of the control group.

[0070] Example 5

[0071] A conventional indica rice variety (Jingliangyou 534) was selected and planted in separate plots within the same field, with a control group and an experimental group established. The control group received conventional rice fertilization and cultivation management throughout the entire process, without being sprayed with the functional fertilizer of this invention. The experimental group, in addition to conventional cultivation management, received the special spray fertilizer of this invention six times at three growth stages: late jointing, early grain filling, and mid-grain filling. Specifically, it was sprayed twice at late jointing, twice at early grain filling, and twice at mid-grain filling, with each spraying occurring 10 days apart.

[0072] The special spray fertilizer contains, by weight parts:

[0073] Eight parts of tourmaline-maifanite composite mineral powder (composed of 4.8 parts tourmaline powder, 2.4 parts maifanite powder, and 0.8 parts neodymium iron boron permanent magnet powder, with a particle size of 200-300 mesh, prepared by mixing and then treating with a 0.4T alternating magnetic field for 40 minutes).

[0074] 40 portions of photosynthetic bacteria nutrient solution (liquid culture of Rhodopseudomonas spheroidae, effective viable count 5 × 10⁻⁶) 8 (CFU / mL)

[0075] Forty portions of Chinese herbal extracts (a mixture of Astragalus membranaceus and Lycium barbarum water extracts, mass ratio 1:1, total solids content 26%).

[0076] One part of foliar penetration enhancer (sodium dodecylbenzene sulfonate);

[0077] Dilute 20 times with water, and apply 50 kg of the diluted solution per hectare per single spray. All other field management procedures are identical to the control group. After maturity, harvest, hull, and grind the crops uniformly, and send them to a third-party CMA testing agency for analysis.

[0078] The results showed that the resistant starch content of the rice in the experimental group was 11.5 times that of the control group, the β-glucan content was 10.9 times that of the control group, and the GI value was 51.8, which was significantly lower than the 82.3 of the control group. The rice grains were plump and had a soft and glutinous texture. The yield per mu was not significantly different from that of the control group.

[0079] Example 6

[0080] A conventional japonica rice variety (Nanjing 9108) was selected and planted in separate plots within the same field, with a control group and an experimental group established. The control group received conventional rice fertilization and cultivation management throughout the entire process, without being sprayed with the functional fertilizer of this invention. The experimental group received conventional cultivation management, but was sprayed with the special spray fertilizer of this invention six times at two growth stages: the end of the jointing stage and the beginning of the grain-filling stage. The spraying was performed three times at the end of the jointing stage and three times at the beginning of the grain-filling stage, with each application spaced nine days apart.

[0081] The special spray fertilizer contains, by weight parts:

[0082] Eight parts of tourmaline-maifanite composite mineral powder (composed of 4.8 parts tourmaline powder, 2.4 parts maifanite powder, and 0.8 parts neodymium iron boron permanent magnet powder, with a particle size of 200-300 mesh, prepared by mixing and then treating with a 0.4T alternating magnetic field for 40 minutes).

[0083] 40 portions of photosynthetic bacteria nutrient solution (liquid culture of Rhodopseudomonas capsulatum, effective viable count 6×10⁻⁶) 8 (CFU / mL)

[0084] Forty portions of Chinese herbal extracts (a mixture of licorice and mulberry leaf water extracts, mass ratio 1:1, total solids content 23%).

[0085] 1.2 parts of foliar penetration enhancer (alkyl glycoside);

[0086] Dilute 150 times with water, and apply 52 kg of the diluted solution per hectare per single spray. All other field management procedures are identical to the control group. After maturity, harvest, hull, and grind the crops uniformly, and send them to a third-party CMA testing agency for analysis.

[0087] The results showed that the resistant starch content of the rice in the experimental group was 10.9 times that of the control group, the β-glucan content was 10.5 times that of the control group, and the GI value was 53.6, which was significantly lower than the 83.6 of the control group. The rice grains were plump and had a soft and glutinous texture. The yield per mu was not significantly different from that of the control group.

[0088] Note: This embodiment verifies that the target effect can be achieved by completing 6 sprays at two key nodes from the end of jointing to the beginning of grouting. However, the effect is slightly lower than that of Embodiment 2, which covers three nodes from the end of jointing to the middle of grouting (13.5 times resistant starch vs. 10.9 times). This indicates that covering the entire window period (from the end of jointing to the middle of grouting) is more effective.

[0089] Example 7

[0090] A conventional japonica rice variety (Nanjing 9108) was selected and planted in separate plots within the same field, with a control group and an experimental group established. The control group received conventional rice fertilization and cultivation management throughout the entire process, without being sprayed with the functional fertilizer of this invention. The experimental group, in addition to conventional cultivation management, received the special spray fertilizer of this invention eight times at two growth stages: the early and middle stages of grain filling. Specifically, it was sprayed four times at the early stage of grain filling and four times at the middle stage of grain filling, with each application spaced seven days apart.

[0091] The special spray fertilizer contains, by weight parts:

[0092] Eight parts of tourmaline-maifanite composite mineral powder (composed of 4.8 parts tourmaline powder, 2.4 parts maifanite powder, and 0.8 parts neodymium iron boron permanent magnet powder, with a particle size of 200-300 mesh, prepared by mixing and then treating with a 0.4T alternating magnetic field for 40 minutes).

[0093] 40 portions of photosynthetic bacteria nutrient solution (liquid culture of Rhodopseudomonas spheroidae, effective viable count 7 × 10⁻⁶) 8 (CFU / mL)

[0094] Forty portions of Chinese herbal extracts (a mixture of water extracts of wolfberry and licorice, mass ratio 2:1, total solids content 25%).

[0095] 1.8 parts of foliar penetration enhancer (fatty alcohol polyoxyethylene ether);

[0096] Dilute the solution 600 times with water, and apply 58 kg of the diluted solution per hectare per single spray. All other field management procedures were identical to the control group. After maturity, the crops were harvested, hulled, and milled uniformly, and then sent to a third-party CMA testing agency for analysis.

[0097] The results showed that the resistant starch content of the rice in the experimental group was 10.6 times that of the control group, the β-glucan content was 10.3 times that of the control group, and the GI value was 53.9, which was significantly lower than the 83.6 of the control group. The rice grains were plump and had a soft and glutinous texture. The yield per mu was not significantly different from that of the control group.

[0098] Note: This embodiment verifies that the target effect can be achieved by completing 8 sprayings during the grouting period (from the initial stage to the middle stage of grouting), but the effect is slightly lower than that of Example 2, which covers the three nodes from the end of jointing to the middle stage of grouting (13.5 times vs 10.6 times resistant starch). This shows that starting the spraying at the end of jointing has a positive effect on maximizing the enrichment of functional components.

[0099] Note, where:

[0100] Preparation method of tourmaline-maifanite composite mineral powder: Take 60 parts by weight of tourmaline powder (particle size 200-300 mesh), 30 parts by weight of maifanite powder (particle size 200-300 mesh), and 10 parts by weight of neodymium iron boron permanent magnet material powder (N35 grade, particle size 100-200 mesh). Mix them thoroughly and then place them in an alternating magnetic field with a magnetic field strength of 0.3-0.5T for 30-45 minutes at a frequency of 50Hz. This will induce a magnetization and activation effect on the surface of the mineral powder, enhancing its ability to release negative ions and far-infrared rays, while also improving its synergistic effect with photosynthetic bacteria nutrient solution and traditional Chinese medicine extracts. After treatment, seal and store for later use.

[0101] Preparation method of photosynthetic bacteria nutrient solution: Inoculate *Rhodopseudomonas capsulata* and / or *Rhodopseudomonas spheroides* into liquid culture medium. The culture medium formula is: sodium acetate 2.0 g / L, ammonium chloride 1.0 g / L, potassium dihydrogen phosphate 0.5 g / L, magnesium sulfate 0.2 g / L, yeast extract 1.0 g / L. Adjust the pH to 7.0. Anaerobically culture for 5-7 days under a light intensity of 2000-3000 lux and a temperature of 30-35℃, until the bacterial solution turns deep red and the effective viable count is ≥5 × 10⁻⁶. 8 Harvest at CFU / mL and store in a sealed container at low temperature for later use.

[0102] Preparation method of Chinese herbal extract: Take dried Astragalus membranaceus, Lycium barbarum, Glycyrrhiza uralensis or mulberry leaves as raw materials, crush them and pass them through a 40-mesh sieve. Add deionized water at a material-to-liquid ratio of 1:10, reflux at 80℃ for 2 hours, filter, and repeat the extraction once under the same conditions with the filter residue. Combine the filtrates, concentrate under reduced pressure until the solid content is ≥20%, cool to room temperature, and seal for later use.

[0103] GI Detection Method Description: In all embodiments and comparative examples of this invention, the glycemic index (GI) of rice was determined in accordance with the People's Republic of China Health Industry Standard WS / T 652-2019 "Method for Determination of Glycemic Index of Food". Specifically, 12 healthy adult volunteers were recruited. Under fasting conditions, each volunteer consumed either a sample of rice containing 50g of available carbohydrates or a standard glucose solution. Finger-prick capillary blood samples were collected at fasting times and at 15, 30, 45, 60, 90, and 120 minutes postprandial. Blood glucose concentrations were measured using a blood glucose meter, and a glycemic response curve was plotted. The area under the glycemic response curve (IAUC) was calculated. Using the standard glucose GI value of 100 as a reference, the GI value of the sample was calculated. Each sample was measured three times, and the average value was taken.

[0104] Comparative Example 1: (Insufficient number of sprayings)

[0105] A conventional japonica rice variety (Nanjing 9108) was selected and planted in separate plots within the same field. The experimental group was sprayed a total of four times (less than the minimum of six times) at three stages: late jointing, early grain filling, and mid-grain filling, with an interval of 10 days. The special spray fertilizer composition was the same as in Example 2, diluted 300 times with water, and 55 kg was sprayed per hectare per single application.

[0106] The results showed that resistant starch was 5.2 times that of the control group, β-glucan was 4.8 times, and the GI value was 67.5. This indicates that fewer than 6 sprayings cannot achieve the enrichment target of more than 10 times.

[0107] Comparative Example 2: (Single-node spraying)

[0108] A conventional japonica rice variety (Nanjing 9108) was selected and planted in separate sections of the same field. The experimental group was sprayed 7 times at a single stage during the mid-grain-filling stage, with an interval of 8 days. The special spray fertilizer composition was the same as in Example 2, diluted 300 times with water, and 55 kg was sprayed per hectare per single application.

[0109] The results showed that resistant starch was 4.5 times that of the control group, β-glucan was 4.1 times that of the control group, and the GI value was 70.3. This indicates that without covering the entire window period from jointing to grain filling, targeted synergistic enrichment of functional components cannot be achieved.

[0110] Comparative Example 3: (Dilution factor exceeded limit)

[0111] A conventional japonica rice variety (Nanjing 9108) was selected and planted in separate plots within the same field. The experimental group received 7 applications of the special spray fertilizer at the end of the jointing stage, the beginning of the grain-filling stage, and the middle of the grain-filling stage, with an 8-day interval between each application. The composition of the special spray fertilizer was the same as in Example 2, diluted 900 times with water (exceeding the 800-fold upper limit), with 55 kg applied per hectare per single application.

[0112] The results showed that resistant starch was 6.8 times that of the control group, β-glucan was 6.3 times, and the GI value was 62.7. This indicates that when the dilution factor exceeds the upper limit, the effective concentration is insufficient to drive the metabolic pathway to fully shift.

[0113] Comparative Example 4: (Insufficient spraying amount)

[0114] A conventional japonica rice variety (Nanjing 9108) was selected and planted in separate plots within the same field. The experimental group was sprayed 7 times at the end of the jointing stage, the beginning of the grain filling stage, and the middle of the grain filling stage, with an interval of 8 days. The special spray fertilizer composition was the same as in Example 2, diluted 300 times with water, and 40 kg per hectare was sprayed at a time (below the lower limit of 50 kg).

[0115] The results showed that resistant starch was 7.2 times that of the control group, β-glucan was 6.9 times that of the control group, and the GI value was 60.5. This indicates that insufficient single-application dosage cannot achieve a sustained absorption concentration on the leaf surface.

[0116] Comparative Example 5: (Permeation aid below the lower limit)

[0117] A conventional japonica rice variety (Nanjing 9108) was selected and planted in separate plots within the same field. The experimental group received seven applications of the special spray fertilizer at the end of the jointing stage, the beginning of the grain-filling stage, and the middle of the grain-filling stage, with an interval of eight days. The composition of the special spray fertilizer was the same as in Example 2, except that the foliar penetration adjuvant was 0.5 parts (below the lower limit of 1 part), diluted 300 times with water, and 55 kg was sprayed per hectare per single application.

[0118] The results showed that resistant starch was 7.8 times that of the control group, β-glucan was 7.2 times that of the control group, and the GI value was 59.3. This indicates that insufficient penetration enhancer reduces leaf surface penetration efficiency, preventing functional components from effectively entering the plant.

[0119] Comparative Example 6: (Permeation aid exceeds the upper limit)

[0120] A conventional japonica rice variety (Nanjing 9108) was selected and planted in separate plots within the same field. The experimental group received 7 applications of the special spray fertilizer at the end of the jointing stage, the beginning of the grain-filling stage, and the middle of the grain-filling stage, with an interval of 8 days. The composition of the special spray fertilizer was the same as in Example 2, except that the foliar penetration adjuvant was 3 parts (higher than the upper limit of 2 parts), diluted 300 times with water, and 55 kg was sprayed per hectare per single application.

[0121] The results showed that resistant starch was 8.1 times that of the control group, β-glucan was 7.6 times, the GI value was 58.1, and some leaves showed slight scorching. This indicates that excessive osmotic pressure on the leaf surface when the penetration enhancer is applied excessively damages the leaf tissue structure and affects normal absorption and metabolic transformation.

[0122] Comparative Example 7: (Missing maifanite powder and neodymium iron boron)

[0123] A conventional japonica rice variety (Nanjing 9108) was selected and planted in separate plots within the same field. The experimental group received seven applications of the special spray fertilizer, applied at the end of the jointing stage, the beginning of the grain-filling stage, and the middle of the grain-filling stage, with an 8-day interval. The composition of the special spray fertilizer was the same as in Example 2, except that 4.8 parts of tourmaline powder replaced the tourmaline-maifanite composite mineral powder (excluding maifanite powder and neodymium iron boron, and untreated with a magnetic field). The fertilizer was diluted 300 times with water, and 55 kg was sprayed per hectare per application.

[0124] The results showed that the resistant starch was 6.5 times that of the control group, the β-glucan was 6.1 times that of the control group, and the GI value was 63.2. This indicates that when tourmaline powder alone is not activated by a magnetic field and is not synergistically combined, the release of negative ions and the far-infrared effect are insufficient, and the synergistic effect is significantly reduced.

[0125] Comparative Example 8: (Without magnetic field treatment)

[0126] A conventional japonica rice variety (Nanjing 9108) was selected and planted in separate plots within the same field. The experimental group received 7 applications of the special spray fertilizer at the end of the jointing stage, the beginning of the grain-filling stage, and the middle of the grain-filling stage, with an 8-day interval. The composition of the special spray fertilizer was the same as in Example 2, except that the tourmaline-maifanite composite mineral powder was not treated with a magnetic field. It was diluted 300 times with water, and 55 kg was sprayed per hectare per application.

[0127] The results showed that the resistant starch was 7.5 times that of the control group, the β-glucan was 7.0 times, and the GI value was 61.8. This indicates that the surface activity of the untreated composite mineral powder was insufficient and could not effectively activate the leaf photosynthetic system and metabolic pathways. The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A cultivation method for reducing the GI value of rice, characterized in that, Includes the following steps: Based on conventional rice land preparation, seedling raising, transplanting, and field water and fertilizer management, apply special spray fertilizer 6-8 times during the rice jointing stage to the grain filling stage. Through metabolic intervention during the growth period, the resistant starch content and β-glucan content of the harvested rice are more than 10 times that of ordinary rice of the same variety and from the same plot of land, and the glycemic index is lower than that of ordinary rice. The special spray fertilizer is diluted with water, and 50-60 kg of diluted solution is sprayed per hectare at a time, with an interval of 7-10 days between sprayings.

2. The cultivation method for reducing the GI value of rice according to claim 1, characterized in that, The special spray fertilizer, by weight, contains 8 parts of magnetic energy active functional component, 40 parts of photosynthetic bacteria nutrient solution, 40 parts of traditional Chinese medicine extract, and 1-2 parts of leaf penetration aid.

3. A special spray fertilizer for the cultivation method described in claim 1 or 2, characterized in that, The special spray fertilizer, by weight, contains 8 parts of magnetic energy active functional component, 40 parts of photosynthetic bacteria nutrient solution, 40 parts of traditional Chinese medicine extract, and 1-2 parts of foliar penetration aid; the special spray fertilizer is used for foliar spraying of rice from the jointing to the grain-filling stage to specifically increase the content of resistant starch and β-glucan in rice and reduce the glycemic index.

4. The special spray fertilizer according to claim 3, characterized in that: Dilute with water 20-800 times before use. Spraying time is at the end of the rice jointing stage, the beginning of the grain filling stage, and the middle of the grain filling stage.

5. A low-GI rice obtained by the cultivation method according to claim 1 or 2, characterized in that, Compared to ordinary rice of the same variety and conventionally cultivated in the same plot, the rice described above has more than 10 times the resistant starch content and more than 10 times the β-glucan content of ordinary rice, and its glycemic index is lower than that of ordinary rice.

6. The low-GI rice according to claim 5, characterized in that, The rice is obtained from harvested paddy through conventional processing such as hulling, milling, and screening. It has the characteristics of low glycemic index, high dietary fiber, and high resistant starch, while retaining the original taste and flavor of rice.

7. The cultivation method according to claim 1 or 2, characterized in that, The entire process does not alter the original rice water and fertilizer, pest and disease control, and field management system, and is suitable for the cultivation of various conventional rice varieties, including indica and japonica rice.