A method of growing corn

Abstract

The application belongs to the technical field of crop production, and particularly relates to a corn planting method. The application adjusts corn root system development through carboxylated nanometer carbon dots, aims to build an ideal root type of dense corn, coordinates and optimizes root layer and crown layer structures, balances root layer and soil water and nutrient supply, and further improves corn yield and water and fertilizer utilization efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of crop production, and particularly relates to a corn planting method. BACKGROUND

[0002] In current corn production, increasing planting density has become an inevitable trend to further increase yield. However, in high-density populations, corn plants shade each other, the light transmittance of the population canopy decreases, and the competition for light resources between individuals intensifies; at the same time, the competition for water and nutrients in the soil by the root system also intensifies, which together leads to serious early decline of corn growth and development under high-density planting conditions, decline of leaf photosynthetic performance, reduction of ear grain number and thousand-grain weight, and ultimately reduction of yield.

[0003] To adapt to high-density planting systems, breeding of corn varieties with high yield under high density is the most important technical means. Breeding techniques effectively improve the canopy structure of densely planted corn by improving leaf angle, tassel size, and flowering-silk shedding interval, enhance the ventilation and light transmittance of the population, and improve the interception of canopy light radiation, thereby obtaining higher population photosynthetic efficiency and dry matter accumulation efficiency.

[0004] Although root architecture improvement is not a breeding target, recent studies have found that the root architecture of corn inbred lines selected in different years has also undergone significant selection, and modern corn varieties with high yield under high density have steeper root systems, i.e., the root angle is smaller, and the plant type is more compact, which may enable the root system to extend to deeper soil layers. Deeper root systems can improve water and nitrogen use efficiency and reduce competition between roots under dense planting conditions. The inventors' previous studies have also shown that using soil deep plowing to reduce the mechanical resistance of the soil to the downward growth of corn roots is an effective means to construct a good root architecture and achieve high yield under dense planting.

[0005] Auxin is considered to be the most core hormone for regulating root geotropism, root elongation, lateral root formation, and root hair development. Moreover, the regulation of auxin on root development has a high concentration dependence: low concentration of auxin stimulates root elongation; medium concentration of auxin promotes root radial expansion and lateral root formation; and high concentration of auxin inhibits root growth.

[0006] The currently used auxins mainly include auxin active substances contained in plants, such as indole acetic acid and indole butyric acid, which are chemically unstable and easy to decompose, and are not easy to accurately control the concentration as plant growth regulators. Another type is naphthalene acetic acid, which is artificially synthesized and has very high auxin activity, and is chemically stable and very sensitive to concentration in plants, and is also not easy to accurately control in production.

[0007] These growth hormones are difficult to accurately control the actual growth hormone concentration acting on the roots when applied to the regulation of root system development which is highly dependent on the concentration, resulting in a significant deviation from the target. SUMMARY

[0008] The present application aims to provide a corn planting method, by regulating corn root development, intending to build a "ideal root type" of densely planted corn, coordinating and optimizing the structure of root layer and canopy, balancing the supply of soil water and nutrients in the root layer, and further improving the yield and water and fertilizer utilization efficiency of corn.

[0009] The present application first provides the application of carboxylated nanocarbon dots in regulating the root configuration of densely planted corn or in corn planting.

[0010] The present application also provides a seed priming solution containing carboxylated nanocarbon dots.

[0011] Specifically, the volume percentage concentration of carboxylated nanocarbon dots in the seed priming solution is 0.001%-0.5%, preferably 0.01%-0.5%, more preferably 0.1%-0.5%, and more preferably 0.2%.

[0012] Specifically, the volume percentage concentration of carboxylated nanocarbon dots in the seed priming solution is 0.001%, 0.01%, 0.1%, 0.2%, or 0.5%.

[0013] Research has found that if the volume percentage concentration of carboxylated nanocarbon dots in the seed priming solution is too high, for example, more than 1.0%, it will inhibit the growth of corn roots.

[0014] Specifically, the seed priming solution also includes the components of conventional seed priming solutions, such as nitrogen, phosphorus, potassium, and calcium, and other nutrient elements.

[0015] In some embodiments, the seed priming solution further includes: 180-220 mg / L of KH2PO4; 180-220 mg / L of CaCl2·2H2O; and 1000-1400 mg / L of (NH4)2SO4;

[0016] In some specific embodiments, the seed priming solution further includes: 200 mg / L of KH2PO4; 200 mg / L of CaCl2·2H2O; and 1200 mg / L of (NH4)2SO4.

[0017] In some embodiments, the pH value of the seed priming solution is 4.5-6.5, preferably 5.5-6.0.

[0018] Citric acid can be used to adjust the pH value of the seed priming solution.

[0019] The application also provides a corn planting method, comprising:

[0020] The corn seeds are primed using the seed priming solution or the carboxylated nanocarbon dots.

[0021] The primed corn seeds are sowed.

[0022] The carboxylated nanocarbon dots are applied at the corn jointing stage.

[0023] Specifically, the priming treatment refers to various hydration treatments performed on the corn seeds before sowing to promote germination.

[0024] Specifically, the corn seeds can be primed using conventional conditions in the art, for example, at a temperature of 25-30°C, and the priming time is 6-8 hours.

[0025] The application has found that priming the corn seeds using the seed priming solution can stimulate the elongation of the roots before the corn jointing stage, thereby forming a deeper root system, which is conducive to the absorption of deep soil water and nutrients by the corn.

[0026] In some embodiments, after being primed using the seed priming solution (the volume percentage concentration of the carboxylated nanocarbon dots is 0.001%-0.5%), the total root length before the corn jointing stage is increased by 11.9%-34.5%, preferably by 20.7%-34.5%, and more preferably by 34.5%.

[0027] The application has also found that applying the carboxylated nanocarbon dots at the jointing stage can inhibit the horizontal extension of the corn joint roots, while promoting the development of lateral roots, thereby forming a narrower tillage layer root system, which is conducive to reducing the competition of the corn plants for the water and nutrients in the tillage layer soil.

[0028] Specifically, the corn jointing stage is the stage when the 6th-10th leaf of the corn is fully expanded.

[0029] In some preferred embodiments, by applying the carboxylated nanocarbon dots at the jointing stage, the total number of joint roots of the elongating joints of the corn is reduced by 5.8%-10.2%, the average length of the joint roots is reduced by 12.5-22.3%, and the dry weight of the joint roots is increased by 5.5%-9.8% due to the increase in the number of lateral roots of the joint roots.

[0030] Specifically, the method for applying the carboxylated nanocarbon dots at the corn jointing stage is that the carboxylated nanocarbon dots are applied to the corn soil layer together with water and fertilizer when water and fertilizer management is performed at the corn jointing stage.

[0031] Specifically, the water and fertilizer management includes drip irrigation.

[0032] Specifically, when the carboxylated nanocarbon dots are applied at the corn jointing stage, the ratio of carboxylated nanocarbon dots to pure nitrogen in the fertilizer is 1.0-3.5 liters per kilogram of pure nitrogen, preferably 2.0-3.0 liters per kilogram of pure nitrogen, and more preferably 2.5 liters per kilogram of pure nitrogen.

[0033] In some preferred embodiments, the method of applying carboxylated nanocarbon dots at the corn jointing stage is to apply them to the soil simultaneously with water and fertilizer using drip irrigation, with the ratio of carboxylated nanocarbon dots to pure nitrogen in the fertilizer being 1.0-3.5 liters per kilogram of pure nitrogen, preferably 2.0-3.0 liters per kilogram of pure nitrogen, and more preferably 2.5 liters per kilogram of pure nitrogen.

[0034] The pure nitrogen is calculated based on the nitrogen element.

[0035] The carboxylated nanocarbon dots described in the present application can be prepared by the method described in the following literature, or can be obtained from commercial sources.

[0036] Li Y, Tang Z, Pan Z, et al. Calcium-Mobilizing Properties of Salvia Miltiorrhiza-Derived Carbon Dots Confer Enhanced Environmental Adaptability in Plants. ACS Nano 2022, 16, 4357-4370.

[0037] Guo Z, Chen Q, Liang T, et al. Functionalized carbon nano-enabled plant ROS signal engineering for growth / defense balance. Nano Today 2023, 53, 102045.

[0038] The above method promotes the elongation of corn seedling root system and the formation of deep root system by applying carboxylated nanocarbon dots twice at the seed priming and jointing stages; the later stage of the joint root narrows and the lateral root develops vigorously, forming an abrupt root type. The "ideal root type" of corn constructed can promote the utilization efficiency of soil nutrients and nutrients, and improve the competition of the aboveground part. Thus, the yield is promoted. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 Typical photos of corn seedling (2 leaves 1 heart) root system under quartz sand culture conditions initiated by seed priming solution (i.e. carboxylated nanocarbon dot concentration 0.2%)

[0040] Figure 2Photos of maize root system at seedling stage (25 days after emergence) treated with seed priming solution (i.e. carboxylated carbon dots at 0.2% concentration) under soil planting condition

[0041] Figure 3 Typical photos of maize second layer node root treated with 2.5 L / kg pure nitrogen carboxylated carbon dots at the jointing stage under field planting condition

[0042] Figure 4 Schematic diagram of constructing ideal root type of maize using carboxylated carbon dots DETAILED DESCRIPTION

[0043] The following examples are intended to illustrate the present application but not to limit the scope of the present application. If a specific technique or condition is not mentioned in the examples, it is performed according to the technique or condition described in the literature in the art or according to the product manual. If the manufacturer of the reagent or instrument is not mentioned, it is a conventional product that can be purchased through a regular channel.

[0044] The following carboxylated carbon dots were purchased from Beijing Xinnaxin Material Co., Ltd. (its synthesis method is described in the literature Guo Z, Chen Q, Liang T, et al. Functionalized carbon nano-enabled plant ROS signal engineering for growth / defense balance. Nano Today 2023, 53: 102045.).

[0045] The following seed priming solution, in addition to carboxylated carbon dots, contains the following components: 200 mg / L KH2PO4; 200 mg / L CaCl2·2H2O; and 1200 mg / L (NH4)2SO4; the pH value is adjusted to 6.0 with citric acid; the volume percentage concentration of carboxylated carbon dots in the seed priming solution is 0.001%, 0.01%, 0.1%, 0.2%, 0.5%, 1.0% and 10.0%, respectively.

[0046] Example 1 Regulation of maize root growth by different concentrations of carboxylated carbon dots priming

[0047] The test variety is widely planted maize hybrid Zhengdan 958. After the maize seeds are cleaned, the seeds are primed with seed priming solution containing different concentrations of carboxylated nanocarbon dots, the temperature is 30°C, and the priming time is 6 hours. The primed seeds are naturally dried for use. The primed seeds are incubated in a petri dish at 30°C for 2 days. The seeds that have germinated are selected and sown in quartz sand, the flowerpot is 18 cm in diameter and 20 cm in height. The seedlings are cultured in an artificial climate chamber, the day and night temperatures are 30°C / 25°C, the humidity is 65%, and the light is on for 14 hours per day. The seedlings are watered with nutrient solution every 3 days. The modified Hoagland nutrient solution is used, and the main components (mg / L) are: 945 Ca(NO3)2·4H2O, 607 KNO3, 115 NH4H2PO4, 241 MgSO4, 36.7 FeNaEDTA, 0.83 KI, 6.2 H3BO3, 16.9 MnSO4·1H2O, 8.6 ZnSO4·7H2O, 0.25 Na2MoO4·2H2O, 0.025 CuSO4·5H2O, 0.025 CoCl2·6H2O. When the maize grows to 2 leaves and 1 heart, the root samples are scanned and analyzed by WinRHIZO root system analysis system to determine the total root length, root surface area, root diameter, root volume, and root tip number. The results show (Table 1) that low concentration of carboxylated nanocarbon dots promotes root elongation, while higher concentration of carboxylated nanocarbon dots inhibits elongation and promotes lateral root formation, which is manifested by a significant increase in the number of root tips Figure 1

[0048] Table 1 Effect of different concentrations of carboxylated nanocarbon dots on the root development of maize seedlings

[0049]

[0050] wherein different letters represent a significant difference (p value less than 0.05); the same letter represents no significant difference.

[0051] Example 2 Regulation of carboxylated nanocarbon dots on the root development of maize seedlings

[0052] To investigate the effect of the seed priming solution (i.e. carboxylated nanocarbon dots concentration 0.2%) in Example 1 on the root and aboveground growth and development of maize seedlings in soil, the dry matter accumulation and nitrogen content of 15-day and 25-day seedlings under potting conditions were further studied, and the results are shown in Table 2. It can be seen that the seed priming treatment significantly increased the dry matter of the aboveground and root of maize after 15 days, and the nitrogen content and nitrogen uptake also significantly increased. Although there was no significant difference in nitrogen content at 25 days, the nitrogen uptake was significantly increased (18.94%) due to the significant difference in dry matter. It is indicated that the carboxylated nanocarbon dots priming treatment of maize seeds may promote the development of root system, significantly increase the dry matter of root system, and improve the ability of absorbing nitrogen from soil, thereby promoting the dry matter accumulation of stems and leaves of the aboveground part.​Figure 2 It is also shown that the root system is significantly increased after the carboxylated nanocarbon dots induced treatment.

[0053] Table 2. Effects of 0.2% carboxylated nanocarbon dots on dry matter accumulation and nitrogen absorption of corn seedlings

[0054]

[0055] Among them, * indicates that the difference reaches a significant level (p value less than 0.05); ** indicates that the difference reaches a very significant level (p value less than 0.01); ns indicates that the difference is not significant.

[0056] Example 3. Regulation of carboxylated nanocarbon dots priming and root irrigation at jointing stage on corn growth and development

[0057] Further, the effects of seed priming and root irrigation at jointing stage on corn growth and development were investigated under field conditions. The variety used was Zhengdan 958, which was primed with a seed priming solution (i.e. carboxylated nanocarbon dots at a concentration of 0.2%) for 6 hours and then air-dried at room temperature for standby. The seeds were sown on June 5, 2022, with a row spacing of 60 cm and a plant spacing of 28 cm. On July 7 (jointing stage), urea was dissolved in water and a certain volume of carboxylated nanocarbon dots was added, so that the volume ratio of nanocarbon dots to pure nitrogen in urea was 1.0, 1.5, 2.0, 2.5, 3.0 and 3.5 liters per kilogram. Each concentration treatment had 30 plants, and the dry matter of the aboveground part and the non-aerial elongated node root was tested at the flowering stage and the harvest stage. The results are shown in Table 3. It is shown that the carboxylated nanocarbon dots root irrigation treatment at the jointing stage significantly increased the dry matter of the root system, and the number and length of the upper lateral roots of the node root increased more obviously, with a larger downward angle. Figure 3 The dry matter accumulation of the aboveground part was not significantly different at the flowering stage, but significantly increased at the harvest stage.

[0058] Table 3. Effects of carboxylated nanocarbon dots root irrigation treatment on corn dry matter accumulation

[0059]

[0060] Among them, different letters indicate significant differences (p value less than 0.05); the same letter indicates no significant difference.

[0061] Example 4. Regulation of carboxylated nanocarbon dots priming and drip irrigation at jointing stage on corn yield

[0062] Furthermore, the effects of two treatments—one using carboxylated nano-carbon dots as seed initiation and the other adding them to drip irrigation at the jointing stage—on the yield of maize under low and high density planting conditions were investigated under field production conditions. The experiment was conducted at the experimental farm of the Institute of Crop Science, Chinese Academy of Agricultural Sciences. The variety Zhengdan 958 was selected. After being treated with a seed initiation solution (i.e., 0.2% concentration of carboxylated nano-carbon dots) for 6 hours, the seeds were air-dried at room temperature for later use. Sowing was carried out on May 25, 2023, with three densities: 4000 plants / mu, 5000 plants / mu, and 6000 plants / mu, and a row spacing of 60 cm. Drip irrigation was used for water and fertilizer management. When applying urea at the jointing stage, urea and carboxylated nano-carbon dots were added sequentially to the fertilizer tank, resulting in a ratio of 2.5 L / kg pure nitrogen. Yield was measured on September 20. The results showed that at high density, the carboxylated nano-carbon dot treatment resulted in a greater increase in yield (Table 4).

[0063] Table 4. Effects of drip irrigation with carboxylated nano-carbon dots at the jointing stage on maize yield (kg / mu)

[0064]

[0065]

[0066] Different letters indicate significant differences (p value less than 0.05); the same letter indicates no significant differences.

[0067] The above embodiments illustrate that the technical solution of the present invention can significantly improve maize yield under high-density planting conditions. The mechanism lies in controlling the treatment concentration and method of carboxylated nanocarbon dots, which can promote root elongation in the early stage, promote lateral root development in the later stage, and regulate their geotropism, thereby constructing an ideal root type for high-density maize populations, namely, a root type that simultaneously possesses deep lower roots and steep surface roots. Figure 4 An ideal root system helps corn utilize nutrients in the subsoil (below 30cm) while avoiding competitive pressure caused by overcrowding of the root system in the topsoil layer (0-20cm soil layer).

[0068] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method of corn planting, characterized by, The application relates to a method for improving the growth of corn by using carboxylated nanometer carbon dots. The method comprises the following steps: carrying out priming treatment on corn seeds by using a seed priming solution or carboxylated nanometer carbon dots; after the priming treatment, the total root length of the corn before the corn emerges is increased by 11.9%-34.5% by using the seed priming solution; sowing the primed corn seeds; applying carboxylated nanometer carbon dots to the corn at the corn emergence stage; the volume percentage concentration of the carboxylated nanometer carbon dots in the seed priming solution is 0.01%-0.5%; when the carboxylated nanometer carbon dots are applied to the corn at the corn emergence stage, the ratio of the carboxylated nanometer carbon dots to the pure nitrogen in the fertilizer is controlled to be 1.0-3.5 L / kg of pure nitrogen; 2. The method of planting of claim 1, wherein, by applying the carboxylated nanometer carbon dots at the corn emergence stage, the total number of node roots of the corn elongation node is reduced by 5.8%-10.2%, the average length of the node roots is reduced by 12.5-22.3%, and the dry weight of the node roots is increased by 5.5%-9.8% due to the increase in the number of lateral roots of the node roots.

3. The method of planting of claim 1, wherein, The volume percentage concentration of the carboxylated nanometer carbon dots in the seed priming solution is 0.2%.

4. The method of planting according to claim 3, wherein, The seed priming solution further comprises 180-220 mg / L of KH2PO4, 180-220 mg / L of CaCl2*2H2O and 1000-1400 mg / L of (NH4)2SO4. The seed priming solution further comprises 200 mg / L of KH2PO4, 200 mg / L of CaCl2*2H2O and 1200 mg / L of (NH4)2SO4.

5. The method of planting of claim 4, wherein, The pH value of the seed priming solution is 4.5-6.

5.

6. The method of planting corn according to claim 1, wherein, The pH value of the seed priming solution is 5.5-6.

0.

7. The method of planting corn according to claim 1, wherein, The priming treatment is carried out at a temperature of 25-30 DEG C for 6-8 hours.

8. The method of planting corn according to claim 7, wherein, The method for applying the carboxylated nanometer carbon dots to the corn at the corn emergence stage is that the carboxylated nanometer carbon dots are applied to the soil together with water and fertilizer by using the drip irrigation method at the corn emergence stage.

9. The method of planting corn according to claim 1, wherein, The water and fertilizer management comprises drip irrigation.

10. The method of planting corn according to claim 9, wherein, When the carboxylated nanometer carbon dots are applied to the corn at the corn emergence stage, the ratio of the carboxylated nanometer carbon dots to the pure nitrogen in the fertilizer is controlled to be 2-3 L / kg of pure nitrogen.

11. The method of planting corn according to claim 7, wherein, When the carboxylated nanometer carbon dots are applied to the corn at the corn emergence stage, the ratio of the carboxylated nanometer carbon dots to the pure nitrogen in the fertilizer is controlled to be 2.5 L / kg of pure nitrogen. The method for applying the carboxylated nanometer carbon dots to the corn at the corn emergence stage is that the carboxylated nanometer carbon dots are applied to the soil together with water and fertilizer by using the drip irrigation method at the corn emergence stage, and the ratio of the carboxylated nanometer carbon dots to the pure nitrogen in the fertilizer is 2.5 L / kg of pure nitrogen.

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