Carbon dioxide fertilization method for improving nitrogen fertilizer utilization rate of cucumbers

Abstract

The invention relates to a carbon dioxide fertilization method for improving the nitrogen fertilizer utilization rate of cucumbers, and the method obviously improves the yield, photosynthesis efficiency, nitrogen absorption amount and nitrogen fertilizer utilization rate of cucumbers by regulating and controlling the CO2 concentration, the moisture content and the ratio of nitrate to ammonium. According to the specific technical scheme, the method comprises the steps that the CO2 fertilization concentration is set to be 1200 [mu] mol.mol <-1 >, the moisture content is 70-80%, the nitrate-ammonium ratio level is 13: 1, and the fertilizer is applied to soil in a dropper mode. The photosynthetic rate, the dry matter accumulation and the nitrogen fertilizer utilization rate of the cucumbers are obviously improved. The application result of the test method shows that compared with control treatment, under CO2 fertilization, when the moisture content is 70-80% and the ratio of nitrate to ammonium is 13: 1, the cucumber yield is increased by 69.4%-92.6%, the dry weight of the whole plant is increased by 52.0%-82.0%, the nitrogen absorption amount is increased by 67.0%-92.8%, and the nitrogen fertilizer utilization rate reaches 48.9%-51.4%. By optimizing the CO2 concentration, the moisture content and the ratio of nitrate to ammonium, the nitrogen fertilizer utilization efficiency of the protected cucumber is remarkably improved, and the method has high application and popularization value.

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural planting, and particularly relates to a method for increasing carbon dioxide fertilization in cucumber planting. Background Art

[0002] At present, the atmospheric CO2 concentration has exceeded 420 μmol mol -1 . According to global climate model predictions, the increase in its concentration will have a significant impact on plant productivity in agricultural ecosystems. Although increasing the CO2 concentration can promote photosynthesis and the accumulation of dry matter in vegetables, long-term CO2 fertilization will reduce the plant nitrogen concentration and limit its productivity. Ammonium nitrogen and nitrate nitrogen are the main nitrogen sources that plants can directly utilize, and the absorption of ammonium nitrogen is more energy-efficient. Research shows that the combined application of ammonium nitrogen and nitrate nitrogen can not only reduce energy consumption, but also more effectively promote plant growth by mutual restraint of rhizosphere acidification and alkalization. In terms of environmental regulation, the conventional CO2 fertilization concentration does not reach the optimal photosynthetic efficiency threshold, and the water management mostly adopts a rough irrigation mode. Research shows that a soil water content of 70 - 80% can reduce nitrogen leaching by 34.7%, but in actual production, water fluctuations often lead to an increase in ammonium nitrogen volatilization. In addition, the customary nitrogen application rate of farmers does not significantly increase the yield, but instead reduces the nitrogen fertilizer utilization rate by 30% - 50%, and the CO2 concentration regulation is mostly lower than 1000 μmol mol -1 , and the carbon-nitrogen synergistic effect cannot be fully exerted.

[0003] Applying nitrogen fertilizer according to the preference of plants for nitrogen fertilizer forms, some studies believe that it can increase the plant nitrogen absorption amount and crop yield, however, there are also studies showing that this has no significant effect on increasing production and improving nitrogen absorption. Therefore, studying the relationship between the preference of plants for nitrogen forms (nitrate-ammonium ratio) and environmental regulation is an important method to increase plant yield. Under CO2 fertilization, supplying nitrate nitrogen will promote the activity of nitrate reductase, and inhibit the activity of nitrate reductase when supplying ammonium nitrogen. CO2 fertilization may inhibit the reduction of nitrate nitrogen. When part of the nitrate nitrogen in the culture medium is replaced by ammonium nitrogen, the dry matter yield of wheat will increase by 50%. Ammonium nitrogen has a stronger promoting effect on CO2 fertilization in wheat growth. However, under CO2 fertilization, there are few studies on regulating the soil water content and increasing the supply ratio of ammonium nitrogen on the photosynthesis and productivity of protected vegetables. Studying CO2 fertilization, water content, and nitrate-ammonium ratio can provide scientific fertilization guidance for protected vegetable cultivation, effectively improve the yield and quality of vegetables, reduce fertilizer waste, and reduce planting costs, which is of great significance for the sustainable development of the protected vegetable industry. Summary of the Invention

[0004] The present invention provides a carbon dioxide fertilization method for improving the nitrogen fertilizer utilization rate of cucumbers, which solves the problems of low nitrogen fertilizer utilization rate of protected vegetables and insufficient synergistic effect of environmental regulation and nitrogen form ratio in the prior art.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0006] A carbon dioxide fertilization method for improving the nitrogen fertilizer utilization rate of cucumbers, comprising the following steps:

[0007] (1) Sow cucumber seeds after germination, and transplant when the seedlings grow to two leaves and one heart.

[0008] (2) Start CO2 fertilization treatment and nitrogen, phosphorus and potassium fertilization on the 7th day after transplantation. The CO2 concentration in the greenhouse is stabilized at 1150 - 1250 μmol·mol -1 , the nitrate - ammonium ratio of nitrogen, phosphorus and potassium fertilization is 12:1 - 14:1, and the soil moisture content is 70 - 80%.

[0009] Further, preferably: the CO2 concentration in the greenhouse is stabilized at 1200 μmol·mol -1 , and the nitrate - ammonium ratio of nitrogen, phosphorus and potassium fertilization is 13:1.

[0010] Further, preferably: the fertilization amounts of nitrogen, phosphorus and potassium for nitrogen, phosphorus and potassium fertilization are 210 - 215, 30 - 35 and 245 - 255 kg per hectare respectively.

[0011] Further, preferably: the fertilizers for nitrogen, phosphorus and potassium fertilization are calcium nitrate, potassium nitrate, ammonium nitrate, ammonium sulfate, calcium dihydrogen phosphate and potassium carbonate.

[0012] Further, preferably: the nitrate - ammonium ratio of nitrogen, phosphorus and potassium fertilization is 13:1, the fertilizers for nitrogen, phosphorus and potassium fertilization are calcium nitrate, potassium nitrate, ammonium nitrate and calcium dihydrogen phosphate, and their molar ratio is 3:6:1:0.5, and the fertilization amounts of nitrogen, phosphorus and potassium are 211, 33.3 and 252 kg per hectare respectively.

[0013] Advantages of the present invention:

[0014] By regulating the CO2 concentration, moisture content and nitrate - ammonium ratio, the present invention significantly improves the cucumber yield, photosynthesis efficiency, nitrogen uptake amount and nitrogen fertilizer utilization rate. The test results show that compared with the control treatment, under CO2 fertilization, when the nitrate - ammonium ratio is 13:1, the cucumber yield increases by 69.4% - 92.6%, the dry weight of the whole plant increases by 52.0% - 82.0%, the nitrogen uptake amount increases by 67.0% - 92.8%, and the nitrogen fertilizer utilization rate reaches 48.9% - 51.4%. It significantly improves the nitrogen fertilizer utilization efficiency of greenhouse cucumbers and has high popularization and application value. Description of the Drawings

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0016] Figure 1 Results of the effects of different methods in Example 1 on cucumber yield (a) and dry weight (b);

[0017] Figure 2 Results of the effects of different methods in Example 1 on the nitrogen uptake of the whole cucumber plant;

[0018] Figure 3 Effects of different methods in Example 1 on the nitrogen fertilizer utilization rate of cucumber plants;

[0019] Figure 4 Results of the effects of different methods in Example 2 on cucumber yield (a) and dry weight (b);

[0020] Figure 5 Results of the effects of different methods in Example 2 on the nitrogen uptake of the whole cucumber plant;

[0021] Figure 6 Effects of different methods in Example 3 on the nitrogen fertilizer utilization rate of cucumber plants.

[0022] Note: Different letters in the figure indicate significant differences between different treatments (p < 0.05). C: CO2 concentration; NA: nitrate-ammonium ratio; W: soil moisture content. Asterisks (*) indicate significance of differences (*p < 0.05, **p < 0.01, ***p < 0.001), and ns indicates no significant difference (p ≥ 0.05). Detailed implementation manners

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts

[0024] Example 1

[0025] A carbon dioxide fertilization method for improving the nitrogen fertilizer utilization rate of cucumbers, comprising the following steps:

[0026] 1. Test site and test variety:

[0027] The experiment was conducted in four open-top chambers (OTCs) in the greenhouse of the Nanjing Institute of Soil Science, Chinese Academy of Sciences. Cucumber seeds (cv. Jinmei No. 3) were placed in an incubator (temperature 28°C, humidity 60%, no light) for 4 days of germination. After the seeds showed white tips, they were sown in a seedling tray filled with cultivation substrate.

[0028] 2. Experimental methods

[0029] The tested soil was taken from a paddy soil in the vegetable planting field of Dianzhan Village, Taicang City, Jiangsu Province. The physical and chemical properties of the soil were pH(H2O) 6.92, electrical conductivity 496 μS cm -1 , organic matter 24.7 g kg -1 , total nitrogen 0.95 g kg -1 , available nitrogen 153 mg kg -1 .

[0030] Cultivation management: After germination, cucumber seeds were sown in a seedling tray. When the seedlings grew to two leaves and one heart, they were transplanted into flower pots. CO2 fertilization treatment started on the 7th day after transplantation. The amounts of nitrogen, phosphorus, and potassium applied to each cucumber plant were 81.1, 12.8, and 96.8 mg kg -1 , corresponding to 211, 33.3, and 252 kg of nitrogen, phosphorus, and potassium per hectare.

[0031] CO2 concentration regulation: In the protected cultivation environment, the CO2 concentration in two OTCs was maintained at the atmospheric CO2 concentration (C1), and the CO2 concentration in the other two OTCs was stabilized at 1200 μmol·mol -1 (C2) using a CO2 generator or gas cylinder.

[0032] Soil water content regulation: Two soil water content levels were set, namely 30 - 40% (W1) and 70 - 80% (W2). Every day, the weighing method was used to adjust and maintain the soil water content at 30 - 40% and 70 - 80% respectively with distilled water.

[0033] Nitrate - ammonium ratio regulation: According to the experimental design, nitrogen - phosphorus - potassium nutrient solutions with different nitrate - ammonium ratios were prepared to ensure that the ratios of nitrate nitrogen to ammonium nitrogen were 5:9 (NA1), 9:5 (NA2), and 13:1 (NA3) respectively. The treatment without CO2 fertilization and nitrogen application was used as the control treatment (CK). The raw materials and ratios of the specific nitrogen - phosphorus - potassium nutrient solutions are shown in Table 1.

[0034] Table 1 Composition of macronutrients for different nitrate - ammonium ratio treatments (mmol / L)

[0035] <![CDATA[NO3 - / NH4 + > <![CDATA[Ca(NO3)2]]> <![CDATA[KNO3]]> <![CDATA[NH4NO3]]> <![CDATA[(NH4)2SO4]]> <![CDATA[Ca(H2PO4)2]]> <![CDATA[Potassium carbonate]]> 5:9 2 0 1 4 0.5 3 9:5 3 2 1 2 0.5 2 13:1 3 6 1 0 0.5 0 12:2 2 6 2 0 0.5 0 11:3 2 6 1 1 0.5 0

[0036] 3. Data measurement and calculation

[0037] Photosynthesis measurement: The photosynthetic rate, stomatal conductance, and transpiration rate of leaves were measured using a portable photosynthesis measuring instrument (Li-6400). During the measurement, the photosynthetic photon flux density, temperature, relative air humidity, and air velocity in the leaf chamber were set to 1500 μmol·m -2 ·s -1 、25.0 °C, 50.0%, and 500 μmol·s -1 .

[0038] Nitrogen uptake measurement: After harvesting, the plants were separated into four parts: roots, stems, leaves, and fruits. The dry weight and nitrogen concentration of each part were measured, and the nitrogen uptake and nitrogen fertilizer utilization rate were calculated.

[0039] Nitrogen fertilizer utilization rate (%) = (Nitrogen uptake in the aboveground part of the nitrogen application area - Nitrogen uptake in the aboveground part of the non-nitrogen application area) / Nitrogen application rate × 100

[0040] 4. Experimental results:

[0041] 4.1 Effects of different methods on increasing cucumber yield, the results are shown in Figure 1 .

[0042] Under CO2 fertilization conditions, when the water content was 70 - 80% and the nitrate-ammonium ratio was 13:1, the cucumber yield increased significantly, with an increase of 69.4%. Compared with the control treatment, when the water content was 70 - 80%, CO2 fertilization significantly increased the dry weight of the whole cucumber plant, with an increase range of 30.8% - 52.0%.

[0043] 4.2 Effects of different methods on the nitrogen uptake of the whole cucumber plant, the results are shown in Table 2.

[0044] Compared with the control treatment, when the water content was 30 - 40% and the nitrate-ammonium ratio was 13:1 under atmospheric CO2, the net photosynthetic rate increased by 112%; CO2 fertilization significantly increased the photosynthetic rate of cucumber leaves. When the water content was 70 - 80% and the nitrate-ammonium ratio was 13:1, the net photosynthetic rate increased by 263%. At the same time, CO2 fertilization reduced the transpiration rate of the leaves and decreased water consumption.

[0045] Table 2 Effects of different CO2 concentrations, water contents, and nitrate-ammonium ratios on the photosynthesis of cucumber leaves

[0046]

[0047] Note: Different letters in the table indicate significant differences between different treatments (p < 0.05). C: CO2 concentration; NA: Nitrate-ammonium ratio; W: Soil water content. Asterisks (*) indicate significance levels (*p < 0.05, **p < 0.01, ***p < 0.001), and ns indicates no significant difference (p ≥ 0.05).

[0048] 4.3 Effects of different methods on improving nitrogen uptake, and the results are shown in Figure 2 .

[0049] Compared with the CK treatment, under atmospheric CO2 concentration, when the water content was 30 - 40% and the nitrate - ammonium ratio was 13:1, the nitrogen uptake of the whole cucumber plant was significantly increased by 69.6%; when the water content was 70 - 80%, with the increase of the nitrate nitrogen ratio, the promotion effect of CO2 fertilization on cucumber nitrogen uptake was greater.

[0050] 4.4 Effects of different methods on improving nitrogen fertilizer utilization efficiency, and the results are shown in Figure 3 , where different letters in the figure indicate significant differences between different treatments (p < 0.05). C: CO2 concentration; NA: nitrate - ammonium ratio; W: soil water content. Asterisks (*) indicate significance of differences (*p < 0.05, **p < 0.01, ***p < 0.001).

[0051] Under atmospheric CO2, the nitrogen utilization efficiency of the treatment with a water content of 30 - 40% and a nitrate - ammonium ratio of 13:1 was 39.6%. Under CO2 fertilization, the nitrogen fertilizer utilization efficiency of the treatment with a water content of 70 - 80% and a nitrate - ammonium ratio of 13:1 was 48.9%. CO2 fertilization and a soil water content of 70 - 80% significantly increased the nitrogen utilization efficiency of the treatment with a nitrate - ammonium ratio of 13:1.

[0052] Example 2

[0053] A method of CO2 fertilization for improving nitrogen fertilizer utilization efficiency of cucumbers, comprising the following steps:

[0054] 1. Test site and test variety:

[0055] The test was carried out in four open - top chambers (OTCs) in the greenhouse of the Nanjing Institute of Soil Science, Chinese Academy of Sciences. Cucumber seeds (variety: Jinyou No. 38) were placed in an incubator (temperature 28°C, humidity 60%, no light), and after 5 days of germination, the germinated seeds were sown in a seedling tray filled with cultivation substrate.

[0056] 2. Test method

[0057] The tested soil was taken from paddy soil in the vegetable planting field of Dianzhan Village, Taicang City, Jiangsu Province. The physical and chemical properties of the soil were pH(H2O) 6.92, electrical conductivity 496 μS cm -1 , organic matter 24.74 g kg -1 , total nitrogen 0.95 g kg -1 , available nitrogen 152.56 mg kg -1 .

[0058] Cultivation management: Cucumber seeds were sown in a seedling tray after germination, and transplanted into flower pots when the seedlings grew to two leaves and one heart. CO2 fertilization treatment was started on the 7th day after transplantation. The amounts of nitrogen, phosphorus, and potassium applied to each cucumber plant were 81.1, 12.8, and 96.8 mg / kg respectively. -1 The amounts of nitrogen, phosphorus, and potassium applied per hectare were converted to 211, 33.3, and 252 kg respectively.

[0059] CO2 concentration regulation: In the protected cultivation environment, the CO2 concentrations in two OTCs were maintained at the atmospheric CO2 concentration (C1), and the CO2 concentrations in the other two OTCs were stabilized at 1200 μmol·mol -1 (C2) using a CO2 generator or CO2 gas cylinder.

[0060] Soil water content regulation: Two soil water content levels were set, namely 30 - 40% (W1) and 70 - 80% (W2). Every day, the weighing method was used to adjust and maintain the soil water content at 30 - 40% and 70 - 80% respectively with distilled water.

[0061] Nitrate - ammonium ratio regulation: According to the experimental design, nutrient solutions with different nitrate - ammonium ratios were prepared to ensure that the ratios of nitrate nitrogen to ammonium nitrogen were 5:9 (NA1), 9:5 (NA2), and 13:1 (NA3) respectively. The treatment without CO2 fertilization and nitrogen application was used as the control treatment (CK). The raw materials and ratios of the specific nitrogen - phosphorus - potassium nutrient solution are shown in Table 1.

[0062] 3. Data measurement and calculation

[0063] Photosynthesis measurement: A portable photosynthesis measuring instrument was used to measure the photosynthetic rate, stomatal conductance, and transpiration rate of cucumber leaves.

[0064] Nitrogen uptake measurement: After harvest, the plants were decomposed into four parts: roots, stems, leaves, and fruits. The dry weights and nitrogen concentrations of each part were measured, and the nitrogen uptake and nitrogen fertilizer utilization rate were calculated.

[0065] Nitrogen fertilizer utilization rate (%) = (Nitrogen uptake in the above - ground part of the nitrogen - applied area - Nitrogen uptake in the above - ground part of the non - nitrogen - applied area) / Nitrogen application rate × 100

[0066] Test results:

[0067] 4.1 Effects of different methods on improving cucumber yield are shown in Figure 4 .

[0068] Under CO2 fertilization conditions, when the water content was 70 - 80% and the nitrate - ammonium ratio was 13:1, the cucumber yield increased significantly, with an increase of 92.6%. Compared with the control treatment, when the water content was 70 - 80%, CO2 fertilization significantly increased the dry weight of the whole cucumber plant, with an increase range of 32.5% - 82.0% (as Figure 4 shown).

[0069] 4.2 Effects of different methods on the nitrogen uptake of the whole melon plant, and the results are shown in Table 3.

[0070] Compared with the control treatment, when the water content was 30 - 40% and the ammonium nitrate ratio in the atmosphere CO2 was 13:1, the net photosynthetic rate increased by 72.3%; CO2 fertilization significantly increased the photosynthetic rate of cucumber leaves. When the water content was 70 - 80% and the ammonium nitrate ratio was 13:1, the net photosynthetic rate increased by 147%. At the same time, CO2 fertilization reduced the transpiration rate of the leaves and decreased water consumption.

[0071] Table 3 Effects of different CO2 concentrations, water contents and ammonium nitrate ratios on the photosynthesis of cucumber leaves

[0072]

[0073]

[0074] 4.3 Effects of different methods on improving nitrogen uptake, and the results are shown in Figure 5 .

[0075] Compared with the CK treatment, under the atmospheric CO2 concentration, when the water content was 30 - 40% and the ammonium nitrate ratio was 13:1, the nitrogen uptake of the whole cucumber plant was significantly increased by 58.1%. When the water content was 70 - 80%, with the increase of the nitrate nitrogen ratio, the promotion effect of CO2 fertilization on cucumber nitrogen uptake was greater.

[0076] 4.4 Effects of different methods on improving nitrogen fertilizer utilization rate, and the results are shown in Figure 6 .

[0077] Under the atmospheric CO2, the nitrogen utilization rate of the treatment with a water content of 30 - 40% and an ammonium nitrate ratio of 13:1 was 43.2%. Under CO2 fertilization, the nitrogen fertilizer utilization rate of the treatment with a water content of 70 - 80% and an ammonium nitrate ratio of 13:1 was 51.4%. CO2 fertilization and a soil water content of 70 - 80% significantly increased the nitrogen utilization rate of the treatment with an ammonium nitrate ratio of 13:1.

[0078] Example 3

[0079] It is basically the same as Example 2, and the difference is that: the ammonium nitrate ratios are 12:2 and 11:3, and the specific raw material ratios are shown in Table 1. When the CO2 concentration was stable at 1150 μmol·mol -1 , the water content was 70 - 80%, and the ammonium nitrate ratio of nitrogen, phosphorus and potassium fertilization was 12:2, the cucumber yield increase was 84.3%. When the ammonium nitrate ratio of nitrogen, phosphorus and potassium fertilization was 11:3, the cucumber yield increase was 78.4%. The cucumber yield increase was obvious;

[0080] At a stable CO2 concentration of 1250 μmol·mol -1 , with a moisture content of 70 - 80%, when the nitrate - ammonium ratio of nitrogen - phosphorus - potassium fertilization is 12:2, the yield increase of cucumbers is 88.2%; when the nitrate - ammonium ratio of nitrogen - phosphorus - potassium fertilization is 11:3, the yield increase of cucumbers is 79.1%. The yield increase of cucumbers is obvious.

[0081] Conclusion

[0082] By optimizing the CO2 concentration, moisture content and nitrate - ammonium ratio, the present invention significantly improves the yield, photosynthetic rate and nitrogen fertilizer utilization rate of greenhouse cucumbers. This method is applicable to the cultivation of greenhouse vegetables, especially suitable for the planting of cucumbers, and has high popularization and application value.

[0083] The above - mentioned are only the preferred embodiments of the present invention, and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A carbon dioxide fertilization method for improving nitrogen fertilizer utilization rate of cucumber, characterized in that: The following steps are involved: (1) Cucumber seeds are sown after germination, and transplanted when the seedlings grow to two leaves and one heart; (2) CO2 fertilization and nitrogen, phosphorus and potassium fertilization were started on the 7th day after planting, and the CO2 concentration in the greenhouse was stabilized at 1150-1250 μmol·mol -1 , the ammonium nitrate ratio of nitrogen, phosphorus and potassium fertilizer is 12:1-14:1, and the soil moisture content is 70-80%.

2. The carbon dioxide fertilization method according to claim 1, characterized in that: The CO2 concentration in the greenhouse is stabilized at 1200 μmol·mol -1 The ratio of ammonium nitrate to nitrogen, phosphorus and potassium fertilizers is 13:

1.

3. The carbon dioxide fertilization method according to claim 2, characterized in that: The application amount of nitrogen, phosphorus and potassium fertilizer is 210-215 kg of nitrogen, 30-35 kg of phosphorus and 245-255 kg of potassium per hectare respectively.

4. The carbon dioxide fertilization method according to claim 1 or 2, characterized in that: The fertilizers for nitrogen, phosphorus and potassium fertilization are calcium nitrate, potassium nitrate, ammonium nitrate, ammonium sulfate, calcium dihydrogen phosphate and potassium carbonate.

5. The carbon dioxide fertilization method according to claim 4, characterized in that: The ammonium nitrate ratio of the nitrogen, phosphorus and potassium fertilizer is 13:1, and the fertilizers of the nitrogen, phosphorus and potassium fertilizer are calcium nitrate, potassium nitrate, ammonium nitrate and calcium dihydrogen phosphate, and the molar ratio thereof is 3:6:1:0.

5. The fertilizer application amount is 211, 33.3 and 252 kg of nitrogen, phosphorus and potassium per hectare respectively.

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