A method for preparing a nutrient solution for promoting the growth of crops on saline-alkali poor land

Abstract

The present application adopts the mixture of porphyridium cruentum and chlorella culture solution to form a plant nutrient solution, which is rich in nutrient elements such as nitrogen and phosphorus, and marine microalgae and porphyridium cruentum cells, and can provide mineral elements required for plant growth for soil, and improve the stress resistance of crops in saline-alkali soil.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of agricultural biotechnology, and relates to a plant nutrient solution for crops on saline-alkali land. BACKGROUND

[0002] Saline-alkali land is a kind of soil with high salinity and alkalinity, high conductivity, and low organic matter, nitrogen, and phosphorus nutrients. Soil salinization and secondary salinization are serious problems in China. There are a large number of saline-alkali lands in northwest, northeast, north China and coastal areas. On saline-alkali land, crops and plants generally cannot grow, and even if they can grow, the yield of crops is very low. Therefore, saline-alkali land improvement and management are very urgent.

[0003] Currently, the main methods for treating saline-alkali land include physical methods (such as leaching, plowing, and guest soil), chemical methods (calcium, acid, organic and mineral resource improvers), and biological methods (saline-alkali plant planting and microbial improvement). The physical method has the problems of large engineering quantity and high cost. The chemical method has the problems of single effect, short duration, and easy secondary pollution. Compared with the above two methods, the biological method is considered to be both a temporary and a permanent solution, and has the advantages of long duration, easy operation, but the current saline-alkali plant planting, microbial inoculant and microbial machine fertilizer also have the problems of long cycle and high cost.

[0004] Microalgae are a kind of small photosynthetic organisms that exist widely and are rich in nutrients, and have the important functions of promoting plant growth and improving soil ecosystem. At present, microalgae can be used as fertilizer for crops, but there are few reports on improving crops under saline-alkali stress. Therefore, it is of great significance to develop a microalgal biological preparation that can significantly improve saline-alkali land based on microalgae for saline-alkali land remediation. SUMMARY

[0005] The purpose of the present application is to provide a plant nutrient solution for improving soil fertility of saline-alkali land, promoting growth of crops on saline-alkali land, and improving saline-alkali land.

[0006] The plant nutrient solution of the present application is prepared by the following steps and methods:

[0007] S1, cultivating purple sulfur bacteria by a mixed culture mode, preferably, when the polysaccharide content in the purple sulfur bacteria culture solution reaches 1 g / L, the cultivation is ended;

[0008] S2, separating the algal cells and the clear liquid in the algal solution to obtain purple sulfur bacteria slurry;

[0009] S3, adding the purple sulfur bacteria slurry into tap water to dissolve and suspend again, so as to remove salt, and there are about 20 g / L of salt substances in the purple sulfur bacteria culture solution, which avoids causing salinization when directly added into soil;

[0010] S4, the re-dissolved and suspended Haematococcus algae liquid and Chlorella culture solution are mixed in a volume ratio of 1:5 to obtain a plant nutrient solution for crops used on saline-alkali poor land.

[0011] The Haematococcus culture medium components are: glycerol 0.1-1 g L-1, sodium chloride 15-30 g L-1, magnesium sulfate heptahydrate 3-7 g L-1, magnesium chloride hexahydrate 3-8 g L-1, dipotassium hydrogen phosphate 0.04-1 g L-1, potassium chloride 0.3-0.8 g L-1, sodium nitrate 0.5-1 g L-1, trace element mother liquor 0.5-2 ml L-1. Preferably, the Haematococcus culture medium components are: glycerol 0.1-1 g L-1, sodium chloride 20-25 g L-1, magnesium sulfate heptahydrate 5-6.6 g L-1, magnesium chloride hexahydrate 4-6 g L-1, dipotassium hydrogen phosphate 0.05-0.07 g L-1, potassium chloride 0.4-0.7 g L-1, sodium nitrate 0.6-0.8 g L-1, Haematococcus trace element mother liquor 1 ml L-1.

[0012] The Haematococcus trace element mother liquor formula is: EDTA 0.5 g L-1, copper sulfate pentahydrate 0.008 g L-1, zinc sulfate heptahydrate 0.222 g L-1, cobalt nitrate hexahydrate 0.005 g L-1, manganese chloride tetrahydrate 1.81 g L-1, cobalt nitrate dihydrate 0.39 g L-1, boric acid 2.86 g L-1.

[0013] The Chlorella culture medium components are: sodium nitrate 0.5-2 g L-1, dipotassium hydrogen phosphate 0.01-0.08 g L-1, magnesium sulfate heptahydrate 0.02-1 g L-1, calcium chloride dihydrate 0.01-0.05 g L-1, citric acid 0.001-0.01 g L-1, ferric ammonium citrate 0.002-0.008 g L-1, disodium EDTA 0.001-0.01 g L-1, sodium carbonate 0.01-0.03 g L-1, Chlorella trace element mother liquor 0.1-2 ml.

[0014] The Chlorella trace element mother liquor formula is: boric acid 2.86 g L-1, manganese chloride tetrahydrate 1.81 g L-1, manganese chloride heptahydrate 0.222 g L-1, sodium molybdate dihydrate 0.39 g L-1, copper sulfate pentahydrate 0.079 g L-1, cobalt nitrate hexahydrate 0.0494 g L-1. Preferably, sodium nitrate 1.5 g L-1, dipotassium hydrogen phosphate 0.04 g L-1, magnesium sulfate heptahydrate 0.075 g L-1, calcium chloride dihydrate 0.036 g L-1, citric acid 0.006 g L-1, ferric ammonium citrate 0.006 g L-1, disodium EDTA 0.001 g L-1, sodium carbonate 0.02 g L-1, trace element mother liquor 1 ml.

[0015] The total volume of the purple sulfur bacteria slurry after being resuspended with tap water is 1 / 8 to 1 / 3 of the volume of the purple sulfur bacteria culture (before centrifugation).

[0016] The mixing ratio of the purple sulfur bacteria slurry and the chlorella liquid is 1:5 to 1:10.

[0017] The concentration of the chlorella cells in the chlorella culture liquid is 1 to 5 x 10 7 cells / mL.

[0018] The present application has the following beneficial effects:

[0019] The present application uses the mixture of the purple sulfur bacteria and the chlorella culture liquid to form a plant nutrient liquid. The active algal cells can continue to survive and grow in the soil, produce active polysaccharides, proteins, peptides, vitamins, and other nutrients for plants to absorb and utilize, promote plant growth, and improve the stress resistance of crops in saline-alkali soil. In addition, active microalgae can also synthesize organic matter through photosynthesis, increase the content of soil organic matter, achieve soil carbon deposition, and improve soil fertility. In addition, the presence of microalgae can improve the soil microbial community structure, increase the soil microbial abundance, and construct a soil algal-bacterial microecological system, achieving a synergistic effect on plant resistance to environmental changes. DETAILED DESCRIPTION

[0020] The preferred embodiments of the present application are described below, and it should be understood that the preferred embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0021] EMBODIMENT

[0022] The purple sulfur bacteria were cultured in a 1L column photobioreactor (800mL liquid volume), and the culture temperature was room temperature (25-28℃), the aeration amount was 0.2vvm, and the column photobioreactor was provided with light by LED lamp, and the light intensity was 5000lux. The culture medium for the culture of the purple sulfur bacteria was glycerol 0.1g L -1 , sodium chloride 20g L -1 , magnesium sulfate heptahydrate 6g L -1 , magnesium chloride hexahydrate 5g L -1 , dipotassium hydrogen phosphate 0.05g L -1 , potassium chloride 0.4g L -1 , sodium nitrate 0.65g L -1 , trace element stock solution 1ml L -1 . The initial inoculation of algal cells was 0.2g L -1 , and after 12 days of culture, the algal cell concentration was 2.5g L -1 , and the purple sulfur bacteria polysaccharide was 1.2g L -1At this point, the cultivation of *Chlorella vulgaris* was completed. The algal solution was then centrifuged to obtain *Chlorella vulgaris* algae. The centrifuged *Chlorella vulgaris* sludge was then diluted with tap water to one-third of the original algal solution volume, and this concentrated algal solution was mixed with *Chlorella proteoglycans* culture medium at a ratio of 1:5 (v / v). *Chlorella vulgaris* was cultured in a 5L column photobioreactor (4000mL liquid volume) using a culture medium containing 1.5g / L sodium nitrate. -1 0.04 g / L dipotassium hydrogen phosphate -1 Magnesium sulfate heptahydrate 0.075 g / L -1 0.036 g / L of calcium chloride dihydrate -1 Citric acid 0.006 g / L -1 Ferric ammonium citrate 0.006 g / L -1 0.001 g / L of disodium EDTA -1 Sodium carbonate 0.02g / L -1 1 ml / L of trace element stock solution -1 The initial concentration of Chlorella proteoglycans was 2 × 10⁻⁶. 6 Cells / mL, aeration rate 0.5 vvm, light intensity 8000 lux, cultured for 4 days, algal cell concentration 2×10⁻⁶ 7 cells / mL. After mixing concentrated *Chlorella vulgaris* and *Chlorella pulvinata* culture media and stirring thoroughly, a plant nutrient solution specifically for saline-alkali land is obtained.

[0023] The prepared plant nutrient solution was used in a potted lettuce experiment. Four treatment groups were set up: ① control group (normal soil, salinity-free); ② algae solution irrigation group (normal soil, salinity-free, nutrient solution irrigation); ③ salinization group (1.5% NaCl added to the soil (w / v)); ④ salinization + algae solution irrigation group (1.5% NaCl added to the soil (w / v), nutrient solution irrigation). During the lettuce growth process, the corresponding treatment groups were irrigated with nutrient solution twice, each time at a rate of 10 mL / kg soil. Lettuce was harvested after 35 days of cultivation, and relevant indicators were measured (see Table 1).

[0024] Table 1. Growth status of lettuce in artificial saline-alkali soil.

[0025]

[0026]

[0027] By comparing the experimental groups ① and ②, under the condition of normal soil, the addition of plant nutrient solution can greatly increase the fresh weight and dry weight of lettuce, which shows that the prepared microalgae nutrient solution has a good promoting effect on the growth of lettuce. By comparing the experimental groups ③ and ④, it is found that under the condition of salinity 1.5%, irrigating with the prepared nutrient solution can increase the fresh weight and dry weight of lettuce, which shows that the prepared plant nutrient solution can improve the growth rate and yield of lettuce in saline-alkali land, and has an effect on the repair of saline-alkali land.

[0028] Example 2

[0029] The porphyridium was cultured in a 500 mL shake flask (200 mL liquid volume), and the shake flask was placed in a light shaking bed with a rotation speed of 120 rpm, a temperature of 25°C, and a light intensity of 4000 lux. The culture medium for porphyridium culture was glycerol 0.1 g / L -1 , sodium chloride 20 g / L -1 , magnesium sulfate heptahydrate 6 g / L -1 , magnesium chloride hexahydrate 5 g / L -1 , dipotassium hydrogen phosphate 0.05 g / L -1 , potassium chloride 0.4 g / L -1 , sodium nitrate 0.65 g / L -1 , trace element stock solution 1 mL / L -1 . The initial inoculation of algal cells was 0.2 g / L -1 , after 10 days of culture, the algal cell concentration was 2 g / L -1 , porphyridium polysaccharide 1.0 g / L -1 , and the porphyridium culture was terminated. Then, the algal liquid was centrifuged by a centrifuge to obtain porphyridium algae. Then, the porphyridium algae mud obtained by centrifugation was diluted with tap water to 1 / 3 of the original algal liquid volume, and the concentrated porphyridium algal liquid was mixed with the chlorella culture solution at a ratio of 1:5 (v / v). The chlorella was cultured in a 1L column type photobioreactor (800 mL liquid volume), and the culture medium was sodium nitrate 1.5 g / L -1 , dipotassium hydrogen phosphate 0.04 g / L -1 , magnesium sulfate heptahydrate 0.075 g / L -1 , calcium chloride dihydrate 0.036 g / L -1 , citric acid 0.006 g / L -1 , ferric ammonium citrate 0.006 g / L -1 , disodium EDTA 0.001 g / L -1 , sodium carbonate 0.02 g / L -1 , trace element stock solution 1 mL / L -1 . The initial concentration of chlorella was 2×10 6 cells / mL, the aeration amount was 0.5vvm, the light intensity was 6000 lux, and the culture was carried out for 4 days, and the algal cell concentration was 2×107 cells / mL. After mixing the concentrated Porphyridium and Chlorella culture solution and stirring well, the plant nutrient solution for saline-alkali land was obtained.

[0030] The prepared plant nutrient solution was used for lettuce potting experiments. Here, saline-alkali soil taken from the coastal beach of Lianyungang was used, and three groups of treatments were set up, namely, a control group (saline-alkali soil, not irrigated with algae solution); a Chlorella solution irrigation group (saline-alkali soil, irrigated with Chlorella algae solution); and a mixed algae solution irrigation group (saline-alkali soil, irrigated with mixed algae solution of Porphyridium and Chlorella). During the growth of the lettuce, the corresponding treatment groups were irrigated with 10 mL / kg of soil of nutrient solution twice. The lettuce was harvested after 30 days of cultivation, and the relevant indicators were measured, as shown in Table 2.

[0031] Table 2 Growth conditions of lettuce in artificial saline-alkali soil

[0032]

[0033] In saline-alkali soil, after adding the mixed algae solution, the fresh weight and dry weight of the lettuce were greatly increased. Compared with the control group, the average fresh weight and dry weight of the lettuce were increased by 79.8% and 91.9%, respectively; compared with the Chlorella solution only group, the fresh weight and dry weight of the lettuce were increased by 40.9% and 42.3%, respectively. The average dry weight and fresh weight of the lettuce in the Chlorella irrigation group were only increased by 27.6% and 34.8% compared with the control group, which was much lower than that of the mixed algae solution irrigation group. It can be seen that the prepared mixed plant nutrient solution of Chlorella and Porphyridium has the ability to improve the stress resistance of crops growing in saline-alkali land and significantly improve the yield.

[0034] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a nutrient solution to promote crop growth on saline-alkali and barren land, characterized in that, Includes the following steps: S1. Cultivate *Purple Gloy Algae*; S2. Separate the algal cells and clear liquid of *Porphyra yezoensis* to obtain *Porphyra yezoensis* algal mud; S3. Add the purple algae mud to tap water to redissolve and suspend it; S4. Mix the redissolved and resuspended *Chlorella vulgaris* algal solution and *Chlorella microphylla* culture solution thoroughly to obtain a plant nutrient solution for use on saline-alkali and barren land.

2. The method for preparing nutrient solution for promoting crop growth on saline-alkali and barren land as described in claim 1, characterized in that, The culture medium used for culturing *Porphyra yezoensis* in S1 was: Glycerin 0.1–1 g / L, sodium chloride 15–30 g / L, magnesium sulfate heptahydrate 3–7 g / L, magnesium chloride hexahydrate 3–8 g / L, dipotassium hydrogen phosphate 0.04–1 g / L, potassium chloride 0.3–0.8 g / L, sodium nitrate 0.5–1 g / L, trace element stock solution 0.5–2 ml / L; The formula for the trace element mother liquor is as follows: EDTA 0.5 g / L, copper sulfate pentahydrate 0.008 g / L, zinc sulfate heptahydrate 0.222 g / L, cobalt nitrate hexahydrate 0.005 g / L, manganese chloride tetrahydrate 1.81 g / L, cobalt nitrate dihydrate 0.39 g / L, and boric acid 2.86 g / L.

3. The method for preparing nutrient solution for promoting crop growth on saline-alkali and barren land as described in claim 2, characterized in that, The culture medium used for culturing *Porphyra yezoensis* in S1 was: Glycerin 0.1–1 g / L, sodium chloride 20–25 g / L, magnesium sulfate heptahydrate 5–6.6 g / L, magnesium chloride hexahydrate 4–6 g / L, dipotassium hydrogen phosphate 0.05–0.07 g / L, potassium chloride 0.4–0.7 g / L, sodium nitrate 0.6–0.8 g / L, and trace element stock solution of *Porphyra yezoensis* 1 ml / L.

4. The method for preparing nutrient solution for promoting crop growth on saline-alkali and barren land as described in any one of claims 1-3, characterized in that, In S1, the culture ends when the polysaccharide content in the *Porphyra yezoensis* culture medium is ≥1 g / L.

5. The method for preparing nutrient solution for promoting crop growth on saline-alkali and barren land as described in claim 1, characterized in that, The total volume of the *Porphyra yezoensis* sludge in S3 after being resuspended in tap water is 1 / 8 to 1 / 3 of the volume of the *Porphyra yezoensis* culture medium before centrifugation.

6. The method for preparing nutrient solution for promoting crop growth on saline-alkali and barren land as described in claim 1, characterized in that, The components of the Chlorella medium in S4 are: sodium nitrate 0.5–2 g / L, dipotassium hydrogen phosphate 0.01–0.08 g / L, magnesium sulfate heptahydrate 0.02–1 g / L, calcium chloride dihydrate 0.01–0.05 g / L, citric acid 0.001–0.01 g / L, ferric ammonium citrate 0.002–0.008 g / L, disodium EDTA 0.001–0.01 g / L, sodium carbonate 0.01–0.03 g / L, and Chlorella trace element stock solution 0.1–2 ml. The formula for the trace element mother liquor is as follows: boric acid 2.86 g / L, manganese chloride tetrahydrate 1.81 g / L, manganese chloride heptahydrate 0.222 g / L, sodium molybdate dihydrate 0.39 g / L, copper sulfate pentahydrate 0.079 g / L, and cobalt nitrate hexahydrate 0.0494 g / L.

7. The method for preparing nutrient solution for promoting crop growth on saline-alkali and barren land as described in claim 1, characterized in that, The S4 Chlorella medium consists of: sodium nitrate 1.5 g / L, dipotassium hydrogen phosphate 0.04 g / L, magnesium sulfate heptahydrate 0.075 g / L, calcium chloride dihydrate 0.036 g / L, citric acid 0.006 g / L, ferric ammonium citrate 0.006 g / L, disodium EDTA 0.001 g / L, sodium carbonate 0.02 g / L, and 1 ml of trace element stock solution.

8. The method for preparing nutrient solution for promoting crop growth on saline-alkali and barren land as described in claim 1, characterized in that, The mixing ratio of *Chlorella vulgaris* algal mud suspension and *Chlorella microphylla* algal liquid in S4 is 1:5 to 1:

10.

9. The method for preparing a nutrient solution for promoting crop growth on saline-alkali and barren land as described in claim 1, characterized in that, The algal cell concentration in the Chlorella culture medium of S4 is 1–5 × 10⁻⁶. 7 cells / mL.

Images