CN114747437A

CN114747437A - Method for relieving cadmium toxicity of tomatoes by using arbuscular mycorrhizal fungi and application

Info

Publication number: CN114747437A
Application number: CN202210378628.XA
Authority: CN
Inventors: 刘俊丽; 郭彬; 刘琛; 裘高扬; 陈晓冬; 李华; 傅庆林; 林义成
Original assignee: Zhejiang Academy of Agricultural Sciences
Current assignee: Zhejiang Academy of Agricultural Sciences
Priority date: 2022-04-12
Filing date: 2022-04-12
Publication date: 2022-07-15
Anticipated expiration: 2042-04-12
Also published as: CN114747437B

Abstract

The invention belongs to the technical field of environmental protection and agriculture, and relates to a method for relieving cadmium poisoning effect of tomatoes by using arbuscular mycorrhizal fungi and application thereof. According to the method, through the steps of preparation of the arbuscular mycorrhizal fungi fungicide, tomato seedling culture, tomato inoculation of fungi and sand culture, a symbiotic relationship is established between the arbuscular mycorrhizal fungi and tomatoes in a sand culture mode, under the stress of cadmium, a large number of arbuscular and hyphae are formed at the roots of the tomatoes symbiotic with the mycorrhizal fungi, the absorption area of the roots of the tomatoes is enlarged, and the absorption of the tomatoes on a large amount of phosphorus and a trace element of manganese is remarkably increased; meanwhile, the absorption of cadmium by the tomato roots and the transfer of cadmium to the overground part are obviously inhibited, and the cadmium resistance of the tomatoes is effectively enhanced.

Description

Method for relieving cadmium toxicity of tomatoes by using arbuscular mycorrhizal fungi and application

Technical Field

The invention belongs to the technical field of environmental protection and agriculture, and relates to a method for relieving cadmium poisoning effect of tomatoes by using arbuscular mycorrhizal fungi and application thereof.

Background

Cadmium (Cd for short) has extremely high toxicity, is very soluble in water and is easily absorbed and accumulated by plants, and is one of the most toxic pollutants in the environment at present. Cadmium is an unnecessary element, and when a certain amount of cadmium is accumulated in plants, serious toxic effects are generated on the plants. For example, cadmium causes peroxidation of plant cell membrane lipids and damages an antioxidant system (zhang et al, 2010), inhibits the photosynthetic system performance of plants (hong et al, 2008; teng et al, 2016), hinders the absorption of other mineral nutrients by plants and destroys the ion balance in plants (zhang et al, 2010), and the like, inhibits the growth and development of plants, and finally affects the yield, quality and safety of plants.

At present, chemical additives (lime, clay minerals, biochar and the like) or a microorganism-enhanced plant control technology are one of important repair technologies for improving the safety of agricultural products, but in the process of controlling the accumulation of heavy metal cadmium in plants, the chemical additives can reduce the effectiveness of other mineral nutrients or have the risk of secondary pollution, so that microorganisms are more widely concerned with the plant control technology. Arbuscular Mycorrhiza (AM) is a reciprocal symbiont formed by the interaction of a beneficial fungus (arbuscular mycorrhizal fungus; AM fungus) belonging to glomus and a plant root system in soil (paraniske, 2008, von solid et al, 2010, Spatafora et al, 2016). For mycorrhizal symbiotic plants, besides direct absorption of nutrients in the soil rhizosphere range by the plant root system (referred to as the direct absorption pathway), absorption of nutrients and water in the soil rhizosphere range can also be achieved by AM fungal hyphae (referred to as the mycorrhizal pathway) (Ferrol et al, 2019, Liu et al, 2020). In addition to the nutrient effects, studies have shown that arbuscular mycorrhizal fungi (AM fungi) can influence the absorption, accumulation and detoxification processes of heavy metals by plants in the case of heavy metal contamination of soil in a variety of ways and improve the ability of plants to resist heavy metal poisoning (Zhang et al, 2015, Wang et al, 2019, Molina et al, 2020). For example, in heavy metal pollution conditions, the AM fungus can reduce the effectiveness of heavy metals in soil by producing secretion such as glycoprotein and globulin (Gil-Cardeza et al, 2015; Malekzadeh et al, 2016), can enhance a plant antioxidant enzyme system (superoxide dismutase, catalase and peroxidase) (Hu et al, 2020; Zhan et al, 2018; Li et al, 2020), and can relieve the toxic action of heavy metals on plants in a mode of promoting phosphorus absorption and plant growth (Jiang et al, 2016). Therefore, the AM fungus has great potential application value for bioremediation and ecological reconstruction of the heavy metal contaminated soil.

Tomatoes are one of the vegetables which are eaten in large quantities in human daily life, the quality of which directly affects the daily food safety of people, and tomatoes are considered as one of the plants which are most sensitive to Cd in quality and quality (Chen et al, 2011b, Luo et al, 2018). Tan et al found that under the stress of 2.0mg/kg Cd, the mass fractions of cadmium at edible parts of 29 tomatoes exceed 0.05mg/kg, and the overproof rate is 100% (Tan et al, 2014). Therefore, the search for an effective method for preventing and controlling the absorption and transportation of cadmium in tomatoes is a technical problem to be solved urgently at present.

The Chinese patent document discloses an exogenous additive for reducing the absorption of tomato Cd, a cultivation method and application thereof [ application number: 202010042895.0] comprises actinomycetes, potassium humate, medical stone and red mud, wherein in 100 parts by mass of soil, the addition amount of the actinomycetes is 0-0.25%, the addition amount of the potassium humate is 0-0.55%, the addition amount of the medical stone is 0-1.5%, the addition amount of the red mud is 0-0.25%, and the addition amounts of the actinomycetes, the medical stone and the red mud are not 0 at the same time. According to the invention, the soil is treated by adopting the exogenous additive, the pH of the soil is increased, the antioxidant enzyme activity of the tomatoes is increased and the photosynthetic rate of the tomatoes is increased by reducing the percentage of exchangeable Cd in the soil, so that the accumulation of Cd in the tomato fruits is reduced by 12.91%, the inhibition of cadmium stress on the growth of the tomatoes is relieved, and the yield of the tomatoes is increased. However, the invention adds the microbial inoculum and other different exogenous additives simultaneously, and the operation process is complex.

The chinese patent document also discloses a method for improving the cadmium resistance of tomatoes [ application number: 201810231150.1], comprising the steps of: 1) transplanting the tomato seedlings into cadmium-polluted soil and inoculating AMF microbial inoculum at the same time; 2) after the tomato seedlings stably grow, inoculating plant rhizosphere growth-promoting bacteria agent into the plant root systems; 3) tomatoes are cultured until they mature and produce fruit. The method realizes the promotion of the growth of the tomatoes under the cadmium stress by the co-inoculation of the plant rhizosphere growth-promoting bacteria and the arbuscular mycorrhizal fungi, can reduce the heavy metal content in the plants, does not influence the property of the soil, provides a direction for the research of the plant growth and the metal tolerance under the combined action of the plant rhizosphere growth-promoting bacteria and the AMF, and provides a line for researching the action mechanisms of the plant growth and the metal tolerance. However, the addition of two microbial agents complicates the operation.

In addition, the above two methods, except the process is complicated, the cadmium concentration of the tomato root and the above ground is not changed or increased.

Disclosure of Invention

The invention aims to solve the problems and provides a method for relieving cadmium toxicity of tomatoes by using arbuscular mycorrhizal fungi.

Another objective of the invention is to provide an application of the method for alleviating cadmium poisoning effect of tomatoes by using arbuscular mycorrhizal fungi in reducing cadmium poisoning effect of tomatoes.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for relieving cadmium poisoning effect of tomatoes by utilizing arbuscular mycorrhizal fungi comprises the following steps:

A. preparing an arbuscular mycorrhizal fungi agent:

the method comprises the steps of taking heterorhizospora heteroclita as an initial microbial inoculum, adding the heterorhizospora heteroclita into a matrix in a cave mode according to the proportion of 2 wt%, then sowing tobacco seeds into the matrix, spraying water at regular intervals, respectively irrigating 1/8, 1/4 and 1/2 low-phosphorus nutrient solutions in the first three weeks after two completely-unfolded leaves grow out of tobacco, then irrigating the low-phosphorus nutrient solutions, culturing for 5-6 months, stopping irrigating the water and the nutrient solutions, naturally dying the tobacco, removing the overground parts of the tobacco, crushing and uniformly mixing tobacco roots, and obtaining an arbuscular mycorrhizal fungal microbial inoculum;

B. tomato seedling culture:

sowing tomato seeds in a moist matrix, regularly spraying a proper amount of water, selecting healthy seedlings with consistent growth vigor when a first true leaf does not completely expand grows out of a plant, cleaning roots, and transferring the seedlings into a water culture box for culture;

C. inoculating fungi to tomatoes and carrying out sand culture:

and (2) filling river sand into a flowerpot, pouring a proper amount of 25 mu mol/L low-phosphorus nutrient solution to moisten the river sand, pricking a plurality of holes on the river sand, adding 20g of arbuscular mycorrhizal fungi microbial inoculum into the holes, covering the holes with the river sand, transferring the tomato seedlings into pots after the tomato seedlings in the step (B) grow out of two completely-unfolded leaves, transferring the tomato seedlings into the pots, transferring one tomato seedling into each pot, pouring the cadmium-containing low-phosphorus nutrient solution, and culturing for 35 days.

In the method for alleviating cadmium poisoning of tomatoes by using arbuscular mycorrhizal fungi, in the step A, the low-phosphorus nutrient solution of 1/8, 1/4 and 1/2 is poured in the first three weeks respectively, namely the low-phosphorus nutrient solution with the concentration of 1/8 is poured in the first week, the low-phosphorus nutrient solution with the concentration of 1/4 is poured in the second week, and the low-phosphorus nutrient solution with the concentration of 1/2 is poured in the third week, wherein the culture conditions are that the illumination is 14 hours, the darkness is 10 hours, the daytime temperature is 24-28 ℃, and the night temperature is 17-22 ℃.

In the above method for alleviating cadmium poisoning effect of tomato by using arbuscular mycorrhizal fungi, in step A, the total nutrient solution comprises 1mM NH₄ ⁺、4mM NO₃ ^-、2mM K⁺、1mM Pi、0.75mM Ca²⁺、0.5mM Mg²⁺、0.5mM Cl^-、1mM SO₄ ^2-、20μM Fe²⁺、9μM Mn²⁺、46μM BO₃ ^3-、8μM Zn²⁺、3μM Cu²⁺And 0.03. mu.M MoO₄ ^2-。

In the above method for alleviating cadmium poisoning effect of tomato by using arbuscular mycorrhizal fungi, in step a, the heterodera rhizospora is rhizospora heterodera rhizospora rhizomorpha provided by institute of plant nutrition and resources of agroforestrial academy of sciences of beijing.

In the method for relieving cadmium poisoning effect of tomato by using arbuscular mycorrhizal fungi, in the step B, the nutrient solution in the water culture box is replaced once every 5 days, the first three nutrient solutions are respectively full nutrient solutions with the concentrations of 1/8, 1/4 and 1/2, and then the full nutrient solutions are replaced, and the components of the full nutrient solutions comprise 1mM NH₄ ⁺、4mM NO₃ ^-、2mM K⁺、1mM Pi、0.75mM Ca²⁺、0.5mM Mg²⁺、0.5mM Cl^-、1mM SO₄ ^2-、20μM Fe²⁺、9μM Mn²⁺、46μM BO₃ ^3-、8μM Zn²⁺、3μM Cu^2、And 0.03. mu.M MoO₄ ^2-。

In the method for relieving cadmium poisoning effect of tomatoes by utilizing arbuscular mycorrhizal fungi, in the step B, the culture conditions of the water culture box are that the light is 14 hours, the dark is 10 hours, and the daytime temperature is as follows: 24 ℃ -28 ℃, night temperature: 17-22 ℃, and the illumination intensity is 5000-8000 Lux, preferably 6000-8000 Lux.

In the method for relieving cadmium poisoning effect of tomato by using arbuscular mycorrhizal fungi, in the step C, the capacity of the flowerpot is 4.5L, the weight of river sand in the flowerpot is 9-10kg, and cadmium is CdCl₂.2H₂Adding O into the nutrient solution in the form of 100 μmol/L of cadmium in the cadmium-containing nutrient solution and 25 μmol/L of phosphorus in the nutrient solution, and irrigating the nutrient solution once a week by 200 ml each time.

In the method for alleviating cadmium poisoning effect of tomatoes by using arbuscular mycorrhizal fungi, in the step C, the culture conditions are that the light is 14 hours, the dark is 10 hours, and the daytime temperature is as follows: 24 ℃ -28 ℃, night temperature: 17 ℃ to 22 ℃.

In the method for relieving cadmium toxicity of tomatoes by using arbuscular mycorrhizal fungi, in the step C, a plurality of 5 holes are punched on river sand, and the hole depth is 7-8 cm.

An application of a method for relieving cadmium poisoning effect of tomatoes by utilizing arbuscular mycorrhizal fungi in reducing cadmium poisoning effect of tomatoes.

Compared with the prior art, the invention has the advantages that:

by adopting a sand culture mode, the arbuscular mycorrhizal fungi and the tomatoes are utilized to establish a symbiotic relationship, under the stress of cadmium, the roots of the tomatoes with symbiotic mycorrhizas form a large amount of arbuscular branches and hyphae, the absorption area of the roots of the tomatoes is enlarged, and the absorption of the tomatoes on a large amount of phosphorus and a trace element of manganese is obviously increased; meanwhile, the absorption of cadmium by the tomato roots and the transfer of cadmium to the overground part are obviously inhibited, and the cadmium resistance of the tomatoes is effectively enhanced.

According to the method, the heterospora rhizomorpha Rhizopus irregularis is symbiotic with the tomatoes, only one microbial agent is utilized, the effects of preventing and controlling cadmium absorption and transfer are good, the absorption of cadmium by the roots of the tomatoes and the transfer of the cadmium to the overground parts are obviously inhibited, the reduction amounts of the cadmium concentration of the roots and the overground parts are respectively 40% and 42%, the reduction amounts are relatively high, and the effect of preventing and controlling the cadmium from being transferred to the overground parts of the tomatoes is better.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Drawings

FIG. 1 is a schematic diagram showing the effect of cadmium stress on the establishment of a symbiotic relationship between arbuscular mycorrhizal fungi and tomatoes.

Detailed Description

Example 1

A. preparing an arbuscular mycorrhizal fungal inoculant:

the method comprises the steps of adopting heteroclita radicicola as an initial microbial agent, adding the heteroclita radicicola, which is provided by institute of plant nutrition and resource of agroforestry academy of sciences of Beijing, into a substrate in a cave mode according to the proportion of 2 wt%, then sowing tobacco seeds into the substrate, regularly spraying water, pouring 1/8, 1/4 and 1/2 low-phosphorus nutrient solution respectively in the first three weeks after two fully-unfolded leaves grow out of tobacco, then pouring the low-phosphorus nutrient solution, culturing for 5-6 months, stopping pouring waterAnd nutrient solution, make it die naturally, remove the overground part of tobacco, pulverize the tobacco root and mix, obtain the arbuscular mycorrhizal fungi fungicide; the low-phosphorus nutrient solution poured 1/8, 1/4 and 1/2 in the first three weeks is the low-phosphorus nutrient solution poured 1/8 concentration in the first week, the low-phosphorus nutrient solution poured 1/4 concentration in the second week and the low-phosphorus nutrient solution poured 1/2 concentration in the third week, and the culture conditions are that the light is 14h, the dark is 10h, the day temperature is 24-28 ℃, the night temperature is 17-22 ℃, the light intensity is 5000-plus 1000Lux, and the preferred light intensity is 6000-plus 8000 Lux. The total nutrient solution comprises 1mM NH₄ ⁺、4mM NO₃ ^-、2mM K⁺、1mM Pi、0.75mM Ca²⁺、0.5mM Mg²⁺、0.5mM Cl^-、1mM SO₄ ^2-、20μM Fe²⁺、9μM Mn²⁺、46μM BO₃ ^3-、8μM Zn²⁺、3μM Cu²⁺And 0.03. mu.M MoO₄ ^2-。

B. Tomato seedling culture:

sowing tomato seeds in a moist matrix, regularly spraying a proper amount of water, selecting healthy seedlings with consistent growth vigor and size after the first true leaves which are not completely unfolded grow out of the plants, cleaning roots, and transferring the seedlings into a water culture box for culture; the nutrient solution in the water culture tank is replaced once every 5 days, the first three nutrient solutions are 1/8, 1/4 and 1/2 concentration total nutrient solutions, and then the nutrient solutions are replaced by the total nutrient solutions, and the total nutrient solution comprises 1mM NH₄ ⁺、4mM NO₃ ^-、2mMK⁺、1mM Pi、0.75mM Ca²⁺、0.5mM Mg²⁺、0.5mM Cl^-、1mM SO₄ ^2-、20μM Fe²⁺、9μM Mn²⁺、46μM BO₃ ^3-、8μM Zn²⁺、3μM Cu²And 0.03. mu.M MoO₄ ^2-. The culture conditions of the water culture box are 14h of illumination, 10h of darkness and daytime temperature: 24 ℃ -28 ℃, night temperature: the illumination intensity is 1000Lux at 5000-.

C. Inoculating fungi to tomatoes and carrying out sand culture:

the river sand is put into a flowerpot, a proper amount of 25 mu mol/L low-phosphorus nutrient solution is poured to moisten the river sand, and a plurality of holes are punched on the river sand, in the embodiment, 5 holes are punched on the river sand, and the depth of each hole is 7-8 cm.

Adding 20g of arbuscular mycorrhizal fungi agent into the holes, covering the holes with river sand, moving the tomato seedlings into pots when two completely-unfolded leaves grow out from the tomato seedlings in the step B, moving one tomato seedling into each pot, irrigating the cadmium-containing low-phosphorus nutrient solution, and culturing for 35 days.

The volume of the flowerpot is 4.5L, the weight of river sand in the flowerpot is 9-10kg, and cadmium is CdCl₂.2H₂Adding O into the nutrient solution in the form of 100 mu mol/L of cadmium in the cadmium-containing nutrient solution and 25 mu mol/L of phosphorus in the nutrient solution, and irrigating the nutrient solution once a week by 300ml of 200-one each time.

The culture conditions are 14h under light, 10h in darkness, and day temperature: 24 ℃ -28 ℃, night temperature: 17-22 ℃, and the illumination intensity is 5000-8000 Lux, preferably 6000-8000 Lux.

The method for relieving the cadmium poisoning effect of the tomatoes by utilizing the arbuscular mycorrhizal fungi is applied to reducing the cadmium poisoning effect of the tomatoes.

Example 2

A. preparing an arbuscular mycorrhizal fungal inoculant:

the primary arbuscular mycorrhizal fungus was Rhizopus irregularis Heterorhizospora (BGC JX04B) provided by the institute of plant nutrition and resources, academy of agroforestry, Beijing. The method comprises the steps of carrying out high-temperature treatment on purchased river sand at 120 ℃ for 1h, then potting, pouring a proper amount of tap water, staying overnight, adding an initial microbial inoculum into a matrix according to a proportion (W/W) of 2% in a cave mode, then sowing tobacco seeds (10-15 particles) sterilized by 30% sodium hypochlorite solution into the matrix, regularly spraying a proper amount of water, pouring low-phosphorus nutrient solutions (with the phosphorus concentration of 25 mu mol/L) with the concentrations of 1/8, 1/4 and 1/2 respectively in the first three weeks after two pieces of completely-unfolded leaves grow out of tobacco, and then pouring the low-phosphorus nutrient solutions (with the phosphorus concentration of 25 mu mol/L). The culture conditions are as follows: light 14h, dark 10h, daytime temperature: 24 ℃ -28 ℃, night temperature: culturing at 17-22 deg.C and illumination intensity of 5000-1000Lux, preferably 6000-8000Lux for 5-6 months, stopping watering and nutrition, and allowing it to die naturally. Removing the overground part of tobacco, cutting tobacco roots to 0.2-0.5cm long, and mixing uniformly to obtain the arbuscular mycorrhizal fungi microbial inoculum formed by mixing tobacco root segments, river sand, spores and hypha of the arbuscular mycorrhizal fungi Rhizopharmagus irregularis.

B. Tomato seedling culture:

the tomato variety name is collaborate 903. Heating tomato seeds in a 50 ℃ water bath for 5min, disinfecting with 30% sodium hypochlorite for 5min, and washing with deionized water; seeds were sown in a moist medium, which was imported peatmoss (0-6 mm). Spraying a proper amount of water regularly, and culturing under the conditions: light 14h, dark 10h, daytime temperature: 24 ℃ -28 ℃, night temperature: 17-22 ℃, and the illumination intensity is 5000-8000 Lux, preferably 6000-8000 Lux.

When the first true leaf which is not completely unfolded grows out of the plant, selecting healthy seedlings with the same growth vigor and size, cleaning the root, and transferring the root into a turnover box. The nutrient solution is changed every 5 days, namely, the total nutrient solution with the concentration of 1/8, 1/4 and 1/2 is changed in sequence, and then the total nutrient solution is changed.

The total nutrient solution comprises the following components: 1mM NH₄ ⁺,4mM NO₃ ^-,2mM K⁺,1mM Pi,0.75mM Ca²⁺,0.5mM Mg²⁺,0.5mM Cl^-,1mM SO₄ ^2-,20μM Fe²⁺,9μM Mn²⁺,46μM BO₃ ^3-,8μM Zn²⁺,3μM Cu²⁺,and 0.03μM MoO₄ ^2-。

The culture conditions are as follows: light 14h, dark 10h, daytime temperature: 24 ℃ -28 ℃, night temperature: 17 ℃ to 22 ℃.

C. Inoculating tomato with fungi, and carrying out sand culture:

treating the purchased river sand at high temperature of 120 ℃ for 1h, firstly filling the river sand into a 4.5L flowerpot (the upper diameter is 18cm, the lower diameter is 15.6cm and the height is 18cm), pouring a proper amount of 1/2 full nutrient solution concentration cadmium-containing and cadmium-free low-phosphorus nutrient solution, ensuring that the sand is completely wet, and keeping the sand overnight for later use. Randomly pricking 5 holes with length of 7-8cm on the substrate, and uniformly adding 20g of AM fungus into the holes respectively to makeThe holes were covered with river sand. After the tomatoes grow out of two fully-unfolded leaves, the root systems of the tomatoes are washed by tap water, the tomatoes are moved into pots, and one tomato seedling is moved into each pot. Cadmium is CdCl₂.2H₂The O form is added into the nutrient solution, the cadmium concentration in the cadmium-containing low-phosphorus nutrient solution is 100 mu mol/L, and the phosphorus concentration is 25 mu mol/L. The nutrient solution is irrigated once a week, 200 ml and 300ml are added once a week, and the culture is carried out for 35 days.

The culture conditions are as follows: light 14h, dark 10h, daytime temperature: 24 ℃ -28 ℃, night temperature: 17-22 ℃, and the illumination intensity is 5000-8000 Lux, preferably 6000-8000 Lux.

Comparative examples 1 to 3

Comparative examples 1 to 3 the method of example 2 was used, respectively, except that in step C of comparative example 1, cadmium was not added to the nutrient solution and AM fungus was not inoculated. In step C of comparative example 2, the nutrient solution was inoculated with AM fungus without cadmium. In the step C of the comparative example 3, cadmium is added into the nutrient solution, namely the nutrient solution containing cadmium, but AM fungus is not inoculated.

Application example

Comparative example 3 and example 2 were processed to form 4 treatments: no cadmium added and no AM fungi inoculated (T0), no cadmium added and AM fungi inoculated (T1), cadmium added and no AM fungi inoculated (T2), cadmium added and AM fungi inoculated (T3). As shown in table 1.

TABLE 1 test design

1. And (3) measuring the infection rate of the mycorrhizal fungi at the root of the tomato:

reference was made to the assay method (Liu et al, 2016; Xue et al, 2018). Collecting the root segments of the tomatoes under different treatment conditions, cleaning, cutting the roots into root segments with the length of 1-2cm, completely soaking the root segments into 10% (w/v) KOH solution, carrying out water bath treatment at 90 ℃ for 50min, pouring off the solution, adding 5% (v/v) HCl solution, reacting for 10min, carrying out rinsing with sterile water, placing the rinsed root segments into 0.05% (w/v) trypan blue staining solution for boiling water bath staining for 30min, pouring off the staining solution, carrying out rinsing with sterile water for three times, adding a proper amount of sterile water, placing the mixture at 25 ℃ for one week, sampling, carrying out microscopic examination, and analyzing the infection rate and the arbuscular mycorrhizal fungi by a cross method.

The measurement results are shown in FIG. 1: the result shows that in the invention, compared with the condition without cadmium, cadmium inhibits the abundance of the tomato roots, but does not influence the total infection rate of the tomato roots, so the arbuscular mycorrhizal fungi adopted by the invention has certain cadmium tolerance.

2. Determination of tomato biomass, phosphorus content and manganese content:

(1) determination of plant biomass

Cleaning the roots of the plant samples by using deionized water, wiping water on the roots, dividing the roots into two parts, namely roots and overground parts, respectively putting the two parts into a kraft paper envelope which is marked, transferring the envelope into a baking oven, deactivating enzymes at 105 ℃, adjusting the temperature to 70 after 1 hour, and weighing the envelope by using an electronic balance after keeping the temperature for 2 to 3 days.

(2) Determination of phosphorus content and manganese content of plants

Digestion: firstly, the dried sample is cut or crushed by using scissors, the more the dried sample is, the better the dried sample is, but the length of the dried sample is usually 2-5mm, so that the sample can be uniformly mixed, and the detection accuracy is improved. Weighing 0.1-0.25g of plant sample, transferring into a digestion tube, and adding 5ml of high-grade pure concentrated HNO₃And (4) overnight, digesting by using a microwave digestion instrument, transferring and fixing the volume to a volumetric flask. The phosphorus content of the plants is determined by molybdenum blue colorimetry, and the specific method refers to Chen et al (2007). The manganese content was determined by ICP-MS.

TABLE 2 Effect of AM fungus on tomato growth, phosphorus and manganese content

As shown in Table 2, in the absence of cadmium, the weight average of the dry root weight and the dry aerial parts weight of the tomato inoculated with the AM fungus was significantly increased by 58% and 50%, respectively, compared with the tomato inoculated with the AM fungus, and the phosphorus content and the manganese content of the root of the tomato were significantly increased. Under the condition of cadmium addition, compared with the tomato not inoculated with the AM fungus, the dry weight of the roots and the overground parts of the tomatoes inoculated with the AM fungus has no obvious change, but the phosphorus content, the manganese content and the manganese content of the overground parts of the roots of the tomatoes are obviously increased by 29 percent, 36 percent and 25 percent respectively. Therefore, under the cadmium stress condition, the AM fungi can remarkably promote the absorption of the tomato roots to a large amount of phosphorus and a trace element of manganese and the transportation of phosphorus to the overground part.

3. Determination of cadmium content in tomato

(1) Determination of cadmium content in plants

Firstly, the dried sample is cut into pieces by using scissors, the more broken the sample is, the better the sample is, the sample can be uniformly mixed, and the detection accuracy is improved. Weighing 0.1-0.25g of plant sample, transferring into a digestion tube, and adding 5ml of high-grade pure concentrated HNO₃And (4) overnight, digesting by using a microwave digestion instrument, transferring and fixing the volume to a volumetric flask, and finally measuring by ICP-MS.

(2) Measurement results

TABLE 3 Effect of AM fungus on cadmium uptake by tomato

As shown in Table 3, under the cadmium stress, compared with the tomato without the AM fungus, the cadmium content of the tomato roots and the overground parts inoculated with the AM fungus is reduced by 40 percent and 42 percent, so that the AM fungus can effectively inhibit the tomato roots from absorbing cadmium and simultaneously prevent and control the cadmium from being transported to the overground parts of the tomato.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications, additions and substitutions for the specific embodiments described may be made by those skilled in the art without departing from the spirit of the invention.

Claims

1. A method for relieving cadmium poisoning effect of tomatoes by utilizing arbuscular mycorrhizal fungi is characterized by comprising the following steps:

A. preparing an arbuscular mycorrhizal fungi agent:

adding 2 wt% of heteroclitic root cystospora serving as an initial microbial inoculum into a substrate in a cave mode, sowing tobacco seeds into the substrate, regularly spraying water, irrigating 1/8, 1/4 and 1/2 low-phosphorus nutrient solutions respectively in the first three weeks after two pieces of completely unfolded leaves grow out of tobacco, then irrigating the low-phosphorus nutrient solutions, culturing for 5-6 months, stopping irrigating the water and the nutrient solutions, naturally dying the water and the nutrient solutions, removing the overground part of the tobacco, and crushing and uniformly mixing tobacco roots to obtain an arbuscular mycorrhizal fungal microbial inoculum;

B. tomato seedling culture:

C. inoculating fungi to tomatoes and carrying out sand culture:

and (3) putting the river sand into a flowerpot, irrigating a proper amount of 25 mu mol/L low-phosphorus nutrient solution to moisten the river sand, pricking a plurality of holes on the river sand, uniformly adding 20g of arbuscular mycorrhizal fungi fungicide into the holes, covering the holes by using the river sand, transferring the tomato seedlings into the pots, transferring one tomato seedling into each pot, irrigating the cadmium-containing low-phosphorus nutrient solution, and culturing for 35 days after the tomato seedlings in the step B grow two fully-unfolded leaves.

2. The method for alleviating cadmium poisoning of tomatoes as claimed in claim 1, wherein the first three weeks of the step A comprise watering 1/8, 1/4 and 1/2 with low-phosphorus nutrient solution in 1/8 concentration for the first week, watering 1/4 concentration for the second week and watering 1/2 concentration for the third week, wherein the cultivation conditions are light for 14h, dark for 10h, day temperature 24-28 ℃ and night temperature 17-22 ℃.

3. The method of claim 1 or 2, wherein in step A, said complete nutrient solution comprises 1mM NH₄ ⁺、4mM NO₃ ^-、2mM K⁺、1mM Pi、0.75mM Ca²⁺、0.5mM Mg²⁺、0.5mM Cl^-、1mM SO₄ ^2-、20μM Fe²⁺、9μM Mn²⁺、46μM BO₃ ^3-、8μM Zn²⁺、3μM Cu²⁺And 0.03. mu.M MoO₄ ^2-。

4. The method for alleviating cadmium poisoning in tomato by arbuscular mycorrhizal fungi according to claim 1, wherein in step a, the rhizospora heteroclita is rhizospora heteroclita of rhizopus irregularis provided by institute of plant nutrition and resource of agroforestry academy of sciences of beijing.

5. The method of claim 1, wherein in step B, the nutrient solution in the hydroponic tank is changed every 5 days, the first three nutrient solutions are 1/8, 1/4 and 1/2 full nutrient solutions, and then the nutrient solutions are changed to full nutrient solutions, and the total nutrient solution comprises 1mM NH₄ ⁺、4mM NO₃ ^-、2mM K⁺、1mM Pi、0.75mM Ca²⁺、0.5mM Mg²⁺、0.5mM Cl^-、1mM SO₄ ^2-、20μM Fe²⁺、9μM Mn²⁺、46μM BO₃ ^3-、8μM Zn²⁺、3μM Cu²And 0.03. mu.M MoO₄ ^2-。

6. The method for alleviating cadmium poisoning of tomatoes according to claim 1, wherein in the step B, the culture conditions of the hydroponic box are 14h under light, 10h under dark, and day temperature: 24 ℃ -28 ℃, night temperature: 17 ℃ to 22 ℃.

7. The method of claim 1 for alleviating the toxic effects of cadmium in tomatoes of claim 1, wherein in step C, the pot capacity is 4.5L, the weight of river sand in the pot is 9-10kg, and cadmium is CdCl₂.2H₂Addition in the form of OIn the nutrient solution, the cadmium concentration in the cadmium-containing nutrient solution is 100 mu mol/L, the phosphorus concentration in the nutrient solution is 25 mu mol/L, and the nutrient solution is irrigated once a week by 200-300ml each time.

8. The method for alleviating cadmium poisoning in tomato using arbuscular mycorrhizal fungi as claimed in claim 1, wherein in step C, the cultivation conditions are 14h light, 10h dark, day temperature: 24 ℃ -28 ℃, night temperature: 17-22 ℃.

9. The method of claim 1, wherein in step C, a plurality of 5 holes are punched in the river sand, the holes having a depth of 7-8 cm.

10. Use of a method according to any one of claims 1 to 9 for alleviating the deleterious effects of cadmium in tomatoes by using an arbuscular mycorrhizal fungus for reducing the deleterious effects of cadmium in tomatoes.