CN107363081B

CN107363081B - Method for remarkably promoting cadmium-enriched plants to restore cadmium-contaminated soil

Info

Publication number: CN107363081B
Application number: CN201710516841.1A
Authority: CN
Inventors: 梁东; 夏惠; 林立金; 廖明安; 吕秀兰; 王进
Original assignee: Sichuan Agricultural University
Current assignee: Sichuan Agricultural University
Priority date: 2017-06-29
Filing date: 2017-06-29
Publication date: 2020-07-28
Anticipated expiration: 2037-06-29
Also published as: CN107363081A

Abstract

The invention belongs to the technical field of soil heavy metal pollution prevention and treatment, and provides a method for remarkably promoting cadmium-enriched plants to restore the capacity of cadmium-contaminated soil. The invention obviously improves the absorption of the chickweed root system and the bovine chickweed root system to cadmium and improves the restoration capability of the chickweed and the bovine chickweed to the cadmium-polluted soil.

Description

Method for remarkably promoting cadmium-enriched plants to restore cadmium-contaminated soil

Technical Field

The invention belongs to the technical field of soil heavy metal pollution prevention and treatment, relates to the field of heavy metal polluted soil phytoremediation, and particularly relates to a method for remarkably promoting cadmium-enriched plants to restore the capacity of cadmium-polluted soil.

Background

Heavy metal contamination is a common problem for human activities and natural events in the last decades. It has been reported that more than 10% of cultivated land is contaminated with heavy metals, such as cadmium, rubidium, chromium, lead, etc., resulting in production losses of more than ten million tons. Cadmium is easily absorbed by the root system of crops, migrates to the seeds and then enters human body through food chain, thus threatening the life health of human beings. Therefore, the remediation of the heavy metal contaminated soil becomes an urgent problem to be solved in all countries in the world.

The phytoremediation is a common method for remedying the heavy metal contaminated soil, and can directly absorb the heavy metal from the soil and transfer the heavy metal to the overground part of the plant through the root system of the plant under the conditions of not damaging the ecological environment of the soil and keeping the soil structure and microorganisms, thereby achieving the purpose of remedying the contaminated soil by times of the plants. Currently, cadmium-enriched plants such as ryegrass and chickweed are found, but because the screened plants are slow in growth and low in biomass, the removal efficiency of the plants on the heavy metal in the polluted soil is limited, and the needs of farmland cadmium pollution remediation are difficult to meet. Therefore, the improvement of the restoration capacity of the enriched plants through the agronomic restoration measures has important practical significance.

In agricultural production, the effective utilization of resources such as soil nutrients, water, light and the like by crops can be improved by utilizing an intercropping (mixing) technique, so that the yield of the crops is increased, and the quality of the crops is improved. The intercropping of different plants can regulate the absorption of heavy metals by the plants. Researches on Jiang-Yong (influence of the mixed cropping of Sedum alfredii and different plants on soil heavy metal absorption [ J ]. China environmental science 2009,29(9): 985-. Researches on the treatment effect of interplanting of sedum alfredii and corn on Zn-polluted sludge [ J ]. environmental science, 2007, 28 (4): 852 + 858.) find that the recovery of the polluted sludge by the intercropping of corn and the sedum alfredii with super-accumulative plants leads the Zn, Cd and Cu concentrations in corn grains to accord with the grain sanitation standard, but the Zn and Cd concentrations in the sedum alfredii are obviously increased. However, the research results of Wangjingwen (influence of intercropping of luffa and Sedum plumbizincicola on the form of Cd in soil and absorption of luffa Cd [ J ]. agricultural environmental science reports, 2016,35 (12): 2292-2298.) and the like show that intercropping of luffa and Sedum plumbizincicola reduces the number of luffa fruits to a certain extent, and at the same time, has the risk of increasing the content of Cd in luffa fruits. The change in the absorption of these heavy metals may be due to changes in the secretion, the kind, amount, function of enzymes, or competition between various elements and plants. This shows that the aim of improving the heavy metal pollution remediation efficiency can be achieved only by intercropping (mixing) through proper plant collocation, otherwise, enrichment plants can be complemented and weakened, competition can be stimulated, and the result is counterproductive. Therefore, there is a need for further screening of suitable plant companion species to improve the repair efficiency of enriched plants.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a method for remarkably promoting cadmium-enriched plants to restore the capability of cadmium-polluted soil, and the method is to carry out mixed cultivation on chickweed and bovine chickweed.

When mixed planting is carried out, it is not easy to significantly improve the cadmium absorption capacity of the mixed planting plants. The interaction between intercropping species has two main aspects, one is interspecific promotion and the other is interspecific competition. Both effects always exist simultaneously, and are manifested as intercropping disadvantage when the competitive effect is greater than the promoting effect and as intercropping advantage when the competitive effect is less than the promoting effect. The inventor of the invention surprisingly discovers that after chickweed and bovine chickweed are mixed, the absorption capacity of both chickweed and bovine chickweed to cadmium is greatly improved.

In a possible embodiment of the present invention, when cultivating in mixed manner, chickweed and bovine chickweed are uniformly mixed and the ratio of the number of plants of chickweed to bovine chickweed is 1: 1.

In a possible embodiment of the invention, both chickweed and bovine chickweed are 3 true-leaf spread plants.

In one possible embodiment of the invention, soil moisture is maintained at 80% of field capacity while planting.

In one possible embodiment of the invention, the cadmium concentration in the cadmium-contaminated soil is not lower than 10 mg/kg.

According to the content recorded in the invention, the skilled person can easily know that the invention finds that after chickweed and bovine chickweed are mixed, the absorption of cadmium in cadmium-polluted soil by chickweed and bovine chickweed can be simultaneously enhanced, thereby realizing the remediation of the cadmium-polluted soil. The method is not limited to the extent of cadmium pollution, and can be used for enhancing the cadmium pollution remediation capability of chickweed and bovine chickweed as long as the cadmium pollutes the soil.

Generally, the concentration of cadmium in the cadmium-polluted soil is not lower than 10 mg/kg. In one possible embodiment of the invention, the cadmium concentration in the cadmium-contaminated soil is 10 mg/kg.

The invention has the beneficial effects that:

the invention obviously improves the absorption of the chickweed root system and the bovine chickweed root system to cadmium and improves the restoration capability of the chickweed and the bovine chickweed to the cadmium-polluted soil.

Detailed Description

The present invention is described in detail below by way of examples, and it should be noted that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention.

Example 1

The soil to be tested is purple soil, is taken from farmlands (29 degrees 59 'N and 102 degrees 59' E) in Yaan school district of Sichuan university of agriculture, and the basic physicochemical properties of the soil are described in the reference documents (the influence of different ecotype chickweeds on the absorption of phosphorus and potassium of cadmium-stressed rootstock cherry plants [ J ]. the Chinese ecological agriculture bulletin, 2013,21(12):1565 and 1568.).

Seedlings of cadmium-enriched plants Stellaria mediae and Stellaria mediae were harvested from farm farmlands in Yaan school district of Sichuan university of agriculture 3 months in 2015, and the soil in the harvest district was not contaminated with heavy metals.

Test method

Cultivation treatment mode

Air drying soil, crushing, sieving with 5mm sieve, weighing 3.0kg respectively, placing in 20cm × 27cm (height × diameter) plastic basin, adding analytically pure CdCl₂·2.5H₂And (3) adding the O solution to ensure that the cadmium concentration is 10mg/kg, fully and uniformly mixing the O solution with the soil, keeping the flooding state, naturally standing and balancing for 4 weeks, and then mixing the O solution again for later use.

The number of plants and the number of repeats for each treatment

And (3) selecting chickweed and cleavers seedlings which grow uniformly and have about 3 true leaves to be unfolded, and transplanting the chickweed and cleavers seedlings into a pot. The experiment set up 3 treatments, respectively: single chickweed, single chickweed and mixed chickweed. The single treatment plants 6 plants per pot, the mixed treatment 3 plants per pot and each treatment repeated 5 times.

The culture conditions are as follows:

the potted plant is placed in a transparent rain shelter, and the soil is watered irregularly according to the actual condition of the soil moisture to ensure that the soil moisture is kept about 80 percent of the field moisture capacity.

Harvesting and material pretreatment:

the photosynthetic pigment content of the three plants was determined after 30 days. Then, the whole plant is harvested, the root system and the overground part of the plant are respectively packaged, washed by tap water and then washed by deionized water for 3 times, then the plant is de-enzymed for 15min at the temperature of 110 ℃, dried to balance weight at the temperature of 75 ℃, weighed, crushed and sieved by a 100-mesh sieve.

And (3) determining the cadmium content by using an atomic absorption spectrometry:

weighing 0.500g of plant sample, adding nitric acid-perchloric acid (in a volume ratio of 4:1), standing for 12h, digesting until the solution is transparent, filtering, fixing the volume to 50ml, measuring the cadmium content (Thermo Scientific, USA) by an iCAP 6300 type ICP spectrometer, air-drying the soil sample, sieving by a 1mm sieve, measuring the pH (soil-water ratio of 1:2.5) of the soil by a pH meter, extracting the effective cadmium in the soil by a DTPA-TEA extraction method, measuring the effective cadmium content of the soil by the iCAP 6300 type ICP spectrometer, measuring the overground part enrichment coefficient (BCF) which is the overground part cadmium content/the soil cadmium content, the transport coefficient (TF) which is the overground part cadmium content/the root cadmium content of the plant, and the transport coefficient (TAF) which is the overground part biomass content ×)/(the root biomass content ×).

Data processing method

Data were analyzed for variance using the SPSS system (multiple comparisons using the Duncan new complex range method).

Results and analysis:

as shown in Table 1, the biomass of the bovine chickweed and chickweed is remarkably improved after the bovine chickweed and chickweed are mixed.

TABLE 1 Effect of Co-planting on plant Individual Biomass

As shown in table 2, the effect of the present invention on the chlorophyll content of plants was not significant compared to the single species.

TABLE 2 Effect of the Mixed species on the photosynthetic pigment content of plants

As shown in Table 3, the present invention significantly increases the cadmium content of chickweed and bovine chickweed root systems compared to single chickweed and single bovine chickweed. The invention reduces the transport coefficient of chickweed and bovine chickweed, which shows that the invention inhibits the conversion of cadmium from chickweed root systems and bovine chickweed root systems to overground parts.

TABLE 3 Effect of the Mixed species on cadmium content of plants

Plant cadmium content is affected by tissue cadmium content and biomass. As shown in Table 4, compared with the single species, the cadmium accumulation of the root system parts of chickweed and bovine chickweed is remarkably improved, and the influence on the overground parts is small. In combination, the method obviously improves the absorption and accumulation of cadmium in the cadmium-polluted soil by the whole chickweed plant, and enhances the capacity of the chickweed to restore the cadmium-polluted soil.

TABLE 4 Effect of Mixed species on cadmium accumulation in individual plants

As shown in Table 5, the present invention significantly improved the single pot cadmium accumulation of the whole chickweed and bovine chickweed plants compared to the single plants.

TABLE 5 Effect of Mixed species on cadmium accumulation per pot of three plants

Claims

1. The method for remarkably promoting the cadmium-enriched plant to restore the cadmium-polluted soil is characterized by comprising the steps of carrying out mixed cultivation on chickweed and bovine chickweed, carrying out uniform mixed cultivation on the chickweed and the bovine chickweed during mixed cultivation, and enabling the number ratio of the chickweed to the bovine chickweed to be 1:1, wherein when carrying out mixed cultivation, the chickweed and the bovine chickweed are 3 plants with unfolded true leaves; when planting, keeping the soil moisture at 80% of the field moisture capacity; the concentration of cadmium in the cadmium-polluted soil is not lower than 10 mg/kg.