Disclosure of Invention
The invention aims to solve the problem that qualified agricultural products can be planted on large-scale heavy metal polluted farmland soil, and further provides a method for reducing the content of Cd in edible parts of solanaceous crops.
In order to solve the technical problems, the invention adopts the technical scheme that:
a method for reducing the content of cadmium (Cd) at the edible part of solanaceous crops is characterized in that tolobam (Solanum torvum) is used as a stock, and solanaceous crops are used as scions for grafting, so that the content of cadmium (Cd) at the edible part of the solanaceous crops is reduced.
The solanaceous crops are cultivated Solanum melongena, and the cultivated solanaceous crops are tomatoes (Solanum lycopersicum L.), Solanum melongena (Solanum melogna) and peppers (Capsicum annuum L.).
The method specifically comprises the following steps:
(1) selecting rootstock and scion: taking wild eggplant Tuolubamu as a stock and a cultivated eggplant crop as a scion;
(2) seedling culture: sowing and growing seedlings on the stock seeds and the scion seeds, and preparing for grafting when the wild solanum toruloides seedlings grow to 5-6 leaf ages and the cotyledon period of the scion crop seedlings;
(3) grafting: grafting by cleft grafting;
(4) and (3) managing after grafting, wherein the grafted seedlings after seedling revival have the characteristic of low Cd enrichment, can be transplanted to Cd-polluted soil for normal field management, and the Cd content of the harvested fruits is remarkably reduced, namely the cadmium (Cd) content of edible parts of the solanaceous crops is reduced.
And (3) cutting off 2-3 true leaves above the stock when the cleft grafting method is adopted for grafting, leaving 2 true leaves, vertically cutting a cut on the top end of the cut stem from top to bottom by using a blade, wherein the cut depth is 1.0-1.5 cm, leaving 2-3 true leaves of the scion, cutting the scion into a wedge shape, the length of the wedge shape is 1.0-1.5 cm, inserting the scion into the cut of the stock, fully combining the scion and fixing the scion by using a grafting clip.
According to the seedling raising method in the step (3), the wild eggplant tolubam stock is sowed 30 days earlier than the scion.
And (4) placing the grafted seedlings after grafting in the step (4) into a shading shed, carrying out heat preservation and moisture preservation culture, sprinkling water on the ground of the shading shed at the noon every day to keep the humidity, keeping the temperature at 25-30 ℃ and the relative humidity at 85%, keeping out of the sun, and carrying out normal seedling raising management after the seedlings are released for one week.
According to the grafting method, the temperature is 25-30 ℃ and the relative humidity is 75% during grafting, so that wind blowing is avoided.
The invention shows that tolubam (Solanum torvum) is a solanaceae plant with low Cd accumulation.
Compared with the prior art, the invention has the following advantages:
1. compared with the existing heavy metal contaminated soil remediation technology, such as physical and chemical measures, the method can reduce the Cd content of the edible parts of the solanaceous crops by 50-80% on the premise of not influencing agricultural production, can produce qualified agricultural products on the light heavy metal contaminated soil, and realizes the safe utilization of the contaminated farmland soil.
2. The wild eggplant torulam stock adopted by the invention is easy to obtain and cultivate, the Cd accumulation is low, the wild eggplant torulam stock has high resistance to soil-borne diseases such as verticillium wilt, fusarium wilt, bacterial wilt and nematode, the plant growth vigor is strong, the root system is developed, and the wild eggplant torulam stock is further grafted with the wild eggplant torulam stock, so that the obtained scion crop has the characteristic of low Cd enrichment, and meanwhile, the disease resistance is obviously enhanced.
3. The grafting method adopted by the invention is a conventional gardening means, is simple to operate, does not need complex technical steps and expensive experimental reagents, and has low requirement on professional knowledge of operators.
The specific implementation mode is as follows:
the following examples are presented to further illustrate embodiments of the present invention, and it should be understood that the embodiments described herein are for purposes of illustration and explanation only and are not intended to limit the invention.
The method adopts the plant with low Cd accumulation as the stock, and controls the transportation and accumulation of Cd to the overground part of crops by the grafting technology; the invention is a blocking technology for heavy metal enrichment of crops, and has important significance in reducing the biological toxicity of heavy metals and ensuring the safety of agricultural products.
The method comprises the following specific steps:
(1) stock and scion: wild eggplant Tuolubamu is used as a stock, and cultivated eggplant crops are used as scions.
(2) Seedling culture: and (3) sowing and seedling the stock seeds and the scion seeds, wherein the wild eggplant tolubam stock is sowed 30 days earlier than the scion, and grafting is prepared when the wild eggplant seedlings grow to 5-6 leaf ages and the cotyledon period of the scion crop seedlings is reached.
(3) Grafting: grafting is carried out by cleft grafting. Cutting off 2-3 true leaves above the stock, reserving 2 true leaves, vertically cutting off a knife from top to bottom at the top end of the broken stem by using the knife, wherein the cut depth is 1.0-1.5 cm, reserving 2-3 true leaves of the scion, cutting into a wedge shape, and the length of the wedge shape is 1.0-1.5 cm. The scion is inserted into the split opening of the stock to be fully combined and then fixed by the grafting clip. The temperature is 25-30 ℃ and the relative humidity is 75% during grafting, so that wind blowing is avoided.
(4) And (3) management after grafting: placing the grafted seedling into a shading shed, carrying out heat preservation and moisture preservation culture, and sprinkling water on the ground of the shading shed every noon to keep humidity. And during the seedling recovering period in a shading shed, the temperature is 25-30 ℃, the relative humidity is 85%, and the seedlings are shaded. And (5) after the seedlings are revived for one week, carrying out normal seedling management.
(5) Transplanting the grafted seedlings: the grafted seedlings after seedling delay are cultured in a greenhouse (natural light, 25-30 ℃ and relative humidity of 75%) for about 7 days, the grafted seedlings can be transplanted to Cd-polluted soil for normal field management, the grafted seedlings have the characteristic of low Cd enrichment, and the Cd content of the harvested fruits is remarkably reduced.
The Toolubamu is a wild allied species of eggplant, which is detailed in Xuxiaming, Xukun and Qibang, in Qin, 2007, the comparison of the growth characteristics of different eggplant rootstock seedlings, Shandong agricultural science, (5): 40-45.
Example l
A method for reducing the content of Cd in edible parts of tomatoes, eggplants and hot peppers comprises the following steps:
(1) stock and scion: wild eggplant Tuolubamu is taken as a stock, and tomatoes, eggplants and hot peppers are taken as scions.
(2) Seedling culture: the method comprises the steps of breeding wild eggplant seedlings at the beginning of 4 months, breeding tomato seeds, eggplant seeds and pepper seeds at the beginning of 5 months, and preparing for grafting when the wild eggplant seedlings grow to 5-6 leaves and the cotyledon period of scion crop seedlings is reached.
(3) Grafting: cutting 2-3 true leaves above the Tuolubamu, reserving 2 true leaves, vertically cutting the top end of the broken stem with a blade from top to bottom, wherein the cut depth is 1.0-1.5 cm, reserving 2-3 true leaves of tomato, eggplant and pepper scions, and cutting into a wedge shape, and the length of the wedge shape is 1.0-1.5 cm. The scion is inserted into the split opening of the stock to be fully combined and then fixed by the grafting clip. The temperature is 25-30 ℃ and the relative humidity is 75% during grafting, so that wind blowing is avoided.
(4) And (3) management after grafting: placing the grafted seedlings of tomato, eggplant and pepper into a shading shed, carrying out heat preservation and moisture preservation culture, and sprinkling water on the ground of the shading shed every noon to keep the humidity. And during the seedling recovering period in a shading shed, the temperature is 25-30 ℃, the relative humidity is 85%, and the seedlings are shaded. And (5) after the seedlings are revived for one week, carrying out normal seedling management.
(5) Pot experiment: culturing the grafted seedlings after seedling delay in a greenhouse (natural light, 25-30 ℃, and relative humidity of 75%) for about 7 days, and transplanting the grafted seedlings with consistent growth vigor until the concentration of Cd is 2.0 mg/kg-1In the flowerpot, self-rooted seedlings are simultaneously set as a control group (the self-rooted seedlings are not grafted tomato, eggplant and pepper seedlings), 2 seedlings are planted in each pot, fertilizer application and watering are regularly carried out to ensure the normal growth of crops, and leaf and fruit samples are collected in the mature period.
(6) Analyzing the Cd contents of edible parts of grafted plants and self-rooted plants: collecting leaves and fruits of the grafted plant and the self-rooted plant, drying at 75 ℃ to constant weight, weighing 0.5g of sample in a high-pressure digestion tank, performing microwave digestion, and measuring the Cd content of the sample by inductively coupled plasma emission spectroscopy (ICP-OES), wherein the leaves and fruits of the self-rooted plant are taken as a reference, and the Cd content is shown in Table 1.
TABLE 12.0 mg kg-1Comparison of Cd content in leaves and fruits of self-rooted Solanum crops and Tuolubamu grafted Solanum crops in Cd pot culture experiment
As can be seen from Table 1, the concentration of the compound is 2.0 mg/kg-1In the Cd pot culture test, compared with the scion self-root plant, the wild eggplant Tuolubam is used as the stock, and the tomato, the eggplant and the hot pepper are used as the grafted plant of the scion, and because of the low Cd enrichment character of the Tuolubam stock, the Cd content in the leaves and fruits of the scion is reduced by 60-80 percent after grafting.
Example 2
The solanum grafted plant with low Cd accumulation is the same as the solanum grafted plant taking tolbam as a stock in the embodiment 1, and the grafting cultivation steps are basically the same as the embodiment 1.
By adopting the technical scheme of the embodiment 1, a field contrast test is carried out on the low Cd-enriched grafted solanum crop obtained by the invention. Transplanting the cultivated self-rooted tomatoes, eggplants and hot peppers (not grafted) and the grafted tomatoes, eggplants and hot peppers (taking Toolubamu as a stock) to farmlands in certain pollution irrigation areas in Shenyang of Liaoning (the average concentration of Cd is 2.76 mg/kg)-1) At the moment, the environmental conditions such as temperature and the like are relatively suitable, and the management of the grafted plants is carried out according to the conventional field management. Leaf and fruit samples were collected during the maturation period, and the Cd content was determined, with the results shown in table 2. It can be seen that in a field test, compared with a scion self-rooted plant, the wild solanum torvum is taken as a stock, tomatoes, solanum and hot peppers are taken as grafted plants of the scions, and the Cd content reduction rate in leaves and fruits can reach 50-70%.
Based on the above test, the partial growth index and nutritional index of the grafted solanum plants were measured, as shown in table 3. As can be seen, the self-rooted solanum plant and the grafted solanum plant have no obvious difference in the indexes such as plant weight, single fruit weight, single plant yield, soluble sugar, titratable acid and the like, and the grafted solanum plant related to the invention can not generate adverse effects on the quality and yield of agricultural products while the Cd content is obviously reduced.
TABLE 2 comparison of Cd content in leaves and fruits from root Solanum crops and Tuolubam grafted Solanum crops in field trials
TABLE 3 comparison of partial growth and nutritional indices for self-rooted solanum crops and for Tolubam grafted solanum crops
The experiments show that compared with the scion self-rooted plant, the grafted solanum plant taking the wild solanum toruloides as the rootstock has the advantages that the Cd content reduction rate of the edible part can reach 50-80 percent, the quality and the yield of crops are not influenced, and the grafted solanum plant can be used as a control technology for enriching the heavy metal Cd in agricultural production.
It should be understood that the detailed description of the present invention is only for illustrating the present invention and is not limited by the technical solutions described in the embodiments of the present invention, and those skilled in the art should understand that the present invention can be modified or substituted equally to achieve the same technical effects; as long as the use requirements are met, the method is within the protection scope of the invention.