Solution cultures and sand-based cultures are important methods for studying material nutrition. This experiment studies the techniques of solution culture and demonstrates the importance of the elements N, P, K, Ca, Mg and Fe for plant growth and development.
Operation method
Solution culture of plants and experiments on symptoms in case of deficiency of essential elements
Principle
Plants must be supplied with the necessary mineral elements for normal growth and development. If a certain element is missing, it will show a deficiency disease. These necessary mineral elements in the form of appropriate inorganic salts formulated into a culture solution, that is, to enable normal growth of plants, this is the solution culture. If the culture solution is added to clean quartz sand to cultivate plants, it is called sand-based culture.
Materials and Instruments
Tomato Corn Seed Move I. Materials, equipment and reagents For more product details, please visit Aladdin Scientific website.
KNO3 MgSO4 KH2PO4 K2SO4 Na2SO4 NaH2PO4 NaNO3 Ca(NO3)2 CaCl2 Fe SO4-7H2O EDTA-Na2
Pipettes Enameled plates Beakers Measuring cylinders Culture jars Reagent bottles Plastic gauze Pipettes
1. Material: tomato or corn seeds;
2. Equipment: one 1 ml pipette; one enameled plate (with lid); one beaker (one each of 250 ml and 500 ml); one 500-1000 ml measuring cylinder; seven culture tanks (available from 1000 ml to 1500 ml porcelain culture tanks); eleven reagent bottles (500 ml); plastic gauze mesh; and ten 5 ml pipettes.
3. Reagents: analytically pure drugs: KNO3, MgSO4, KH2PO4, K2SO4, Na2SO4, NaH2PO4, NaNO3, Ca(NO3)2, CaCl2, Fe SO4-7H2O, EDTA-Na2 (ethylenediammonium tetraacetic acid disodium salt).
4. Preparation of the master batches of macroelements and EDTA-Fe
All kinds of large amount of elements and EDTA-Fe mother liquor according to the following table separate preparation 
5. Preparation of trace element master batch
Weigh 2.86g of H3BO4, 1.81g of MnC1-4H2O, 0.08g of CuSO4-5H2O, 0.22g of ZnSO4-7H2O, 0.09g of H2MOO4-H2O, and dissolve them in 1000 ml of distilled water.
Experimental steps
1. Seedling culture
Take a 1000-2000 ml beaker, tie a piece of plastic screen tightly at the mouth of the beaker and add water so that the surface of the water is almost level with the mouth of the beaker. Arrange the germinated tomato (or corn) seeds evenly on the net, and then place them at 25-30℃. When the cotyledons are fully expanded, switch to diluted culture solution (concentration of 1 / 4 of the complete culture solution), (if cultivating maize seedlings, they can be cultivated with water all the time). When the tomato seedlings grow to about 10cm high and unfold one true leaf or when the second true leaf appears in the corn seedlings, select the seedlings with consistent growth as experimental materials and transfer them to various kinds of deficient culture medium, and be careful not to damage the root system when transplanting.
2. Preparation of different culture solutions
Take 7 culture tanks, respectively labeled with complete liquid, N, P, K, Ca, Mg, Fe deficiency, according to the table below to prepare different culture solutions. Pour the culture solution prepared for each treatment into the culture tank so that the liquid level is 1.5cm from the tank cover. 
3. Material culture
After wrapping the young stem of the plant with sponge and fixing it in the round hole in the center of the tank cover, so that the roots are immersed in the culture solution, the culture tank is placed in a sunny place with suitable temperature (20~25℃) for culture.
4. Experimental observation
Observe the roots every two days after the experiment started, and record the symptoms of deficiency and the first part of the roots to show symptoms. The pH of the culture medium should be checked with precision pH paper. If the pH is higher than 6, it should be adjusted to 5-6 with dilute hydrochloric acid. Change the culture solution once a week. For good root growth, a certain gap should be kept between the cap and the culture solution to facilitate aeration. After the seedlings in each deficient culture solution show obvious symptoms, replace all deficient culture solutions with complete culture solutions, and then observe and record the gradual disappearance of symptoms.