- This is the basic procedure for the project. Be sure to research the subject before you start, to fine tune the procedure you plan to follow. Change the tables as needed to fit your needs. Keep all your research materials to help you in writing the research paper.
- The time required for for this project is from 3 to 4 weeks. Once the experiment is set up, measurements must be made every few days.
- Plants obtain energy reserves and the bulk of their structural material from the carbon dioxide that they take in from the air. In order to carry out the metabolic processes necessary to convert CO2 to carbohydrates and cellulose and to simply maintain the components of their cytoplasm, however, they need many other substances in lesser amounts.
- Macronutrients: Nitrogen (N) and phosphorus (P) are elements needed for synthesis of amino acids and nucleotides. Potassium (K) is the main cation (ion with a + charge) in plant tissue and has many functions. These elements are needed in the greatest amount. Sulfur (S) is needed in lesser amounts for amino acids. Calcium (Ca) is required for many enzyme reactions (as are iron, manganese, and magnesium). Magnesium (Mg) forms part of the structure of the chlorophyll molecule.
- Micronutrients: Many elements are needed in tiny amounts by all plants, and others are especially needed by certain plants for specialized functions. One example of this is when plants are associated with nitrogen-fixing bacteria. Molybdenum is required because it is necessary for that reaction.This element is also needed by plants for their enzyme nitrate reductase when nitrate is the source of nitrogen. Cobalt, a component of vitamin B12, is also needed for nitrogen fixation. Iron (Fe) is required by many enzymes, including those of the electron transport chain and those that synthesize chlorophyll. Zinc is necessary for the synthesis of auxins. Silicon, boron, copper, sodium, chlorine, and selenium are all important in at least some plants but are needed in only tiny amounts.
- Plants generally take up the minerals they need from the soil solution through their roots. Since the concentration of the minerals in soil solution is low, most of them (except Ca++ and Mg ++) are actively transported into the root cells. Poor soils are those in which minerals are insufficient or are unavailable to the plant. Acid soils tend to be especially deficient in nutrients, because some minerals dissolve readily in acid and are leached (washed out) from the soil.
- Plants that are deficient in a mineral will grow poorly and will also show signs of deficiency characteristic of that mineral. The characteristic effects that certain mineral deficiencies have on growing plants are shown in Table 1.
TABLE: 1. Symptoms of Mineral Deficiencies in Plants Mineral that
is
deficient:Symptoms that result: Nitrogen Leaves change from a green-yellow at the top to yellow to brown, dead leaves at the bottom. In many species a red or purpling occurs along the veins. Plant shows stunting. Potassium Limited growth, weak stems, and a yellow mottling of the older leaves; ultimately necrotic areas on leaf tips and edges; a general overall yellowing appearance of the leaves. Phosphorus Plant stunted; leaves small and dark green; occasionally production of anthocyanins causes a red or purple color. Dead areas develop on leaves, petioles, and (in older plants) fruits, causing some dropping. Roots are poorly developed. Sulfur Yellowing of the younger leaves in the early stages; ultimately an overall pale green may dominate (chlorosis). Roots are poorly developed. Calcium First symptom usually deformation of younger leaves, and then a disintegration of terminal growing areas, due to the death of the meristem tissue. Magnesium Lower leaves show symptoms first, mottled yellowing (chlorosis) from the tip, and eventually falling. Veins remain green longer than the rest of the leaf. Micronutrients Iron: Young leaves light green or almost white (chlorosis), while older leaves are green. Unlike most other elements, iron cannot be withdrawn from the older leaves, so they retain a normal appearance. The yellowing of the younger leaves is most obvious between the veins.
Boron: Abnormally dark green leaves; abnormal growth with malformations; root tip growth slows.
Manganese: Leaves become spotted with dead areas and fall.
Copper: Tips of young leaves wither; plant may wilt even when it is watered; impaired protein synthesis.
Zinc: Yellowing of lower leaves at tips and margins; leaves small and deformed; stems stunted.
Chlorine: Retarded photosynthesis causes very small leaves that become wilted, chlorotic, or necrotic; growth slows.
Molybdenum: Required for nitrogen metabolism, so symptoms resemble those of nitrogen deficiency.- In this project, you will provide the plants with the nutrients in a readily available form and do not need to consider problems of availability, uptake, or transport. Iron, for example, will be provided bound to the chelator EDTA to ensure its solubility.
- In some cases a plant will actually be deficient for a certain nutrient but will compensate so that the effect of the deficiency is minimal. If , for example, calcium is required for a certain reaction but is present only in small amounts, magnesium or manganese, also divalent cations, will be able to substitute. Sometimes minerals can be removed from an older part of a plant and relocated to the new, growing part where they are more urgently needed. This type of recycling can prolong the active life of a plant growing under poor conditions. Compensation will complicate nutritional studies because the differences between a healthy plant and one with a deficiency will tend to be masked. Since most nutrients are needed for many processes, however, a deficiency will usually at least result in a slower growth rate, even if no overt deficiency symptoms appear in the experiment.
MEASURING THE EFFECT OF NUTRITIONAL DEFICIENCIES:
Hypothesis
- We will hypothesize that a particular mineral is needed for at least one process critical for the normal growth and development of the seedlings.
Experiment
- In this project you will test the effect of different deficiencies on your young seedlings. You will measure the growth rate and observe the appearance of the experimental. The control seedlings will be given all the necessary nutrients. All of the seedlings will be grown under identical conditions of light, temperature, and moisture.
PROCEDURE
- Obtain 30 seedlings that have been grown in washed sand. Obtain 10 (quart) growth jars and label them as follows:
A = experimental solution deficient in Calcium (Ca)
B = experimental solution deficient in Sulfur (S)
C = experimental solution deficient in Magnesium (Mg)
D = experimental solution deficient in Potassium (K)
E = experimental solution deficient in Nitrogen (N)
F = experimental solution deficient in Phosphorus (P)
G = experimental solution deficient in Iron (Fe)
H = experimental solution deficient in Micronutrients
I = control solution with no deficiency
J = all minerals deficient (DISTILLED WATER)
- The chemicals and amounts to make one liter of micronutrient stock solution is in Table 2. Because of the small masses involved, you need to make a full liter.
- Remember, the one liter volume is the total volume, chemicals and distilled water.
- The components of the experimental solutions are given in Table 3 (a and b). You are making molar concentrations of the chemicals. Follow the standard procedure for this in preparing the individual solutions. Prepare all the stock chemical solutions before you combine them to prepare the experimental solutions.
- Follow these instructions exactly in filling your jars:
1. Add 200 mL of distilled water to each jar.
2. Locate the column in the table for the first mineral deficiency and mark it (A).
3. Add each of the ingredients called for in turn, MIXING THOROUGHLY AFTER EACH ADDITION.
4. Fill jar (A) with distilled water.Continue with the other jars as above.
Measure the pH of one of your solutions by adding a drop of it to a piece of pH paper.
Iron is insoluble at neutral or basic pH values. Why is the iron provided in the form of FeNaEDTA? What kind of compound is EDTA?
TABLE 2. Chemicals and amounts to prepare one liter of Micronutrient stock solution. CHEMICAL MASS MnSO4 *H2O 2.28 g H3BO3 0.5 g ZnSO4 * 7 H2O 0.5 g CoCl2 * 6 H2O 0.025 g CuSO4 * 5 H2O 0.025 g Na2MoO4 * 2 H2O 0.025 g H2SO4 0.5 g TABLE:3a. Preparation of Experimental Solutions Solutions Deficient In: Stock
SolutionNo minerals
deficient
CONTROLCa S Mg K N P Add
(mL)Add
(mL)Add
(mL)Add
(mL)Add
(mL)Add
(mL)0.5M CaNO3 5 0 5 5 5 0 5 0.5M KNO3 5 5 5 5 0 0 5 0.5M MgSO4 2 2 0 0 2 2 2 0.5M KH2PO4 1 1 1 1 0 1 0 FeNa EDTA 1 1 1 1 1 1 1 Micronutrients 1 1 1 1 1 1 1 0.5M NaNO3 0 5 0 0 5 0 0 0.5M MgCl2 0 0 2 0 0 0 0 0.5M NaSO4 0 0 0 2 0 0 0 0.5M NaH2PO4 0 0 0 0 1 0 0 0.5M CaCl2 0 0 0 0 0 5 0 0.5M KCl 0 0 0 0 0 5 1 TOTAL: 15 15 15 15 15 15 15 TABLE:3b. Preparation of Experimental Solutions Solutions Deficient In: Stock
SolutionFe Micronutrients All minerals
DISTILLED
WATER0.5M CaNO3 5 5 0 0.5M KNO3 5 5 0 0.5M MgSO4 2 2 0 0.5M KH2PO4 1 1 0 FeNa EDTA 0 1 0 Micronutrients 1 0 0 0.5M NaNO3 0 0 0 0.5M MgCl2 0 0 0 0.5M NaSO4 0 0 0 0.5M NaH2PO4 0 0 0 0.5M CaCl2 0 0 0 0.5M Kcl 0 0 0 TOTAL: 14 14 0 - Obtain 10 aluminum (or plastic) lids for your jars, punch four holes in each, and cover your jars. One hole is for adding distilled water to your plants and the other three are for the plants themselves. Label three holes in each lid 1, 2, and 3, so you will be able to identify the individual plants.
- When your jars are ready, obtain thirty 10-day-old corn or sunflower seedlings that have been grown in washed sand, and a few pieces of cotton. The plants should be about 8 cm long. Rinse the roots of the plants carefully in distilled water to remove the sand. Wrap a piece of cotton around the stem of each plant and insert three plants into the lid of each jar. Arrange the jars neatly in the greenhouse space you have chosen for conducting the study. All jars should be labelled with your name and the date.
Results
- When the plants are in place in the greenhouse or under the grow light, measure the height of each plant and record the data in Table 4. Repeat the measurements once or twice each week for four weeks and note the appearance of the plants in the table.
- Be sure to keep the jars full, by replacing water lost with distilled water, through the fourth hole in the lid.
- At the end of the experiment summarize your results. Summarize the data in Table 5. Write your report in the form your instructor gives you to use.
- A graph is a good way to summarize data in a form that is easily understood. Remember that "by convention" we graph a variable on the (Y) axis, and a constant on the (X) axis. A good graph would be, average growth vs. time in days. You can build this graph from the raw data in Table 4. The average growth of the 3 test plants from each experimental group can be calculated for each collection date.
TABLE 4. Experimental Data on Mineral-deficient Plants. Date:_______ Date:_______ Date:_______ Plant Deficiency Height Appearance Height Appearance Height Appearance A-1 
A-2 A-3 B-1 B-2 B-3 C-1 C-2 C-3 D-1 D-2 D-3 E-1 E-2 E-3 F-1 F-2 F-3 G-1 G-2 G-3 H-1 H-2 H-3 I-1 I-2 I-3 J-1 J-2 J-3
TABLE 5. Summary of Effects of Nutritional Deficiencies. Seedling type:____________________ Plants Deficiency Total
Growth (cm)Final Appearance Control none Expt. Ca Expt. S Expt. Mg Expt. K Expt. N Expt. P Expt. Fe Expt. micronutrients Expt. all minerals Back to Projects Table of Contents
Back to Lab Dad's Laboratory
- The time required for for this project is from 3 to 4 weeks. Once the experiment is set up, measurements must be made every few days.
NUTRITIONAL NEEDS OF PLANTS