Science Buddies: "Ask an Expert"

We are doing a lab on nutrition deficiency in nutrients what would be the approaite nutrients to be deficient in and what amount difference.
And what would be the control?
And how would we form a hypothesis?

athalia wrote:We are doing a lab on nutrition deficiency in nutrients what would be the approaite nutrients to be deficient in and what amount difference.
And what would be the control?
And how would we form a hypothesis?

in raddish sprouts

Plants are pretty self-reliant. Photosynthesis allows them to create things from very basic nutrients such as phosphates, nitrates, sulfates, and ammonium salts, including those with calcium, magnesium, and numerous other metal ions.

Google the following keywords:

plant nutrient concentrations phosphate sulfate


Here is one example:
http://www.extension.uiuc.edu/~vista/ht ... tting.html
Try varying the concentrations of the nutrients described in the section titled "Nutrient Solutions." To keep it simple, try varying only two of them and leave the others constant. Phosphate concentrations are very important, and you can vary them a lot without killing the plant.

Try 3 doses of each of two of the nutrients, plus a control concentration of zero (Group 1, below). For example:



Group 1
Potassium phosphate 0 ounces (0 teaspoons)
Magnesium sulfate (MgSO4) 0 ounces (0 teaspoons)
Potassium nitrate (KNO3) 2 ounces (4 teaspoons)
Calcium nitrate (CaNO3) 3 ounces (7 teaspoons)

Group 2
Potassium phosphate 0 ounces (0 teaspoons)
Magnesium sulfate (MgSO4) 0.375 ounces (1 teaspoons)
Potassium nitrate (KNO3) 2 ounces (4 teaspoons)
Calcium nitrate (CaNO3) 3 ounces (7 teaspoons)

Group 3
Potassium phosphate 0 ounces (0 teaspoons)
Magnesium sulfate (MgSO4) 0.75 ounces (2 teaspoons)
Potassium nitrate (KNO3) 2 ounces (4 teaspoons)
Calcium nitrate (CaNO3) 3 ounces (7 teaspoons)

Group 4
Potassium phosphate 0 ounces (0 teaspoons)
Magnesium sulfate (MgSO4) 1.5 ounces (4 teaspoons)
Potassium nitrate (KNO3) 2 ounces (4 teaspoons)
Calcium nitrate (CaNO3) 3 ounces (7 teaspoons)



Group 5
Potassium phosphate 0.125 ounces (1/4 teaspoons)
Magnesium sulfate (MgSO4) 0 ounces (0 teaspoons)
Potassium nitrate (KNO3) 2 ounces (4 teaspoons)
Calcium nitrate (CaNO3) 3 ounces (7 teaspoons)

Group 6
Potassium phosphate 0.125 ounces (1/4 teaspoons)
Magnesium sulfate (MgSO4) 0.375 ounces (1 teaspoons)
Potassium nitrate (KNO3) 2 ounces (4 teaspoons)
Calcium nitrate (CaNO3) 3 ounces (7 teaspoons)

Group 7
Potassium phosphate 0.125 ounces (1/4 teaspoons)
Magnesium sulfate (MgSO4) 0.75 ounces (2 teaspoons)
Potassium nitrate (KNO3) 2 ounces (4 teaspoons)
Calcium nitrate (CaNO3) 3 ounces (7 teaspoons)

Group 8
Potassium phosphate 0.125 ounces (1/4 teaspoons)
Magnesium sulfate (MgSO4) 1.5 ounces (4 teaspoons)
Potassium nitrate (KNO3) 2 ounces (4 teaspoons)
Calcium nitrate (CaNO3) 3 ounces (7 teaspoons)




Group 9
Potassium phosphate 0.25 ounces (1/2 teaspoons)
Magnesium sulfate (MgSO4) 0 ounces (0 teaspoons)
Potassium nitrate (KNO3) 2 ounces (4 teaspoons)
Calcium nitrate (CaNO3) 3 ounces (7 teaspoons)

Group 10
Potassium phosphate 0.25 ounces (1/2 teaspoons)
Magnesium sulfate (MgSO4) 0.375 ounces (1 teaspoons)
Potassium nitrate (KNO3) 2 ounces (4 teaspoons)
Calcium nitrate (CaNO3) 3 ounces (7 teaspoons)

Group 11
Potassium phosphate 0.25 ounces (1/2 teaspoons)
Magnesium sulfate (MgSO4) 0.75 ounces (2 teaspoons)
Potassium nitrate (KNO3) 2 ounces (4 teaspoons)
Calcium nitrate (CaNO3) 3 ounces (7 teaspoons)

Group 12
Potassium phosphate 0.25 ounces (1/2 teaspoons)
Magnesium sulfate (MgSO4) 1.5 ounces (4 teaspoons)
Potassium nitrate (KNO3) 2 ounces (4 teaspoons)
Calcium nitrate (CaNO3) 3 ounces (7 teaspoons)




Group 13
Potassium phosphate 0.5 ounces (1 teaspoons)
Magnesium sulfate (MgSO4) 0 ounces (0 teaspoons)
Potassium nitrate (KNO3) 2 ounces (4 teaspoons)
Calcium nitrate (CaNO3) 3 ounces (7 teaspoons)

Group 14
Potassium phosphate 0.5 ounces (1 teaspoons)
Magnesium sulfate (MgSO4) 0.375 ounces (1 teaspoons)
Potassium nitrate (KNO3) 2 ounces (4 teaspoons)
Calcium nitrate (CaNO3) 3 ounces (7 teaspoons)

Group 15
Potassium phosphate 0.5 ounces (1 teaspoons)
Magnesium sulfate (MgSO4) 0.75 ounces (2 teaspoons)
Potassium nitrate (KNO3) 2 ounces (4 teaspoons)
Calcium nitrate (CaNO3) 3 ounces (7 teaspoons)

Group 16
Potassium phosphate 0.5 ounces (1 teaspoons)
Magnesium sulfate (MgSO4) 1.5 ounces (4 teaspoons)
Potassium nitrate (KNO3) 2 ounces (4 teaspoons)
Calcium nitrate (CaNO3) 3 ounces (7 teaspoons)

These test groups systematically test doses ranging from zero up to the doses recommended in the above web page. Don't just run out and do this, however. You may want to:
1) vary some other pair of nutrients
2) vary the doses from zero to a dose double the recommended one to see if you can find an optimal combination

Also, you will need to double check to make sure the concentrations recommended in that web page are actually sensible or not. These nutrients may or may not matter during germination. It may be that the big differences start to show up after the plants are a few weeks old.

You will need to have 4 or more plants/seedlings per group so that 1) you will compensate for the inevitable seeds that either fail to germinate or have some random severe problem, and 2) so that you can perform a Student's t Test (look this up) and determine which dose combinations are statistically different from each other. That is VERY IMPORTANT! That is the ONLY way you can credibly claim whether or not you saw a difference in growth rates. You will need to have at least 3 surviving plants in each group at the end of the experiment, preferably more than 5.

Let me know if you need more info, but I'm sure you can take it from here and find everything else you need at the library, the bookstore, or on the web. Feel free to ask your science teacher for advice and help preparing the nutrient solutions.

How many groups of 4 are needed to make an inference about growth rate? My younger sister has a science fair project too. She grew 4 beans in vermiculite and used 4 water sources - temperature, amount of water, sunlight, pot size etc. all constant. Does she need to run several trials or should she redo the project using groups of beans? How many beans are necessary for an experiment? They are Magic Sproutz in cans that are prepackaged in vermiculite.
Thank you.

The set of groups I posted above systematically varies the things you are testing, in this case Potassium phosphate and Magnesium sulfate. This means that all possible combinations of doses are tested, including doses of zero (Group 1).

Also, I mentioned that you need to have at least three survivng plants in each group at the end of the experiment. For that to happen, you should start out with four or five, because some may die for one reason or another, either accidentally or for reasons not necessarily due ot the dose of nutrients. This is done because at the end you need to calculate the average of your dependent variable, such as heiight, number of leaves, number of flowers, etc. within each group.

You need an average because a single plant may not be typical of what the particular combination of nutrients can do. Just as some people are taller or shorter than others, plants can vary a bit even under carefully controlled conditions. An average value over several plants will give you a better idea of how the nutrients really affect growth.

In addition to the mean or average, you need to calculate the standard deviation (research this), which is easy to do, especially if you have a spreadsheet such as Open Office (openoffice.org, it's free), or Microsoft Excel. This gives you an estimate of how variable the effect is. If the standard deviation, or stddev for short, is high, there is a lot of variability, if it is low there isn't. The standard deviavtion can only be calculated if you have three or more measurements per group.

Also, and this is the key reason, if you have two groups of plants, and the average height in one group is 12 cm and in the other it is 15 cm, are they different? You need an objective way to determine whether they are significantly different in height or not. There is a simple such test, called Student's t Test (research this). It is available in the spreadsheet program. What it does is compare both the average and the standard deviation of the two groups. If the standard deviations overlap, the test will tell you that there is no significant difference. If the standard deviations do not overlap, the test will tell you that they are significantly different. If they are far from overlapping, the test will tell you that the differences are highly significant. For example:

If the average height of Group 1 is 10 cm with a stddev of 5 and Group 2 has an average height of 15 also with a std dev of 5, the range in Group 1 is about 5 - 15 cm, and in Group 2 it is about 10 - 20cm. As you can see, the ranges overlap, so there does not appear to be a statistically significant difference in height between the groups. Expressed another way, we say that the diference in average height is due to chance and the random variability in plant height.

If the average height of Group 1 were 10 cm with a stddev 0f 1.5 cm, and for Group 2 15 cm with a stddev of 2 cm, then the ranges are 8.5 - 11.5 and 13 - 17 cm respectively. There is no overlap in the ranges, and they are in fact reletively far from each other, so the t Test would tell you that there is a statistically significant difference between Groups 1 and 2.

You don't really need to do all 16 of the groups I posted above unless you are testing several doses. You can just as easily do a "with and without" experiment in which group 1 receives a treatment and Group 2 does not. In that case by the way, Group 2 would be the control group. Also, you could do a "with and without" experiment with two different treatments, but you would need to be systematic. Group 1 would be the main control (without A or B), Group 2 tests treatment A (with A, without B), Group 3 tests treatment B (without A, with B), and group 4 tests thier interaction (with A, with B). As you can see, adding treatments rapidly increases the number of test groups.


I hope this isn't too long an explanation. If you have any questions, please post them.

nahendri,

To answer your question about the four water sources, you only need one group per water source. The control group would be the "normal" or conventional water source.

She does not need to run more than one trial. A single trial with four or five beans per group, treated identically in the same location except for the different water sources would be enough. The important part is the statistical analysis described above.

I suspect that there will be no major differences between water sources, unless one of them has significant impurities. Nevertheless, if she is able to demonstrate that there is no statistically significant difference between the water sources, that would be a finding to reckon with, especially if someone is claiming that one of the water sources has special properties.

Although I wasn't the one who originally asked the question. This helped me and I thank you. I hope it also helped the person with the radish project.
Thank you.

hey there

i think you can also do like vitamins A, B, C, D, E and iron and stuff like that. you can use http://www.wikipedia.com to study certain vitamins for more info