Science Buddies: "Ask an Expert"

I am a sixth grade teacher posting on behalf of two students.

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Dear Science Buddy,

My partner and I are in sixth grade, and we are thinking about our project for next year. We are starting early because we want to grow plants so you need to leave a lot of time. We are interested in the project "Bacteria Can Fix It" that we found on this website. We already learned about the nitrogen cycle and the problem of nitrate runoff. The thing is that we really want to grow strawberries, there are alot grown in our area (in CA).

We found an article about an experiment some people in Turkey did that our teacher helped us read. It is at http://www.ecofruit.net/2010/33_RP_H_Ka ... bis226.pdf It took us about 2 hours, but we think it basically says, when you use bacteria with organic fertilizers the plants make about as much fruit as if you used mineral (N) fertilizer, or, if you use bacteria with N fertilizer you can use less (of the fertilizer). We want to make our experiments to test this. But, we have some questions our teacher can't answer and she told us to write this letter.

1. When we read these articles
http://aces.nmsu.edu/pubs/_a/a-129.pdf
http://aces.nmsu.edu/pubs/_a/a-130.pdf
http://efotg.sc.egov.usda.gov/reference ... e_No_3.pdf
we think the bacteria go in through a plant's root and make a nodule. But then how does putting bacteria on the seeds (before there is any root) help?

2. In the strawberry experiment, they did innoculation by dipping the roots in the bacteria culture. We are thinking about comparing the two ways. But we are confused about the strawberry experiment because: lots of articles say that you have to use the right bacteria for the right kind of plant, and most don't list any for strawberries except the one we found, which has one we can get at Carolina.com (It is Rhizobium Rubi). But nothing in the the experiment talks about nodules, so were not sure they make them, and if they don't how does the bacteria help? Also in the experiment they started with beds that already had manure with a little bit of nitrogen (2.2%) and they used small plants instead of seeds. If we did an experiment comparing the two ways (seeds vs. root) then how would we compare them?

Thank you in advance for any questions you can answer.

[S. and S.]

P.S. We are hoping if we do strawberries to plant them in the middle of April, so if you could answer before then it would be really appreciated. Also if we don't do strawberries we are thinking about beans or peas, which is better?

Hi,

I think you have found a really super project. In looking into it I found that microrrhizomial infections of strawberries are extremely important even to strawberry plant survival, and that strawberry breeders are using micro propagation techniques to breed virus free strawberry plants are routinely infecting the young plants with microrhizomial fungi to improve plant survival. Here is a background article on one type of fungi used:
http://www.plantmanagementnetwork.org/p ... 4/amfungi/

Here is an article pointing out the difficulties in demonstrating positive results though:

http://ddr.nal.usda.gov/bitstream/10113 ... 806207.pdf

http://www.ddsis.lv/Konference/pdf/C-Bo ... a_2008.pdf

Here is a description of micro propagation of strawberries:

http://www.idosi.org/aejsr/2(2)07/15.pdf

http://psasir.upm.edu.my/6310/

Here are some resources on mycorrhization of strawberries:

http://www.actahort.org/books/530/530_37.htm

http://books.google.com/books?id=0lSCIB ... ry&f=false

http://www.insad.pl/files/journal_pdf/j ... 202008.pdf

http://books.google.com/books?id=ISp8Ca ... ry&f=false

If you do a Google search you can find lots more information if you need to.

I think you have an absolutely terrific project idea, but I suggest you do a LOT of research and reading before you commit to an experiment. I am not convinced the experiment with the nodule forming agent you identified will work on strawberries, and fron what I have read unless you do a micro propagation of the strawberry plants you experiment on they may already be infected with rhizome forming fungi, invalidating your control experiment. Infection with these fungi may help some varieties of strawberries more than others, so it would be wise to try to identify a cultivar that it has been reported to help.

Thank you for asking this excellent question = I learned a lor from trying to answer it!!! I had been under the imptession that only legumes(beans, peas, etc.) were omfected by rhyzome forming fungi and could fix their own nitrogen, and strawberries are not legumes. Your question led me to discover that many if not most plants are subject to helpful symbiotic relationships with fungi that help protect them from pathogens , improve access to nutrients, and generally help the plants thrive, and that farmers are waking up to this worldwide.

Have fun with this great project!!!!

Best regards,

Barrett L Tomlinson

Hi,

I found this paper related to the use of Rhizobium Rubi to enhance the yields of strawberries:

http://www.ecofruit.net/2010/33_RP_H_Ka ... bis226.pdf

I hopr it helps

Best regards,.

Barrett L Tomlinson

barretttomlinson wrote:Hi,

I found this paper related to the use of Rhizobium Rubi to enhance the yields of strawberries:

http://www.ecofruit.net/2010/33_RP_H_Ka ... bis226.pdf

I hopr it helps

Best regards,.

Barrett L Tomlinson

This is the paper we read!

Thank you for writing back! We read a lot more. We didn’t know to use micropropogation to make an experimental control before. It seems really hard, but our teacher is going to try to find a plant scientist at an agricultural company to help us either do micropropogation with them or get some micropropogated plants.

We have decided that basically our experiment is about whether organic microogranisms can possibly reduce the amount of nitrogen farmers have to add to the soil as fertilizer, so that there could be less nitrate runoff. So we are comparing whether plants do better with the bacteria or fungi added or with just fertilizer.

Experiment Choices

Choice 1. bacterial: testing nodule-forming rhizobacteria (Rhizobium rubi or Rhizobium leguminosarum or both) on a legume, which is basically, the Science buddies experiment but maybe with peas or beans instead of clovers (Choice A). (This is because clovers are not an economically important crop for our region.)

If we did this choice, our experiment groups would be: nitrate fertilizer with no bacteria (control 1, 5 plants), organic fertilizer with no bacteria (control 2, 5 plants),
Rhizobium rubi with: nitrate fertilizer (same amount as the control 5 plants), less nitrate fertilizers (5 plants), and organic fertilizer (5 plants)
Rhizobium leguminosarum with: nitrate fertilizer (5 plants), less nitrate fertilizer (5 plants, organic fertilizer (5 plants)

For this choice we would grow the plants from seeds.

Advantages of this choice: we have time to do more than one growing cycle over the summer and fall because they only take 60-70 days to grow. Also, we would do it without micropropogation if we used “sterile” peat or planting material (which we don’t know how to get, but we’re going to have to find for all of the choices or the control isn’t really a control).

Disadvantages of this choice: it will take a lot of plants because there is 8 experimental groups, and even with only five plants for each group there is a lot of data. When we started we wanted to do 10 plants with each variable we tested but that would be 80 plants and our school doesn’t have room for that many pots. Also, we don’t really like legumes. And also, we wanted to do something new.

Choice 2. bacterial: testing nodule-forming rhizobacteria (Rhizobium rubi and Rhizobium leguminosarum) on strawberries. (To repeat part of the experiment that they did in Turkey.)

Our experiment groups would be the same as with the legumes. (40 plants).

For this experiment we would try to get micropropogated plants.

Advantages of this choice: we wanted to do strawberries, and its new.

Disadvantages of this choice: we don’t know why the bacteria would work if it doesn’t make nodules. It still takes lots of plants. And, we only have time to grow them once because they grow during the summer.

Choice 3. fungal : testing abruscular microhizae fungi on strawberries

We would pretty much have to have micropropogated strawberries for this choice.

For this, our experiment groups would be:

nitrate fertilizer with no fungi (control 1, 10 plants), organic fertilizer with no fungi (control 2, 10 plants), 3 cultivar/fungi pairs with 10 plants each (total 50 plants)

Advantages of this choice: It seems most like what farmers are actually studying most of the time. And we could do 10 plants for each experiment group which is better.

Disadvantages of this choice: We can’t do it unless a plant scientist helps us figure out which cultivars and fungi to use and how to get them.


Choice 4. comparing bacteria-treated and fungi-treated plants

For this choice we would only do 3 plants in each experiment group, and maybe compare the two bacteria groups to two fungi groups.

Should we add more to our choices? Also we had two more questions:

1. How many plants is enough?
2. For choice one, the reason we think it doesn’t need micropropogated plants is that we are growing the plants from seeds. But could the seeds be contaminated with bacteria or fungi? If we do that choice should we wash them off first?

Thank you for your help.

Hi,

I think your teacher’s idea of locating a agricultural scientist familiar with strawberries to work with you as a mentor or partner is exactly right, even brilliant. Such a person is likely to be far more helpful to you than I can possibly be.

One place you might consider looking for such a person is UC Davis. They have a very active strawberry research program that could be very helpful to you, and as a ( or the ) major agricultural education program in California they are fairly likely to be sympathetic to your interests. Here is a relevant link:

http://innovationaccess.ucdavis.edu/str ... rogram.htm

I recommend exploring this site very carefully - their list of certified nurseries could also provide leads to helpful people who might be more local to you.

How many plants do you need for each trial set? The more the better. I think 10 is quite reasonable, 3 is better than one, but a bir on the small side. Discus this with your agricultural scientist.

You need to pay a lot of attention to the sterility of your soil, and to avoiding cross contamination between your experimental groups. The fungi and bacteria you are interested in can survive a year or more in soil without access to strawberry plants, and might be transferred easily from place to place by water splashes or insects or tools or even plant to plant contact (roots or leaves). This is another area to discuss with you agricultural mentor.

Here are other references on meristem propagation (aka micro propagation):

http://www.idosi.org/wjas/wjas3(6)/9.pdf

http://www.plantsciences.ucdavis.edu/uc ... 723_09.pdf

http://books.google.com/books?id=lDYL67 ... IES&f=true

Before you conclude micro propagation of strawberries is too hard to attempt, read this:

http://www.omnisterra.com/botany/cp/slides/tc/tc.htm

Go find a mentor. For ideas on how to do this see:

https://www.sciencebuddies.org/science- ... tors.shtml


Good luck!

Barrett L Tomlinson