The Effects of Mycorrhizae Fungus on the Growth of Lupine (Lupinus)
David Truong
Department of Biological Sciences
Saddleback College
Mission Viejo, CA 92692
The objective of this study was to determine if mycorrhizae fungus has an effect on
lupine, Lupinus, in different environments. In this experiment, thirty lupine seeds were
divided into two groups and placed into different environments.(what types of
environments?) It was expected that mycorrhizae would have a low effect or no effect at
all on the growth of the lupine seeds. Average height of the control group had an average
of 1.4533± 0.062(±S.E.) centimeters and the experimental had an average of 0.0 ±
0.0(±S.E.) centimeters. Statistical analysis showed that there was a significant difference
between the control and experimental group (P-value = 6.74E-13). This experiment
proved the hypothesis that mycorrhizae bacteria would not have an effect on lupine
plants.
Introduction
Plants have a major role in the Earth’s ecosystem from providing shelter to
organisms to oxygen for us to breathe. Like every living organism, plants have to gain
nutrients and other necessities in order to survive. With that knowledge, plants have
many different profiles when it comes to obtaining their nutrients in order for them to
survive and grow. Many plants take on different forms of taking in nutrients from the soil
such as phosphorus or nitrogen which are both important in plant growth and survival.
Some plants use nitrogen fixation to get nitrogen from the air into their roots while others
use fungus to absorb nutrients around their surroundings. With the Earth’s atmosphere
containing eighty percent of nitrogen gas (N2) which many living organism cannot use by
it because it is unstable by itself to many organisms (??? clarify sentence). Combined
with hydrogen gas (H2) it creates ammonia (NH3) which living organisms use to create
proteins and other nitrogen components to live (Johnson et al., 1987). The process where
unstable N2 is changed into useful NH3 is called nitrogen fixation. With about 200 to over
500 different kinds of species in its own genus, most lupine plants can fix N2 into NH3 by
nitrogen fixation (Ainouche and Bayer, 1999). The lupine roots would get infected by the
Rhizobium bacteria and end up creating nodules in the lupine plant where the nitrogen
fixation would take place. This is where the plant and the bacteria communicate
chemically to form the nodules (González-Sama et al., 2004). Plants also need to gain
nutrients from the soil that they reside in. Some plants use fungus, such as Mycorrhizae,
to aid them in the gain of water and nutrients from the surrounding. Plants are sometimes
incapable of absorbing minerals such as phosphate ions, but with the aid of the
mycorrhizae, they are able to reach the ones that are immobilized in the soil for the plants
that they colonize in. The mycorrhizae in return gain direct access to carbohydrates that
are produced from the plant during photosynthesis. The effect that mycorrhizae has on
plants varied depending on the plant that the mycorrhizae’s host plant (Bray, 2003). (
hypothesis )
Materials and Methods
Thirty lupine seeds, how much?-->nitrogen soil, and thirty pots were obtained
from Lowe’s of Westminster, Westminster, CA on eighth day of October 2009( October
8, 2009). The thirty lupine seeds were divided into two groups, fifteen each, and were
placed into two environments ( what type of environments?) of nitrogen soil. Nitrogen
soil was divided equally throughout the thirty pots with the aid of a measuring cup (The
amount of Nitrogen soil per pot). Half a tablespoon of mycorrhizae fungus, obtained from
Saddleback College Biology Lab, Mission Viejo, CA, was placed into fifteen of the pots,
containing nitrogen soil, one inch into them(??? Clarify). The two groups were labeled to
determine the difference between the group containing mycorrhizae and the group
without. The plants were kept in a greenhouse at Natasha Nguyen’s house, Lake Forest,
CA. The plants were watered every other day and observed to see any kind of growth
above the soil. As the plants grew above the soil, they are measured to see their growth
and compared next to each other( How did u measure them ? ruler?). ( Did u record daily
observation?) ( How many days did it take for the plants to grow?) need to be more
specific.
Results
A one-tailed t-test was run on the numbers of total heights of each group and the result
came out to be that there was a significant difference between the control and
experimental group. A graph showing the average height between the two groups is
shown in Figure 1. (so the control group had more growth?, explain)
1.6
Height Above Soil (cm)
1.4
1.2
1
0.8
0.6
0.4
0.2
0
Control
Experimental
Figure 1 - Bar graph displaying the height means for the control and experimental groups.
Error bars indicate standard deviation. Control had an average of 1.4533± 0.062(±S.E.)
centimeters and the experimental had an average of 0.0 ± 0.0(±S.D.) centimeters, N=15. (
label horizontal axis)
Discussion
The experiment came out to support the hypothesis that the group that did not
contain mycorrhizae fungus would grow more than the group containing the fungus.
(You state a different hypothesis in the abstract. Clarify) However there could have been
unaccounted variables in the experiment causing the experiment to fluctuate. A factor
that could have effected the results could be the ration proportion of the mycorrhizae to
the lupine seed and if it was enough to inhibit the seed at all. With lupine plants they
undergo nitrogen fixation to help fertilize their soil and allow them to be tolerant towards
the change or barren and poor quality soil, so for that, mycorrhizae may have a low or no
effect at all on the lupine plants (Bray 2003). But for mycorrhizae to be in the
environment of a plant that regulates its growth through nitrogen fixation would be a
factor in its survival and growth. Mycorrhizae could have been blocking a lot of the
nitrogen soil from the lupine plant to have access to causing it to have any kind of growth
at all. The mycorrhizae being under the lupine seed may be the reason why the lupine
seed could not have access to the nitrogen to undergo nitrogen fixation and allow it to
grow as the control group did. Need to talk more about other studies and how it relates to
yours.
Acknowledgements
I would like to thank Natasha Nguyen for the provision of her greenhouse and weight
balance; also I would like Professor Teh and Dr. Huntley in the provision of the
mycorrhizae fungus.
Literature Cited
Ainouche, Abdel-Kader, Randall J. Bayer. (1999) “Phylogenetic relationships in Lupinus
(Fabaceae: Papilionoideae) based on internal transcribed spacer sequences (ITS) of
nuclear ribosomal DNA.” American Journal of Botany. Vol. 86, No. 4, pp. 590-607
Bray, Sarah R., Kaoru Kitajima and David M. Sylvia. (2003) “Mycorrhizae Differentially
Alter Growth, Physioogy, and Competitive Ability of an Invasive Shrub.” Ecological
Applications, Vol. 13, No. 3, pp. 565-574
González-Sama, Alfonso, M. Mercedes Lucas, María R. de Felipe and José J. Pueyo
(2004) “An Unusual Infection Mechanism and Nodule Morphogenesis in White
Lupin (Lupinus albus).” New Phytologist, Vol. 163, No. 2, pp. 371-380
Johnson, D. N., B. Liu, B. L. Bentley. (1987) “The Effects of Nitrogen Fixation, Soil
Nitrate, and Defoliation on the Growth, Alkaloids, and Nitrogen Levels of Lupinus
succulentus (Fabaceae).” Oecologia. Vol. 74, No. 3, pp. 425-431
Marvel, J. Deborah, John G: Torrey, Frederick M. Ausubel (1987) “Rhizobium
Symbiotic Genes Required for Nodulation of Legume and Nonlegume Hosts.”
Proceedings of the National Academy of Sciences of the United States of America.
Vol. 84, No. 5, pp. 1319-1323
Sawada, H., L. David Kuykendall, John M. Young. (2003) “Changing concepts in the
systematics of bacterial nitrogen-fixing legume symbionts.” J. Gen. Appl. Microbiol.
Waughman, J. G., D. J. Bellamy. (1980) “Nitrogen Fixation and the Nitrogen Balance in
Peatland Ecosystems.” Ecology. Vol. 61, No. 5, pp. 1185-1198
Wilson, Gail W. T., David C. Hartnett, Melinda D. Smith and Kerri Kobbeman. (2001)
“Effects of Mycorrhizae on Growth and Demography of Tallgrass Prairie Forbs.”
American Journal of Botany, Vol. 88, No. 8, pp. 1452-1457
Review Form
Department of Biological Sciences
Saddleback College, Mission Viejo, CA 92692
Author (s): David Truong
Title: The Effects of Mycorrhizae Fungus on the Growth of Lupine (Lupinus)
Summary
Summarize the paper succinctly and dispassionately. Do not criticize here, just show that you understood the
paper.
This research project is about the effect of Fungus ( Mycorrhizae) on the growth of Lupine. There are
2 groups in this experiment a control and experimental group. Each group contains15 pots
containing nitrogen soil, making a total of thirty pots. Micorrhizae was placed in fifteen of the pots
which were the experimental group and the other fifteen did not contain Micorrhizae. Lupine seeds
were placed on all pots. After plants grew above the nitrogen soil, the height of the plants above the
soil were recorded. T-test was run on the data and the statistical analysis indicates that there was a
significant difference between the control and experimental group. The hypothesis was not very
clear (2 diff hypothesis stated throughout the paper), so I wouldn’t know if the results supported it or
not.
General Comments
Generally explain the paper’s strengths and weaknesses and whether they are serious, or important
to our current state of knowledge.
This paper did not have a clear hypothesis, which is the most important part of the paper. The
introduction was full of useful information and effectively explains to the reader the reason for this
study as you go on through the paper you can see that the methods and materials does not do a good
job in explaining the process. Most of the measurements were left out. Clearly this section needs to be
more specific and detailed. The result does not state which group had more growth. The horizontal
axis on the graph needs a label. The discussion was very short and did not have enough citations
from other studies done. Overall the paper needs more revisionand the writer needs to be more
specific with their hypothesis is.
Technical Criticism
Review technical issues, organization and clarity. Provide a table of typographical errors,
grammatical errors, and minor textual problems. It's not the reviewer's job to copy Edit the paper,
mark the manuscript.
This paper was a final version
This paper was a rough draft
Introduction You need to include your hypothesis and aim of the study.
Method  you need to give more information about details in the actual process, for
example how many grams of nitrogen soil did you put in each pot? You also need to
explain how u measured the height of plants. If you recorded the daily observation,
you should write that down in a table or in the methods section.
Result  need to state which group had more growth than the other (reader
shouldn’t be guessing). Also label horizontal axis on graph.
Discussion  Need more examples from other studies related to your paper.