Volume 6, Spring 2008 - Saddleback College

Fall 2007 Biology 3A Abstracts
Phaseolus vulgaris
Gregory Nelson and Elena Novak
Department of Biological Science
Saddleback College
Mission Viejo, CA 92692
The majority of plants growing under natural conditions contain fungal tissue in their
roots called mychorrizae. Mycorrhizal fungus establishes a symbiotic relationship with
plants. Many plants directly benefit from this connection because the fungus enhances
nutrient uptake within the plant’s roots and improves growth of the plant. Mycorrhizal
fungus, in turn, receives sugars which it extracts directly from the roots of the plant. This
study examined whether or not mycorrhizal content would affect bean plant growth and
development. Two groups of 14 bush beans were planted on October 15, 2007. The
experimental group was planted in the organic soil rich in mycorrhizal (Ecto Mycorrhizae
Inoculant: 3,000,000 viable organisms per cubic foot and Endo Mycorrhizae Inoculant:
1,900 viable organisms per cubic foot). The control group was planted in organic potting
soil. After 36 days of growth, plant heights were measured. Results showed that there was
no significant difference between experimental and control group (unpaired t-Test:
p=0.3058). The number of pea pods were counted from the experimental and control
groups and the difference was significant. There was a greater amount of pea pods growing
on control plants than on experimental plant (p=0.0340). These results did not support our
initial hypothesis that bean plants grown with mycorrhizal compose will grow taller and
would produce a greater amount of pea pods. Beans do not require mycorrhizea fungi for
nitrogen fixation or mineral uptake which promotes growth and development. This may be
the reason why our hypothesis was not proven.
Introduction
Plant growth and development is dependent
on many factors, such as the nutrient abundance in soil,
water availability, and light. A region of intense
microbial activity exists in the soil surrounding plant
roots. Soil-inhabiting organisms and more specialized
parasitic organisms infect living roots and utilize them
as a source of food. Plant tissue becomes disorganized
in this process and the root system becomes infected
(Gerdemann, 1968).
Mychorrhizae obtain food from the host
without destroying the functioning of root tissue, and a
balanced relationship between host and microorganism
is established. This type of symbiotic relationship can
be regarded as the highest level of parasitic
specialization (Daft, 1966). Plants that grow under
natural conditions are symbiotic organisms which
uptake water and nutrients through the root system and
fungus tissue. These fungi like roots are called
mycorrhizae.
Relatively few plants are completely free from
mycorrhizae. The root system of an individual plant
70
Saddleback Journal of Biology
Spring 2008
can be completely mycorrhizal or only a little portion
of it can be infected. Mycorrhizal fungi colonize plant
roots and the purpose of the following experiment is to
compare plant growth with mycorrhizal and without it.
Mycorrhizae often enhance the host plant’s growth and
mineral uptake, particularly for plants grown under low
nutrient and mineral stress conditions (Clark, 1997).
The initial hypothesis for this experiment is:
soil concentrated with mycorrhizae will enhance the
plant’s ability to take up all the nutrients from the soil
and will result in much healthier, larger plants than the
soil which is not going to be treated with mycorrhizae.
Materials and Methods
Two groups of Bush Beans (Phaseolus
vulgaris) seedlings were planted, in two separate
planting trays, with organic potting soil in the green
house of Saddleback College on October 15, 2007.
Fourteen seeds for each group were planted in a
planting tray with the recommended distance between
rows of 3 to 4 inches and a seed depth and spacing of 1
inch. The experimental group was planted with