Sean, 7 minutes only, we have to cut down the left side to about 3. then the rest for
discussion and results.
Nutrition of Pea Plants
The chart shows the high nutrition available in pea plants, or Pisum sativum. They are cheap and
can be used by many poor countries as a major source of protein and fiber. Here is the most
common pea plant, the sugar or snap pea.
Cobalt in Soil
Shown in this graph is the cobalt concentrations in soil samples taken from the major pea
producing states. The x axis lists the states where the sample was taken and the y axis represents
the amount of cobalt found in ppm. The graph shows that the cobalt concentrations are very low
and also inconsistent; therefore the cobalt must be supplemented into the soil in order to affect
plants.
Cobalt in Plants
Cobalt is an essential element for certain microorganisms particularly those fixing atmospheric
Nitrogen such as Rhizobium. Cobalt deficiency seems to depress the efficiency of Nitrogen
fixation. The picture on the left shows the microorganism Rhizobium attaching to the roots of a
pea plant. The picture on the right shows Cobalt Sulfate (CoSO4) which is the compound often
added to soil to fertilize plants.
Vitamin B12 in Plants
Vitamin B12 is essential to plant growth and with more of the nutrient, the plant grows much
better, having thicker, taller stems and being more fertile. (which means more pea pods). Cobalt
allows the cell to manufacture the B-Complex vitamins, especially Vitamin B-12.
Necessary Chemicals
There are three chemicals that plants need to survive, Nitrogen, Phosphorous and Potassium.
Together they are known as NPK.
N = Nitrogen is the first major element responsible for the vegetative growth of plants above
ground. With a good supply, plants grow sturdily and mature rapidly, with rich, dark green
foliage.
P = Phosphorus is the second major element in plant nutrition, phosphorus is essential for
healthy growth, strong roots, fruit and flower development, and greater resistance to disease.
K = Potassium is the third major plant nutrient, potassium oxide is essential for the development
of strong plants. It helps plants to resist diseases, protects them from the cold and protects during
dry weather by preventing excessive water loss.
Nitrogen Cycle
This picture shows the nitrogen cycle. The role of pea plants in the nitrogen cycle is to absorb
atmospheric nitrogen into the root nodules where the Rhizobium bacteria use the enzyme
Nitrogenase to convert them to soil nitrates.
Don’t Say-For Questions: (N2 + 16 ATP + 8e- + 8H+ => 2NH3 + 16 ADP + 16 Pi + H2)
(Cobalt Stimulates Nitrogenase)
Literature Review
Miller and Tarrant (1983) experimented with Douglas Fir Plantation. Applying Vitamin B12
fertilizer at a concentration of 8 ppm to a 35-year-old Douglas-fir plantation resulted in
significant increases in trunk diameter, height, and volume growth. The chart shows the starting
trunk diameter of the trees and then shows the trunk diameter after 15 years of fertilization. As
the amount of Vitamin B12 fertilizer used increased the more the trunk diameter increased.
LR 2
Gad (2006) tested plants with and without the presence of Cobalt. She used different amounts of
fertilizer to further show the effects. The highest, 100%, represents 8ppm.
This chart shows the pea plant growth in his experiment. The left bars show the density of the
plant, in grams, without the Cobalt, and the right bars show them with Cobalt. The Cobalt made
the plants denser and healthier.
LR 3
Kandil (2007) studied the effects of Cobalt fertilization on the Growth of Faba Beans, another
nitrogen fixing plant. Her results are shown here. She noted the stem length, stem diameter,
number of nodules and number of pea pods. She then weighed the plants shoots and roots and
counted the number of seeds the plant produced. All concentrations of Cobalt showed healthier,
larger and more fertile plants then the control plants. With each increasing concentration up to 20
ppm showing more and more improvement.
Purpose
This experiment will test the effects of Cobalt and Vitamin B12 fertilization on the growth of
Pisum sativum L. Vitamin B12 is a much more expensive method of fertilization then Cobalt.
Both methods have been tested separately but not together. The purpose of this experiment is to
compare the two methods of fertilization directly. We also will be comparing the different effects
that these two fertilizations have with growth stimulating bacteria found in their natural habitat.
This picture shows the pea plant seeds used in this experiment.
Hypothesis
Alternate Hypothesis-H(a)- Both Cobalt and the Vitamin B12 fertilization have significant
effects on the growth of the pea plants with the presence of Rhizobium Leguminosarum, which
supports the work of Gad and Kandil
Null Hypothesis-H(o)- Neither the cobalt or the Vitamin B12 have an effect on the growth of the
peas with or without the presence of Rhizobium Leguminosarum
Methodology
The plant used in this experiment is the Pisum Sativum L. and they are grown in a .25-pint pot of
soil. They grow in moist well-drained pots and they need to be in the light. They were kept at 7075 degrees F.
(Switch to Flow Chart)
The experiment is begun with 60 seeds planted. Half the seeds are inoculated with Rhizobium
Inoculant and the other thirty are planted without. Within each division there will be three more
groups of ten made. The first ten are planted as the control and are only fertilized with standard
spring water. The next ten seeds are planted and fertilized with an 8ppm concentration of Cobalt
Sulfate solution. The final ten are planted and fertilized with an 8ppm concentrated solution of
Vitamin B12. After 50 days of germination the plants data will be recorded for plant height,
number of pea pods and germination and flowering rates. At the end there will be a Statistical
Analysis by One Way ANOVA (P<.05) with a Scheffe Post-Hoc Test to support or refute the
hypothesis.
Results:
The title: Effects of Different Fertilizers on Mean Growth of Pisum sativum (n=230) X-axis
shows groups, y axis shows plant height in cm
Figure 1: Statistical Analysis by One-Way ANOVA (p<.05) followed by an Scheffe post-hoc
test showed that there was a significant difference between groups Water without Rhizobium
and Vitamin B12 without Rhizobium/ Cobalt Sulfate with Rhizobium.
Effects of Different Fertilizers on Germination Rate (n=230)
X-axis shows groups, y axis
shows germination rate
Figure 2: Statistical Analysis by One-Way ANOVA (p<.05) followed by an Scheffe post-hoc
test showed that there was a significant difference between group CoSO4 with Rhizobium
and both Water groups, and Water with Rhizobium and both Vitamin B12 Groups.
Effects of Different Fertilizers on Mean Growth of Pisum sativum by day
axis shows height in cm, legend, each group different color
X-axis shows day, y
Figure 3: Mean plant growth of Pisum sativum plants in all groups. Data collection was taken
over a thirty six day period.
Discussion:
The data demonstrates that cobalt sulfate and vitamin B12 were both significantly more effective
than water. The presence of rhizobium did not affect plant growth significantly. No nodules were
found, no data collected. The data also demonstrates that water significantly raised germination
rates for the plants. This supports the work of Gad and Kandil.
The Limitations included, Vitamin B12 without rhizobium group had an outlier in each trial,
Human error in measuring and planting seeds, and that Germination rates affected the overall
mean growth (0 growth is factored in). Also no nodules were recorded, which means that either
the cobalt sulfate negatively affected the soil life, or that something went wrong in the
experiment.
Conclusion:
Cobalt Sulfate was just as effective as Vitamin B12 in stimulating plant growth. However, both
Cobalt Sulfate and Vitamin B12 lowered the germiatnation rates for the plants. Cobalt Sulfate is
unhealthy for the microorganisms that live in the soil. The data supports the alternate hypothesis
Future Studies:
Try these culturing techniques with other leguminous plants that produce food like Beans. The
seeds could be chemically analyzed to see how they are affected, which could help determine the
effects that Cobalt Sulfate has on the nutritional value of the seeds. Also different concentrations
of solution could also be used on the plants.
Thank you, are there any questions?