Volume 6, Spring 2008 - Saddleback College

Fall 2007 Biology 3A Abstracts
After five weeks of watering and feeding the
plants with fertilizer, the chlorophyll concentration of
each group of plants was determined using a Beckman
DU 720 Spectrophotometer. From one leaf of each
plant, two 5 mm diameter chads were cut using a
standard hole punch and soaked in an 80% acetone
solution for 48 hours in the refrigerator at 40°C. Then
the absorption of acetone extracted chlorophyll was
measured at wavelengths of 645 and 663 nm as
described by MacKinney’s (1941).
Results
The control group started with 2 flowers, and
after five weeks, had 57 flowers. The Liquinox group
had no flower initially, and after five weeks, had 17
flowers. The MiracleGro group 1 flower and no flower
survived after five weeks.
The stems of the Control group had an overall
average growth of 3.02 cm, which was the highest
exponential growth from all three groups. The
MiracleGro group grew the least and after Week 4,
there was no growth of the stems. The stems of the
Liquinox group had an overall average growth of 2.74
cm.
After five weeks of growth (Figure 1), the
control group had a 3.0 ± 0.7 cm change in length. The
MiracleGro had a 1.5 ± 0.5 cm change in growth, while
the Liquinox group had a 2.7 ± 0.4 cm change in
length. There was no statistical difference between the
three groups (p=0.15, ANOVA).
Average Change in Stem Lengths
(cm )
3.5
3
2.5
2
1.5
1
0.5
0
Control MiracleGro Liquinox
Groups
Figure 1. There was no difference in the change in
stem lengths among the three groups (p=0.15,
ANOVA).
Figure 2. Mean chlorophyll concentration of the
control group was 47% less than the mean chlorophyll
concentration of the Liquinox group (p=0.009,
unpaired t-test).
Discussion
There was no difference in the change in stem
lengths due to a short duration of time and a small
sample size. The plants may have been still in the
process of development. Long-term experiments can
identify correlative relationships between two variables
(Reed and Martiny, 2007). Therefore, short-term
experiments are unable to demonstrate a change.
The MiracleGro plants’ failure to mature was
partially due the 11% nitrogen content of the
MiracleGro fertilizer. The amount of nitrogen in
MiracleGro was twice as much as the amount of
nitrogen in Liquinox, which limited the MiracleGro
group’s plant growth, like in Vitousek’s et al. (1993)
study where the results showed that the contents of
nitrogen inhibited plant growth. This does not support
the hypothesis that MiracleGro fertilizer would work
best for plants because the ratio of the three groups’
length was equal to each other.
Liquinox facilitated an increase in the
chlorophyll concentration in the leaves of the plants,
which allowed for more photosynthetic processes to
occur which enables more plant growth. The Liquinox
chlorophyll concentration was 47% more than the
chlorophyll concentration of the control group.
Based upon our findings, we would choose the
generic brand of Liquinox fertilizer for our house
plants because it results in a higher concentration of
chlorophyll content, which will allow for more
photosynthesis to take place.
Acknowledgements
We would like to thank the Saddleback
College Department of Biological Sciences for
providing the potting soil, pots, and fertilizers to
conduct our study in the Math and Science
63
Saddleback Journal of Biology
Spring 2008