Volume 6, Spring 2008 - Saddleback College

Fall 2007 Biology 3A Abstracts
The sixteen Early Girl Tomato plants were
purchased from Armstrong Gardens in San Juan
Capistrano, California. The tomatoes were potted in
plastic pots (11 cm in diameter) with four drainage
holes at the bottom of each pot. The plants were placed
together outside in direct sunlight and the temperature
was dependent on the outside weather in the city of San
Juan Capistrano, California. All sixteen tomato plants
were centered between two sprinklers providing the
equal amounts of water daily. Once a week, one group
of eight tomato plants were given 9.92 ml of E.B.
Stone Organic Fertilizer and the other eight tomato
plants were given 9.92 ml of Miracle Gro Fertilizer
(chemical). For one month each individual tomato
plant was measured for height of stalk every two weeks
(see Fig. 1). Also, counted were the numbers of
blossoms per group at the end of week four for the Chi-
Square analysis (see Fig. 2). There are group pictures
displaying the progress of both groups of tomato
plants.
Chlorophyll concentration in tomato plant
leaves between organic and chemical fertilizers were
taken using the Beckmann Du 700 spectrophotometer.
A total of three samples of chlorophyll extract were
taken from each organic and chemical fertilizer groups.
Each vial sample contained two 6.1 mm leaf discs
(using a paper hole puncher) added to 5ml of 80 %
(v/v) acetone. All forty-eight vials (24 of each group)
placed into the refrigerator (4º C) for 24 hours.
Concentration of chlorophyll was then measured using
the Beckmann Du 700 spectrophotometer. An average
of 3ml per sample in the vial were transferred into a
cuvette for absorbance reading which is a measure of
the light absorbed by the solution in nanometers (nm).
The average total chlorophyll concentration of organic
and chemical fertilizers was calculated in mg/L and a
T· test was done (see Fig. 3).
Results
The tomato plants that were fed chemical
fertilizer (Miracle Gro) grew to be taller in height (cm)
than the tomato plants grown in organic fertilizer. Our
experiment suggests that chemical fertilizer produces
more fruit because the count of blossoms was 84 versus
the organic tomato plants which produced 63 blossoms
at the end of the four week period. Both groups of
tomato plants initially started out at with an average
height of 13cm. For the first measurement after two
weeks, the average chemical fertilizer grew 10cm and
the average organic fertilizer plants grew 9cm. The
second measurement at the end of four weeks
displayed a significant difference in that the chemically
fed tomato plants with an additional average growth of
19cm (total in 4 weeks = 29cm) while the organically
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Saddleback Journal of Biology
Spring 2008
fed tomato plants with only an additional average
growth of 14cm (total in 4 weeks = 23cm). We also
measured the chlorophyll concentration of the different
plants leaves. We found that there was a significant
difference between plants grown chemically had more
chlorophyll than organic fertilizer (P = 0.000518, one
tail unpaired T · test).
Chlorophyll concentration (mg/L)
400
350
300
250
200
150
100
50
0
Non-organic
Organic
Fertilizer Groups
Figure 1. Plants grown in a chemical fertilizer had a
higher average chlorophyll concentration that organic.
(P= 0.000518, one tail unpaired T·test) 333.75 ±
9.28mg/L.
Average Height of Tomato Plants for
One Month in cm
45
40
35
30
25
20
15
10
5
0
Figure 2. Average height growth of chemically fed
tomato plants displayed a 5cm difference over
organically fed tomato plants at the final measurement
of week 4.
Average Number of Blossoms
Yielded
12
10
8
6
4
2
0
Chemical
Non-Organic
Figure 3. Tomato plants grown in a chemical fertilizer
yielded more blossoms than tomato plants grown in
organic (p=0.001804, one tail unpaired T ·test 11.25 ±
0.647799 blossoms.
Discussion
Organic
Organic