caffeine’s effect on - centralcatholichs.com science/pjas/pjas 15 pdf... · caffeine’s effect...
TRANSCRIPT
CAFFEINE’S EFFECT ON
MUNG BEAN
GERMINATION AND
GROWTH
TODD ORAVITZ
9TH
GRADE
CENTRAL CATHOLIC
INSPIRATION
CAFFEINE
• Naturally occurring substance
• Bitter, white purine compound
• Similar chemical structure to
adenine and guanine
CAFFEINE EFFECTS
• Blocks adenosine receptors, leading to calcium loss in plant cells
• Low calcium can cause problems with
• Cell membrane permeability
• Cell plate formation
CAFFEINE EFFECTS
• Interferes with plant cytokinesis
• Stops Golgi vesicles from fusing
with membranes by decreasing
ATP activity
• Has been shown to inhibit cell
division in plants
CAFFEINE IN NATURE
• Pesticide-like protection to
plants containing it
• Germination of competing
seedlings may be slowed by
plants depositing caffeine in
nearby soil
GUARANA PLANT
• Effective natural stimulant
• Seeds contain about twice the
caffeine concentration as those
from coffee
GUARANA PLANT
• Naturally alters one’s
perception of fullness, leading
to weight loss
• FDA recognizes it as “generally
safe”
PURPOSE
• To determine if caffeine has an effect on germination and growth of mung beans
HYPOTHESES
• Null
• Caffeine will not have a
significant effect on mung
bean germination and growth
• Alternative
• Caffeine will have a
significant effect on mung
bean germination and growth
MATERIALS
• Seed starter trays
• Potting soil
• Mung beans
• Guarana –
caffeine source
• Sunlight via
window
• Room lights
• Tap water
• Pyrex 500mL
measuring cup (to
make test solution)
• 10mL measuring
cup (for watering)
• Ruler
• Scientific scale
(no continuous, dedicated light source)
PROCEDURE
• Planted mung beans
• 72 plants each in test and control
groups
• 5 mL caffeine solution [200mg/L] given
every other day to test group
• 5 mL tap water given every other day to
control group
PROCEDURE
• Main shoot height of mung beans measured daily for 28 days
• Mung bean mass measured on day 28:
• Plant removed, rinsed with tap water and cut at ground level
• Above and below ground wet masses measured, then added for total
• Procedure repeated after air drying for three hours to obtain dry mass
CAFFEINE CONTROL
DAY
28
GERMINATION ANALYSIS
No growth Growth Total
Caffeine 51 21 72
Control 19 53 72
Total 70 74 144
Χ2 = 28.466, p < 0.00001
CONCLUSIONS
• Null hypothesis rejected
• Alternative hypothesis accepted –
caffeine had a significant effect on
mung bean germination and growth
• Specifically, it significantly decreased
the number of mung beans that
germinated
QUESTION
• When caffeine group mung
beans did germinate, did they
exhibit similar growth
characteristics to control?
avg
sh
oo
t h
eig
ht
(mm
)
day
blue-
caffeine
green-
control
CAFFEINE EFFECT ON SHOOT HEIGHT
general
linear
modeling,
p = 0.812
HEIGHT ANALYSIS
• Daily average mung bean shoot
height compared
• Only plants that germinated
• No significant difference between
caffeine and control average daily
shoot heights
0
0.1
0.2
0.3
0.4
0.5
0.6
above ground below ground total
caffeine
control
AVG MASS/PLANT – WET
wet mass above ground below ground total
caffeine, g 0.297 0.261 0.558
control, g 0.259 0.308 0.567
p value 0.052 0.035 0.785
significant? no yes no
mass (
g)
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
above ground below ground total
caffeine
control
ma
ss (
g)
AVG MASS/PLANT – DRY
dry mass above ground below ground total
caffeine, g 0.224 0.129 0.353
control, g 0.176 0.142 0.318
p value 0.009 0.262 0.125
significant? yes no no
ABOVE/BELOW GROUND
WET MASS RATIO
0
0.2
0.4
0.6
0.8
1
1.2
mass ratio
Caffeine 0.297/0.261 = 1.138
Control 0.259/0.308 = 0.841
MASS ANALYSIS
• T-test done for all 6 subgroups
• Significant difference seen in 2
• Below wet (p=0.035) and above
dry (p=0.009)
• No significant difference in the
other 4
• Above wet, total wet, below dry
and total dry
HEIGHT, WET MASS CORRELATION
heig
ht
(mm
)
total wet mass (g)
blue – caffeine;
R=0.963
green – control;
R=0.807
p<0.001
HEIGHT, DRY MASS CORRELATION
heig
ht
(mm
)
total dry mass (g)
blue – caffeine;
R=0.941
green – control;
R=0.815
p<0.001
HEIGHT VS MASS
ANALYSIS
• Height vs total wet and dry mass
• Only plants that germinated
• Pearson correlation coefficient
• Height correlated with mass in both
wet and dry groups
CONCLUSIONS
• Null hypothesis rejected
• Alternative hypothesis accepted
– caffeine had a significant
effect on mung bean
germination and growth
• Specifically, it reduced the
number of plants that germinated
CONCLUSIONS
• Mung beans in the caffeine group
that did germinate, however,
showed similar growth to control
• No significant differences in
• Average daily shoot height
• Average total wet mass
• Average total dry mass
LIMITATIONS AND
EXTENSIONS
• Limitations
• Did not control soil content
• Short drying time
• Inconsistent lighting
• Extensions
• Different caffeine concentrations
• Correlate pre-planting mung bean mass with germination
• Defined non-sunlight source
BIBLIOGRAPHY
• ag.arizona.edu/pubs/garden/mg/soils/types.html
• Arnaud, M.J. 1987. The pharmacology of caffeine. Prog.
Drug Res. 31: 273-313.
• Bonsignore, C.L, and Hepler, P.K. “Caffeine Inhibition of
Cytokinesis: Dynamics of Cell Plate Formation-
Deformation in vivo.” Protoplasma. 129, 28-35; 1985.
• en.wikipedia.org/wiki/guarana
• Etherdon, G.M., and M.S. Kochar. 1993. Coffee: Facts and
controversies. Arch. Fam. Med. 2(3):317-322.
• extension.oregonstate.edu/lane/sites/default/files/docume
nts/cffee07.pdf
• Hazardous Substances Data Bank. 1997. Caffeine. HSDB
number 36. Bethesda, MD: National Library of Medicine.
BIBLIOGRAPHY
• Hepler, P.K. “Calcium: A Central Regulator of Plant Growth and Development.” Plant Cell 2005; 17; 2142-55.
• Kabagambe, Edmond K. "Benefits and Risks of Caffeine and Caffeinated Beverages." UpToDate. Wolters Kluwer Health, 27 Feb 2013.
• Lopez-Saez, J.F. et al. “ATP level and caffeine efficiency on cytokinesis inhibition in plants.” Eur J Cell Biol. 1982 Jun; 27(2): 185-90.
• Nathanson, J.A. “Caffeine and related methylxanthines: possible naturally occurring pesticides.” Science. 226 (4671), 184-7; 1984.
• www.hort.purdue/edu/ext/groundsforgardening.html
• www.hort.purdue.edu/newcrop/afcm/mungbean.html
ACKNOWLEDGEMENTS
• Thanks to Mr. Krotec for support and guidance throughout the experiment.
• Thanks to James Ibinson, MD, PhD, for help with statistical analysis.
• Thanks to my parents for helping me with ideas and suggestions, as well as supply of materials.
ANOVA TESTING –
ABOVE/BELOW WET MASS
Anova: Single Factor
SUMMARY
Groups Count Sum Average Variance
Column 1 21 6.233 0.29681 0.004239
Column 2 21 5.489 0.261381 0.006237
Column 3 53 13.718 0.25883 0.008701
Column 4 53 16.345 0.308396 0.007563
ANOVA
Source of Variation SS df MS F P-value F crit
Between Groups 0.078898 3 0.026299 3.588881 0.015321 2.667443
Within Groups 1.055238 144 0.007328
Total 1.134137 147
ANOVA TESTING –
ABOVE/BELOW DRY MASS
Anova: Single Factor
SUMMARY
Groups Count Sum Average Variance
Column 1 21 4.701 0.223857 0.004027
Column 2 21 2.71 0.129048 0.001461
Column 3 53 9.332 0.176075 0.005073
Column 4 53 7.547 0.142396 0.002345
ANOVA
Source of Variation SS df MS F P-value F crit
Between Groups 0.133358 3 0.044453 12.91884 1.6E-07 2.667443
Within Groups 0.495492 144 0.003441
Total 0.62885 147
ABOVE/BELOW GROUND
DRY MASS RATIO
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
mass ratio
Caffeine 0.224/0.129 = 1.736
Control 0.176/0.142 = 1.239