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

DAY28

GERMINATION ANALYSISNo 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-caffeinegreen-control

CAFFEINE EFFECT ON SHOOT HEIGHT

generallinearmodeling,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

above ground below ground total0

0.1

0.2

0.3

0.4

0.5

0.6caffeinecontrol

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

mas

s (g

)

above ground below ground total0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

caffeinecontrol

mas

s (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

mass ratio0

0.2

0.4

0.6

0.8

1

1.2

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

hei

gh

t (m

m)

total wet mass (g)

blue – caffeine;R=0.963green – control;R=0.807

p<0.001

HEIGHT, DRY MASS CORRELATION

hei

gh

t (m

m)

total dry mass (g)

blue – caffeine;R=0.941green – control;R=0.815

p<0.001

HEIGHT VS MASSANALYSIS

• 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/documents/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 MASSAnova: 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

mass ratio0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

Caffeine 0.224/0.129 = 1.736

Control 0.176/0.142 = 1.239