The Non-Thermal Effect of UV-B Irradiation on Onion Growth

(1) Yarmouth Consolidated Memorial High School, Yarmouth, Nova Scotia, Canada
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Both terrestrial and aquatic plants, the chief autotrophs supporting life on earth, can be threatened by global warming and particularly by UV-B radiation due to the depletion of the ozone layer. Ozone depletion may also threaten the biodiversity of ecosystems and dismantle food webs. The deleterious effects of UV-B have been studied mostly through in vitro studies and vary significantly according to the dose received, the irradiation period and the sensitivity of the species. Examined adaptive mechanisms encompass increases in antioxidant enzymes, phenolic compounds and flavonoids which function as protective screens. The interaction of UV-B radiation with DNA, lipid and protein molecules is vital in determining how photosynthesis and cellular respiration are affected by UV-B radiation. Hence, this study seeks to explore the non-thermal effects of UV-B irradiation on the physiology and morphology of Allium cepa. This was completed by comparing the mitotic index of the control to the irradiated populations. A paired samples two-tailed t-test was performed, and the results demonstrated a decline in mitotic vitality, suggesting that UV-B can generate biochemical stress, which can influence Allium cepa’s physiology.

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