Page 41 - CSHS 2022 Book of Abstracts - 2022-08-22 web version

CSHS 2022 Conference

(VP.3) Extreme Water-stress Effect on Jamaican Thyme (Plectranthus amboinicus)
Zijing Wang, Sparsha Chada*, Raphael Ofoe, Lord Abbey
Department of Plant, Food, and Environmental Sciences, Faculty of Agriculture, Dalhousie University, Bible Hill, NS
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Water-stress is one of the most important threats to the attainment of global food security. A study was conducted
to investigate extreme water-stress impact on Jamaican thyme (Plectranthus amboinicus) plant morpho-physiology
and secondary metabolites accumulation. The treatments were regular watering (RW), continuous flooding (FL),
continuous drought (DR), and dehydration (DH) after regular watering and rehydration (RH) after drought. Leaf
relative water content was significantly (P<0.01) increased by RH followed by RW, and the least by DR and DH. The
concentration of leaf cell electrolyte leakage from plants grown in the RH and RW were respectively 91% and 76%
high, compared to the least from plants grown FL. Photosynthetic rate, transpiration rate, and stomatal conductance
were enhanced by RW, but were reduced remarkably by DR. Chlorophyll fluorometric indices including maximum
quantum yield or efficiency of Photosystem II (Fv/Fm) and potential photosynthesis capacity (Fv/Fo) were
increased by FL followed by RH compared to DH. Comparatively, tricarboxylic acid cycle metabolites i.e., glucose and
acetoacetic acid were significantly (P<0.01) increased by DR, while pyruvic acid and succinic acid were increased by
FL, and malic acid by RH. Overall, the study revealed how Jamaican thyme responds to various water stress
situations and demonstrated that DR severely stressed plants.

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