TITLE:
Effects of Rising Temperature on Secondary Compounds of Yeheb (Cordeauxia edulis Hemsley)
AUTHORS:
Meseret C. Egigu, Mohamed A. Ibrahim, Johanna Riikonen, Asha Yahya, Toini Holopainen, Riitta Julkunen-Tiitto, Jarmo K. Holopainen
KEYWORDS:
Cordeauxia edulis; Climatic Warming; Elevated Temperature; Gas Exchange; Isoprenoids; Phenolics
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.5 No.5,
March
7,
2014
ABSTRACT: The effects of temperature on net photosynthesis and
stomatal conductance, emission of foliar volatile organic compounds (VOCs), and
phenolics were investigated after exposing Cordeauxia
edulis seedlings to control (27/19°C) and three levels of
elevated (32/23, 37/27, or 42/31°C) day/night
temperature regimes in controlled growth chambers. Emissions of foliar
VOC were measured on 7th and 14th day (d) of exposures,
whereas net photosynthesis and stomatal conductance were measured on the 8th and 15th d. Net photosynthesis and stomatal conductance were not
significantly affected by elevated temperatures. Emission rate of isoprene
increased by 4-fold with 10°C rise from the control on 7th d of exposure. Emission rates of monoterpenes, sesquiterpenes and total isoprenoids
increased to 2-5-fold higher than that
of control plants with 5°C rise. Foliar isoprene emission peaked at daytime maximum of 37°C and the mono- and
sesquiterpenes at 32°C. Few individual foliar
phenolics, and total foliar phenolics showed significant concentration differences
between treatments. Although high VOC emissions under warming appeared to help plants to
sustain abiotic stresses, arid/semi-arid species might substantially release
highly reactive compounds that affect atmospheric chemistry. Hence, more studies are required on plant
species of arid/semi-arid ecosystems of Africa to estimate the emission patterns and their role in atmospheric chemistry under the predicted
future atmospheric warming.