Сибирский лесной журнал (Dec 2018)
Photosynthetic responses of Amygdalus arabica Olivier and Atriplex canescens (Pursh) Nutt. to drought stress under field conditions
Abstract
The central Anatolian region of Turkey is exposed to increasing temperatures and severe drought stress. Due to aridity and desertification brought about by global warming, climate change and overutilization, plant species in these regions are under the risk of extinction. Thus, plant species have to adapt to these harsh environmental conditions of extremely high temperatures and low precipitation. In this study, gas exchange and water potentials of the Arabian almond tree Amygdalus arabica Olivier (C3-photosynthesis) and four-winged saltbush Atriplex canescens (Pursh) Nutt. (C4-photosynthesis), two drought-tolerant woody species planted previously in an effort to reduce desertification at Karapınar, Konya, and Central Anatolian Region, were periodically measured from May until September under field conditions. Net photosynthesis and transpiration rates, mid-day water potential and water use efficiency were determined throughout the vegetation period in 2015. Maximum net photosynthetic rates were 12.4 μmol m–2 s–1 in the Arabian almond tree and 29.7 μmol m–2 s–1 in four-winged saltbush, measured in July and September, respectively. Also, the highest transpiration rates were 4.8 mmol m–2 s–1 in the Arabian almond tree and 7.1 mmol m–2 s–1 in four-winged saltbush. Maximum water use efficiency values were measured in June in both species, which made up 5.7 and 7.7 mmol CO2 mol–1 H2O for the Arabian almond tree and four-winged saltbush, respectively. Lowest midday water potentials for both species were recorded in August. The results indicate that both species have the ability to tolerate drought stress in the region, though due to its C4 nature of photosynthesis, the four-winged saltbush might overcome those stresses more efficiently than the Arabian almond tree in arid and barren areas.
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