Abstract
The aim of this work was to investigate the response of physiological parameters of winter wheat (Triticum aestivum L. cv. ʾAdaʾ) and pea (Pisum sativum L. cv. ’Early onward’) to different levels of salinity stress under changing climate conditions. Experimental plants were grown in growth chambers under the conditions of current climate (400 µmol mol-1 CO2 and day/night temperatures of 21/14 °C) and warmed climate (800 µmol mol-1 CO2 and day/night temperatures of 25/18 °C). Under both climate conditions plants were exposed to 100 mM and 200 mM concentrations of sodium chloride. Exposure to salinity stress was initiated when plants developed the second true leaf or their pair. After salinity treatments, which lasted 2 weeks, the response of photosynthetic and transpiration rate, stomatal conductivity, intracellular content of CO2, water use efficiency, II photosystem quantum efficiency rate and photosynthesis performance index were measured. Physiological parameters of pea plants were mostly affected at current climate conditions. The biggest reductions were found in photosynthetic and transpiration rate, which decreased by 57.0 %, and 71.5 %, under 200mM effect respectively. Assessment of intensity of fluctuation of wheat and pea physiological parameters at current climate has shown that changes were bigger in pea plants (51.3 %), in comparison with wheat (29.3 %). While at warmed climate conditions, the changes in physiological parameters of pea and wheat were the opposite: for wheat they have increased and became 52.6 %, and for pea they have decreased till 41.1 %, in comparison with the control plants (p <0.05).DOI: http://dx.doi.org/10.5755/j01.erem.73.4.19444
Highlights
Carbon dioxide is estimated to continually increase from currently 400 ppm to between 750 and 1300 ppm by the end of this century (IPCC 2014)
The effect of NaCl on plants at the current climate conditions is presented in Figure 1A; 100 mM and 200 mM concentrations reduced the photosynthetic rate of wheat by 9.5% and 16.3%, respectively, compared with control plants (p < 0.05)
Higher changes of physiological parameters of wheat were detected at warmed climate conditions, as the biggest reduction was detected in the transpiration rate, the photosynthesis performance index and the water use efficiency, when the mentioned parameters fluctuated by 68.3%, 81.2% and 87.7%, respectively, over control
Summary
Carbon dioxide is estimated to continually increase from currently 400 ppm to between 750 and 1300 ppm by the end of this century (IPCC 2014). The global mean surface air temperature is predicted to increase about 1.8–6.0 °C by the end of the 21st century (IPCC 2014). It is well known that rising [CO2] has a direct effect on plant metabolism and growth because CO2 is the carbon substrate of photosynthesis, and there is a common assumption that the rising temperature will directly increase the release of CO2 via respiration both in light and darkness (Zhang et al 2017, Kacienė et al 2017). Many recent papers and reviews emphasize how the enhancement of atmospheric CO2 directly impacts the physiology of plants, generally accelerates the photosynthetic rate and increases plant growth and yield (He et al 2010, Sun et al 2010, de la Mata et al 2012, Zhang et al 2012). A progressive increase in CO2 could decrease the ratio of photosynthesis to photorespiration and the ratio of gross photosynthesis to dark respiration at a higher temperature. Long (1991) has demonstrated that an increase in CO2 from 350 to 650 micro mol mol−1 could raise the optimum temperature of light-saturated leaf photosynthesis by 5 °C and the relative stimulation of light compensation point by elevated CO2 was reduced at a high temperature (Chang et al 2016)
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