The response of photosynthetic parameters of different growth stage winter wheat and pea to different levels of salinity stress

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 and evaluate their resistance. The main experiment was divided into two separate experiments. The first group of plants was treated with 100 mM and 200 mM salinity concentrations 2 days after seedling (germination stage according to BBCH scale) in the first experiment. The second group of plants was exposed to an identical salinity treatment when developed the second true leaf (leaf development stage according to BBCH scale). After salinity treatments, which lasted 2 weeks each, the response of physiological parameters as chlorophylls fluorescence ratio (Fv/Fm), photosynthetic and transpiration rate, water use efficiency, chlorophyll and carotenoid concentration were measured. The greatest effect of salinity was identified in net photosynthetic rate, transpiration rate and chlorophyll a/b ratio in pea plants. Photosynthetic and transpiration rate significantly decreased, while chlorophyll a/b ratio increased. At leaf development stage, investigated parameters of pea plants were more sensitive to salinity than wheat. The physiological parameters similarly to the germination stage, transpiration and photosynthetic rate decreased mostly and showed the greatest percentage reduction over control. The results of the experiment have shown that both plants were sensitive to salinity stress. According to all parameters investigated, wheat plants were more resistant to increasing salinity stress than pea plants.