Growth and Physicochemical Changes of Carpinus betulus L. Influenced by Salinity Treatments

Abstract

Carpinus betulus L. is a deciduous tree widely distributed in Europe with strong adaptation, and it plays a key role in landscaping and timbering because of its variety of colors and shapes. Recently introduced to China for similar purposes, this species needs further study as to its physiological adaptability under various soil salinity conditions. In this study, the growth and physicochemical changes of C. betulus seedlings cultivated in soil under six different levels of salinity stress (NaCl: 0, 17, 34, 51, 68, and 85 mM) were studied for 14, 28 and 42 days. The plant growth and gas exchange parameters were not changed much by 17 and 34 mM NaCl, but they were significantly affected after treatments with 51~85 mM NaCl. The chlorophyll content was not significantly affected at 17 and 34 mM salinity, and the relative water content, malondialdehyde content and cell membrane stability of C. betulus did not change obviously under the 17 and 34 mM treatments, indicating that C. betulus is able to adapt to low-salinity conditions. The amount of osmotic adjustment substances and the antioxidant enzyme activity of C. betulus increased after 14 and 28 days and then decreased with increasing salinity gradients, but the proline content was increased during the entire time for different salinities. The Na content of different organs increased in response to salinity, and the K/Na, Ca/Na, and Mg/Na ratios were significantly affected by salinity. These results suggest that the ability of C. betulus to synthesize osmotic substances and enzymatic antioxidants may be impaired under severe saline conditions (68~85 mM NaCl) but that it can tolerate and accumulate salt at low salinity concentrations (17~34 mM NaCl). Such information is useful for land managers considering introducing this species to sites with various soil salinity conditions.

Effect of NaCl road salt on the ionic composition of soils and Aesculus hippocastanum L. foliage and leaf damage intensity

“…Increasing evidence points to the involvement of ROS in salt stress response mechanisms and salinity tolerance 14 , 63 . K + –Na + ratios have also been shown to decrease in salinity in many plant species, both herbaceous 54 , 64 and woody 44 , 65 . Under typical physiological conditions, plants maintain a high cytosolic K + –Na + ratio, which is necessary for optimal plant growth and leaf photosynthesis 66 .…”

Ecophysiological Responses of Carpinus turczaninowii L. to Various Salinity Treatments

“…Salinity stress can cause the close of stomata, the decrease of stomatal size and leaf thickness, and the atrophy of leaf tissues [42]. In our previous study on Carpinus betulus L. [43], we found the stomata, palisade, and spongy parenchyma tissues were seriously influenced over 51 mM NaCl, worse than C. turczaninowii. These changes in leaf morphology can adversely affect photosynthesis in plants.…”

Physiological Responses to Abiotic and Biotic Stress in Forest Trees

“…An overabundance of ROS, which cannot be compensated by antioxidative systems, leads to damage symptoms such as chlorophyll degradation, membrane leakage, and eventually necrosis [13]. Some examples for salt damage symptoms at the tissue and organelle levels are also demonstrated in this Special Issue [14,15]. Since soil degradation with enhanced salinization is an increasing problem, identification of salt-tolerant plant species and measures to enhance the resistance of crops and horticultural plants are urgently needed.…”

“…Hornbeam (Carpinus turczaninowii) is known for its beautiful autumn colors and fine-textured wood. Zhou et al [15,17] systematically tested the performance of this tree species as well as its European counterpart Carpinus betulus under moderate salt stress (up to 85 mM). They found that antioxidant systems of the European species collapsed after about 1 month and that of the Asian species after about 2 months in the presence of low salinity levels (30 to 50 mM).…”