Résumé:
Two varieties of tomato (Lycopersicon esculentum Mill.)ORPI and 53 were studied under four concentrations of NaCl (50 mM, 100 mM, 200 mM, 300 mM). The results of the study indicate that salt treatments have variable effects on different characteristics of tomato plants, including chlorophyll content, stomatal density, stem length, root length, water content, in soluble sugars and proline content. For chlorophyll content, both tomato varieties showed a significant increase in chlorophyll a content in response to saline treatments, while chlorophyll b content remained relatively stable. Total chlorophyll content decreased at higher NaCl concentrations, except at 100 mM where a significant increase was observed. Tomato plant leaf stomatal density decreased with increasing NaCl concentrations, indicating a downregulation altered stoma in response to salt stress. Tomato plant stem length showed variable responses to salt treatments, with an increase in length at a concentration of 50 mM NaCl in variety V1, while variety V2 showed showed a slight decrease at 100 mM NaCl. Root length also showed variations in response to saline treatments, with an increase in length at 50 mM NaCl in variety V1, while variety V2 showed a slight decrease at 200 mM NaCl. The relative water content increased with increasing NaCl concentrations in variety V1, but showed variations in variety V2. The content of soluble sugars increased in response to salt treatments in both tomato varieties, which can be considered as an adaptive response to cope with salt stress. Finally, proline content increased in response to salt treatments in both tomato varieties, suggesting a role of proline in protecting against osmotic stress. It is important to note that responses to salt treatments may vary depending on various factors such as plant species, varieties, growing conditions and salt concentrations used. These results highlight the importance of taking these variations into account when evaluating the effect of salt stress on plants.
