Seasonal Effects on Some Eco-Morphological and Physiological Characters of Tamarix nilotica (Ehrenb) Bunge Growing Naturally in Egyptian Northern Coastal Salt Marshes

Abstract

Tamarix nilotica is a perennial halophyte growing naturally at the Mediterranean coastal salt marshes. Vegetative parts were collected in two successive winters and summers to investigate the seasonal effects on the ecomorphological and physiological responses of T. nilotica. The results indicated that either in winter or summer seasons, T. nilotica can reduce the effect of soil salinity by excreting salts outside its body through salt glands. Summer season was characterized by low content of soil moisture (due to rare rainfall), high soil EC, high light intensity and high temperature; there-fore, plant induced certain morphoanatomical changes in leaves and stem to face the previously mentioned adverse conditions. The most remarkable changes to reduce transpiration process was found by decreasing leaf area and increasing cuticle thickness and mesophyll tissue thickness. In addition, the most marked physiological changes in summer were the significant in-crease in total phenols, proline, free amino acids and total soluble sugars. These compounds can work as osmotic regulators and/or antioxidants. These features enhance the defensive mechanism against dehydration and permit T. nilotica to tolerate the stress conditions in salt marsh habitat.

Keywords

• seasonal changes
• salinity
• drought
• salt marches
• tamarix nilotica