The book will describe the ecology of photosynthesis of Prof. Serag completed his PhD in Ecology from Mansoura-Lund Universities Channel System 1989. Currently working as professor of Ecology at Damietta University. He published more than 100 research papers in national and international journals. He is interested in plant diversity and management of natural resources. Ecology of medicinal herbs of Egypt in response to stress and the diurnal regulation of photosynthesis in relation to water budget (water management strategies). The roles of the transcription factors in the regulation of photosynthesis will evaluated under different conditions.A. halimus small seedlings were spotted in the field where field capacity (FC) was 73-75% (i.e. drought condition where the appropriate FC for a proper growth is 87%). These small seedlings were divided into three groups; the first group exposed to no treatment, the second group was recovered with water and the third group was recovered with300 mM NaCl. We used the term "recovery" in the case of 300 mM NaCl treatment because A. halimus is an obligate Atriplex halimus is a C4 evergreen plant, xerohalophyte.