Ecophysiological responses of Calligonum polygonoides and Artemisia judaica plants to severe desert aridity

Abstract

The present study, conducted in 2011 and 2012, deals with the response of Calligonum polygonoides and Artemisia judaica to the drought conditions in Wadi El-Assiuty and its tributary Wadi Habib in the middle part of the Eastern Desert of Egypt. Soil and plant samples were collected from 50 stands in the wet (winter) and dry (summer) seasons. In the selected plants chlorophyll (Chl a and b) contents as well as the Chl stability index tended to increase significantly during the summer season. Calcium and magnesium were accumulated in considerable amounts in the studied plants. Amounts of calcium accumulated were higher than those of magnesium. Phosphates appeared in the plants in low amounts and correlated positively with those found in the soil. The studied plants showed an increase in soluble sugars accumulation. Soluble protein content increased significantly during the winter season with a corresponding decrease in free amino acids. It is quite clear that Calligonum polygonoides plants were better adapted to drought conditions prevailing in the area under study than Artemisia judaica. This was judged by the average metabolic potentiality as soluble metabolites (soluble sugars and soluble proteins) are much higher in Calligonum than in Artemisia.