Effect of Drought Stress on Physiological Characteristics of Different Salad Burent (Poterium sanguisorba) Ecotypes under Different Irrigation Regimes

To evaluate the effect of drought stress on the physiological characteristics of salad burent (Poterium sanguisorba)، a field experiment was conducted in split-plot based on randomized complete block design with three replications during 2010 growing season. Four levels of irrigation (20، 40، 60 and 80 percentage of available soil moisture) and three different ecotypes of Tehran، Semirom and Fereidon Shahr were used as main and sub plots، respectively at the three harvest stages (82، 112 and 142 days after planting). Water stress significantly affected on the shoot dry weight، leaf relative water content، protein (%)، total chlorophyll and chlorophyll a and b، but effect of the ecotypes was only significant on shoot dry weight at all three stages and relative water content at second and third stages. Maximum shoot dry weight obtained in Tehran ecotype under 20 and 40% of available water at each three harvest stage. More relative water content was observed at 40% of available water at each harvest stage.