Salt stress effect on some agronomical and physiological traits in Thymus daenensis subsp. daenensis ecotypes

Salinity is one of the major abiotic stresses that affects physiological processes of plants and reduces crop growth and yield. In order to study the effect of salinity stress on some physiological and agronomical traits of Thymus daenensis subsp. daenensis ecotypes and their classification, a factorial experiment was carried out using randomized complete block design with three replications in Abarkouh city in 2018. Experimental treatments were twelve Thymus daenensis subsp. daenensis ecotypes and three salinity levels including 0 (non-stress), 60 and 120 mM NaCl. Analysis of variance revealed that the difference among ecotypes and among salinity levels were significant (p<0.01) in all studied traits. Salinity stress led to a significant decrease in concentration of total chlorophyll, carotenoid, concentration of potassium, relative water content and shoot dry weigh and an significant increase in concentration of proline, concentration of sodium, sodium to potassium ratio and ion leakage. Studied ecotypes under two salinity levels including 0 (control) and 120 mM NaCl using cluster analysis based on Ward method and by using Eucilidian distance classified into three groups. Khoramabad1, Khoramabad2, Arak2, Fereydunshahr and Semirom ecotypes were suggested as salt tolerant ecotypes based on cluster analysis using all studied traits.