Application of Chlorophyll Fluorescence Attributes in Selection for Cold Tolerance in Some Clover Species

To study chlorophyll fluorescence attributes and physiological traits of some clover species in low temperature conditions a field experiment was carried out in 2011-2012 cropping cycle in Seed and Plant Improvement Institute in Karaj، Iran. Ten clover genotypes and three sampling times were arranged as split-plot in randomized complete blocks with three replications. Results showed that clover genotypes were significantly different in chlorophyll fluorescence attributes and physiological traits. Fv/Fm ratio (0. 597-0. 755) showed that low temperature stress affected clover genotypes. The highest Fv/Fm ratio belonged to Persian clover and the lowest was estimated for Red clover which were indentified as most tolerant and susceptible genotypes، respectively. Chlorophyll content index (CCI) had the highest significant correlation with chlorophyll fluorescence attributes in dark conditions. Considering the results of this research، Fv/Fm، electrolyte leakage (EL) and CCI were identified as suitable criteria in selection for cold tolerance of clover genotypes.