evaluation of relative genome content and response of tall fescue seedling under drought stress collected in iran

decrease in genome content may play a role in environmental adaptation. many studies were reported significant correlation between genome size, weather condition and germination percentage. relative genome content and its correlation with seedling establishment of 14 populations of tall fescue collected from various regions in iran and two commercial tall fescue cultivars were studied under drought conditions. results showed that except one entry diploid (brojen = 2x), all entries were hexaploid (6x). cluster analysis revealed that the populations fell into four groups. isfahan (group ii: average dna content 17.92 pg) and ghochan (group vі: average dna content 18.56 pg) with 100% and 6.7% final emergence and 8.8, 2.3 cm leaf length respectively in 40% fc soil water content wree the most tolerable and sensitive entries under drought stress. relative genom content of the wild populations and two commercial cultivar were negatively correlated with emergence (r=-0.56) and leaf length (r=-0.61). the reduction in genome size may be a mechanism of adaptation to arid environments. the drought tolerance was observed among the entries that grouped in cluster i and ii represent potentially useful germplasm for a breeding program.