evaluation of response to water deficit stress in thymus daenensis subsp.daenensis using stress tolerance indices

in order to study water deficit tolerance in thymus daenensis subsp. daenensis ecotypes, seeds of eight ecotypes were collected from different locations. seedling are produced in greenhouse, and then transferred to field as an experiment of split plot design based on rcbd with three replicates. three irrigation treatments (normal irrigation, prevention of irrigation at the start of flowering and at the vegetative stages) were considered as main plots. sub plots were formed by the ecotypes. plants were harvested at the full bloom stage and measured for dry matter, essential oil percentage and tolerance indices. generally, results showed that sever stress led to reduction of dry matter yield. the ecotypes under different level of irrigation showed different responses for essential oil content. high correlation observed between dry matter yields and tolerance indices. based on the results, gmp, sti, mp and ham were the best indices for selecting the most tolerant and the best ecotypes. according to these indexes, the ecotypes of arak, khan- e- miran bala and khan- e -miran paien were appropriate options for future studies. totally, this plant showed high tolerance to water deficit stress and may be a good choice for culturing in water deficit conditions.