Effects of water stress on physiological growth indices and phonological traits in Thymus kotschyanus Boiss

This study was conducted to evaluate the effects of water stress on growth indices and phenological traits and growth indices of Thymus kotschyanus during 2010 and 2011 growing seasons. A field experiment was carried out with three irrigation regims (T20، T50 and T80 representing irrigation after 20، 50 and 80% soil water depletion، respectively) using a randomized complete block design with four replications at Experimental Station of Isfahan Agricultural and Natural Resources Research Center. Dry matter (DM)، leaf area index (LAI)، crop growth rate (CGR) and growth lenghth were decreased under water stress. DM in second year (152 gr m-2) was more than 2 times of the first year (67 gr m-2). The highest rate of CGR، LAI and DM were obtained at early blooming، 50 and 100% flowering stage، respectively. Phenological stages provoked 100-150 GDD under water stresses. DM was decreased 60% over increasing water stress from T20 to T80. The results suggested that for the highest yield production، 20% soil water depletion is recommended and harvesting should be done at fully flowering stage and prevention of water stress in early blooming stage is also recommended.