Effects of drought stress and manure on relative water content and cell membrane stability in dragonhead (Dracocephalum moldavica)

In the current study, the effect of water deficit stress or drought on relative water content and cell membrane stabili-ty of dragonhead (Dracocephalum moldavica) was studied in a greenhouse experiment carried out at Islamic Azad University, Jiroft branch, in 2009. It was a split plot experiment based on Randomized Complete Block Design with three replications, in which vertical factor included three levels of drought stress (irrigation when soil moisture reached 75% of field capacity [mild stress], irrigation when soil moisture reached 50% of field capacity [moderate stress] and irrigation when soil moisture reached 25% of field capacity [severe stress]). The results showed that the effect of water deficit stress was significant on relative water content at 5% level and on cell membrane stability at 1% level. Water stress significantly decreased relative water content from 77.69% under mild stress under severe stress. Relative water content increased as manure level increased. As the stress was intensified, the electrolyte lea-kage increased, but it started to decrease under severe stress. The manure treatment of 40 t/ha had the greatest electrolyte leakage (328.89 dS.m-1).