Effects of drought stress and manure on plant growth promoting stability in dragonhead (Dracocephalum moldavica).

In the current study, the effect of water deficit stress or drought on relative water content and cell membrane stability of dragonhead (Dracocepha lummoldavica) was studied in a greenhouse experiment carried out at Islamic Azad University, Jiroftbranch, 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 same trend was observed in dry weight of vegetative body meaning that by increase in drought stress, dry weight of vegetative body was decreased but the difference of mild (FC=75%) and medium (FC=5%) stress on dry vegetative body yield was or non significant. correlation coefficients among the measured traits show that there is strong positive correlation between dry weight of vegetative body of Dracocephalum with vegetative body fresh weight, stem number per plant, plant height, shoot dry weight and leaf dry weight which constitute its components (p<0.01), but dry weight of vegetative body of Dracocephalum was negatively correlated with inter node length and there was or non significant correlation between of dry weight of vegetative body and stem diameter. Leaf dry weight had significant and positive correlation with fresh weight of vegetative body, dry weight of vegetative body and plant height and stem number but was or non significantly correlated with diameter and length of stem inter node.