Evaluation of Water Deficit on Morphological and Physiological Traits of Hyssop (Hyssopus officinalis L.)

Water deficit stress is the main limiting factor of crop growth and yield in arid and semi-arid environments. Hyssop (Hyssopus officinalis L.) is one of the most important medicinal plants that have numerous medical uses. In order to study the effect of drought stress on physiological and morphological traits of Hyssop, an experiment based on randomized completely design was conducted with four replications at Research Greenhouse of Agricultural College of Shirvan. Water deficit levels included 100% field capacity (control), 75% field capacity (mild stress), 50% field capacity (medium stress) and 25% field capacity (severe stress). Results showed that enhance water deficit (medium and severe stress) declined plant height, leaf weight, stem and shoot weight, root volume and weight. However, root dry weight to shoot weight ratio increased with increasing drought stress levels. Water deficit led increasing electrolyte leakage and decreasing relative water content (RWC). Mild stress increased chlorophyll a, chlorophyll b and total chlorophyll content, but enhance water deficit reduced chlorophyll pigments compared with control. Mechanisms of tolerant to Water deficit such as increasing soluble sugars, carotenoides and anthocyanins content were observed in plants under water deficit with increasing stress levels. In general, the experiment results showed relative tolerance of Hyssop to mild stress.