Effects of hydro and osmopriming in different temperatures on germination and seedling growth of Satureja khuzistanica Jamzad. under drought stress

Satureja khuzistanica Jamzad. belongs to the family labiateae of which several species are growing in different regions of Iran. Germination is one of the important growth stages in plant life cycle that usually is affected and disturbed by unfavorable conditions. Drought stress is considered as an important unfavorable factor for a main part of Iran. Seed priming is a technique to improve seed quality for stress conditions. The study was performed in a factorial experiment based on a completely randomized design with three replications and three factors. The first factor consisted of three levels of moisture stress (0, -4 and -8 bar), the second factor was osmopriming (0, -4 and -8 bar) and the third factor consisted of two levels of priming temperature (15 and 25 °C). PEG6000 was used to induce osmotic stress in priming and germination medium. Germination percentage and rate, seedling fresh and dry weights, seedling length and vigor index decreased by increasing drought stress, while the number of root increased up to -4 bars and then decreased. Hydro and osmopriming could improve the seed quality. Interaction effect of drought and osmotic potential of priming was significant for germination percentage and rate, seedling dry weight, number of root and vigor index. The seeds hydroprimed at 15°C had the highest germination percentage and rate, vigor index, seedling dry weight and number of roots under control (0 bar) and mid stress (-4 bar) conditions, while the highest germination rate and vigor index were recorded for the seeds primed at -4 bar and 15°C under severe drought condition (-8 bar). The longest roots were obtained at osmopriming at -8 bars and 25°C in control and drought conditions. All traits were affected by priming temperature, except the number of root, as most of the traits primed at 15°C showed a better condition.