Influence of chemical stimulators on germination improvement, growth and resistance of Bromus inermis Leyss. species under stress allelopathic components of Thymus kotschyanus Boiss. & Hohen.

Plants maybe affected directly or indirectly by allelochemicals which released from plants or microorganisms. The objective of this study was to evaluate the effectiveness of chemical stimulators in improving seed germination and growth of Bromus inermis in response to five concentration of the allelopathic extract of Thymus kotschyanus (0, 5%, 25%, 50% and 75 %) under laboratory conditions. Pretreatments included: gibberlic acid (250,500 and 1000 ppm), potassium nitrate (0.1%, 0.2 % and 0.3%) and salicylic acid (100,200 and 300 mg/l). This experiment was carried out as a factorial experiment based on a randomized completely design with four replications. The results showed that seed germination, germination speed and seedling vigor were significantly (P <0.01) decreased by increasing extract concentration of Thymus kotschyanus allelopathic compounds in unprimed seed (control) compared with primed seeds. Seed priming enhanced germination percentage, germination speed and initial growth. Overall, the results of this study showed that reaction of the Bromus inermis to pretreatment of seed was positive. Thus, pretreatments of seeds with the above treatments prior to planting can significantly reduce negative effect of allelopathic components of Thymus kotschyanus during germination stage and establishment of plant by increasing germination speed and growth of embryo.