The effect of different priming pretreatments on the morphological and physiological traits of two species of Sanguisorba minor and Elymus hispidus in short-term greenhouse conditions

 The germination and establishment of plants resistant to drought is one of the most important and effective aspects of rangeland improvement. Investigating changes in rangeland species' morphological and physiological characteristics under different pretreatments under laboratory, greenhouse, and field conditions is necessary. As a result, elite and promising species can be selected, and improvement efforts can be evaluated favorably.

 This study investigated the effect of different pretreatments on the germination and establishment of Sanguisorba minor and Elymus hispidus under drought stress. In this regard, the effect of priming treatments with distilled water, polyethylene glycol, potassium nitrate, and silver nanoparticles was studied to improve germination characteristics and establishment of species under agricultural capacity. The experiment was conducted as a factorial in a randomized complete block design in four replications. To conduct the research, 168 pots were used, and ten seeds were planted in each pot. The measured attributes included the percentage and velocity of seedling appearance from the soil, establishment and survival, length and weight of root and stem, vigor, proline, carotenoid, soluble sugar, total chlorophyll, catalase, and superoxide dismutase enzymes. After sampling the studied traits in the greenhouse and obtaining the results in the laboratory, variance and data analysis in SPSS software. A comparison of mean data with Duncan's multiple range tests at a 5% level for the studied traits was performed on both species.

 The results showed that drought stress significantly differs in characteristics, such as the dry weight of aerial parts or the length of plant roots. The mutual effects of priming and stress were significant on the traits of emergence from the soil, speed of emergence, establishment, survival, and dry weight of aerial parts. Still, it affected several other traits as well. The application of silver nanoparticles had positive or negative effects on seeds' vegetative characteristics, and seedlings grown from the seeds of the studied plants did not show significant changes to characteristics such as plant root length under different priming treatments at a specific moisture level. Some characteristics, including ability, had significant changes due to humidity levels varying up to 20 percent. The positive effects of polyethylene treatment and the negative effects of high nanoparticle concentration were evident. Applying polyethylene glycol and potassium nitrate in E. hispidus and polyethylene glycol and silver nanoparticles at a concentration of 30 mg/l in S. minor showed the highest positive effects on plant resistance under drought stress. Application of silver nanoparticles at concentrations of 60 and 90 mg/L showed negative effects on the vegetative and physiological characteristics of the two studied species.

 drought stress caused negative effects on the structural characteristics of the studied species, and using hydropriming treatments, potassium nitrate, polyethylene glycol, and silver nanoparticles (with a concentration of 30 mg/liter) reduced stress adverse effects. The reason for this is mainly the changes in the physiological factors, such as the amount of proline, catalase, and superoxide dismutase enzymes, and the application of various pretreatments causes positive changes in pretreatment factors and increases the species' drought resistance. The results related to the effect of different pretreatments on the germination of the mentioned species under laboratory and field conditions also confirm this issue.