Morphological and physiological responses of two species of Festuca arundinacea Schreb. and Dactylis glomerata L. at 4 °C

low temperature is one of the limiting factors for survival and growth of many species and plays a major role on their habitats. In the present study, the effects of cold on morphological and physiological characteristics of Festuca arundinaceae and Dactylis glomerata were investigated through a factorial design. At the first step seeds were prepared and cultivated in a pot to reach at an acceptable growth in a greenhouse. 10 replicates of each species were exposed to cold at 4 ° C for two weeks. And 10 replicates were placed in non-stress conditions (control). Every two weeks, the greenhouse seedlings were returned to the normal conditions of the greenhouse to continue the research process. The results showed that cold treatment reduced the air and undergrowth biomass of both species. Cold treatment has been responsible for the loss of photosynthetic system and stomatal conductance and leaf temperature in studied species. The rate of photosynthesis in F. arundinaceae in the control was 0.10 mol / m-2 / sec-1 greater than cold treatment with 0.080 mol / m-2 / sec-1. In D.glomerata, the photosynthesis rate in the control was 0.078 moles / m-2 / sec-1 more than cold treatment with 0.045 moles / m-2 / s-1 seconds. The amount of chlorophyll a, b, total in cold treatment decreased and electrolyte leakage in both species increased under cold treatment. Considering the important role of these two species in rangeland regeneration and improvement, knowledge of the effect of cold on their physiology and morphology characteristics can be useful in determining the readiness of rangeland and the capacity of rangeland and grazing livestock for proper range management in the country.