Some growth and biochemical changes of viola (Viola × wittrockiana) and Snapdragon (Antirrhinum majus) ornamental plants to freezing stress

Exposure to freezing stress causes physiological, biochemical and molecular changes in plants, that are associated with reduced growth and development. In these areas, sensitive species are removed and the geographical distribution is changed. This study was conducted to evaluate some vegetative and biochemical responses of two cold-resistant ornamental plants, viola (Viola wittrockiana) and Snapdragon (Antirrhinum majus), under freezing stress. For this purpose, the minimum temperature in January in three different locations (greenhouse, Isfahan, Fereydun shahr, respectively) was used to apply freezing treatment on 70-day-old seedlings (20, -3 and -11 Celsius degrees, respectively). After 15 days, following the increase in cold, seedling weight changes and dry weight of both plants were significantly reduced. The highest decrease in growth was related to the lowest temperature. Lowering the temperature increased the amount of chlorophyll, carotenoids, anthocyanin’s, proline, glycine betaine and malondialdehyde (MDA). It seems that increasing photosynthetic and vacuole pigments along with the accumulation of osmolites such as proline and glycine betaine not only concentrated the cytoplasm through osmotic regulation, but also protected plans from freezing in sub-zero temperatures, It has also somewhat reduced the destructive effects of freezing caused by the formation of free radicals and peroxidation of cell membranes.