Evaluation of biochemical and morphophysiological responses of Viola× wittrockiana to drought and cold stress

Today, the ornamental plants survival in the green space due to climate change and a sudden increase in temperature in cold seasons has been compromised. In order to evaluate the effect of irrigations and temperatures on viola plants, a factorial experiment was conducted based on completely randomized design with four replications in faculty of agriculture, Ferdowsi University of Mashhad. Experimental factors include levels of irrigation water (80%, 60 % and 40 % FC) and levels of temperatures (20, 0, -3, -6, -9, -12, -15, -18, -21 and -24 °C). After irrigation treatments, some traits including proline, carbohydrate, chlorophyll (a, b and total), carotenoid and relative water content and after temperature treatments activity of superoxide dismutase, ascorbate peroxidase and total phenol were determined. The results showed that carbohydrate and proline significantly increased and chlorophyll and relative water content decreased at 40% irrigation treatment. Interaction effects of irrigation and temperature treatments significantly affected the activity of two enzymes. The maximum activity of superoxide dismutase and ascorbate peroxidase in 40% FC level of irrigation water at 0 °C were seen, but with decreasing temperature, the activity of these enzymes were reduced. In three irrigation levels, the amounts of total phenols were increased from 20 to 0 °C and reached to minimum at -24 °C. After the recovery period, plants treated with 60% FC at 0 °C showed the highest vegetative traits (height, number of nodes, leaves, offshoot and flower diameter).