Effects of potassium dichromate on some morphological and biochemical indicators of three rose cultivars suitable for urban green spaces

Chromium is one of the most important heavy metals, that has been excessively added to the environment in recent years due to extensive uses in industry, agricultural toxins and the release of industrial wastes into the water. To evaluate the impact of stress at different levels of chromium (0, 75, and 150 mg/kg soil) on three cultivars of rose (White, Mohandesi, and Haft rang) a greenhouse factorial experiment was conducted in a completely randomized design (CRD) with three replications in pots at the Faculty of Agriculture, Ferdowsi University of Mashhad in 2018. Four months after planting, morphological and biochemical traits were evaluated. According to the results, it was found that the greatest decrease in chlorophyll a and the ratio of chlorophyll a/b was in Haft rang cultivar with a decrease of 53.3 and 80.3%, respectively. Amount of carotenoids in the White cultivar was 85.6%, amount of chlorophyll b in the Mohandesi cultivar showed 5.1% decrease in comparison to the control at a concentration of 150 mg/kg of soil chromium. The highest amount of chromium accumulation at a concentration of 150 mg/kg was in the roots of the Haft rang rose cultivar and the leaves of the Mohandesi rose cultivar, with a ratio of 610 and 3915 times respectively, compared to the control of these cultivars. The highest accumulation of chromium in the leaves was in the Mohandesi cultivar with an average of 3915 ppm, in the root of Haft rang cultivar with an average of 10988 ppm, and the soil in the white variety with an average of 597 ppm at the concentration of 150 mg/kg of chromium. With the increase in chromium concentration, the content of soluble carbohydrates increased, and this increase was higher in the Mohandesi cultivar than in the other cultivars. Leaf area, chlorophyll index, and wet and dry weight of aerial parts increased in all cultivars with increasing chromium concentration. Also, the results showed that Haft rang cultivar was more resistant to the increase of chromium than the other cultivars.