Morphological and Antioxidant Responses to Chromium-Induced and Metal Accumulation in Contrasting Tomato Cultivars

Chromium (Cr) in soil and water exceeding safe level has brought a series of problems to food safety and human health, and considered as major environmental concern that poorly affects plant physiology. Four Cr concentrations at (0, 25, 50 and 100 mg/kg) along with composite mix in soil were applied to determine the root morphological characters, fruit yield Cr antioxidant enzyme activity, accumulation, bioaccumulation and translocation in two Tomato ( Solanum lycopersicum L. ) (Red Pearl and Purple Beauty) screened cultivars. A randomized complete block design experiment was conducted in a controlled greenhouse with five replications. The results demonstrate that Red Pearl was significantly lower affected by Cr stress than Purple Beauty in some biochemical indicators, such as APX activity in leaf and shoot, MDA content in root, ASC content. However, Purple Beauty was significantly higher than Red Pearl in certain indicators such as CAT activity in leaf and shoot, indicating difference in their physiological mechanisms. The results also indicated that at 50 and 100 mg/kg Cr concentration Red Pearl accumulated significantly more Cr in its shoots and roots than Purple Beauty. The Cr absorbed by the entire plant was significantly higher in Red Pearl than in Purple Beauty under three Cr concentrations. Although bioaccumulation factor of Red Pearl was significantly higher than that of Purple Beauty, the translocation factors of the two cultivars differ but had not reached a significant level. Overall, the results of this experiment emphasized that Red Pearl showed more obvious Cr tolerance under experimental treatments, through enhanced antioxidant defense, efficient root sequestration of Cr and restricted translocation to aerial tissues. Therefore, it is concluded that Red Pearl can be a potential tomato cultivar for cultivation in moderately Cr contaminated soil, and provide genetic resources for breeding tomato cultivars, but further field experiment is worth studying