Authors:Burcu Dinler, Emel Demir and Yasemin Kompe
In the present study, the effect of ascorbic acid (5 mM) on some physiological parameters and three hormones (auxin, abscisic acid, salicylic acid) was determined under heat stress (40 °C) in maize tolerant cv. (MAY 69) and sensitive cv. SHEMAL (SH) at 0 h, 4 h and 8 h. Heat stress reduced total chlorophyll content (CHL), relative water content (RWC) and stomatal conductance (gs) in SH but did not lead to changes in MAY 69 at 4 h and 8 h. However, pretreatment with ascorbic acid increased (CHL), (RWC) and (gs) in SH under heat stress while it reduced MDA content significantly in both cv. We also observed that heat stress led to a reduction in SA level but increased ABA and IAA levels in SH, whereas it increased SA and IAA levels but did not change ABA level in MAY 69 at 4 h. Furthermore, in SH, ASC application under heat stress increased SA level and decreased IAA and ABA levels at 4 h, but it had no effect on SA and ABA at 8 h.
In this study, Eruca sativa (Rocket) seedlings were treated with different cadmium (Cd) concentrations (0, 150, 300 and 450 μg ∙ g−1). The effects of Cd on lipid peroxidation, enzymatic (APx, CAT, GPX, SOD) and non-enzymatic antioxidants (total ascorbate, dehydroascorbate, ascorbate, non-protein thiol), fresh and dry masses, water content were determined. Also, Cd content of the leaves and the roots were analysed. The highest cadmium accumulation of leaves was at 450 μg ∙ g−1 Cd treatment and the accumulation was 2.62 times greater than those in the roots. The translocation factor was 3.89 at 300 μg ∙ g−1 Cd treatment. Cd treatments caused decreases of fresh, dry mass and water content of leaves and roots. Malondialdehyde content, which is an index of lipid peroxidation, was increased in proportion with the increase in Cd. While there was not change in the activity of GPX according to control, a decrease in activities of SOD, CAT and APX were observed with the increase of cadmium concentration. Although a significant increase in the amounts of non-protein thiol groups and proline were observed in 450 μg ∙ g−1 Cd treated plants, Cd did not lead to a significant change in AsA, DHA and total AsA contents. According to the results of the research, E. sativa may be a Cd hyperaccumulator plant and we suggest that the plant may be a candidate plant for remediation of Cd-contaminated soil.