Determination of drought tolerance clones in Tea (Camellia sinensis L.) by investigating the activity of antioxidant enzymes

In order to investigate the activity of antioxidant enzymes of 14 tea clones under normal and drought stress conditions, two separate experiments were carried out in a randomized complete block design with two replications in 2017 at Fashalem Tea Research Station in Rasht. Irrigation in both designs was carried out routinely until July 22 followed by a drought stress treatment for one plot until August 22 when tea leaves were harvested. Tea leaves from each plot of the both experiments were then removed and transferred to a freezer at -80 °C. The activity of the antioxidant such as ascorbate peroxidase, superoxide dismutase, catalase, peroxidase, phenylalanine ammoniaase, lipid peroxidase, malondialdehyde, β-carotene, and lycopene were measured. The results showed that drought stress increased the activity of antioxidant enzymes. Based on the results obtained from the mean comparisons, clones 100, 399 and Bazri, had the highest activity for ascorbate peroxidase, superoxide dismutase, catalase, peroxidase, phenylalanine ammoniaase, and lipid peroxidase under drought stress conditions. On the other hand, these clones had the lowest contents of malondialdehyde. Clones 278 and 276 on the other hand, had the least values of antioxidant enzymes under drought stress conditions (except malondialdehyde) and were considered as sensitive clones.