The comparison of two methods of cystein treatment for growth improvement in Ocimum basilicum L. under cobalt stress

In this research, the effects of cysteine on alleviation of heavy metal stress in purple basil plants were studied and some parameters such as fresh weight of shoot and root, chlorophyll a and b content, carotenoids, anthocyanin, and total phenolic compounds and reducing sugar was measured. Research was conducted in two separate trials for the two group pre-treated cysteine and cysteine -cobalt combined treatments. The treatments containing of 0, 500 and 2500 mM cysteine and 0, 100 and 500 mM cobalt was used. Higher concentrations of cobalt decreased photosynthetic pigments, leaf, root and shoot length, fresh weight of roots and shoots while cobalt stress increased, caused reducing sugars, anthocyanins and total phenolics content. Cysteine reduced the fresh weight of roots, reduction sugar, anthocyanins, and total phenolics of plants compared to plant treated with cobalt treatments without cysteine. Thus, this amino acid improved leaf area, root and shoot length, shoot fresh weight and photosynthetic pigments in stress conditions. Generally, the results showed that pre-treatment of cysteine could alleviate low concentrations of cobalt stress effects than higher amounts application of this heavy metal, while combined treatments containing cysteine was more effective at higher concentrations of cobalt.