Physiological effects of aluminium toxicity on sesame (Sesamum indicum L.)

Aluminum is the most abundant metal and the third most abundant element in the earth's crust. Aluminium toxicity is one of the major factors that limit plant growth and development in many acid soil. Sesamum indicum (sesame) is a flowering plant that grows throughout the world and is cultivated for its edible seeds. Therefore, it is essential to investigate the effects of Al toxicity on some physiological and biochemical characteristics of sesame seedlings. Sesame seeds sterilized with 5% sodium hypochloride solution for 15 min, and washed with distiled water three times and then were germinated in perlite. After germination periods, sesame seedlings were then transferred to 2 L plastic vessels containingaerated nutrient solution. After seedlings were acclimatized, they were supplied with 0, 5, 25 and 50 mg/L Al. At the end of the Al application period, the seedlings were harvested and analyses were carried out. Growth and development of the seedlings were reduced by Al. The study indicated that Al toxicity on photosynthetic pigments and protein contents in the seedling parts (root, stem and leaf) were dependent upon Al concentration. In general, toxicity was also increased with increasing Al concentration. Increases in H2O2 and malondialdehid contents showed that Al concentrations caused oxidative stress. It is possible that increased non-protein SH groups and total phenolic contents by Al may be due to their roles in Al stres response.