Effect of vanadium on germination, growth and activities of amylase and antioxidant enzymes in genotypes of rice

Vanadium causes metabolic interruption with normal growth of plants, and therefore, contamination issues are of major concern. Seed germination is a critical point in seedling establishment and subsequent plant health and vigor. The present study was carried out to assess the physio-biochemical responses: seed germination, seedling growth, activities of antioxidant enzymes and non-enzymes, and amylase contents in rice varieties. The obtained results showed variations in all observed parameters, and the rice varieties respond differently to vanadium treatments. Overall, the protrusion and germination rates of rice seeds were affected and reduced when exposed to vanadium. The fresh biomass and height of shoots and roots were also decreased when seedlings of rice were exposed to vanadium, especially at 30 mg L-1. The results about antioxidant enzymes and non-enzymes indicated that rice varieties respond differently; however, the activities of antioxidant enzymes were increased when treated with vanadium. Furthermore, the contents of antioxidant non-enzymes were also altered in all rice varieties seedlings when exposed to vanadium. The soluble protein contents were also significantly declined in all rice varieties when treated with vanadium. The activities of alpha, beta and total amylase enzymes in rice seeds were also affected when exposed to vanadium; taken as whole, the maximum observed inhibition in amylolytic enzyme activities was observed at 30 mg L-1 of vanadium treatment. In summary, rice seedlings were markedly influenced in terms of seed germination, early growth as well as amylase contents when exposed to vanadium. Overall, the toxic effects of vanadium with respect to rice varieties are maximum during seed germination and growth while variations regarding amylase activities were recorded. These results suggested that rice varieties: Chao you 37 and Chao ji 1 hao exhibited maximum losses, while less damage in Tai guo xiang nuo and Qi dao 2000 might be related to strong antioxidant defense system proved them to be tolerant against vanadium.