Alterações morfofisiológicas da aplicação de metais pesados e alumínio em plantas jovens de seringueira

Abstract

Heavy metals are important environmental pollutants, and its toxicity is an issue of growing importance, usually in soils located near industrial complexes, urban districts and rural areas of intense technology, whereas, the plants should be evaluated for their ability to tolerate this type of stress. This study aimed to evaluate the morphological and physiological changes in young rubber tree plants when grown in solutions with different concentrations of Al and heavy metals, Cd, Ni and Zn. Thirty days after germination, seedlings were transplanted into trays with a capacity of 30L containing nutrient solution modified Bolle-Jones where they stayed for one hundred and twenty days. Elapsed this period added to the nutrient solution in the following concentrations heavy metals (Cd: 0, 30, 45 e 60 ppm; Ni: 0, 1,7, 3 e 5 ppm; Zn: 0, 16,6, 25 e 33 ppm; e Al: 0, 28, 48 e 96 ppm). After one hundred twenty days in nutrient solution containing heavy metals evaluated the following parameters: mean number of stomata, stomatal conductance and transpiration; photochemical efficiency of photosystem II and enzyme activity of nitrate reductase (NR). Higher concentrations of Al up to 96 ppm, Ni up to 3 ppm and Zn up to 16,6 ppm increase stomatal resistence and reduce the rate of transpiration of rubber plants. The values of maximum photochemical efficiency (Fv / Fm) in rubber tree fluctuate depending on the evaluation period and the concentration of heavy metals Cd, Ni and Zn and Al chemical element. Increases in concentrations of Cd, Ni and Zn reduce stomatal density of rubber plants. The enzyme nitrate reductase (NR) in rubber tree had a reduced activity in the presence of heavy metals Cd, Ni and Zn and Al chemical element.