Hydroponic culture and physiological responses to arsenic in Borreria verticillata populations with differential tolerance to the metalloid

Abstract

Studies on pollutant accumulation in plants are essential for the diagnosis of species with potential for revegetation and remediation of contaminated environments. Hydroponic systems are commonly used for this purpose, but little is known about the influence of the nutrient solution in the results. Borreria verticillata can be found in arsenic (As)-contaminated environments, and research using Hoagland's nutrient solution has reported a differential tolerance to the metalloid in populations from contaminated (CS) and non-contaminated (NCS) sites. However, some authors suggest the use of Clark's solution to study As tolerance in plants. We evaluated the growth and nutritional status of plants from these populations, cultivated in Hoagland's and Clark's solutions, and determined the most appropriate solution for comparative studies on tolerance to As. The selected solution was used in plant cultivation for As exposure. In Hoagland's solution plants from the NCS exhibited higher root volume, fresh and dry weight and macronutrient accumulation than those from the CS. Clark's solution promoted more similar responses and was used in plant exposure to 0, 33 and 66 lM As, for 4 days. The metalloid promoted reduction of total fresh weight in both populations. Alterations were more severe on plants from the NCS, with decreased values of root volume, gas exchanges, height and nutrient concentration in shoots. The severe damage caused by As in plants from the NCS demonstrates its sensitivity to this metalloid, while the responses of the CS population confirm the As-tolerance. These findings suggest that these populations are different ecotypes of B. verticillata.