Response of common buckwheat and Tartary buckwheat from different elevations to selenium treatment

Common buckwheat and Tartary buckwheat were grown in Slovenia outdoors at different elevations – 300 m, 600 m and 1180 m a.s.l. Both species were foliarly treated with selenium twice (in the vegetative phase and in the flowering phase). The effects of Se treatment and different growing locations on selected biochemical, physiological and anatomical traits were monitored. In Se treated common buckwheat, amount of chlorophylls was higher in plants from Ljubljana (the lowest elevation – 300 m a.s.l.) than in plants grown in Podbeže (600 m a.s.l.), whereas in control group, plants grown in Ljubljana contained more chlorophylls than plants from Javorje (the highest elevation – 1180 m a.s.l.). In both buckwheat species, Se alone did not affect amount of chlorophylls in any of location. In Se treated common buckwheat plants, the amount of UV absorbing compounds was the highest in plants, grown at the highest elevation. In common buckwheat, Se lowered the number of CaOx in plants, grown in Javorje. Conditions at different elevations, as well as treatments with Se, did not affect potential and effective photochemical efficiency of Photosystem II. Keywords: common buckwheat, Tartary buckwheat, elevation, selenium, morphological characteristics, biochemical characteristics

Physiological response of Arundo donax L. to thallium accumulation in a simulated wetland

A simulated wetland experiment was used to investigate the effect of thallium (Tl) accumulation on the growth of Arundo donax L., its photosynthetic characteristics and its antioxidant enzyme activities. Tl accumulated in the order of stems<leaves<roots and increased gradually with increasing Tl concentrations (from 0 to 2.5µgL–1). Moderate Tl applications (from 0.2 to 2.5µgL–1) increased the rate of both photosynthesises (Pn) and transpiration (Tr), as well as catalase and peroxidase activity. Tl significantly affected stomatal conductivity, but had no effect on the relative chlorophyll content (SPAD values) or the potential and effective photochemical efficiency of photosystem II. However, intercellular CO2 concentrations and superoxide dismutase decreased in response to increasing Tl concentrations. Although 50µgL–1 Tl significantly decreased the SPAD values, as well as the potential and effective photochemical efficiency of photosystem II, it had no effect on Pn or Tr. These results suggest that root restriction and oxidative stress are involved in the mechanism of Tl toxicity, but the photosynthetic system of A. donax was not harmed by certain concentrations of Tl, indicating the strong tolerance of this species to increased Tl pollution.