Isatis cappadocica Desv. is a newly found As-hyperaccumulator showing very high remediation efficiency in polluted soils. We studied the effects of arsenic at 0-1400 μM concentrations on seed germination, relative root length, relative shoot height, and root and shoot biomass in young seedlings of I. cappadocica. The seeds were from Iranian arsenic-contaminated mine spoils and from a non-contaminated population. The control for reference was brassica (Descurenia sofia). Germination decreased significantly versus the control with increasing arsenic concentrations. The response to arsenic exposure differed between the I. cappadocica populations and D. sofia. I. cappadocica from mine spoil seeds showed strong resistance to the highest As concentration, with no adverse effects until the 1000 μM dose. Germination from non-mine seeds of I. cappadocica decreased to 89.6% at 1400 μM As. D. sofia germination was completely inhibited at 400 μM As. Relative root length (RRL) and relative shoot height (RSH) decreased with increasing As concentration. Overall, RRL correlated with RSH. Shoot height and root length were more sensitive to arsenic than other endpoints, and might be used as arsenic toxicity indicators. I. cappadocica showed more As tolerance than the reference brassica.
It has long been observed that toxic heavy metals at different concentrations can induce root hair development in plants. In oilseed rape we studied ethylene levels and root hair initiation under Cd2+ stress. Growth of the primary root was inhibited but close to root tips the development of subapical root hairs was significantly stimulated by Cd2+ at 30 μM. Versus the control, the distance between the root tip and the root hair zone and the length of the epidermal cell in the elongation zone were significantly reduced by Cd2+ at the same concentration. Exogenous application of Cd2+ and 1-aminocyclopropane-1-carboxylate (ACC) to roots had similar effects on subapical root hair development. Hair density increase and hair elongation in the presence of Cd2+ were reduced by the ethylene inhibitors CoCl2 at 15 μM and aminooxyacetic acid (AOA) at 10 μM. Exposing roots to Cd2+ caused a rapid increase in superoxide radical (O2 ·-) production in the root hair differentiation zone, and at the tips of emerging and newly formed root hairs. Cd2+-induced O2 ·- production at the growing hair tips was blocked in the presence of AOA. Our findings suggest that Cd2+-induced ethylene signaling may act upstream of O2 ·-. Cd2+ promotion of O2 ·- production may operate through an ethylene signaling pathway, and O2 ·- itself may stimulate root hair elongation.
The influence of external factors, temperature and flow velocity on the corrosion processes St3 in model solutions petrochemical plant recycled water with high salinity and hardness without open systems and in the presence of the inhibiting composition. It was found that an increase in temperature leads to a linear increase in corrosion rates, and the change in circulating water flow rate leads to the extreme nature of corrosion processes; optimal conditions are determined. Recommended use of cathodic inhibitors or mixed type inhibitor, in particular, the composition "SVOD-BI" (means for controlling the biological corrosion), which can significantly reduce the effect of temperature and flow on the corrosion rate St3, promotes the growth and strengthening of the oxide film in the presence of oxygen, increases the degree of protection of steel and preventing the formation of at its surface carbonate-calcium deposits.