• ammendante
• genotossicità
• fitotossicità
• scambio gassoso
• fitoestrazione
• stress ossidativo
• pianta
• arsenico

In the present study, carried out at IBBA (Institute of Agricultural Biology and Biotechnology) and ISE (Institute of Ecosystem Study), CNR, the effects of arsenic on Cannabis sativa L. was analyzed in order to evaluate the phytoextraction capacity of the plant. Phytoextraction is a subprocess of phytoremediation in which plants are used to clean up contaminated matrices of various types (soil, sediments, water, etc.). Additionally, additive substances are often used in phytoextraction process (assisted phytoextraction).
For our experiments, plants of Cannabis sativa L., var Ferimon, were grown in a soil contaminated by arsenic, a polluting and toxic metalloid; the soil was sampled in a contaminated industrial area, where the As concentration was extremely high (approximately 2000 mg/kg). This soil sample was used to set up microcosms with or without phosphate amendment (KH2PO4 0.1 M).
When used as phosphate, phosphorus (P) is a plant nutrient and for its chemical properties and similarities with As, it can compete with the most oxidized form of As (arsenate) in plant nutrition and with soil binding sites. Moreover phosphate is very important for the As mobilization in soil and consequently it can influence As absorption and accumulation in plants.
The phytoextractive capacity of hemp plant has been evaluated by analyzing the following parameters: the bioavailability variation of As in the soil, the As content into the roots, stems, and leaves; the effects of As on plant biomass production.
Results indicated that Cannabis sativa L. was able to grow on the considered
As-contaminated soil, and it was capable to phyto-accumulate a low concentration of As in aerial part, so the whole phytoextraction processes will have to be implemented.
Moreover biochemical analyses, with appropriate enzymatic assays, were carried out to evaluate oxidative stress on Cannabis sativa L. leaves; results suggested a general increase of enzymes involved in the oxidative stress response, except the catalase. In addition analysis of gas exchanges in leaves evidenced negative effects on plant physiology due to As contamination.
Genotoxic and phytotoxic effects of different As contaminated matrices (derived from As polluted soil treated or not with phosphate and/or soil vegetated with hemp for 30 days), were analyzed in Vicia faba L. (a model plant for genotoxicity study) and for comparison in Cannabis sativa L.. Results indicated that the As contaminated matrices induced phytotoxic effects highlighted by germination index and primary root length reduction.
Cytotoxic and genotoxic effects were evaluated by means of cytogenetic analyses of a statistically significant number of plant root apices derived from the different treatments. Cytotoxic effect was determined considering the variation of mitotic activity (Mitotic Index, MI) of plant meristems in comparison with control plant; genotoxic effect was estimated by micronucleus test (MN-test), a test based on the appearance of micronuclei as a results of DNA breakage caused by clastogenic agents.
Cytogenetic analysis revealed the significant decrease of MI, the increase of chromosome anomalies and micronuclei in the root meristems from plants exposed to As contaminated soil.
As a whole, the results obtained in this work indicated that the hemp, being a very resistant plant to environmental stresses and capable of producing a large biomass, can represent an interesting system, yet to be investigated and implement for its use in remediation projects of As contaminated soils.