title: Nitrogen fertilizer improves boron phytoextraction by Brassica juncea grown in contaminated sediments and alleviates plant stress.
abstract: In this study we evaluated the effect of different fertilizer treatments on Brassica plants grown on boron-contaminated sediments. Experiments were conducted in the laboratory and on the lysimeter scale. At laboratory scale (microcosm), five different fertilizers were tested for a 35-d period. On the lysimeter scale, nitrogen fertilization was tested at three different doses and plants were allowed to grow until the end of the vegetative phase (70 d). Results showed that nitrogen application had effectively increased plant biomass production, while B uptake was not affected. Total B phytoextracted increased three-fold when the highest nitrogen dose was applied. Phytotoxicity on Brassica was evaluated by biochemical parameters. In plants grown in unfertilized B-contaminated sediments, the activity of antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX) and pyrogallol peroxidase (PPX) increased, whereas catalase (CAT) decreased with respect to control plants. Addition of N progressively mitigated the alteration of enzymatic activity, thus suggesting that N can aid in alleviating B-induced oxidative stress. SOD activity was restored to control levels just at the lowest N treatment, whereas the CAT inhibition was partially restored only at the highest one. N application also lowered the B-induced increase in APX and PPX activities. Increased glutathione reductase activity indicated the need to restore the oxidative balance of glutathione. Data also suggest a role of glutathione and phytochelatins in B defense mechanisms. Results suggest that the nitrogen fertilizer was effective in improving B phytoextraction by increasing Brassica biomass and by alleviating B-induced oxidative stress.
authors.affiliation: National Research Council, Institute of Ecosystem Study, Section of Pisa, Via Moruzzi, 1, 56124 Pisa, Italy.
authors.forename: Virginia
authors.initials: V
authors.lastname: Giansoldati
authors.forename: Eliana
authors.initials: E
authors.lastname: Tassi
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Morelli
authors.forename: Edi
authors.initials: E
authors.lastname: Gabellieri
authors.forename: Francesca
authors.initials: F
authors.lastname: Pedron
authors.forename: Meri
authors.initials: M
authors.lastname: Barbafieri
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D001673:Biodegradation, Environmental; D001895:Boron / Q000378:metabolism* / Q000633:toxicity; D002851:Chromatography, High Pressure Liquid; D004305:Dose-Response Relationship, Drug; D005308:Fertilizers / Q000032:analysis; D019015:Geologic Sediments / Q000032:analysis; D007558:Italy; D009149:Mustard Plant / Q000187:drug effects / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D009584:Nitrogen / Q000494:pharmacology*; D012989:Soil Pollutants / Q000378:metabolism*; D013312:Stress, Physiological; D014508:Urea / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D005308:Fertilizers; D012989:Soil Pollutants; D014508:Urea; D009584:Nitrogen; D001895:Boron