Effect Of Different N Treatment On The P Accumulation Characteristics And Premoval Potentials Of P. Sinofasciata Grown Under P Enriched Soils

Quantities of P fertilizer and organic fertilizer were input into the agroecosystems to improve the available P to plants and soil fertility has ultimately resulted in P immobilization and accumulation in soil, raising the possibility of P enriched in soils and eutrophication. P accumulator used for phytoremediation is an effective method for extracting excess P from P-based fertilizers impacted soil. However, most of them were annual plant, biomass and P accumulation may be relatively low of some common row crops and forage grasses when used for extracting excess soil P. So, how to improve the P accumulation capacity and P removal potential of P accumulators is particularly important. Nitrogen ?N? was widely used in common crops to improve the P absorb capacities; however, rarely reported were found in P accumulators. Therefore, a mining ecotype ?ME? was used in this study to investigate the effects of different nitrogen ?N? treatments on growth, P accumulation characteristics, and P removal potentials of P. sinofasciata, with a non-mining ecotype ?NME? as contrast. The relationship between root morphology, plant phosphorus form, relative enzyme activities and the ability of P accumulation of P. sinofasciata grown under high P soils supplied with N were revealed in this research. The summary of the primary results is as following:?1? Shoot and root biomass of P. sinofasciata significantly increased with the N supply levels up to 140 mg kg^-1, beyond which significant decrease was found. P concentration and bioaccumulation coefficient also increased with ascending N treatment. No significant tendency was found in translation rate of it. Maximum P accumulation of P. sinofasciata was noticed in soil amended with 140 mg kg^-1, reached 223.73 mg plant^-1 in the ME and 159.79 mg plant^-1 in the NME. The ME demonstrated higher biomass, P accumulation than that of the NME. Availabie P concentration of the ME apparently higher than the NME under 70,140, and 210 mg kg^-1. The activities of acid phosphatase and phytase of root and shoot of the ME were the highest with 350,140 mg kg^-1 N supply, respectively. The ME displayed significantly greater root and shoot acid phosphatase, phytase activities compared to the NME.?2? Biomass of root, stem, and leaf of P. sinofasciata significantly increased in response to the prolonged growth period. The ME showed significantly higher biomass in stem and leaf than that of the NME under 9 and 11 weeks of growth. Shoot P concentration of both ecotypes was in the order of root>leaf>stem, and the ME demonstrated greater P concentration compared to the NME. A highest P accumulation rate in shoot was noticed in both ecotypes when grown for 11 ?the ME? and 13 weeks ?the NME?, suggesting that the ME and the NME had the greatest P accumulation capacity at 11 and 13 weeks, respectively. P mainly distributed in stems and leaf of both ecotypes, reached 90%. Shoot P accumulation of the ME significantly increased with the ascending growth periods up to 13 weeks, beyond which a parallel was found. P accumulation of the ME reached 141.33 and 165.81 mg plant^-1 at 11 and 13 weeks, respectively, and it was 1.28 and 1.08 fold higher than the NME. Shoot Pi ?inorganic phosphorus?, ester P, nucleic P, and residual P notably decreased in response to the prolonged growth period. The Pi, ester P, and residual P concentration in root of the ME significantly increased with the adding growth periods, but nucleic P concentration decreased. The ME showed higher ester P, nucleic P, and residual P content than the NME, but lower Pi content than the NME. The result suggesting that lowering the shoot Pi content of the ME is beneficial to reduce the mobility of P, ultimately contributing to accumulation of P in plants.?3? P content of P. sinofasciata notably increased with the adding P treatment, and reached a peak value under 800 mg kg^-1. Tissue P content ranged from 5.75-8.25 g kg^-1 in the ME and 5.21-7.10 g kg^-1 in the NME. P accumulation rate in the stem and leaf of the ME notably greater than in the root, and reached a peak value under 800 mg kg^-1. P mainly distributed in stems and leaves, and the total distribution ratio of the ME was significantly higher than that of the NME. P accumulation in the stem and leaf of the ME significantly increased with the increasing P supply levels, and reached 121.04 and 196.65 mg pot^-1 under 800 mg kg^-1, respectively; P accumulation in the stem and leaf of the NME reached 105.85 and 151.84 mg pot^-1 under 800 mg kg^-1. P extraction rate, plant effective number ?PEN?, and maximum potential yield of both ecotypes obviously decreased in response to increasing concentrations of P, P removed from soil and maximum potential P removal significantly increased with the ascending P concentration. In addition, the ME demonstrated higher P removed from soil, maximum potential yield, and maximum potential P removal compared to the NME. P extraction rate, plant effective number ?PEN? of the NME significantly greater than the ME. The result showing that the ME could uptake and remove more P from various high P concentrations.?4? Maximum biomass of P. sinofasciata was noticed under 70 mg L^-1. Shoot P accumulation reached its peak value at 70 mg L^-1. Under different nitrogen treatment, the ME displayed significantly greater biomass, and P accumulation compared to the NME. In addition, root length, root surface area, and root volume of the ME increased until the N concentration reached 105 mg L^-1, specific root length evidently decreased with N concentration up to 70 mg L^-1 for the ME, beyond which an increase was found. Furthermore, the ME showed higher total root length, specific root length, root volume, root surface area compared to the NME under 5?105 mg L^-1, indicating that optimal root morphology is a good advantage for P uptake and removal of the ME from P enriched media.