Chin J Plan Ecolo ›› 2012, Vol. 36 ›› Issue (2): 159-168.DOI: 10.3724/SP.J.1258.2012.00159

• Research Articles • Previous Articles     Next Articles

Dynamics of nitrogen and phosphorus concentrations and nitrate reductase and acidic phosphatase activities in Imperata cylindrica on copper mine tailings

SHEN Zhang-Jun1,2, SUN Qing-Ye1*, and TIAN Sheng-Ni3   

  1. 1School of Resources and Environment Engineering, Anhui University, Hefei 230039, China;

    2School of Life Sciences, Hefei Normal University, Hefei 230061, China; and 3School of Life Sciences, Anhui Agricultural University, Hefei 230036, China
  • Received:2011-09-21 Revised:2011-11-14 Online:2012-02-01 Published:2012-02-22
  • Contact: SUN Qing-Ye

Abstract:

Aims Our objective was to study self-regulation of nitrogen (N) and phosphorus (P) nutrient use by Imperata cylindrica at different growth stages on copper mine tailings.
Methods We obtained samples from two different nutrient habitats: copper mine tailings and farmlands. We investigated N and P distributions, N P, nutrient resorption rate, nitrate reductase and acidic phosphatase ∶ activities in I. cylindrica organs.
Important findings The N and P distributions in I. cylindrica differed by growth period. During the initial stage of growth, N and P in both populations were mainly in the rhizomes. At bud and mature times, N and P concentrations were highest in leaves and lowest in roots and rhizome. At the decay period, N and P concentrations in senescent leaves were (9.19 ± 0.80) and (0.05 ± 0.03) mg·g–1, respectively, which were significantly lower than for the control farmland. The N and P resorption efficiencies of I. cylindrica leaves in the tailings were 49.54%–65.22% and 74.71%–98.71%, respectively, with P in senescent leaves resorbed completely. However, values for the farmland system were 18.18%–52.81% and 71.39%–84.07%, respectively. These results indicated that the poor nutrition condition of the tailings can increase I. cylindrica nutrient resorption efficiency. Nitrate reductase activity of I. cylindrica leaves in the tailings was significantly higher than in the farmlands (p < 0.05); this is useful to regulate I. cylindrica nitrogen metabolism activities. But with plant growth, the differences gradually disappeared. At the same growth period, acidic phosphatase activity of I. cylindrica leaves between the tailings and the farmlands were not significantly significant (p > 0.05). With plant growth, the acidic phosphatase activities increased, which was conducive to decompose organophosphate in senescent leaves and increase P resorption efficiencies.