首页|Nitrogen fertilization enhances water-use efficiency in a saline environment

Nitrogen fertilization enhances water-use efficiency in a saline environment

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Effects of salinity and nutrients on carbon gain in relation to water use were studied in the grey mangrove, Avicennia marina, growing along a natural salinity gradient in south-eastern Australia. Tall trees characterized areas of seawater salinities (fringe zone) and stunted trees dominated landward hypersaline areas (scrub zone). Trees were fertilized with nitrogen (+N) or phosphorus (+P) or unfertilized. There was no significant effect of +P on shoot growth, whereas +N enhanced canopy development, particularly in scrub trees. Scrub trees maintained greater CO assimilation per unit water transpired (water-use efficiency, WUE) and had lower nitrogen-use efficiency (NUE; CO assimilation rate per unit leaf nitrogen) than fringe trees. The CO assimilation rates of +N trees were similar to those in other treatments, but were achieved at lower transpiration rates, stomatal conductance and intercellular CO concentrations. Maintaining comparable assimilation rates at lower stomatal conductance requires greater ribulose 1p"5-bisphosphate carboxylase/oxygenase activity, consistent with greater N content per unit leaf area in +N trees. Hence, +N enhanced WUE at the expense of NUE. Instantaneous WUE estimates were supported by less negative foliar tp#pdC values for +N trees and scrub control trees. Thus, nutrient enrichment may alter the structure and function of mangrove forests along salinity gradients.

salinity gradientcanopy developmentstomatal conductancetranspiration ratemangrove forestshoot growthwater usesaline environmentseawater salinityscrub zone

MARTIN, KATHERINE C.、BRUHN, DAN、LOVELOCK, CATHERINE E.、FELLER, ILKA C.、EVANS, JOHN R.、BALL, MARILYN C.

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Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia

Centre for Marine Studies and School of Biological Sciences, University of Queensland, St. Lucia, Queensland 4072, Australia

Smithsonian Institution, Smithsonian Environmental Research Center, 647 Contees Wharf Rd., PO Box 28, Edgewater, MD 21037, USA

2010

10.1111/j.1365-3040.2009.02072.

Plant, Cell & Environment

Plant, Cell & Environment

ISSN：0140-7791
年,卷(期)：2010.33(3)