科研之友
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摘要
Above- and below-ground productivities and tissue N content were measured monthly to quantify N incorporation to sustain eelgrass growth in Koje Bay on the south coast of Korea from January to December 2002. N acquisition was also estimated through measurements of N uptake kinetics, tissue biomass, and in situ inorganic N concentrations in water column and sediments. Above-and below-ground productivities were highest in summer and lowest in late fall and winter. Leaf tissue N content was highest in December and lowest in July, while rhizome tissue N content was highest in October and lowest in April. Estimated monthly N incorporation by leaf tissues based on the leaf productivity and N content ranged from 0.4 g N m(-2) month(-1) in November to 2.0 g N m(-2) month(-1) in May. N incorporation by below-ground tissues ranged from 0.1 g N m(-2) month(-1) in February to 0.2 g N m(-2) month(-1) in October. Annual whole plant N incorporation was 14.5 g N m(-2) y(-1), and N incorporation by leaf tissues accounted for about 87 % of total N incorporation. Maximum uptake rate (V-max) and half saturation constant (K-m) of leaf NH4+ uptake were significantly lower than those of root NH4+ uptake. Above-and below-ground biomass ranged from 20.8 g DW m(-2) and 8.6 g DW m(-2) in winter to 350.0 g DW m(-2) and 81.3 g DW m(-2) in spring, respectively. NH4+ concentrations varied from 0.2 to 4.3 mM in water column and from 93.0 to 551.7 mM in sediment pore water. Based on these measurements, annual N acquisition by root tissues contributed slightly higher than that by leaf tissues to total plant N acquisition. During winter, monthly leaf N acquisition was lower than monthly leaf N incorporation. This implies that Z. marina has internal nitrogen retention system to offset the shortage and excess of nitrogen.
- 出版日期2013-12
