硝态氮和铵态氮供应比例对雷竹碳、氮、磷化学计量的影响

【目的】硝态氮（NO₃--N）和铵态氮（NO₄+-N）是土壤中容易被植物吸收利用的两种无机态氮，对植物养分吸收的影响不同。研究不同比例硝态氮（NO₃--N）和铵态氮（NO₄+-N）供应下植物器官碳（C）、氮（N）、磷（P）化学计量特征，有助于了解土壤养分对植物体内C、N、P营养元素分配规律的影响。【方法】采用盆栽方法，以一年生雷竹（Phyllostachys violascens）为试材，进行了NO₃--N和NO₄+-N配比试验。在供氮量均为12.5 g/pot的前提下，设5个硝、铵供应比例处理:1:0、2:1、1:1、1:2、0:1。试验处理20天后，取雷竹竹冠上、中、下部叶片和细根样品，测定其C、N、P含量，并对其异速生长关系进行分析。【结果】不同硝铵比例处理间雷竹叶片和细根C含量差异不显著，N、P含量差异显著。随着氮素供应中NO₄+-N比例的增加，叶片和细根的N、P含量均在硝铵比为1:1、1:2时显著高于其他处理，C:N、C:P、N:P总体上呈降低趋势，表明生长速率提高；叶片和细根N与C、N与P的Ⅱ类线性回归斜率在硝铵比为1:1、1:2时显著增大，表明相同N供应水平下，硝铵比为1:1、1:2时，C、P有更多的积累量。【结论】不同硝铵比显著影响着雷竹叶片和细根C、N、P的化学计量特征，合理的硝铵混合比例可促进雷竹对C的固定和N、P吸收，以硝铵比为1:1、1:2较适宜雷竹生长与养分积累。

Effects of nitrate and ammonia supply ratio on the C,N and P stoichiometric characteristics ofPhyllostachys violascens

[Objectives]Nitrate nitrogen (NO3–-N) and ammonium nitrogen (NH4+-N) are the two main types of soil inorganic nitrogen absorbed by plant easily, different plants are in favor of different types. Study the carbon (C), nitrogen (N) and phosphorus (P) stoichiometric characteristics of plants supplied with different NO3–-N and NH4+-N ratio will help understanding the suitability of soil nutrition supply.[Methods]A hydroponic pot experiment was conducted using one-year-oldPhyllostachys violascens as materials. At the same N applying rate of 12.5 g/pot, five different ratios of NO3–-N and NH4+-N were set up: 1∶0, 2∶1, 1∶1, 1∶2, 0∶1. The C, N and P contents were measured and their stoichiometric characteristics of leaves and fine roots were discussed after the experiment 20 days.[Results]Different forms of nitrogen supply had no significant effects on the C contents of leaves or fine roots, but significantly influenced the stoichiometric characteristics of N and P of Phyllostachys violascens. With the increasing of NH4+-N proportion in nitrogen supply, both the N and P contents in the ratios of 1∶1 and 1∶2 were higher than in the others. The ratios of C∶N, C∶P and N∶P in leaves and fine roots were decreased with increasing of NO3–-N∶ NH4+-N ratio, indicating the increasing growth rates of leaves and fine roots. The SMA slopes for N vs C and N vs P in leaves and fine roots also followed a shape of inverted-V, which increased significantly in the NO3–-N∶NH4+-N ratios of 1∶1 and 1∶2, indicated that more C and P was accumulated.[Conclusions]NO3–-N∶NH4+-N supply ratios significantly affect the C, N and P stoichiometric characteristics of leaves and fine roots ofPhyllostachys violascens. Mixing supply of ammonium and nitrate nutrition is in favor of the fixation of C and absorption of N and P. The suggested ratios of nitrate to ammonium are 1∶1 and 1∶2 for the growth and nutrient accumulation of testedPhyllostachys violascens.