ObjectivesNitrate nitrogen (NO3--N) and ammonium nitrogen (NO4+-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 NO4+-N ratio will help understanding the suitability of soil nutrition supply.
MethodsA hydroponic pot experiment was conducted using one-year-old Phyllostachys violascens as materials. At the same N applying rate of 12.5 g/pot, five different ratios of NO3--N and NO4+-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.
ResultsDifferent 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 NO4+-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:NO4+-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:NO4+-N ratios of 1:1 and 1:2, indicated that more C and P was accumulated.
ConclusionsNO3--N:NO4+-N supply ratios significantly affect the C, N and P stoichiometric characteristics of leaves and fine roots of Phyllostachys 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 tested Phyllostachys violascens.
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