Abstract: In order to provide scientific guidance for nitrogen fertilization in Phyllostachys violascens stands, a pot experiment was  carried out with five ratios of NO₃^--N∶NH₄⁺-N at 1∶0, 2∶1, 1∶1, 1∶2 and 0∶1. Measured indicators included chlorophyll a (Chla), chlorophyll b (Chlb) and carotenoids (Car) contents, net photosynthetic rate (P_n), stomatal conductance (G_s), intercellular CO₂ concentration (C_i), transpiration rate (T_r), and activities of nitrate reductase (NR) and glutamine synthetase (GS) in leaves of Phyllostachys violascens. Results showed that, with increasing NH₄⁺-N proportion in nitrogen supply, the  photosynthetic pigment contents, G_s, C_i and T_r  rose at first and then fell. These variables under the treatment of ammonium/nitrate ratio at 1∶2 were significantly higher than those under the other treatments, while C_i variation was opposite. With increasing the proportion of NH₄⁺-N, the activities of NR and GS showed a trend of increase at first and then decrease, being not significantly different among the mixed nutrition treatment, but higher in the mixed nutrition treatments than in the single nitrogen treatments. Overall, it might be concluded that P. violascens  is a kind of plant that slightly prefers ammonium, and that mixture of ammonium and nitrate can facilitate leaf photosynthesis and nitrogen assimilation.

Key words: salt and alkali, grapevine, ion distribution.