Effects of foliar nitrogen application on growth and photosynthetic characteristics of Taxus cuspidata seedlings.

In order to find the growth responseto nitrogen fertilizing during the breeding of Taxus cuspidata, six-year-old seedlings were taken as experimental materials to study the fertilizing effects of foliar nitrogen on growth, leaf nitrogen content, chlorophyll content and photosynthetic characteristics. The seedlings were treated with three nitrogen levels (0.5, 1.0, 1.5 g/L) and three nitrogen forms, namely, urea, nitrate-nitrogen and ammonium nitrogen. The results showed that the growth of seedlings treated with nitrogen were better than the seedlings treated with water (CK), and the branch growth treated with 1 g/L urea was 39.1% longer than that of CK (P 0.01). Leaf nitrogen content and chlorophyll content of all nitrogen treated seedlings increased obviously, the seedlings treated with 1.5 g/L urea had the highest nitrogen content which was 20.0% higher than CK (P0.01), total chlorophyll content and chlorophyll a content of the seedlings fertilized with 1 g/L urea were 20.5% and 27.1% higher than that of CK, respectively (P0.01). The seedlings treated with nitrogen had better photosynthetic indexes than that of CK (except for the seedlings treated with 1.5 g/L ammonium sulfate) including the net photosynthetic rate (Pn), the maximum net photosynthetic rate (Pmax), apparent quantum efficiency (AQY) and light saturated point (LSP), and Pmax of seedlings treated with 1 g/L urea was improved by 62.0% (P 0.01) compared with CK. In general, total chlorophyll content and Pmax of seedlings showed an increasing trend as leaf nitrogen content increased, 1 g/L urea treatment had the best result, and there was no obvious difference between nitrate-nitrogen and ammonium nitrogen treatment.