The effects of enhanced ultraviolet-B and nitrogen supply on growth,photosynthesis and nutrient status of Abies faxoniana seedlings

Abies faxoniana is a key species in reforestation processes in the southeast of the Qinghai-Tibetan Plateau of China. The changes in growth, photosynthesis and nutrient status of A. faxoniana seedlings exposed to enhanced ultraviolet-B (UV-B), nitrogen supply and their combination were investigated. The experimental design included two levels of UV-B treatments (ambient UV-B, 11.02 KJ m(-2) day(-1); enhanced UV-B, 14.33 KJ m(-2) day(-1)) and two nitrogen levels (0; 20 g N m(-2)). The results indicated that: (1) enhanced UV-B significantly caused a marked decline in growth parameters, net photosynthetic rate (Pn), photosynthetic pigments and F (v)/F (m), (2) supplemental nitrogen supply increased the accumulation of total biomass, Pn, photosynthetic pigments and F (v)/F (m) under ambient UV-B, whereas supplemental nitrogen supply reduced Pn, and not affect biomass under enhanced UV-B, (3) enhanced UV-B or nitrogen supply changed the concentration of nutrient elements of various organs