In this study,we measured the photosynthetic rate,the contents of primary inorganic elements,and nitrate reductase activity and leaf N content of Torreya grandis seedlings subjected to different inorganic nitrogen treatments. The results showed that the nitrogen forms and the ratio had significant impact on the photosynthetic rate,N,P,K content, and the nitrate reductase ( NR) activity of T. grandis seedlings. With the mixture of NH4 +-N and NO3 --N at the ratio of 1:1 and 3:1,the photosynthetic rate,and stomatal conductance (Gs) and transpiration rate (Tr) were significant higher compared to plants fed with sole NH4 +-N or NO3 --N. However,there were no different significances in intercellular CO2 concentration (Ci) among the different inorganic nitrogen treatments. The sole NH4 +-N and NO3 --N fed plants had lower phosphorus ( P ) and potassium ( K ) content than that treated with mixed nitrogen of NH4 +-N and NO3 --N. Plants supplied with both forms of N ( NH4 +-N /NO3 --N =25/75 and 50/50 ) had higher NO3 - content and NR activity in comparison to the plants only fed with NO3 --N. Compared to the plants fed with NH4 +-N or NO3 --N alone,significant higher N content was observed in the plants fed with mixture of NH4 +-N and NO3 --N ( NH4 +-N /NO3 --N =50/50 and 25/75). It is concluded that Torreya grandis seedlings have no obvious preference to NH4 +-N or NO3 --N. The mixture of NH4 +-N and NO3 --N at the ratio of 1∶1 is able to boost the photosynthesis,nutrients absorption and nitrogen metabolism of T. grandis seedlings.
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