不同供氮水平对蒙古栎幼苗生物量与光合特性的影响

采用盆栽试验方法，从1、4、8、16、32 mmol·L^-1 5个N素处理对蒙古栎幼苗的生物量、相关生理指标以及光合特性等方面的影响进行研究。结果表明，随着供N水平的提高，蒙古栎幼苗根、茎和全株的生物量均在N₁₆供应下达最高，但与N₈、N₃₂处理间差异不显著，叶片生物量在N₃₂水平达最大，与N₁₆的差异不显著。根冠比随着供N水平的提高呈现降低的趋势。蒙古栎幼苗的光合参数（P_n、T_r、G_s、C_i）随供N量的增加呈现出先增加后减小的趋势，均在N₈水平下达最大。除叶绿素b之外，叶绿素a、叶绿素总量、类胡萝卜素以及可溶性蛋白含量与光合参数的变化一致，同样在N₈水平达最大。试验结果表明，增加N素供应可促进蒙古栎幼苗的生物量，或高或低的供N都会影响蒙古栎幼苗的光合作用。

Effects of Different Levels of Nitrogen Supply on Biomass and Photosynthetic Characteristics of Quercus mongolica Seedlings

A pot culture experisment was carried out to examine the effects of different levels of nitrogen supply (1,4,8,16,and 32 mmol·L^-1,represented by N₁,N₄,N₈,N₁₆ and N₃₂,respectively) on the biomass,related physiological indicators and photosynthetic parameters of Quercus mongolica seedlings.The results suggested that the biomass of roots,stems and the whole plants were the highest with the nitrogen supply of N₁₆,which was not significantly different with those of N₈ and N₃₂.The leaf biomass was the highest with the nitrogen supply of N₃₂,which was not significantly different from that of N₁₆.The root/shoot ratio decreased with the increase of nitrogen supply.The photosynthetic parameters（P_n,T_r,G_s,and C_i）in seedlings increased first and then decreased,and the maximum values appeared at N₈ level.The contents of chlorophyll a,total chlorophyll,carotenoids and soluble protein were consistent with the changes in photosynthesis parameters.These results suggested that increasing nitrogen supply can promote the biomass of Q.mongolica seedlings,and higher or lower nitrogen supply will influence the photosynthesis.