Abstract: The effect of applying nitrogen on the photosynthetic characteristics of two-year Quercus liaotungensis seedlings results showed that applying nitrogen had significant effects on the growth and photosythetic product distribution of Quercus liaotungensis seedlings. Proper nitrogen level could increase the total biomass and promote the growth of above-ground part. Nitrogen could significantly increase the net photosynthetic rate (P_n) of Quercus liaotungensis and expand the period of vigorous growth. The P_ns of treatment N10 were 16.62%, 23.35%, 25.43% in June, July and August that were higher than that of CK. Daily P_n curves had single-peaks in June and August, whereas curves had double-peaks in July. This phenomenon was related to "photosynthesis midday depression". The major factor that affected P_n was the concentration of intercellular CO₂. Nitrogen application might influence the concentration of leaf nitrogen content and the activity of nitrate reductase which affects ABA contents and ultimately causes P_n variation of Quercus liaotungensis seedlings.

Key words: Applying nitrogen, Photosynthesis character, Quercus liaotungensis

摘要： 采用盆栽控制试验研究0.05,0.10,0.15,0.20 g·kg^-1施氮处理对2年生辽东栎(Quercus liaotungensis)幼苗光合生理特征的影响,以期为黄土高原生态环境建设工程的可持续发展提供科学依据。结果表明:施氮对其幼苗的生长及光合产物的分配产生显著影响。适量施氮可促进幼苗生物量增加,一定程度上改善了幼苗生长不良的现象;施氮可提高其幼苗净光合速率(P_n),延长光合作用的旺盛期,其中0.1 g·kg^-1施氮处理下P_n峰值在6-8月比对照分别提高16.62%,23.35%和25.43%;幼苗P_n日变化在6月和8月呈单峰曲线,7月呈双峰曲线,这与气孔因素造成的光合"午休"现象有关;影响光合速率的因素中,胞间CO₂浓度(C_i)对辽东栎P_n影响最大。这可能是因为施氮影响叶片氮含量和硝酸还原酶活性,影响辽东栎叶片内源ABA水平,调节气孔开闭,从而调节C_i,最终影响其P_n。

关键词: 辽东栎, 光合特性, 施氮