黄土高原油松和刺槐叶片光合生理适应性比较

以黄土高原地区由南向北分布的杨凌、永寿、富县、安塞、米脂、神木等县为研究地点，研究不同地区油松和刺槐的光合特性与叶结构性状间的关系.结果表明，不同地区油松针叶和刺槐叶片的净光合速率（P_n）、光合氮利用效率（PNUE）、水分利用效率（WUE）、比叶质量（LMA）、氮含量（N_mass）和叶绿素相对含量（Chl）差异均达极显著水平（P＜0.001）,说明不同地区油松和刺槐的光合能力和叶结构性状参数差异很大.由南向北，油松的P_n、WUE和PNUE呈略微增加趋势，而刺槐则呈显著降低趋势，表明油松在干旱生境下仍能维持较高的光合能力，而刺槐光合能力明显受到抑制；油松和刺槐的LMA均呈略微上升趋势，而N_mass和Chl均呈略微下降趋势，且刺槐的变化幅度高于油松，说明油松从生理代谢和叶结构性状上对干旱环境的适应能力均强于刺槐.相关分析表明，不同地区油松和刺槐的LMA与N_mass整体上呈极显著负相关；P_n、PNUE与LMA、N_mass相关不显著，与Chl呈极显著正相关；WUE与LMA呈显著负相关（P＜0.05），与N_mass呈显著正相关.

Photosynthetic physiological adaptabilities of Pinus tabulaeformis and Robinia pseudoacacia in the Loess Plateau

With Yangling,Yongshou,Fuxian,Ansai,Mizhi and Shenmu,the six counties from the south to the north in the Loess Plateau as study sites,this paper studied the photosynthetic characteristics and leaf traits of Pinus tabulaeformis and Robinia pseudoacacia.The results showed that among the six sites,there were significant differences in the photosynthetic rate(P_n),photosynthetic nitrogen use efficiency(PNUE),water use efficiency(WUE),leaf mass per area(LMA),nitrogen content(N_ mass),and chlorophyll content(Chl)of P.tabulaeformis and R.pseudoacacia,suggesting that the photosynthetic capacity and leaf traits of the two species differed with sites.From the south to the north,the P_n,PNUE and WUE of P.tabulaeformis increased slightly while those of R.pseudoacacia decreased significantly,indicating that in drought habitat,P.tabulaeformis could still maintain high photosynthetic capacity,but the photosynthetic capacity of R.pseudoacacia was greatly restrained.Also from the south to the north,the LMA of P.tabulaeformis and R.pseudoacacia had a slight increasing trend,while N_ mass and Chl decreased slightly.The variation ranges of the three parameters were greater for R.pseudoacacia than for P.tabulaeformis,indicating that P.tabulaeformis had stronger drought-tolerant capability than R.pseudoacacia,which was not only exhibited in physiological metabolism,but also in leaf morphological acclimation.The correlation analysis between photosynthetic parameters and leaf traits of P.tabulaeformis and R.pseudoacacia in the six sites showed that there was a significant negative correlation between LMA and N_ mass.The P_n and PNUE of both test species had no correlations with LMA and N_ mass,but had significant positive correlation with Chl.The WUE of the species was negatively correlated with LMA,but positively correlated with N_ mass.