氮沉降对香樟叶片光合及叶绿素荧光特性的影响研究

摘要

以香樟(Cinnamomum cam phora)为试验材料,通过模拟氮沉降的方法,研究了不同氮沉降条件下香樟叶片的光合、叶绿素荧光生理的表现,揭示了相应的生理生态机制.结果表明,适当浓度的氮沉降对香樟的生长具有促进作用,而过量的氮沉降会降低其净光合速率,从而对其生长产生抑制作用；不同处理组香樟的光补偿点(LCP)、光饱和点(LSP)高低顺序均为高氮组(HN)、低氮组(LN)、对照组(CK),前者组问存在显著差异,而后者组间差异不显著,氮沉降降低了香樟叶片对弱光的利用能力,但对其强光利用能力的影响不显著；不同处理组香樟的叶色值高低顺序为HN、LN、CK,香樟叶片的叶绿素含量随着氮沉降量的增加而增加;氮素的增加抑制了香樟叶片光系统Ⅱ(PSⅡ)反应中心的潜在活性,以及其捕获激发能的效率,氮素的增加对提高香樟叶片的电子传递速率起到了促进作用,且适量的氮沉降能够促进香樟叶片PSⅡ反应中心的反应效率.%The simulated nitrogen deposition experiment was conducted on Cinnamomum camphora to investigate the photosynthesis and chlorophyll fluorescence of Cinnamomum camphora under different nitrogen treatment. The results showed that the proper nitrogen deposition had positive effect on Cinnamomum camphora growth, while the excessive nitrogen supply would decrease the photosynthetic rate and further inhibited the Cinnamomum camphora growth. The light compensation point (LCP) and light saturation point (LSP) of different nitrogen deposition treated Cinnamomum camphora follow the order of high nitrogen treatment (HN)>low nitrogen treatment (LN)>control group (CK). There was significantly difference between LCP of different nitrogen deposition treated Cinnamomum camphora , while the difference between LSP was not obvious. Nitrogen deposition could decrease the utilization capability of Cinnamomum camphora for weak light, but it had little effect on strong light utilization. The SPAD value of different nitrogen deposition treated Cinnamomum camphora was in order of HN>LN>CK, which means the chlorophyll content of Cinnamomum camphora was increased with increasing the nitrogen supply. The increasing nitrogen content inhibited the potential activity of PS II reaction centers and further decreased the capture efficiency for excitation energies. Proper nitrogen deposition could enhanced the photochemical efficiency of PS II reaction center.