不同氮形态对杉木叶绿素荧光参数和叶绿体超微结构的影响

Effects of Nitrogen Forms on the Chlorophyll Fluorescence Parameters and Chloroplast Ultra-structure of Cunninghamia lanceolata

以1个月生杉木实生苗为试验材料,分析了硝态N、铵态N和铵硝混合(NH 4+∶NO 3-=3∶1)态N对杉木生长、叶绿素荧光参数和叶绿体超微结构的影响。结果表明:1)不同处理下植株根系和地上部生物量大小表现为铵硝混合处理>全硝处理>全铵处理,但不同处理间杉木植株生物量不存在显著差异(P>0.05)。2)铵硝混合处理下可变荧光强度(F v)和最大荧光强度(F m)显著高于全硝和全铵处理,而非化学荧光猝灭系数(n P q)显著低于全铵处理。3)铵硝混合处理下PSⅡ最大光化学效率(F v/F m)、PSⅡ潜在活性(F o/F v)、光化学猝灭系数(q p)和PSⅡ实际光化学效率值(QY)均显著高于全硝处理,但与铵硝混合处理间不存在显著差异(P>0.05)。4)叶绿体超微结构结果表明,全硝处理下部分叶绿体膨大隆起,基粒片层排列松散,且数量明显少于全铵和铵硝混合处理,全铵处理显著增加了叶绿体中淀粉粒的数量,而铵硝混合处理中淀粉粒则完全消失,但显著增加了嗜锇颗粒的数量。综上所述,铵硝混合处理一方面能通过增强PSⅡ反应中心电子传递效率和光能的利用能力,促进光合同化产物的积累;另一方面通过抑制淀粉粒的形成,减轻淀粉粒对光合作用的抑制,同时促进光合同化产物的输出,促进杉木幼苗的生长。

The effects of different forms of nitrogen and its composition,namely NO 3--N,NH 4+-N and NH 4+∶NO 3-=3∶1,on the seedlings growth,chlorophyll fluorescence parameters and chloroplast ultra-structure in the leaves of Cunninghamia lanceolata were investigated in this study by using 1-month-old C.lanceolata seedlings.The results showed that:1)the root and shoot biomass of the seedlings under various treatments decreased with the order of NH 4+∶NO 3-=3∶1>NO 3--N>NH 4+-N,however,the roots and shoots biomass among these treatments did not varied significantly.2)The variable fluorescence(F v)and maximal fluorescence(F m)in NH 4+∶NO 3-=3∶1 treatment were significantly higher than those in NO 3--N and NH 4+-N treatments,while it was opposite for non-chemical fluorescence quenching(n P q).(3)Moreover,the PSⅡmaximal photochemical efficiency(F v/F m),PSⅡpotential efficiency(F o/F v),photochemical quenching coefficient(q p)and PSⅡactual photochemical efficiency(QY)in NH 4+∶NO 3-=3∶1 treatment were significantly higher than those in NO 3--N treatment,while no differences were observed between NH 4+∶NO 3-=3∶1 and NH 4+-N treatments.4)Chloroplast ultra-structure results showed that some of the chloroplasts in NO 3--N treatment were swelling bulge and the numbers of grana lamellas were lower than those in NH 4+∶NO 3-=3∶1 and NO 3--N treatments,NH 4+-treatment significantly increased the starch granules numbers,while starch granules were not observed in NH 4+∶NO 3-=3∶1 treatment,and NH 4+∶NO 3-=3∶1 treatment increased osmiophilic granules numbers in chloroplast.In conclusion,NH 4+∶NO 3-=3∶1 treatment promotes the accumulation of photoassimilate by enhancing the electron transport efficiency and light energy utilization capacity in PSⅡreaction center.On the other hand,the treatment alleviates the inhibition of starch granules to photosynthesis by inhibiting their formation,meanwhile,the output of photoassimilates are promoted to accelerate the growth of the seedlings.