CO2浓度升高对杉木幼苗生长及其光合特性和养分含量的影响

Effect of Elevated CO2 on Growth,Photosynthetic Characteristics and Nutrient Concentration of Cunninghamia lanceolata Seedlings

以杉木优良无性系‘洋061’幼苗为材料,设置常规CO2浓度400μL·L^-1(对照组)和CO2加富浓度800μL·L^-1(处理组)两个处理,研究CO2浓度加富对杉木幼苗生长、根系形态特征、光合生理以及养分含量的影响,以明确杉木优良无性系对CO2浓度升高的响应特征,为杉木苗木高效培育提供理论依据。结果表明:(1)CO2加富能显著促进杉木幼苗生物量的积累和苗高的生长,并显著促进杉木根系生长,其根长、根系表面积、根系体积和根系直径分别较对照增加14.60%、28.26%、41.98%和14.70%。(2)CO2加富能促进杉木叶片类胡萝卜素含量显著增加,使杉木叶片净光合速率(Pn)、胞间二氧化碳浓度(Ci)和水分利用效率(WUE)分别较对照显著提高51.03%、14.13%和151.20%,并使气孔导度(Gs)和蒸腾速率(Tr)分别显著下降58.72%和44.00%。(3)CO2加富使杉木叶片最大荧光(Fm)、可变荧光(Fv)、PSⅡ潜在光化学效率(Fv/Fo)、PSⅡ实际光化学效率(ΦPSⅡ)和光化学淬灭系数(qP)分别较对照显著增加11.48%、11.25%、6.33%、20.38%和30.34%,且不同处理间差异显著,非光化学淬灭系数(NPQ)较对照显著下降21.90%(P<0.05),但对初始荧光(Fo)和PSⅡ最大光化学效率(Fv/Fm)无显著影响(P>0.05)。(4)CO2加富处理显著增加植株钙元素的含量,并显著降低植株磷元素的含量。研究认为,短期CO2加富处理可通过增加光合色素含量,提高叶片净光合速率和光能利用效率,进而增强叶片光合能力,同时促进根系生长,增强植物对养分吸收的能力,最终促进杉木幼苗的生长。

We conducted a pot experiment in growth chamber with two CO2 concentrations(400μL·L^-1 and 800μL·L^-1)in this study by using seedlings of superior clone of Cunninghamia lanceolata‘Yang 061’to investigate the effects of CO2 enrichment on seedlings growth,roots morphology,photosynthetic physiology,and nutrient concentration of C.lanceolata seedlings,and to explore the response characteristics of superior clone of C.lanceolata to elevated CO2 concentration,and ultimately providing theoretical basis for high-quality and efficient cultivation of C.lanceolata seedlings.The results showed that:(1)CO2 enrichment significantly promoted the biomass accumulation and the height growth of C.lanceolata seedlings,and significantly promoted the roots growth as well.The root length,root surface area,root volume and root diameter under CO2 enrichment treatment were 14.60%,28.26%,41.98%and 14.70%higher than that of control,respectively.(2)CO2 enrichment significantly increased the carotenoid content in leaves of C.lanceolata seedlings,and this was also true for net photosynthetic rate(Pn),intercellular CO2 concentration(Ci)and water use efficiency(WUE),which were 51.03%,14.13%and 151.20%higher in CO2 enrichment treatment as compared with control,respectively,while stomatal conductance(Gs)and transpiration rate(Tr)were decreased by 58.72%and 44.00%,respectively,when compared with control.(3)CO2 enrichment significantly increased the maximal fluorescence(Fm),variable fluorescence(Fv),PSⅡpotential efficiency(Fv/Fo),PSⅡactual photochemical efficiency(ΦPSⅡ)and photochemical quenching coefficient(qP),which were 11.48%,11.25%,6.33%,20.38%and 30.34%higher than that in control,respectively,while non-photochemical quenching coefficient(NPQ)were significantly decreased by 21.90%,and no significant difference was observed in initial fluorescence(Fo)and PSⅡmaximal photochemical efficiency(Fv/Fm)between treatments.(4)CO2 enrichment significantly increased plant calcium concentration,while significantly decreased plant phosphorus concentration.Taken all these results together,our results showed that short-term CO2 enrichment can promote the growth of C.lanceolata seedlings by increasing photosynthetic pigment contents and net photosynthetic rate and light use efficiency in leaves,which resulted in a higher photosynthetic capacity,and by promoting the growth of roots,which in-turn enhanced plant nutrient uptake capacity.