兰州北山3个灌木优势种光合特性

Research on photosynthesis characteristics of three tree bushes in Beishan Mountain of Lanzhou City

本研究对兰州北山植被优势种柽柳(Tamarix austromongolica)、侧柏(Platycladus orientalis)和柠条(Caragana korshinskii)的光合特性和微气象环境进行了测定,分析了其日变化特点,并通过灰色关联度分析方法探讨了净光合速率(Pn)与生理因素及环境因素的关联程度。结果表明,1)自然条件下,3种植物的P_n日变化均为不对称的双峰曲线,存在明显的光合"午休"现象,这是由于午间高光强、高温构成光抑制现象。2)生理因素分别与3种植物P_n的关联度由大到小依次为,柽柳:胞间CO_2浓度(C_i)>叶温(T_l)>蒸腾速率(T_r)>气孔导度(G_s)>饱和水汽压(VPD)>气孔限制值(Ls),侧柏:T_r>T_l>VPD>C_i>L_s>G_s,柠条:Tr>Tl>Ci>Gs>VPD>Ls;生理因素中C_i对柽柳P_n的影响最大,T_r对侧柏和柠条P_n的影响最大。3)环境因素分别与3种植物Pn的关联度由大到小依次为,柽柳:光合有效辐射(PAR)>相对湿度(RH)>土壤温度(Ts)>土壤湿度(SM)>大气温度(Ta)>大气CO_2浓度(Ca),侧柏:PAR>SM>T_a>T_s>RH>C_a,柠条:RH>PAR>SM>T_a>C_a>T_s;环境因素中PAR对柽柳和侧柏P_n的影响最大,RH则对柠条P_n的影响最大。

This study mainly measured the diurnal change of photosynthesis characteristics of Tamarix austromongolica,Platycladus orientalis and Caragana korshinskii in the Beishan Mountain of Lanzhou,as well as environmental factors.By using the relational grade analysis of grey system theory,the relational grade between Net photosynthetic rate（Pn）,physiological and environmental factors were calculated.The results showed：The diurnal variation of Pnof three species showed asymmetric bimodal peak curve,with a remarkable photosynthetic＂midday depressions＂.It is caused by the midday high light intensity and temperature,rather than stomatal factors.The relation grades between Pnand physiological factors was Intercellular CO2 concentration（Ci） 〉Leaf temperature（Tl）〉 Transpiration rate Tr 〉Stomatal conductance（Gs） 〉Saturation vapor pressure difference foliage（VPD） 〉Stomatal limitating value（Ls）for T.austromongolica,Tr 〉Tl〉VPD〉 Ci〉 Ls〉 Gs for P.orientalis and Tr〉 Tl 〉Ci〉 Gs〉 VPD〉 Ls for C.korshinskii.Among them,Ci has a obvious effect on Pn of T.austromongolicaand it is Tr for P.orientalis and C.korshinskii.The relation grades between Pnan environmental factors was Photosynthetically active radiation（PAR） 〉Air relative humidity（RH） 〉Soil temperature（Ts）〉 Soil moisture（SM） Air temperature（Ta） 〉Atmospheric CO2 concentration（Ca）for T.austromongolica,PAR〉 SM〉 Ta 〉Ts〉 RH〉 Ca for P.orientalis and RH PAR〉 SM 〉Ta〉 Ca〉 Ts for C.korshinskii.Among them,PAR,has a deeply effect on Pnfor P.orientalis and T.austromongolica,while itis RH for C.korshinskii.