不同生境对栓皮栎幼苗光合生理特性的影响

Effects of habitat change on the photosynthetic characteristics of Quercus variabilis seedlings

以栓皮栎天然分布的北界(北京,NP)、中心(陕西,CP)和南界(云南,SP)3个种源的实生苗为试验材料,通过在北缘(北京)和南缘(云南)的交互移植试验,探讨不同种源幼苗光合生理性状的差异及其来源。结果表明:(1)各种源在北缘生境下的潜在最大净光合速率(Pmax)、光饱和点(LSP)、羧化效率(CE)、光呼吸速率(Rp)、光化学猝灭系数(PQ)均显著高于南缘生境(P<0.05);(2)南界种源(SP)则具有更高的CE、Rp、PSⅡ原初光能转换效率(F_v/F_m)和PSⅡ潜在活性(F_v/F_o)(SP>CP>NP);北界种源(NP)具有更高的非光化学猝灭系数(NPQ)(NP>CP>SP);(3)生境和种源的交互作用对最大羧化速率(A_(max))和LSP影响显著,Amax在南北缘生境下均以当地种源的最高;而LSP在北缘生境下以中心种源(CP)最高,在南缘生境下以北界种源(NP)最高。不同生境对表观量子效率(AQY)、CO2补偿点(CCP)、暗呼吸速率(Rd)以及叶绿素荧光参数如F_v/F_m、F_v/F_o以及NPQ影响不显著,其中AQY和Rd不受生境变化及其与种源的交互影响,这可能与栓皮栎自身遗传因素有关;(4)生长表现方面,栓皮栎幼苗在南、北不同生境下生长表现出明显差异,各种源在北缘生境下生长状况均明显优于南缘生境,且均以南界种源(SP)生长优势明显。

To explore ecophysiological variances and their sources among different geographical origins of Quercus variabilis, a reciprocal transplanting experiment was carried out at its northern （Beijing） and southern （Kunming, Yunnan Province） distributed edges at the end of April 2013. The seedlings were bred from seeds collected from three provenances： north （ Pinggu in Beijing, NP）, central （ Huanglong in Shanxi Province, CP）, and south （Anning in Yunnan Province, SP） in the autumn of 2012. After three months of acclimation, we measured two response curves, A-Par and A-Ci. More specifically, A-Par calculated light response parameters, including apparent quantum yield, AQY; maximum net photosynthetic rate, Pmax ; light saturation point, LSP ; light compensation point, LCP ; and dark respiration rate, Rd. A-Ci measured CO2 response parameters, including carboxylation efficiency, CE; maximum net photosynthetic rate, Am~ ; COz compensation point, CCP; and photorespiration rate, Rp. The proceeding values were all measured using the Li-6400 gas analyzer. Relative chlorophyll content was calculated with the SPAD-502 analyzer, and chlorophyll fluorescence parameters, including primary conversion of light energy of photosystem I1 , FJFm ; potential activation of photosystem lI , FJFo ; the non-photochemical quenching coefficient, NPQ; and photochemical quenching coefficient, PQ, were measured with the Fluropen-FP100 at the two distinctive habitats during the mid-growing season （August 15--30）. In addition, growth rate （ height and ground diameter） was measured. Our results showed that （ 1 ） the seedlings growing in the north habitat presented significantly higher P LSP, CE, PQ, and Rp than in the south habitat （P〈0.05）. （2） In both habitats, the SP had higher CE, LSP, Fv/Fm, Fv/Fo, with an order of SP, CP, and NP, while the NP had higher NPQ, with an order of NP, CP, and SP. （3） The interaction of habitats and provenances significantly affected Amax and LSP. Furthermore, the highest Areax occurred in the local provenance over the two habitats. The CP and the NP exhibited the highest LSP in the north and south habitats, respectively. Between the two different habitats, there were significant differences in AQY, CCP, Rd, F~/Fm, FiFo, and NPQ. There was no interaction of habitats and provenances found on AQY and Rd, which may indicate the determination of species genetic background. （4） Relative growth rates were significantly different between the two habitats with a higher growth rate in the north habitat for all tested provenances, and the SP consistently had the highest relative growth rate. In conclusion, our results suggest that, to varying degrees, the two distinctive habitats and the interaction of habitats and provenances affected the growth and photosynthetic characteristics of Q. variabilis seedlings. We preliminarily deduced that the SP could be well adapted to the northern habitats.