黄土高原矿区典型先锋木本植物幼苗光合特性研究

Photosynthetic Characteristics of Typical Pioneer Species of Woody Plant Seedlings in the Mining Areas of the Loess Plateau

为揭示黄土高原矿区典型先锋木本植物(臭椿、刺槐、荆条、沙棘和紫穗槐)的生态适应特征,通过温室土培实验,采用Li-6400XT便携式光合仪,对这5种木本植物幼苗不同光强和CO2浓度下的光合特征进行了分析。结果表明:直角双曲线修正模型可以较好地拟合5种植物幼苗的光响应和CO2响应曲线;5种植物幼苗光饱和点的最大净光合速率(Pmax)、表观量子效率(AQY)、暗呼吸速率(Rd)、光饱和点(LSP)、光补偿点(LCP)、CO2饱和点的最大净光合速率(Amax)、羧化效率(CE)、光呼吸速率(Rp)、CO2饱和点(CSP)和CO2补偿点(CCP)差异均显著(P<0.05),其中沙棘幼苗的Pmax、Amax、CE、Rd和Rp均显著高于其他4种植物幼苗,LSP和LCP显著高于紫穗槐、刺槐和荆条幼苗(P<0.05),其光合生产潜力和呼吸较高,对不同光强和CO2浓度的适应能力均较强;臭椿幼苗的Pmax和AQY显著低于其他4种植物幼苗,LSP和LCP显著高于紫穗槐、刺槐和荆条幼苗,其对弱光的利用效率、耐阴性及光合能力较弱;紫穗槐和刺槐幼苗的Amax显著低于其他3种植物幼苗,光合潜能较低;CO2浓度的升高有利于提高5种植物幼苗的水分利用效率;在黄土高原矿区生态恢复实践中,应参考该5种木本植物幼苗对光照和CO2浓度的适应性进行合理配置。

In order to reveal the ecological adaptation of typical pioneer woody plants（Ailanthus altissima,Robinia pseudoacacia, Vitex negundo L. var. heterophylla,Hippophae rhamnoides and Amorpha fruticosa） in the mining areas of the Loess Plateau, this paper analyzed the photosynthetic characteristics of these five plant seedlings under different light intensity and CO2 concentration conditions by using Li-6400 XT portablephotosynthesis system based on greenhouse soil culturing experiment. The results showed that the modified rectangular hyperbola model could better fit the light and CO2 response curves. Firstly, the indexes of these fiveplant seedlings such as Pmax, AQY, Rd, LSP, LCP, Amax, CE, Rp, CSP and CCP presented significant difference（P〈0.05）. The indexes of Pmax, Amax, CE, Rd and Rpabout Hippophae rhamnoides were significantly higher thanthat of the other four plant seedlings and the indexes of LSP and LCP were significantly higher than those seedlings of Robinia pseudoacacia, Amorpha fruticosa, and Vitex negundo（P〈0.05）. Hippophae rhamnoides seedlings could better adapt to different light intensity and CO2 concentration conditions, and contained stronger photosynthesis producing and breathing potential. Secondly, the indexes of Pmax and AQY of Ailanthus altissima seedlings were significantly lower than that of the other four plant seedlings, and its LSP and LCPwere higher than those seedlings of Robinia pseudoacacia, Amorpha fruticosa and Vitex negundo L. var.heterophylla. Ailanthus altissima seedlings had weak shade tolerance and photosynthetic capacity, and failed to take advantage of weak light. Thirdly, the Amax of Amorpha fruticosa and Robinia pseudoacacia seedlings were significantly lower than that of the other three plant seedlings and contained lower photosynthetic potential.Finally, the increase of CO2 concentration was conducive to the improvement of water use efficiency of these five plant seedlings. As a result, it is important to conduct reasonable allocation referring to their ecological adaptability to the light and CO2 concentration in the practice of ecological restoration in mining areas of the Loess Plateau.