黄土高原半干旱区典型植物资源利用效率及光合日变化探析

Diurnal variation of photosynthesis and resource utilization efficiency of the typical plants in the semi-arid area of Loess Plateau

为探明黄土高原半干旱区6种典型植物刺槐(Robinia pseudoacacia)、垂柳(Salix babylonica)、山桃(Amygdalus davidiana)、银杏(Ginkgo biloba)、榆树(Ulmus pumila)及槭树(Acer miyabei)的资源利用效率及对环境因子的响应机制。本研究采用Li-6400便携式光合作用测定系统对光合生理指标进行测定,分析光合速率与环境因子间的关系,并使用贝叶斯信息准则验证多元回归方程拟合度;同时计算了叶片光能利用效率(LUE)、长期水分利用效率(WUE)、叶碳利用效率(C_(i)UE_(L))光合氮、磷素利用效率(PNUE、PPUE)。结果表明:(1) 6种植物的最大净光合速率(P_(n))、LUE、WUE、PNUE、PPUE及CUE均有显著性差异;(2)6种植物的净光合速率(P_(nmax))、蒸腾速率(T_(r))、胞间CO_(2)浓度(C_(i))、气孔导度(G_(s))、气孔限制值(L)日变化趋势不同。除山桃外,其他5种植物的P日变化均有明显的光合午休现象;刺槐和垂柳的P日均值较高;(3)不同环境因子与植物P均存在紧密联系,其中光合有效辐射、土壤含水率对植物光合速率影响最大;(4) 6种植物的多元线性回归模型间均有显著差异,且刺槐与环境因子间的模型是拟合优度最佳的模型;(5)用隶属函数法评价结果表明,6种植物的综合资源利用效率大小为刺槐>银杏>垂柳>榆树>槭树>山桃。总体来看,银杏和垂柳有较高的光合元素利用效率,生长速度快,且抗旱能力强。因此,在黄土高原区植树造林优选树种时,可优先选择垂柳和银杏,以提高造林成活率,缩短生态恢复进程。

To explore the resource utilization efficiency and response mechanism of the typical plants Robinia pseudoacacia,Salix babylonica,Amygdalus davidiana,Ginkgo biloba,Ulmus pumila,and Acer miyabei in the semi-arid area of the Loess Plateau,the photosynthetic physiological and ecological indexes of six plants were measured by Li-6400 portable photosynthesis measurement system,the relationship between photosynthetic rate and environmental factors was analyzed,and Bayesian information criterion was used to verify the model fitting degree;and calculated the leaf light use efficiency (LUE),long-term water use efficiency (WUE_(L)),photosynthetic nitrogen use efficiency (PNUE),photosynthetic phosphorus use efficiency(PPUE) and leaf carbon use efficiency (CUE_(L)) were calculated.The results show that:(1) There were significant differences in the maximum net photosynthetic rate (P_(nmax)),LUE,WUE,PNUE,PPUE,and CUEamong the six plants (P<0.05).(2) The photosynthetic physiological indexes of six plants are:net photosynthetic rate (P_(n)),transpiration rate (T_(r)),intercellular CO_(2)concentration (C_(i)),stomatal conductance (G_(s)),and stomatal limit (L_(s)) showed differences.(3) Except for Amygdalus davidiana,the diurnal variation of Pin the other five plants showed an obvious“noon break”phenomenon,among which Robinia and Salix babylonica had higher diurnal mean value of P.(4) There were significant differences among the six plant multiple linear regression models (P<0.001),and the model between Robinia pseudoacacia and environmental factors was the best model of good fit.(5) The results showed that the comprehensive resource utilization efficiency of six plants was Robinia>Ginkgo>Salix babylonica>Ulmus pumila>Acer miyabei>Amygdalus davidian.Overall,Ginkgo biloba and Salix babylonica have high photosynthetic resource utilization efficiency,fast growth speed and strong drought resistance.Therefore,when selecting tree species for afforestation in the Loess Plateau,Salix babylonica and Ginkgo biloba can be preferentially selected to improve the survival rate of afforestation and shorten the process of ecological restoration.