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以北京典型绿化树种元宝枫(Acer truncatum)幼苗为试验对象,设置透水硬化地表、不透水硬化地表和对照(自然地表)3种地表类型,分析了元宝枫幼苗主要生理生态指标和生长指标对硬化地表的响应特征。结果表明:相比于对照,2种硬化地表引起地表温度显著升高,元宝枫幼苗叶片净光合速率(Pn)、气孔导度(gs)、蒸腾速率(Tr)、光合色素含量、光系统II光化学有效量子产量(Fv’/Fm’)、PSII实际光量子效率(ФPSII)、光合电子传递速率(ETR)、光化学猝灭系数(qp)及最大净光合速率(Pmax)、表观量子效率(AQY)和光饱和点(LSP)均下降,叶片丙二醛(MDA)含量增加,株高和基径降低。硬化地表引起地表温度升高,对元宝枫幼苗生长造成了热胁迫,严重伤害了植物光系统II,光合电子传递被限制,减少了植物叶片的光合作用,抑制了植物生长。与不透水地表相比,透水地表粗糙度和孔隙度较高,增加了透水地表的热储存和热传导能力,地表温度显著升高形成的热胁迫对植物的生理伤害和生长影响更大。因此,在城市建设中,应考虑降低硬化地表的温度,以缓解城市绿化树种可能受到的热胁迫。
Acer truncatum seedlings of typical greening tree species in Beijing were used as experimental objects to establish three types of surface water-permeable hardened, impervious hardened and control (natural surface) types. The main physiological and ecological indexes and growth indexes of the seedlings of Acer truncatum were analyzed. Surface response characteristics. The results showed that compared with the control, the surface temperature of two hardened ground surfaces increased significantly. The net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), photosynthetic pigment content, photosystem II (Fv ’/ Fm’), PSII actual photon efficiency (ФPSII), photosynthetic electron transfer rate (ETR), photochemical quenching coefficient (qp) and maximum net photosynthetic rate (Pmax), apparent quantum yield ) And light saturation point (LSP) decreased, MDA content and leaf height decreased. Hardening the surface causes the surface temperature to rise, causing heat stress on the seedling growth of A. fortunei and seriously injuring the photosystem II of the plant. The photosynthetic electron transfer is limited, reducing the photosynthesis of the plant leaves and inhibiting the growth of the plant. Compared with the impervious surface, the permeability of surface roughness and porosity is higher, which increases the thermal storage and thermal conductivity of the permeable ground surface. The heat stress caused by the significant increase of surface temperature has a greater impact on the physiological damage and growth of plants. Therefore, in the urban construction, we should consider reducing the temperature of hardened surface to alleviate the possible heat stress of urban greening trees.