滨海盐碱地隔盐改良对两种草本地被的光合特性影响

Effects of Salt-isolation Treatments on Photosynthesis Characteristics of Two Herbaceous Ground Cover Plants in Coastal Saline-Alkaline Land

在上海崇明岛瀛东村研究碎石铺设盐碱土改良措施对土壤EC值的影响,以及土壤盐分变化对紫鸭趾草(Setcreasea purpurea B.K.Boom)和中华常春藤(Hedera nepalensis var.sinensis)两种植物光合特性的影响。结果表明:实施土壤改良措施后,不同处理间EC值差异逐渐显著。土壤EC值的变化对紫鸭趾草的净光合速率和蒸腾速率影响不大,而对中华常春藤影响显著。在光响应曲线和参数比较中,采用非直角双曲线模型模拟,光响应曲线的变化趋势基本一致;在同等光合有效辐射(PFD)时Pn值表现为4cm铺设厚度>2cm铺设厚度>0cm铺设厚度。随着土壤盐分浓度降低,紫鸭趾草和中华常春藤的最大净光合速率(Ama)x、表观量子效率(AQY)、光饱和点(LSP)和光补偿点(LCP)均逐渐升高。紫鸭趾草的光合作用对土壤盐分具有较强的适应性,并对强光保持了很强的利用能力,但对弱光的调节作用不显著,而中华常春藤适应性较弱,对强光的利用能力较低,但对弱光利用能力强。总之,两种植物的光合适应性均受到土壤盐分的影响,紫鸭趾草比中华常春藤适应性更强。在盐碱地植物应用中从光合特性考虑,紫鸭趾草更适应当地土壤,但通过碎石铺设盐碱土改良技术,降低土壤盐分浓度后,亦可提高植物对光环境的适应性。

The effect of amelioration methods of stone paving on soil EC value had been studied in Yingdong Village on Shanghai Chongming Island,which also affected photosynthetic characteristics of Setcreasea purpurea B.K.Boom and Hedera nepalensis var.sinensis.In this study,we used stone paving measure to reduce soil salinity and EC values.The different treatments showed significant difference.The influence of soil EC value changes on the net photosynthetic rate and transpiration rate of Setcreasea purpurea B.K.Boom was not distinguished as opposed to Hedera nepalensis var.sinensis.The light response curves and several parameters of photosynthesis were measured,and by nonrectangular hyperbola model showed a similar trend under different EC values.Pn of two herbaceous ground cover plants under stone paving thickness for 4 cmthat under thickness for 2 cmthat under thickness for 0 cm at the same PFD was represented.The decreasing soil salinity influenced by soil amelioration caused the fact that maximum net photosynthetic rate,apparent quantum yield,light saturation point and light compensation point of two kinds of plants gradually increased,respectively.Compared to Hedera nepalensis var.sinensis,Setcreasea purpurea B.K.Boom showed the stronger adaptability of its photosynthesis to soil salinity and it maintained the significant ability to use strong light,but had unsignificant ability to use weak light.Whereas Hedera nepalensis var.sinensis showed the opposite results that the ability of using strong light was less than that of using weak light.Consequently,photosynthetic adaptability of Setcreasea purpurea B.K.Boom was better than Hedera nepalensis var.sinensis.Affected by soil salinity,Setcreasea purpurea B.K.Boom was more adapted to local soil.The amelioration methods could help reducing soil salinity and also enhance the adaptability of plants to light environment.