AM宿主植物金银花对喀斯特干湿交替的光合响应

Effects of AM Fungi on Photosynthetic Capacity of Lonicera Hypoglanca under Dry and Wet Alternation in Southwest Karst Area

以盆栽的方式,探究了接种丛枝菌根(AM)真菌后金银花在西南岩溶地干湿交替的变水环境下光合响应的变化,期望为喀斯特地区生态环境的恢复提供思路.结果表明:在适宜水分条件下,接种AM真菌促进了金银花的净光合速率(Pn),蒸腾速率(Tr),气孔导度(Gs)和气孔密度.在短期干旱条件下,接种AM真菌对Pn和Tr均没有明显影响;然而干旱持续时间加长后,Pn有显著提高,Gs受到抑制,Tr相比未接种组反而降低,水分利用效率(WUEi)有所上升.在短期干湿交替下,接种AM真菌后各项光合指标均没有显著提高,反而金银花植株的Pn和Tr被抑制,长期干湿交替的WUEi虽然提高但是以牺牲植物的光合作用为代价.总之,接种真菌对适宜水分下金银花光合能力的促进最为明显,干旱下有一定促进能力,但是在反复的干湿交替变水下,接种植株的光合作用没有得到显著促进.

Plants growing in the karst region of southwest China are frequently subjected to drought and repeated dry and wet alternating water habitat because of shallow soil,high rate of naked rock and frequent precipitation led by global climate.AM fungi can improve the tolerance of host plants to drought.However,it is not known whether AM fungi stimulate the tolerance of host plants to dry and wet alternation.On the other hand,photosynthesis is the basis of plant physiological processes and life activities,and is highly sensitive to changes of the external environment.Therefore,it is very necessary to explore the photosynthetic response of plants to frequent alternation of drying and wetting in vulnerable karst vegitation.In this study,we observed the effects of AM fungi on the photosynthetic capacity of Lonicera hypoglanca in different water treatments by indoor pot experiment.The results show that the net photosynthetic rate(Pn),transpiration rate(Tr),stomatal conductance(Gs)and stomatal density of Lonicera hypoglanca were promoted by AM fungi under normal water condition.Under the condition of short-term drought,Pn and Tr were not significantly affected by AM fungi.However,with the prolongation of drought time,Pn and water use efficiency(WUEi)were significantly increased,while Gs and Tr were declined.In the short-term dry and wet alternation,the photosynthetic indexes were not promoted by inoculation of AM fungi.However,in long-term dry and wet alternation,Pn and Tr were inhibited,but WUEi was stimulated by sacrificing plants photosynthesis.In conclusion,the effects of inoculation of fungi on Pn of Lonicera hypoglanca under normal water supply were the most obvious.AM fungi also had a positive effect under drought conditions.However,in the face of repeated dry and wet alternation,the inoculation of fungi had no obvious effects on photosynthetic capacity of Lonicera hypoglanca.