Climate Change and Dryland Agricultural Ecosystem Management

Response of chlorophyll fluorescence characteristics of Populus
euphratica heteromorphic leaves to high temperature
Wang Haizhen1,2, Han Lu1,2, ∗, Xu Yali2,Wang Lin
1 Xinjiang Production & Construction CorPS key laboratory of Protection and Utilization of Biological Resources in
Tarim Basin. Alar 843300, China
2.College of Plant Science of Tarim University, Alar, 843300,China.
Abstract: Populus euphratica Oliv is the only naturally-distributed tall arbor species in arid desert
regions of Tarim basin. The long term adaptation to such desert environment induces the formation of
heteromorphic leaves of Populus euphratica,and a single adult tree commonly has ploymophic leaves,
such as lanceolate, oval and serrated broad-oval leaves. The extremely high ternperature in desert is
much higher than in other regions, so the study of the response of Populus euphratica on high
temperature stress will help understanding the resistance mechanism of heteromorphic leaves to heat
stress. Taking three heteromorphic leaves of Peuphratica as the material, chlorophyll fluorescence
characteristics and excitation energy distribution in different leaves of Peuphratica were investigated
under different temperature treatment. The results showed that there is little variation of Fo ,Fm ,Fv/Fm
and Fv/Fo of Peuphratica heteromorphic leaves from 25℃ to 45℃,especially Fv/Fm can maintain 0.78
and normal photosynthesis reaction. But Fm , Fv/Fo , Fv/Fm , Fv'/Fm', qP, ΦPSⅡ, P and ETR decreased
obviously with heat stress(>45℃), Fo , qN and E increased significantly, and D fluctuated up or
down. It illustrated that high temperature stress decreased the activity of PSⅡreaction center and
photochemical electron transfer rate, inhibiting the heat dissipation and distribution balance of
excitation energy between PSⅠand PSⅡ, leading to photosynthetic apparatus damaged and
photosynthetic rate decreased. The chlorophyll fluorescence parameters of Peuphratica heteromorphic
leaves varied significantly different with temperature increasing, chlorophyll fluorescence parameters
of serrated broad-oval leave has obviously higher than that of lanceolate and oval leaves. The result
suggested that serrated broad-oval leave has greater heat tolerance ability than others. A fuzzy
membership function was defined to synthetically evaluate the high-temperature resistance ability of
three heteromorphic leaves. And the result suggested that serrated broad-oval leave was the most
heat-tolerant.
Keywords: Populus euphratica Oliv; heteromorphic leaves; high-temperature stress; heat-tolerance;
chlorophyll fluorescence characteristics
∗ Corresponding author: HAN Lu, Email:hlzky@163.com
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