Response of chlorophyll fluorescence characteristic of Trifolium repens L. to water stress.

[Objective] The aim was to study response of chlorophyll fluorescence parameters in Trifolium repens L. leaves to water stress from perspective of physiology. [Method] With T. repens cultivar Haifa as tested material,three soil water content levels were set to culture plants,including 75% (no stress,CK),50% (moderate stress,LD) and 25% (severe stress,HD),the effects of water stress on chlorophyll fluorescence parameters were determined. [Result] The results showed that the chlorophyll fluorescence parameters changed a little when the relative soil moisture content was 75% and 50%,while the chlorophyll fluorescence parameters such as conversion efficiency of primary light energy (Fv/Fm) of PSⅡ,the photochemical quenching coefficient (qP) and the quantum yield of PSⅡ electron transport (ΦPSⅡ) decreased respectively when the relative soil moisture content was 25%. [Conclusion] When T. repens in severe drought conditions,the physiological functions were damaged,showing symptoms of drought injury.