Effects of soil compaction stress on photosynthesis，chlorophyll fluorescence parameters of cucumber (Cucumis sativus L.) leaves

Soil compaction, one of the fatigue signals of greenhouse soil, affects growth, yield and nutrition absorption of crops grown in greenhouse conditions. In the present study, effects of soil compaction stress were investigated on photosynthesis，chlorophyll fluorescence parameters of cucumber(Cucumis sativus L.) leaves. Results showed that net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) decreased, while intercellular CO2 concentration (Ci) increased in cucumber plants grown under soil compaction stress. These changes further resulted in reduction of specific leaf weight (SLW), lowering of node position for the first female flower bud initiation and thus early development of fruits. Decreased photosynthesis of leaves was associated with chlorophyll content, electron transport activity (Fm/Fo), maximal photochemical transformation efficiency (Fv/Fm) and potential activity (Fv/Fo) of photosystem Ⅱ reaction center（PSⅡ）in cucumber plants grown under soil compaction stress.