Abstract: 【Objective】Sour cucumber shows a high resistance to the root-knot nematode Meloidogyne incognita. To make clear on the photosynthetic responsive characteristics of its resistance will provide a theoretical basis for isolation and functional identification of resistance gene. 【Method】 The effects of nematode infection on photosynthesis, chlorophyll fluorescence parameters and physiological indices related of cucumber leaves resistant and susceptible to M. incognita were investigated by using seedling inoculation in greenhouse.【Result】 Nematode infection induced a significantly lower decrease of cucumber leaf chlorophyll (Chl) content in resistant Sour cucumber than in susceptible Beijingjietou. Decreased extents of Chl content with nitrogen content reduction in Sour cucumber leaves were less than in Beijingjietou. Net photosynthetic rate(Pn), stomatal conductance (Gs) decreased in two varieties leaves after nematode infection, intercellular CO2 concentration (Ci) of leaves decreased in Sour cucumber, while its value have a sharp rise in Beijingjietou. Gs reduction in response to relative water content (RWC) declining in Sour cucumber leaves was more sensitive than Beijingjietou. Nematode infection led to a lower reduction of actual photochemical efficiency (ΦPSⅡ) and photochemical quenching (qP), while induced a significantly higher increase of non-photochemical quenching (qN) in Sour cucumber than in Beijingjietou. Nematode infection has little effect on the initial slope of Pn/Ci in Sour cucumber, leaving a sharp decrease in Beijingjietou. 【Conclusion】 The results indicated that there is a lower decrease of chlorophyll content in Sour cucumber, so as to maintain a higher net photosynthetic rate in resistant compared with susceptible ones. All these did not cause significant effect on the plant growth of Sour cucumber.

Key words: sourcucumber, Meloidogyneincognita, resistance, photosynthesis