Effect of the Different Grass Species Inter-planting on the Photosynthetic Characteristics of Pear

[Objective] The grass species suitable for the pear planting was selected through the research on the effect of different grass-planting systems on the photosynthetic characteristics of pear.[Method] The diurnal variation of net photosynthetic rate and photosynthesis of pear,which was planted in four species of grass growths,was measured with CIRAS-2 portable photosynthesis system.[Result] The diurnal variation of net photosynthetic rate(Pn) of pear showed a single peak.The Pn value of pear in the different grass-planting system was different.The highest Pn value of pear was from the treatment of the alfalfa planted between two lines of pear trees,which was 11.08 μmol/(m2·s);then,the ryegrass,10.48 μmol/(m2·s);and the lowest value was from the CK,without grass planted between two lines,9.28 μmol/(m2·s).The largest prevention value of the pear stomata value was 0.349 5,which was from the CK;and the minimum,0.234 8,from ryegrass.The maximum of water-using efficiency was 2.848,which was from the treatment of alfalfa planting and the minimum,2.048.[Conclusion] The theoretical basis of the grass planted between the pear tree lines in orchard was provided.