Study on Photosynthetic Characters of Ten Apple Cultivars in Middle Region of Guizhou Province

To provide the basis for cultivar screening and technical application of apple in middle region of Guizhou Province,the photosynthetic characters of ten apple cultivars were investigated.The results showed that the photosynthetic characters varied among the cultivars.Four groups were obtained by cluster analysis based on photosynthetic rate (Pn),and the Pn of Meng \[12.44 μmol/(m·s)\] was the largest,which was followed by New Gala,Yanfu No.1,Changfu No.2,Fuji 2001 and Benishogun.The light compensation point (LCP) diversified from 15 (Changfu No.2) to 70 (Honggailu) μmol/(m·s),and the light saturation point (LSP) ranged from 1080 (New Gala) to 1330μmol/(m·s)(Yanfu No.1).The response equations of Pn to photosynthetic active radiation (PAR) were parabolic,with the exception of New Gala.Also,the response equations were obtained between Pn and temperature (T),and the optimal T varied from 26℃ to 30℃,which different from the cultivars.Pn was closely correlated to stomatal conductance (Sc),conversely,the correlation between Pn and intercellular CO2 concentration (CO2int) was negatively significant.No obvious correlation was obtained between Pn and relative humidity (Hr).Collectively,PAR was the most important environmental factors for photosynthetic in the locality,ie.the importance of other factors were lesser relatively.