Photosynthetic Characteristics of Zizyphus jujuba var. inermis 'Lubei-Dongzao'

Diurnal variations and light response of photosynthesis in leaves of Zizyphus jujuba var.inermis 'Lubei-Dongzao' were measured with GFS-3000 portable photosynthesis system.The results showed that the diurnal variation of net photosynthetic rate(Pn) exhibited dual-peak curves with midday depression,showing obvious 'midday depression' phenomenon.The significant positive correlation was found between the net photosynthesis rate and stomatal conductance;but the stoma limit ratio was negatively correlated to intercellular CO2 concentration.It was indicated that the photosynthesis decline during midday time was principally influenced by stomatal conductance limitation.The light compensation point(LCP) and light saturation point(LSP) of the target species were 16.0 μmol/(m2·s) and 1 500.0 μmol/(m2·s) individually,its apparent quantum yield(AQY) was 0.058,indicating that Zizyphus jujuba var.inermis 'Lubei-Dongzao' was a heliophilous plant species.The results showed that its carbon dioxide compensation point(CCP) and saturation point(CSP) was 29.54 μmol/mol and 1 352.5 μmol/mol respectively,and its carboxylation efficiency(CE) was 0.054.