台湾青枣品种及野生种的光合作用日变化及光响应特征

 在冬季田间条件下，对3个台湾青枣品种与野生种的光合作用日变化和光响应进行观测。结果表明：4种青枣的净光合速率日变化曲线均为“双峰”型，其中‘大脆蜜’的日平均光合速率、蒸腾速率和水分利用率在3个经济栽培品种中表现最高；午间光合速率和气孔限制值出现降低，胞间CO2浓度略有升高，表明光合速率午间降低主要是受非气孔限制因素影响。这几种青枣品种的光补偿点在21.2～51.6 (mol·m^-2·s^-1之间，光饱和点在 800～1800 (mol·m^-2·s^-1之间，表观量子效率在0.032～0.057之间，说明这几个品种均属喜阳植物。‘大脆蜜'和野生种具有较高的光饱和点，表现出较强的喜光性，‘五千’的光补偿点和光饱和点相对于其他两个品种和野生种都比较低，显示喜光耐荫植物特性。建议在青枣生产中，应根据光合速率、水分利用率、蒸腾速率等不同光合特性来选种和管理。

Diurnal Variations and Light Response of Photosynthesis in Three Cultivars and Wild Type of Ziziphus mauritiana Lam

Under the field conditions in winter, diurnal variations and light response of photosynthesis in leaves of three cultivated species and their wild species of Ziziphus mauritiana Lam. were investigated by using the Li-6400 portable photosynthesis system. The results indicated that the diurnal variation of net photosynthetic rate (Pn) exhibited dual-peak curves because of midday depression. Pn, transpiration rate (Tr) and water use efficiency (WUE) of Dacuimi cultivar were significantly higher than those of Misi and Wuqian cultivars. The lightly increase in Ci and the decrease in stomatal limitation (Ls) accompanied a reduction of Pn at noon indicated that the depression of photosynthetic rate was mainly due to the non-stomatal limitations. The light compensation point (LCP) and saturation point (LSP) were 21.2～51.6 (mol·m-2·s-1 and 800～1800 (mol·m-2·s-1 ,respectively, in these cultivars, and the apparent quantum yield(AQY) were 0.032～0.057. Thus, it is suggested that the tested four Ziziphus mauritiana Lam. were heliophilous plants. Because of higher LSP in Dacuimi and wild species, these plants showed heliophilous abilities. However, the LSP and LCP of Wuqian were lower than the others, which might reveal a helioskiophyte feature. Therefore, it was suggested that appropriate cultivars and managing methods should be chosen by different photosynthetic traits such as Pn, WUE and Tr in the production of Ziziphus mauritiana Lam.