山豆根叶片光合特性对光强和干旱的响应

Response of Photosynthetic Characteristics to Light Intensity and Drought of Euchresta japonica Leaves

摘要:

山豆根(Euchresta japonica)为我国II级重点保护野生植物。该研究通过设置不同遮阴网的层数和采用不同浓度的聚乙二醇溶液浇灌，探讨了山豆根光合特性对光强和干旱的响应。结果表明, 山豆根叶片的饱和光强为683.06~907.07mmol/(m²·s); 单层遮阴处理叶片的最大电子传递速率和最大净光合速率整体高于双层遮阴处理，其中单层遮阴且未进行干旱处理的叶片最大电子传递速率和最大净光合速率最高，分别为55.36和6.73mmol/(m²·s)；相同遮阴条件下，叶片的最大净光合速率及其对应的饱和光强均随干旱程度增加整体呈下降趋势；单层遮阴条件下的蒸腾速率和水分利用效率均整体高于双层遮阴条件下的。不同处理下叶片光系统II的实际光化学效率、光化学猝灭系数以及非光化学猝灭系数等整体上均无显著差异(P>0.05)。山豆根属半阳生植物，其叶片利用弱光能力较强，植株具有较强的耐干旱能力。因此，建议在开展野外回归、迁地保护、人工栽培等工作时，进行适当遮阴处理并保持充足的土壤含水量。

Abstract:

Euchresta japonica is a Class II key protected wild plant in China. The response of photosynthetic characteristics to light intensity and drought was studied by setting different layers of shade nets and watering with different concentrations of polyethylene glycol solution. The results showed that the saturated light intensity of E. japonica leaves was 683.06~907.07 mmol/(m²·s). The maximum electron transfer rates (ETR_max) and the maximum net photosynthetic rate (P_nmax) under single layer shading were higher than those under double layer shading. The ETR_max and P_nmax under single layer shading without drought were the highest of 55.36 and 6.73 mmol/(m²·s), respectively. Under the same shading condition, the P_nmax and the corresponding saturated light intensity of E. japonica decreased with the increase of drought degree. The transpiration rate and water use efficiency under single layer shading were higher than those under double layer shading. The actual photochemical efficiency, photochemical quenching coefficient and non-photochemical quenching coefficient of photosystem II of E. japonica leaves showed no significant difference among different treatments (P>0.05). Euchresta japonica is a semi-sunny plant, whose leaves whose leaves can take advantage of weak light and its plants have strong drought tolerance. Therefore, it is suggested that proper shading and adequate soil water content should be maintained during field return, ex situ conservation and artificial cultivation.