摘要:水分供应对甘薯生长发育、产量形成具有重要影响。为探讨不同水分处理对甘薯光合与荧光特性的影响，本研究以鲜食型甘薯‘烟薯25号’为试验材料，研究不同水分处理下甘薯叶片的光合-光响应过程及其荧光特性，并利用不同模型对光响应过程进行拟合。研究结果表明：干旱和淹水处理显著降低了甘薯叶片净光合速率（Pn）、气孔导度（Gs）和蒸腾速率（Tr）；当PAR≤1 000 μmol·m-2·s-1时，干旱及淹水处理Pn的降低主要受气孔限制，当PAR>1 000 μmol·m-2·s-1时，Pn的降低主要受非气孔限制。荧光参数表明，干旱及淹水处理下甘薯叶片光系统Ⅱ（PSⅡ）对光的捕获及吸收能力下降，热耗散增加。光响应模型以直角双曲线修正模型拟合精度最高，且能拟合出饱和光强，适用于不同的土壤水分环境。模型拟合参数显示，所有处理甘薯叶片初始量子效率（α）为0.039~0.055，位于0~0.125的理论范围值内，干旱、淹水处理下甘薯叶片表现出显著的光饱和、光抑制现象，光能利用减弱，且淹水处理的光利用能力小于干旱处理。综合分析认为，直角双曲线修正模型是甘薯不同水分条件下光响应变化最佳模型。干旱及淹水处理均会对甘薯光系统造成损伤，使甘薯光合能力下降，淹水比干旱更易于降低甘薯叶片对光的利用能力，高光强会加重甘薯水分的胁迫程度。
关键词:甘薯/
水分供应/
光合特性/
荧光特性/
光响应曲线模型
Abstract:Water supply plays a vital role in the growth and yield of sweet potato. In this paper, the edible sweet potato 'Yanshu 25' was used to study the photosynthesis-light response process and fluorescence characteristics of sweet potato leaves under different water treatments. Different models were used to study the light response process, and the effects of different water treatments on photosynthesis and fluorescence characteristics of sweet potato were analyzed. The results showed that:drought and flooding treatment significantly reduced the net photosynthetic rate (Pn), stomatal conductance (Gs), and transpiration rate (Tr) of sweet potato leaves; at PAR ≤ 1 000 μmol·m-2·s-1, the decrease of Pn under drought and flooding treatment was induced by stomatal restrictions, and at PAR > 1 000 μmol·m-2·s-1, the decrease of Pn was induced by non-stomatal restrictions. The fluorescence parameters indicated that the light capture and absorption capacity of photosystem Ⅱ (PS Ⅱ) of sweet potato leaves decreased under drought and flooding treatment, while the heat dissipation increased. The modified rectangular hyperbola model demonstrated the best fit among all the light response models and matched the light saturation point. The model was, therefore, suitable for simulation of photoresponse simulation under different soil water environments. The model parameters showed that the initial quantum efficiency (α) of sweet potato leaves ranged from 0.039 to 0.055 under different water treatments, falling within the theoretical range of 0-0.125. The sweet potato leaves demonstrated significant photo-saturation and photo-inhibition under drought and flooding treatment, resulting in a reduced light utilization capacity. The light utilization capacity under flooding treatment was lower than that under drought treatment. It can be concluded that the modified rectangular hyperbola model is the optimal model to analyze light response changes of sweet potato under different water conditions. Both the drought and flooding treatment damage the photosynthetic system of sweet potato and reduce its photosynthetic capacity. Flooding is more likely to reduce the light utilization capacity of sweet potato leaves when compared with drought, and high light intensity increases the degree of water stress of sweet potato.
Key words:Sweet potato/
Water supply/
Photosynthesis characteristics/
Chlorophyll fluorescence characteristics/
Light response curve model
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