持续土壤干旱对甘薯光合性能及产量的影响

Effects of soil drought stress on photosynthesis and yield of sweetpotato

以广泛种植的徐薯32和宁紫薯1号为试验材料,研究持续土壤干旱对甘薯功能叶光合参数及块根产量和碳水化合物的影响.结果表明:干旱胁迫下,徐薯32可通过自身的品种属性(丰产性)弥补受旱甘薯产量降低的部分损失,但2个试验品种抗旱指数均小于0.5,仍属于低抗品种.受持续土壤干旱影响,甘薯净光合速率降低是由气孔限制和非气孔限制共同作用引起的,其中气孔限制占主导因素.此外,干旱胁迫下,甘薯叶片净光合速率的降低并不是块根产量降低的主要原因,而是干旱胁迫影响了甘薯块根中可溶性糖(蔗糖)/淀粉的平衡调节能力,使蔗糖转化为淀粉的生理过程受抑制,才显著降低块根淀粉累积和产量.

The photosynthetic parameters of functional leaves and yield and carbohydrate in tuberous root of sweetpotato were studied under soil drought stress,taking two sweetpotato cultivars,Xushu 32 and Ningzishu 1,grown in 2018 as examples.The results showed that Xushu 32 could make up for part of the loss of yield reduction through its own variety attribute(high yield)under drought stress.However,the drought resistance indexes of Xushu 32 and Ningzishu 1 were less than 0.5,and both of them still belonged to low-resistant varieties.Under soil drought stress,both stomatal limitation and non-stomatal limitation worked together to reduce the photosynthetic performance in sweetpotato,but stomatal limitation accounted for the major factor.In addition,the decrease of net photosynthesis rate in sweetpotato leaves was not the main reason for the decrease of tuberous root yield under drought stress.In fact,the maim reason was the effect of drought stress on the balance regulation ability of soluble sugar(sucrose)/starch in tuberous root of sweetpotato,which inhibited the physiological process of converting sucrose into starch,thus significantly reduced the starch accumulation and yield of tuberous root.