高温对马铃薯块茎形成期光合及抗氧化特性的影响

Effects of high temperature on potato photosynthetic and antioxidant properties during tuber formation period

块茎形成期高温是影响宁南山区马铃薯产量和品质的重要因素。本研究通过连续2年试验,选用当地主栽品种'青薯9号',设置自然温度(对照)、低温、高温3个处理,研究马铃薯块茎形成初期、中期、后期、块茎膨大期及主要淀粉积累期的光合特性和抗氧化酶活性。结果表明:高温降低了马铃薯功能叶片的净光合速率(P_n)、荧光综合指标(P_I)、光能供应化学反应的最大效率(F_v/F_m)及潜在光化学活性(F_v/F_o);P_n在马铃薯块茎形成后期高温较自然温度降低34.55%,较低温处理降低53.15%,PI在块茎形成后期高温较低温降低了42.22%;高温处理的根系活力、超氧化物歧化酶(SOD)及过氧化物酶(POD)活性也有所降低,丙二醛(MDA)、脯氨酸(Pro)和过氧化氢酶(CAT)均有不同程度的升高;相关性分析表明,除抗氧化系统中的CAT活性、MDA和Pro含量与产量呈负相关外,其余指标与产量呈正相关,与根系活力的相关性最为显著;马铃薯块茎形成中期高温天气不利于马铃薯功能叶片的光合作用,降低了P_n、P_I等光合指标,使功能叶片的抗氧化系统遭到一定的破坏,导致产量下降。

High temperature during tuber formation is an important factor affecting the yield and quality of potatoes in mountainous areas of southern Ningxia.A 2-year field experiment was conducted to investigate the effects of normal temperature(CK),low temperature and high temperature on the photosynthesis and antioxidant enzyme activities of potato cultivar‘Qingshu 9’during the initial,middle,and late stages of tuber formation,stage of tuber expansion,and main stage of starch accumulation.The results showed that net photosynthetic rate(Pn),fluorescent composite index(PI),maximal efficiency of light energy conversion(Fv/Fm),and potential photochemical activity(Fv/Fo)in potato decreased significantly under high temperature compared with normal temperature and low temperature.In the late stage of tuber formation,Pnat high temperature decreased by 34.55%and 53.15%compared to normal and low temperature respectively,while PIat high temperature decreased by 42.22%compared to low temperature.At high temperature,root activity,and the activities of protective enzymes such as superoxide dismutase SOD and POD significantly decreased,whereas malondialdehyde(MDA),proline(Pro)and catalase(CAT)increased in varying degrees.The yield of potato was negatively correlated with CAT activity,MDA and Pro concentrations in the antioxidant system,while it was positively correlated with other measured variables,especially the root activity.High temperature in the middle stage of tuber formation was not conducive to the photosynthesis in functional leaves of potatoes,which reduced Pn,PIand other photosynthetic indices.Meanwhile,the antioxidant system of functional leaves was damaged in a certain extent,resulting in a yield decline.