尖孢镰刀菌侵染对马铃薯光合效率和叶绿素荧光参数影响

Effects of Fusarium oxysporum infection on photosynthetic efficiency and chlorophyll fluorescence parameters of potato plants

为研究枯萎病对马铃薯光合特性的影响,在幼苗期接种尖孢镰刀菌Fusarium oxysporum后,统计抗病品种陇薯10号和感病品种新大坪的病情指数,并测定叶绿素含量、光合及荧光参数。结果表明,尖孢镰刀菌侵染30 d后马铃薯表现出枯萎病症状,叶绿素含量显著降低,其中叶绿素a含量降幅最大,抗病品种陇薯10号比对照降低9.64%,感病品种新大坪比对照降低14.24%。尖孢镰刀菌侵染后马铃薯光合效率显著降低,侵染30 d后,抗病品种陇薯10号净光合速率比对照降低39.56%,感病品种新大坪比对照降低47.13%。病株的光响应曲线参数光补偿点、暗呼吸速率和表观量子效率都显著提高;而光饱和点和最大净光合速率都显著低于对照,表明尖孢镰刀菌侵染缩小了马铃薯对光能的利用有效范围。病株CO_(2)响应曲线参数CO_(2)饱和点、最大净光合速率和羧化效率分别显著低于对照;病株CO_(2)补偿点和光呼吸速率反而升高,说明碳同化过程受到尖孢镰刀菌的限制。暗适应下的初始荧光、最小荧光、最大荧光、PSII最大光化学效率、光适应下PSII最大光化学效率及实际光化学效率、光化学猝灭系数、非光化学猝灭系数和光合电子传递速率均显著低于对照,说明光合色素含量的降低导致PSII反应中心捕光能力减弱,尤其是叶绿素a含量的降低导致了光化学转化效率降低,从而使马铃薯净光合速率降低。尖孢镰刀菌侵染对马铃薯的生长发育产生了较大影响,株高、主茎数、结薯数量、经济产量和生物产量显著降低,且抗病品种陇薯10号的这些指标降低幅度小于感病品种新大坪。陇薯10号发病株光合色素含量、光合特性和农艺性状等参数降低幅度都小于新大坪。

To study the effects of Fusarium oxysporum infection on photosynthetic characteristics of potato,the disease indexes on resistant cultivar Longshu 10 and susceptible cultivar Xindaping were calculated after inoculation with F.oxysporum at seedling stage,and the chlorophyll content,photosynthesis and fluorescence parameters were measured.The results showed that inoculation of F.oxysporum resulted in potato wilt disease.Chlorophyll content decreased significantly compared with the control,with greatest reduction in chlorophyll a.Chlorophyll content decreased 9.64%in Longshu 10 and 14.24%in Xindaping.F.oxysporum infection significantly reduced the photosynthetic efficiency of potato.After 30 days of infection,compared with the control,the net photosynthetic rate decreased 39.56%in Longshu 10 and 47.13%in Xindaping.The light compensation point,dark respiration rate,apparent quantum yield were significantly higher in the diseased plants than those in the control uninoculated plants;however,the light saturation point and maximum net photosynthetic rate were significantly lower in diseased plants than those of the control,indicating that F.oxysporum infection reduced the effective range of light energy utilization of potatoes.The CO_(2) saturation point,maximum net photosynthetic rate and carboxylation efficiency of diseased plants were significantly lower than those of the control;the CO_(2) compensation point and photorespiration rate of diseased plants increased,suggesting that the carbon assimilation process was limited by F.oxysporum infection.Fluorescence parameters of the diseased plants,including indicators initial fluorescence,minimum fluorescence,maximum fluorescence,maximum photochemical efficiency of PSII,maximum photochemical efficiency of PSII under light adaptation and actual photochemical efficiency of PSII under light adaptation,photosynthetic rate,non photochemical quenching coefficient and photosynthetic electron transfer rate,were significantly lower than those of the control.This indicates that the decrease of photosynthetic pigment content leads to the weakening of light harvesting capacity of PSII reaction center,especially the decrease of chlorophyll a leads to a decrease in photochemical conversion efficiency,which reduces the net photosynthetic rate of potato.Fusarium oxysporum infection had a major impact on potato growth and development.After harvest,the plant height,number of main stems,number of tubers,economic yield and biological yield of the diseased plants decreased significantly,and the reduction rates were lower for Longshu 10 than those for Xindaping.The reduction ranges of photosynthetic pigment content,photosynthetic characteristics and agronomic traits were lower for Longshu 10 than those for Xindaping.