铁胁迫对小麦幼苗叶绿素荧光与光合特性的影响

Effects of iron stress on chlorophyll fluorescence and photosynthetic characteristics in wheat seedlings

以小麦西旱3号为实验材料,分析了不同浓度(0、100、300和500μmol/L)铁处理对幼苗叶片叶绿素荧光和光合生理特性的影响.结果显示,小麦幼苗叶片随c(Fe)增大,w(叶绿素a)和w(总叶绿素)及叶绿素a/叶绿素b呈先升高后降低的变化趋势,w(类胡萝卜素)、潜在最大光量子产量、光适应下最大光量子产量、实际光量子产量、光系统Ⅱ潜在活性、光化学淬灭、电子传递速率、光系统Ⅱ潜在电子传递速率等参数均减小,而非光化学淬灭和调节性能量耗散的量子产量显著升高,小麦幼苗叶片净光合速率、蒸腾速率、气孔导度及水分利用率随胁迫浓度的升高均不同程度的降低.铁胁迫抑制了小麦幼苗的正常生长,导致叶和根生物量下降.总之,铁胁迫诱导小麦幼苗叶片光合色素减少,减弱了对光能的捕获和传递,并使光系统Ⅱ反应中心受到损伤,致使激发能捕获效率、电子传递效率及光合效率降低,而抑制了小麦幼苗的生长发育,导致生物量减少.

To explore the response of photosynthetic physiological characteristics to iron toxicity,wheat Xihan3 seedlings were used to investigate the changes of chlorophyll(CHL)fluorescence and photosynthetic characteristics after treatment with different FeCl3 concentrations(0,100,300 and 500μmol/L).The amount of CHLa and total CHL as well as the value of CHLa/CHLb showed a trend of first increasing and then decreasing in wheat leaves with an increasing iron concentration.Iron-treated seedlings exhibited significant decreases of carotenoid content,potential maximum quantum yield,maximum light quantum yield under light adaptation,actual photon yield,photosystemⅡpotential activity,photochemical annihilation,electron transfer rate,photosystemⅡpotential electron transfer rate,as well as increases of non-photochemical annihilation and quantum yield of regulatory energy dissipation.At the same time,increasing iron concentration led to decreases in photosynthetic rate,transposition rate,stomatal conductance and water use efficiency in seedling leaves.In conclusion,iron stress inhibited seedling growth and reduced the biomass of leaves and roots,which were associated with iron-induced reduction of photosynthetic pigments,thus decreasing light energy capture and transmission,and iron-mediated damage on the reaction center of photosystemⅡ,thus leading to the decreases in the capture efficiency of excitation energy and electron transfer rate.