外源硅对盐胁迫下黄瓜幼苗生长和光合荧光特性的影响

摘要

The present study was conducted to investigate the effects of exogenous si1icon on p1ant growth, ch1orophy11 content, gas exchange parameter and structure and function of photosynthetic apparatus in sa1t-sensitive cucumber cu1tivar (Jinyou No. 4) exposed to NaC1 stress. Sa1t stress at 70 mmo1/L NaC1 for 9 d resu1ted in severe reductions of growth, ch1orophy11 contents and photosynthesis. App1ication of exogenous si1icon ( 2 mmo1/L K2 SiO3 ) a11eviated the inhibition induced by sa1t stress. Sa1t stress caused an increase in functiona1 size of the anten-na per active reaction center ( ABS/RC) and non-photochemica1 energy dissipated per active reaction center ( DIo/RC) and a decrease, 1eading to the decreases the abi1ity of non-cyc1ic e1ectron transport in photosystem II ( PSII) in structure performance index ( PIABS) and riving force of photosynthesis ( DFABS) . However, si1icon app1ication to sa1t-stressed p1ants counteracted the adverse effects of sa1inity on the structure of photosynthetic apparatus. These resu1ts suggest that si1icon a11eviates sa1t-induced growth inhibition by regu1ating the photochemica1 efficiency of PSII of cucumber seed1ings, which contributes to the sa1t to1erance of cucumber p1ants.%以耐盐性较弱的黄瓜品种津优4号为材料,采用营养液栽培法,研究外源硅对盐胁迫下黄瓜幼苗生长、叶绿素含量、气体交换参数以及叶绿素荧光特性的影响。结果表明,70 mmo1/L NaC1处理显著降低了黄瓜幼苗叶片的净光合速率( Pn ),抑制黄瓜幼苗生长,而2 mmo1/L 外源硅处理缓解了盐胁迫诱导的光合和生长抑制；盐胁迫下,黄瓜幼苗叶片单位反应中心吸收的光能( ABS/RC)和单位反应中心的能态淬灭( DIo/RC)显著上升,降低了光系统II( PSII)非环式电子传递的能力,引起黄瓜幼苗叶片光合器官的结构性能( PIABS )和光合作用质子驱动力( DFABS )显著下降；外源硅处理逆转了盐胁迫导致的叶绿素荧光参数的变化。这些结果表明外源硅处理可缓解盐胁迫对黄瓜幼苗光合器官结构和功能的伤害,促进黄瓜幼苗的生长,从而有助于增强黄瓜植株对盐胁迫的耐受性。