硅对盐胁迫下西葫芦幼苗水分代谢及光合特性的影响

Effects of silicon on water metabolism and photosynthetic characteristics of Cucurbita pepo L.seedlings under salt stress

【目的】探究外源硅对盐胁迫下西葫芦幼苗水分代谢及光合作用的保护机制,可为西葫芦抗盐栽培提供理论参考。【方法】以西葫芦品种‘寒绿7042’为试材,通过水培试验,共设置对照、硅处理(0.3 mmol/L Na_(2)SiO_(3)·9H_(2)O)、盐胁迫(150 mmol/L NaCl)、盐胁迫+硅等4个处理,处理10 d后测定幼苗的根系形态和活力,叶片含水量、水势、光合气体交换参数、叶绿素含量、叶绿素荧光参数及根系质膜水通道蛋白基因的表达等指标。【结果】盐胁迫显著抑制了西葫芦幼苗根系的生长,降低了根系活力、叶片含水量、叶片水势和蒸腾作用,还破坏了植株的光合系统,导致净光合速率、气孔导度、叶绿素含量和PSⅡ光化学效率显著降低。外源硅显著改善了盐胁迫下西葫芦幼苗的根系形态,提高了根系活力,并通过促进根系质膜水通道蛋白基因PIP1;2、PIP1;3、PIP1;5、PIP1;7、PIP2;1、PIP2;4、PIP2;6、PIP2;8、PIP2;9和PIP2;12的表达改善植株体内的水分状况,提高叶片含水量和水势,增强蒸腾作用;外源硅还通过提高叶片气孔导度、叶绿素含量、净光合速率、PSⅡ最大光化学效率、PSⅡ实际光化学效率、光化学淬灭系数,降低胞间CO_(2)浓度和非光化学淬灭系数来增强盐胁迫下幼苗的光合作用。【结论】盐胁迫下添加0.3 mmol/L的硅可以有效改善西葫芦幼苗的水分代谢和光合作用状况,从而提高西葫芦幼苗抗盐胁迫能力。

[Objective]This study aims to explore the protective mechanism of exogenous silicon on water metabolism and photosynthesis of Cucurbita pepo L.seedlings under salt stress,and to provide theoretical reference for salt resistance of C.pepo L..[Methods]Using“Hanlu 7042”C.pepo L.variety as the test material and hydroponic experiment,four treatments were set:Control,silicon treatment(0.3 mmol/L Na_(2)SiO_(3)·9H_(2)O),salt stress(150 mmol/L NaCl),salt stress+silicon treatment(0.3 mmol/L Na2SiO3·9H2O+150 mmol/L NaCl).After 10 days of treatment,root morphology and activity,leaf water content and water potential,photosynthetic parameters,chlorophyll content,chlorophyll fluorescence parameters,and expression of aquaporin genes were determined.[Results]Salt stress inhibited the growth of C.pepo L.seedling roots,and decreased root activity,leaf water content,and leaf water potential and transpiration.Salt stress also affected the photosynthetic system,net photosynthetic rate,stomatal conductance,chlorophyll content,and PSⅡphotochemical efficiency.Exogenous silicon improved the root morphology and activity of C.pepo L.seedlings under salt stress,also improved plant water status,and leaf water content,leaf water potential,and transpiration by promoting the expression of genes PIP1;2,PIP1;3,PIP1;5,PIP1;7,PIP2;1,PIP2;4,PIP2;6,and PIP2;8,PIP2;9 and PIP2;12.The exogenous silicon also increased the stomatal conductance,chlorophyll content,net photosynthetic rate,PSⅡmaximum photochemical efficiency,PSⅡactual photochemical efficiency,and photochemical quenching coefficient,decreased intercellular carbon dioxide concentration and non-photochemical quenching coefficient,enhanced the photosynthesis of seedlings under salt stress.[Conclusion]0.3 mmol/L silicon could improve the water metabolism and photosynthesis of C.pepo L.seedlings under salt stress,and thus enhance the ability of C.pepo L.seedlings to resist salt stress.