Effects of silicon on water metabolism and photosynthetic characteristics of Cucurbita pepo L.seedlings under salt stress
[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 Na2SiO3·9H2O),salt stress(150 mmol/L NaCl),salt stress+silicon treatment(0.3 mmol/L Na2SiO3·9H2 O+150 mmol/L NaCl).After 10 days of treatment,root morphology and activity,leaf water con-tent and water potential,photosynthetic parameters,chlorophyll content,chlorophyll fluorescence param-eters,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 tran-spiration.Salt stress also affected the photosynthetic system,net photosynthetic rate,stomatal conduct-ance,chlorophyll content,and PS Ⅱ photochemical efficiency.Exogenous silicon improved the root mor-phology 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,PS Ⅱ maximum photochemical efficiency,PS Ⅱ actual photochemical efficiency,and photochemical quenching coefficient,decreased intercellular carbon dioxide concentration and non-photochemical quench-ing coefficient,enhanced the photosynthesis of seedlings under salt stress.[Conclusion]0.3 mmol/L sili-con 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.
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