title: [Effects of different water potentials on leaf gas exchange and chlorophyll fluorescence parameters of cucumber during post-flowering growth stage].
abstract: Impacts of different substrate water potentials (SWP) on leaf gas exchange and chlorophyll fluorescence parameters of greenhouse cucumber during its post-flowering growth stage were analyzed in this study. The results demonstrated that -10 and -30 kPa were the critical values for initiating stomatal and non-stomatal limitation of drought stress, respectively. During the stage of no drought stress (-10 kPa < SWP ≤ 0 kPa), gas exchange parameters and chlorophyll fluorescence parameters were not different significantly among treatments. During the stage of stomatal limitation of drought stress (-30 kPa<SWP ≤ -10 kPa), with the decrease of SWP, the stomatal conductance (gs), intercellular carbon dioxide concentration (Ci), net photosynthetic rate (Pn) , apparent quantum efficiency (ε), transpiration rate (Tr), carboxylation efficiency (CE), maximum Rubisco-limited rate of carboxylation (Vc max), maximum rate of electron transport (Jmax), rate of triosephosphate utilization (VTPU), maximum and actual quantum efficiency of PSII (ΦPSII, and Fv/Fm) and photochemical quenching (qP) decreased, but the light compensation point (LCP), dark respiration rate (Rd), carbon dioxide compensation point (CCP), stomatal limitation value (LS), instantaneous water use efficiency (WUEi) and non-photochemical quenching (qN) increased. In this stage, gas exchange parameters changed faster than chlorophyll fluorescence parameters and differed significantly among treatments. During the stage of non-stomatal limitation of drought stress (-45 kPa≤SWP ≤ -30 kPa), with the decrease of SWP, light saturation point (LSP), Rd, CE, Vcmax, VTPU, LS, WUEi, ΦpPSII, Fv/Fm and qp decreased, while CCP, Ci and qN increased. In this stage, chlorophyll fluorescence parameters changed faster than gas exchange parameters and differed significantly among treatments. In production of greenhouse cucumber, -10 and -5 kPa should be the lower and upper limit value of irrigation, respectively. The stomatal limitation of drought stress could be relieved by irrigation before SWP decreased to -30 kPa. While, the non-stomatal injury of drought stress would be unrecoverable once SWP decreased to lower than -30 kPa.
authors.forename: Lu
authors.initials: L
authors.lastname: Lin
authors.forename: Yun
authors.initials: Y
authors.lastname: Tang
authors.forename: Ji-tao
authors.initials: JT
authors.lastname: Zhang
authors.forename: Wan-li
authors.initials: WL
authors.lastname: Yan
authors.forename: Jian-hong
authors.initials: JH
authors.lastname: Xiao
authors.forename: Chao
authors.initials: C
authors.lastname: Ding
authors.forename: Chuan
authors.initials: C
authors.lastname: Dong
authors.forename: Zeng-shun
authors.initials: ZS
authors.lastname: Ji
mesh_terms: D002245:Carbon Dioxide; D002734:Chlorophyll / Q000737:chemistry*; D018553:Cucumis sativus / Q000502:physiology*; D055864:Droughts; D005453:Fluorescence; D008027:Light; D010788:Photosynthesis; D018515:Plant Leaves / Q000502:physiology*; D018526:Plant Transpiration; D014867:Water / Q000502:physiology*
chemical_list: D014867:Water; D002734:Chlorophyll; D002245:Carbon Dioxide