title: Differences on photosynthetic limitations between leaf margins and leaf centers under potassium deficiency for Brassica napus L.
abstract: Analyzing the proportions of stomatal (SL), mesophyll conductance (MCL) and biochemical limitations (BL) imposed by potassium (K) deficit, and evaluating their relationships to leaf K status will be helpful to understand the mechanism underlying the inhibition of K deficiency on photosynthesis (A). A quantitative limitation analysis of K deficiency on photosynthesis was performed on leaf margins and centers under K deficiency and sufficient K supply treatments of Brassica napus L. Potassium deficiency decreased A, stomatal (gs) and mesophyll conductance (gm) of margins, SL, MCL and BL accounted for 23.9%, 33.0% and 43.1% of the total limitations. While for leaf centers, relatively low limitations occurred. Nonlinear curve fitting analysis indicated that each limiting factor generated at same leaf K status (1.07%). Although MCL was the main component of limitations when A began to fall, BL replaced it at a leaf K concentration below 0.78%. Up-regulated MCL was related to lower surface area of chloroplasts exposed to intercellular airspaces (Sc/S) and larger cytosol diffusion resistance but not the cell wall thickness. Our results highlighted that photosynthetic limitations appear simultaneously under K deficiency and vary with increasing K deficiency intensity.
authors.affiliation: College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.|Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River) Ministry of Agriculture, Wuhan 430070, China.
authors.forename: Zhifeng
authors.initials: Z
authors.lastname: Lu
authors.affiliation: College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.|Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River) Ministry of Agriculture, Wuhan 430070, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Ren
authors.affiliation: College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.|Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River) Ministry of Agriculture, Wuhan 430070, China.
authors.forename: Yonghui
authors.initials: Y
authors.lastname: Pan
authors.affiliation: College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.|Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River) Ministry of Agriculture, Wuhan 430070, China.
authors.forename: Xiaokun
authors.initials: X
authors.lastname: Li
authors.affiliation: College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.|Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River) Ministry of Agriculture, Wuhan 430070, China.
authors.forename: Rihuan
authors.initials: R
authors.lastname: Cong
authors.affiliation: College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.|Key Laboratory of Arable Land Conservation (Middle and Lower Reaches of Yangtze River) Ministry of Agriculture, Wuhan 430070, China.
authors.forename: Jianwei
authors.initials: J
authors.lastname: Lu
mesh_terms: D029688:Brassica napus / Q000187:drug effects* / Q000502:physiology; D002245:Carbon Dioxide / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism; D004553:Electric Conductivity; D017136:Ion Transport; D007700:Kinetics; D058503:Mesophyll Cells / Q000187:drug effects* / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects* / Q000502:physiology; D054046:Plant Stomata / Q000187:drug effects* / Q000378:metabolism; D011188:Potassium / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D002734:Chlorophyll; D002245:Carbon Dioxide; D011188:Potassium