Relationship between the photosynthetic activity and the performance of Cakile maritima after long-term salt treatment.
Cakile maritima is a halophyte with potential for ecological, economical and medicinal uses. We address here the impact of salinity on its growth, photosynthesis and seed quality. Whole plant growth rate and shoot development were stimulated at moderate salinity (100-200 mM NaCl) and inhibited at higher salt concentrations. Although diminished in the presence of salt, potassium and calcium uptake per unit of root biomass was maintained at relatively high value, while nutrient-use efficiency (NUE) was improved in salt-treated plants. Chl and carotenoid concentrations decreased at extreme salinities, but anthocyanin concentration continuously grew with salinity. Net photosynthetic rate (A), stomatal conductance, maximum quantum efficiency of PSII and quantum yield were stimulated in the 100-200 mM NaCl range. Higher salinity adversely affected gas exchange and changed PSII functional characteristics, resulting in a reduction of A per leaf area unit. This phenomenon was associated with increased non-photochemical quenching. Harvest index, silique number and seeds per fruit valve were maximal at 100 mM NaCl. Despite the decreasing salt accumulation gradient from the vegetative to the reproductive organs, high salinities were detrimental for the seed viability and increased the proportion of empty siliques. Overall, the salt-induced changes in the plant photosynthetic activity resulted into analogous responses at the vegetative and reproductive stages. The enhancement of NUE, the absence of pigment degradation, the reduction of water loss and the concomitant PSII protection from photodamage through thermal dissipation of excess excitation significantly accounted for Cakile survival capacity at high salinity.
Debez
Ahmed
A
Laboratoire d'Adaptation des Plantes aux Stress Abiotiques, Centre de Biotechnologie à la Technopole de Borj-Cedria, BP 901, Hammam-Lif 2050, Tunisia. ahmed_debez@yahoo.com
Koyro
Hans-Werner
HW
Grignon
Claude
C
Abdelly
Chedly
C
Huchzermeyer
Bernhard
B
D018533:Biomass; D019607:Brassicaceae / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology*; D002734:Chlorophyll / Q000378:metabolism; D005453:Fluorescence; D005740:Gases / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects*; D045332:Photosystem II Protein Complex / Q000378:metabolism; D010860:Pigments, Biological / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D018547:Plant Stems / Q000187:drug effects / Q000378:metabolism; D012639:Seeds / Q000187:drug effects / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*; D013997:Time Factors
D005740:Gases; D045332:Photosystem II Protein Complex; D010860:Pigments, Biological; D002734:Chlorophyll; D012965:Sodium Chloride; D012964:Sodium