褪黑素对盐胁迫下大丽花生长及光合特性的影响OA

Dahlia pinnata Cav.is a perennial herbaceous plant widely used in landscape design for its vibrant flowers,diverse floral forms,and extended ornamental period.The entire plant also possesses medicinal value and is employed in treating various diseases.This experiment utilized three species of Dahlia as materials,with seven treatments established to investigate the effects of salt stress and exoge-nous melatonin on the growth and photosynthetic characteristics of Dahlia seedlings.The results demon-strated that under salt stress,Dahlia seedlings exhibited leaf wilting,yellowing,scorched leaf tips and margins,slender rhizomes,poor growth vigor,and significant reductions in plant height,leaf length,leaf width,leaf area,aboveground biomass,belowground biomass,and total biomass.The root-to-shoot ratio increased significantly,while stomatal conductance(Gs),transpiration rate(Tr),intercellular CO2 concentration(Ci),and net photosynthetic rate(Pn)declined markedly.After exog-enous melatonin application,the yellowing and wilting of Dahlia seedlings was significantly reduced,with notable increases in plant height,leaf length,leaf width,leaf area,aboveground and below-ground biomass,and total biomass.The root-to-shoot ratio decreased significantly,while stomatal conductance(Gs),transpiration rate(Tr),intercellular CO2 concentration(Ci),and net photosyn-thetic rate(Pn)increased substantially.