Salicylic Acid Alleviates the Copper Toxicity in Zinnia Elegans

Salicylic acid (sa) plays akey role in plant disease resistance and hypersensitivecell death but is also implicated in hardening responses to abioticstress. the aim of this study is to examine the effects of salicylic acid on thegrowth, eco-physiological and biochemical characteristics in zinnia elegansplant exposed to copper stress. effects of copper (cu) on biomass, root lengthand shoot height and cu uptake are also discussed. this experiment wasarranged as a factorial experiment based on completely randomized design withfour replications in greenhouse conditions. the experimental treatment consistedof four levels of cu (0, 100, 200, and 400 mg/kg in potted soil) and three levelsof salicylic acid (0, 1, 2 mm) as foliar spray and chelate to soil. results showedthat with increasing levels of copper, reductions in shoot and root growth, leafarea and leaf number were statistically significant (p < 0.01). analysis of somebiochemical indices (chlorophyll content) and eco-physiological indices such asprimary florescence chlorophyll (fo), ratio of variable chlorophyll to maximum(fv/fm) in treated plants were statistically significant (p < 0.01). the resultsshowed that copper accumulation was higher in the roots than shoots. the fluorescencemeasurements showed that primary florescence chlorophyll (fo) wasincreased but maximum florescence chlorophyll (fm) was decreased progressivelywith increasing cu. salicylic acid significantly increased root and shoot growthand chlorophyll content in copper stressed plants. sa applying as chelate 2 mmalso showed an increased level of tolerance toward high cu concentrations. theresults support the conclusion that sa alleviates cu toxicity.