Effect of the foliar application of cyanobacterial hydrolysate (Arthrospira platensis) on the growth ofPetunia x hybridaunder salinity conditions

Salinity is one of the environmental factors inhibiting productivity in crop plants. Available strategies to mitigate the abiotic stresses are limited. Microalgae and cyanobacteria can mitigate the adverse effects of abiotic stress due to their biostimulant properties. The aim of this work was to study the effect of hydrolysate of the ciyanobacteriumArthrospira platensison the growth ofPetuniaplants under salt stress conditions over two growing seasons (winter and spring). Plants were exposed to 2.0, 2.5, and 3.0 dS m(-1)EC, with and without application ofA. platensishydrolysate. At the end of the trial, biometric parameters and plant analysis were determined. Petunias had a negative response when the salinity level rose from 2 to 3 dS m(-1)and exhibited moderate tolerance to high internal Na and Cl concentrations. Results show that a high salinity reduces the Ca, Mg, K, and S contents in the leaves and provokes a sharp reduction in the K+/Na(+)relationship. ApplyingA. platensishydrolysate alleviates the effects of NaCl stress and stimulates shoot and bud formation in the petunia mother plant while inducing flowering in commercialPetuniaplants. TheA. platensishydrolysate application increased the K+/Na(+)relationship in treatments with an EC of 3.0 dS m(-1).