Improvement of morpho-physiological and biochemical characteristics of stock flower (Matthiola incana L.) by Gamma-aminobutyric acid and spermine

Common stock (Matthiola incana L.) is an important cut flower, bedding and aromatic plant. Increasing its flower number and size is a desired objective among florists. Plant growth regulators including γ-aminobutyric acid (GABA) and spermine have proved beneficial for improving flowers’ characteristics. This study was designed on a completely randomized design with 4 replicates and 16 treatments. GABA (0, 2.5, 5 and 10 mM) and spermine (0, 1, 2 and 3 mM) were sprayed on six leaves seedlings. Increasing concentration of GABA and spermine significantly decreased the flowering time and conversely increased plant height, number of flowers, stem diameter, flower diameter, shoot and root dry weight, leaf relative water content, chlorophyll, and antioxidant enzymes activity. The highest number of flower shoot and root dry weight, chlorophyll, and antioxidant enzymes in addition to the lowest electrolyte leakage were obtained by 10 mM GABA in combination with 3 mM Spermine. Also, maximum plant height and earliest flowering time were gained using 3 mM spermine, while the greatest leaf relative water content was obtained by 10 mM GABA. Application of GABA and spermine could be suggested as a promising way to improve stock flower’s aesthetic characteristics and possibly enhance their stress tolerance.