Foliar application of citric and malic acid to stock plants of rose alters the rooting of stem cuttings

Abstract

Background: As the world's best-selling cut flower, there is a high demand for propagated rose plants. Auxins are the dominant growth regulator used to improve the rooting of cutting; however, their application remains a labor-intensive process, and on the other hand, side effects like poor shoot growth exist. Organic acid sprays have enhanced many physiological traits of plants which justified surveying their possible effect on the rooting process in the current study. Methods: Different concentrations of citric or malic acid were sprayed to stock plants of rose (Rosa x hybrida cv. 'Sherbet') prior to taking cuttings. Malic or citric acid (3, 6, or 9 mM) was applied five times on a 14-day interval in a commercial cut flower production greenhouse. Single-node cuttings were prepared and were rooted under mist. Data collected included rooting percentage, root count, root and shoot length and dry weight, and root-to-shoot ratio (R:S). Results and discussion: The rooting percentage was enhanced by all treatments. Citric acid enhanced root number at 6 mM level followed by 3 mM citric acid. Average root length was increased by all treatments except 3 and 6 mM malic acid. All CA treatments increased shoot length, while it remained unaffected by MA treatments. CA at 3 and 6 mM level and 6 mM MA increased shoot dry weight, but only 9 mM CA increased the root dry weight. Conclusion: Both organic acids had positive effects on rooting response of'Sherbet' roses. However, the mechanism of observed responses to organic acids remains to be studied. While they enhance the physiological performance of stock plants, they can also simultaneously both enhance the rooting as well as the shoot growth of the new plantlets.