Changes in Growth and Physiological Parameters of ×Amarine Following an Exogenous Application of Gibberellic Acid and Methyl Jasmonate

Abstract

×Amarine hybrids are attractive ornamental geophytes grown for cut flower production. Their cultivation is limited due to lesser flowering percentages and lesser bulb weight gain. To optimize the growth and propagation of geophytes, plant growth regulators (PGRs) are used, but so far none have been tested in ×Amarine. We investigated the effect of gibberellic acid (GA3; 50, 100, and 200 mg dm−3) and methyl jasmonate (MeJA; 100, 500, and 1000 µmol dm−3) on growth, flowering, bulb yield, and select physiological parameters of ×A. tubergenii “Zwanenburg”. PGRs were applied as foliar sprays on the 70th and 77th day after planting. GA3 treatment at 200 mg dm−3 exhibited the greatest leaf number, leaf length, bulb weight, daughter bulb number, CO2 assimilation intensity, greenness index, total sugars, and total protein content in bulbs. GA3 application at 100 and 200 mg dm−3 accelerated flowering and at 50 and 100 mg dm−3 significantly increased the bulb flowering percentage. MeJA at all tested concentrations prolonged anthesis time and reduced the bulb flowering percentage. GA3 at all concentrations and MeJA at 500 and 1000 µmol dm−3 stimulated daughter bulbs formation. GA3, especially at 200 mg dm−3 can improve anthesis and increase ×A. tubergenii “Zwanenburg” bulb yield.