Investigating the role of Ethephon in the stem-bending mechanism and petal senescence of two different gerbera flowers

We investigated whether ethylene is involved in the stem-bending mechanism of the two different gerberas [long-lived cultivar ‘Mary Queen’ and short-lived cultivar ‘Harmony’] by pretreating the stems with an ethylene-releasing compound (Ethephon), an ethylene-action inhibitor [silver thiosulfate (STS)], or Ethephon in combination with STS (Ethephon + STS), using distilled water as the control. In the cv. ‘Mary Queen,’ the control stems did not show stem bending, while the treatment groups showed bending at 6 and 9 days after treatment (DAT). In the cv. ‘Harmony,’ the bending rate observed in the Ethephon-treated stems was lower than the other treatments at 9 DAT. However, a lower bending rate in the Ethephon group relative to the other treatments is unlikely to be associated with ethylene action, because the bending rate observed in the Ethephon + STS group was significantly higher than the STS group. In addition, the bending rates of both cultivars were not associated with lignin contents or the expression of lignin biosynthesis genes in the stems. As it is complicated to conclude the role of Ethephon in stem bending of the gerberas, these results suggest that the use of Ethephon to delay stem bending in cut gerberas is not warranted.