Journal of Taiwan Agricultural Research

Author:Chao-Chia Huang, Tsu-Tsuen Wang and Hui-Sui Huang

Abstract:

    Phalaenopsis florets after had been stored at 7℃ for 7 or 10 days exhibited early senescence as a symptom of chilling injury. Noticeable amount of ethylene production were observed ahead the onset of floret senescence. The role of ethylene in the chilling-induced early senescence of Phalaenopsis floret was studied. Dripping aminooxy acetic acid (AOA) into the cavity of column right after cold storage inhibited ethylene production and retarded the early senescence. Holding florets under 0.2 atmosphere pressure after cold storage also delayed senescence. Both pulsing cut flower with silver thiosulfate (STS) before cold storage, and treating florets with 2,5-norbornadiene (NBD) after cold storage were effective in slowing down the senescence rate of these florets. These data indicated that ethylene might play an important role in the early senescence of chilling injured Phalaenopsis floret. Short time exposure of exogenous ethylene induced rapid senescence in non-chilled Phalaenopsis florets, but didn’t affect the senescence rate of chilled florets. Ethylene treatment also induced high amount of ethylene production in non-chilled florets but had very little effect on the ethylene production rate of chilled floret. The ACC content in the column of non-chilled floret was unchanged after storage but increased 30 fold after 2 days of ethylene treatment. The ACC content in the column of chilled floret increased 7 fold after cold storage but increased only 1.5 fold after ethylene treatment. High levels of ethylene production were observed in both non-chilled and chilled florets upon feeding with ACC, indicating the intactness of ACC oxidase (ACO) in both systems. Pulsing cut flowers with STS before cold storage, or dripping AOA onto floret column after cold storage, effectively inhibited ethylene production and rapid senescence in those ethylene-treated non-chilled florets as well as in those chilled florets. It was suggested that these two ethylene-related senescence processes were regulated through two different ethylene biosynthesis systems. In non-chilled florets, both ethylene sensing and ethylene induced autocatalytic ethylene production were required for the ethylene-induced senescence. But in chilled florets, chilling induced endogenous ethylene synthesis was responsible for floret senescence and the ethylene sensing and the autocatalytic ethylene production system were damaged after chilling treatment.

Key words:Phalaenopsis, Cut flower, Senescence, Chilling injury, Ethylene

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