Development of means for delaying senescence and prolonging the vase life of cut flowers of Vanda orchid 'Sansai Blue'

S. Khunmuang, S. Kanlayanarat, S. Wongchaochant, C. Wongs-Aree, S. Meir, M. Buanong
The Vanda orchid cut flowers have become now popular in Thailand. However, the cut Vanda ‘Sansai Blue’ flowers show rapid senescence symptoms, expressed in petal discoloration, distinct venation, necrosis, wilting, and abscission. Therefore, the Vanda flowers need proper postharvest treatments to extend their longevity and marketability period. In this study we examined the efficiency of applying various solutions in delaying senescence and extending the vase life longevity of cut Vanda orchid ‘Sansai Blue’. The experiment was conducted in a controlled observation room (21 ± 2°C, 70-80% RH, cool-white fluorescent light for 12 h d-1). Inflorescences of Vanda ‘Sansai Blue’ were pulsed for 24 h with different commercial solutions of plant growth regulators and glucose, combined with preservatives (all from GADOT Agro Ltd., Israel). The solutions included: 0.25% TOG-L-101® (110 μMbenzyladenine, BA), 0.25% STS-75® (0.19 mM STS), LONG LIFE, LL (10 g L-1 glucose), and 0.025% TOG-6® (140 mg L-1 active chlorine). Distilled water (DW) served as control. After pulsing, all treated flowers were held in a vase solution containing chlorine, except the LL-treated flowers which remained in the same LL pulsing solution. The vase life was terminated when 30% of the florets in the inflorescence showed the senescence symptoms. The results showed that the LL, chlorine and STS treatments extended the vase life of cut Vanda flowers to 15, 16, and 19 days, respectively, as compared to only 11 days of the control flowers in DW. The BA treatment did not improve vase life as compared to chlorine alone. The STS treatment significantly delayed the fresh weight loss, while LL improved the solution uptake. All the treated flowers had initially a low ethylene production rate below 0.3 µL kg-1 h-1, which gradually increased to 0.9 µL kg-1 h-1 on day 15 due to flower senescence. Nevertheless, the Vanda flowers were very sensitive to ethylene, and the ethylene action inhibitor, STS was very effective in inhibiting the endogenous ethylene effects. Therefore, the best practice to preserve the quality of cut Vanda ‘Sansai Blue’ orchids was pulsing with STS and subsequently being held in chlorine vase solution.
Khunmuang, S., Kanlayanarat, S., Wongchaochant, S., Wongs-Aree, C., Meir, S. and Buanong, M. (2018). Development of means for delaying senescence and prolonging the vase life of cut flowers of Vanda orchid 'Sansai Blue'. Acta Hortic. 1213, 581-586
DOI: 10.17660/ActaHortic.2018.1213.88
Vanda, senescence, preservative solutions, ethylene, STS, cut flower food

Acta Horticulturae