Effects of pre- and postharvest conditions on vase life of Eustoma grandiflorum (Raf.) Shinn

Postharvest quality of Eustoma grandiflorum (Raf) Shinn. was investigated after growing plants at different photosynthetic photon flux density (PPFD), lighting periods, supplements of lime to the peat medium and different levels of boron fertilization. The plants were harvested at three open flowers and were placed in glass bottles with 500 ml vase solution of the desired preservatives under the following conditions: 21 degreesC, 45% relative humidity (RH) and 12-h photoperiod with a PPFD of 15 mumol m(-2) s(-1) provided by white fluorescent tubes. Wilted flowers, leaves and buds were recorded every day and post-harvest fife was evaluated. In general, an increase in preharvest PPFD level increased the vase fife. In our first experiment, the plants grown with a 20-h fighting period under a low PPFD (60 mumol m(-2) s(-1)) with high RH (90 %) in the canopy showed the shorter vase life than those grown under a high light level (240 mumol m(-2) s(-1)) and low RH (70 %). In the second experiment, a few hours of high RH at the canopy level during night with a 16-h fighting period and a PPFD of 240 mumol m(-2) s(-1) resulted in a shorter vase life than 24-h and constant low RH. When temperature and RH were better controlled in a third experiment under a PPFD of 105 mumol m(-2) s(-1), the vase life was slightly longer in stems from 16-h than from 24-h fighting period. Compared to their long vase life (26 to 28 days), the differences (2-4 days), however, must be regarded as small, and we therefore suggest that there is no adverse effect of 24-h lighting on vase life. Vase life was only affected when the commercial preservative Chrysal Clear (CC) or sucrose with 8-hydroxyquinoline sulphate (HQS) was used in the vase solution, and not when either sucrose or HQS was compared with the water control (reverse osmosis water). These results suggest that high PPFD, long fighting period, low RH during the growing period and use of sugar combined with HQS in the vase solution, are all important factors for prolonging the vase fife of Eustoma.