EFFECT OF ETHEPHON PRETREATMENT ON LAST INTERNODE ELONGATION OF CUT TULIPA FLOWERS

Elongation of the last internode, as well as tepal opening of cut Tulipa flowers were notably inhibited by ethephon treatments applied at 25–50 ppm for 10 mins. A 30 mins ethephon treatment at 50 ppm reduced elongation of the last internode of cut ‘Apeldoorn’ by 24% compared with the control. Inhibition of elongation was greater when flowers were harvested at an immature stage than when they were mature. The decorative value of both ‘Apeldoorn’ and ‘Golden Apeldoorn’ was affected similarly by treatment with ethephon at 25–50 ppm.

The level of ethylene production was higher in flower organs than in stem tissue, and it increased strikingly following a 50 ppm ethephon pretreatment which inhibited elongation of the last internode. This shows that ethephon is capable of inhibiting biosynthesis and basipetal translocation of auxin which is produced in the gynoecium at pre- and post-flowering, and as a result, elongation of the last internode was inhibited by ethephon treatment.

It is suggested that ethephon pretreatment can be used effectively for controlling growth of the last internode without reducing and possibly improving the decorative value of cut Tulipa flowers.

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