THE EFFECTS OF 6-BENZYLAMINOPURINE AND GIBBERELLIC ACID ON POSTHARVEST PHYSIOLOGY OF LISIANTHUS (EUSTOMA GRANDIFLORUM) FLOWERS: I. NOVEL SYNERGISM IMPROVES WATER BALANCE AND VASE LIFE
Lisianthus (Eustoma grandiflorum), a rose-like cut flower with full range of colours, has gained popularity in recent times to be one of the top ten internationally. However, its florets are sensitive to ethylene and bent-neck is a common problem. This study-investigated responses of lisianthus cut flower to exogenous 6-benzylaminopurine (BA) and gibberellic acid (GA3) applied in a basal sucrose (60 mM) plus NaOCl (0.7 mM) vase solution at pH 3.5 (citric acid). Effects of BA (0, 70, 140 or 210 µM) and/or GA3 (0, 5, 10 or 15 µM) combined in a factorial design were assessed on water uptake, transpiration, water balance and vase life against silver thiosulphate (STS) and deionised water. Water balance was significantly influenced (P=0.002) by synergistic interaction between BA and GA3. BA and GA3 combined gave the overall highest cumulative water balance peak late in the cut shoots life and thereafter maintained a relatively high water balance until the end of the 19 days experiment. The synergistic effects on water balance and delay of florets senescence were dependent on the BA-to-GA3 ratio used. Duration to peak cumulative water balance was significantly positively correlated (r2=0.99***) to occurrence of bent-neck, whereas cumulative water balance was significantly positively correlated (r2=0.769**) to occurrence of 50% florets senescence. The synergistic BA and GA3 combination treatments were significantly more potent than the ethylene inhibitor STS, which had significant efficacy compared to the deionised water control. Thus, ethylene involvement in water status regulation was minimal. This is the first report of synergism between exogenously applied cytokinin and gibberellin hormones in harvested cut flowers.
Musembi, N.N., Hutchinson, M.J. and Waithaka, K. (2015). THE EFFECTS OF 6-BENZYLAMINOPURINE AND GIBBERELLIC ACID ON POSTHARVEST PHYSIOLOGY OF LISIANTHUS (EUSTOMA GRANDIFLORUM) FLOWERS: I. NOVEL SYNERGISM IMPROVES WATER BALANCE AND VASE LIFE. Acta Hortic. 1077, 47-56
cytokinin, gibberellin, plant growth regulator, ethylene, hormonal crosstalk