Combination Treatment of Silver Thio-Sulfate Complex with 6-Benzyladenine Improves the Cut Flower Quality after Cold Dry Storage in Dutch Iris ‘Blue Magic’

Abstract

To improve flower opening and vase life of Dutch iris (Iris × hollandica) cut flowers after cold-dry storage, we investigated the effects of silver thio-sulfate complex (STS), as an alternative to expensive gibberellin (GA₃), and the combination of STS and benzyladenine (BA). The flowering rate at 0.2 mM STS treatment before dry storage at 5°C for 5 days was 60%, higher than 0% in the control (tap water) but lower than 100% in 100-ppm GA₃. The vase life of cut flowers treated with STS or GA₃ was extended from 4.0 to 5.0 days, but it was shorter than those treated with 100-ppm BA, i.e., 5.8 days. STS or BA treatment after storage promoted the flowering rate and extended vase life more than the control, but GA₃ treatment decreased the flowering rate to 20%, and did not extend the vase life. The combination treatment of STS and BA before storage extended the vase life by 2.5, 1.7, and 1.1 days, compared with the control, STS, and BA, respectively. The effect of STS plus BA was not significantly different from that of the combination of GA₃ and BA. The cut flowers pre-treated with the combination of STS and BA showed accelerated flowering and a prolonged vase life even after storage at 5°C for 15 days. The cost of STS treatment per 5 mL at 0.2 mM was estimated to be 0.04 Japanese yen, which was lower than that of 2.3 yen for 100 ppm GA₃. Therefore, the combination treatment of STS and BA can be recommended as an economical method to improve postharvest quality after cold-dry storage in cut Dutch iris.