Effects of Silver Thiosulphate pretreatments on harvested lisianthus (Eustoma grandiflorum) cut flowers

Abstract

This study aimed at developing postharvest pretreatments for improving vase life and display quality oflisianthus cut flowers. Equally spaced doses (0, 0.25, 0.5, and 0.75 mMAg) ofsilverthiosulphate (STS) pretreatments were applied for equally spaced durations of exposure (0, 2, 4 and 6 h) to harvested lisianthus cut flowers. STS pretreatment was followed by vase solutions containing 2% sucrose and 1.5% sodium hypochlorite (Jikj. Pretreatment with 0.75 mlvlAg" for duration of 2 or 6 h improved vase life by 55% and 40%, compared to distilled water control and the placebo, respectively. The interaction effect of STS dose and duration of exposure significantly influenced water uptake, transpiration, and water balance rates. Vase-life constituted of duration to 50%: wilted florets, or bent-necks, or chlorotic leaves; whichever came first. Out of the above recommended dosages and duration of exposure, 2 h was found less reliable than 6 hrs. The duration of exposure of 4 h was found to be detrimental for STS doses above 0.25 mlvlAg'. The significant efficacy ofSTS at low doses and duration of exposure revealed in this study presents an immediate solution towards the gradual phase-out of STS which is a potent environmental pollutant due to the silver content. Further research is recommended to identify alternatives to STS.