Post harvest Management of Horticultural Crops (2+1)

Pulsing

PULSING – Flowers

Pulsing is ‘supplying a solution through transpiration stream’. Term pulsing means placing freshly harvested flowers for a relatively short time from few seconds to hours in a solution specially formulated to extend their vase life. This process is also called as hydration and it can be facilitated by addition of wetting agent to water.

Methods of Pulsing
Cut flowers are pulsed with sugars, such as sucrose. Sucrose pulsing involves concentration of 5 -20% treated for overnight at 20C or at warm temperature of 210C for 10 minutes.
Cut flowers such as carnation and delphiniums are pulsed with anti ethylene agents like silver thio sulfate (STS) or aminooxyacetic acids(AOA). AOA is toxic to most flowers except carnation. Pulsing is also done through applying 2-4 mM silver ions for 15-45 minutes at ambient temperature or 0.5mM silver overnight at 10C.

Cut flowers are also pulsed with dyes, such as the food grades blue used on white carnation to give interesting visual effects like blue coloured petal veins and margins.
Drying - Cut flowers and foliages reserved for desiccation/drying can be pulsed for one to a few days with humectants, such as 20-30% glycerol. This process is known as uptake preservation. This retains suppleness (flexible), associated with the humectants chemical attracting water vapour from the atmosphere in to the tissue. During pulsing with humectants, often brown, red, green, blue and others dyes are frequently supplied along with the humectants.