What Flowers Want - Hydration components
This is a pertinent issue considering the many stereotypes surrounding cut flower post- harvest freshness management. Therefore, before we discuss what actually adds value to your post-harvest value chain in terms of hydration products; let us first understand flower quality indicators.
I like to categories quality indicators into two; the visible attributes like flower regular opening, uniform green color ?on the foliage, free from pest and diseases, no petal browning or bronzing, free from chemical residues and the list goes on and on. The invisible attribute on the other hand is the biggest quality indicator and it refers to the longevity or rather vase life.
Look for these in a hydration product:
So what properties do we need a hydration solution to have so that we can check all the boxes mentioned?
Use of acidifiers like Citric acid, Aluminum sulfate among others has proved to increase water uptake and consequently the fresh weight of flowers. This is because, at lower pH, microorganisms’ activity decreases reducing the chances of xylem blockage. Studies have shown that solution uptake is much higher at a pH of 3.5-5.5 in roses.
It is therefore important to check if your post-harvest product has an inbuilt acidifying system that will give you these added advantages. ?Low pH alone can extend your vase life by up to 3 days. However, when using Chlorine based biocides, we cannot maintain very low pH as it becomes unstable below 5.5.
Wetting agents really improve vase life by reducing resistance during solution uptake and breaking the surface tension to bubbles trapped in the xylem in the harvesting process. Flowers treated with surfactant containing solution also recover faster after dry storage as compared to normal treatments.
This does not mean that you pick up teepol for use in roses, most industrial soaps show toxicity resulting in leaf curling and abscission. Only go for the formulated soaps incorporated into post-harvest products because they also improve dissolution profiles of the other actives.
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It is widely believed that this is the only requirement for flower postharvest but truth is it is not. It is very important to have a biocide in your solution but just low pH alone can help you manage micro-organisms. Biocides are categorized as fast acting or instant biocides like chlorines and alcohol; these are ideal for use as harvesting solutions to instantly sanitize the stems, buckets and water. Slow acting or long residual effect biocides are ideal for holding flowers since they take longer to work but provide longer protection. Eg. Quaternary ammonium, Hydroxy-quinoline etc
These aggregate dirt and contaminants allowing our stems to only take up clean solution. The most common flocculant is Aluminium sulfate that has a high molecular weight making all dirt to settle at the bottom of the container.
It is advisable to do the mixing on the previous night or use a very large container where the stems cannot get to the base where the dirt has settled.
o??Plant Growth Regulators (PGRs): For flowers that face premature yellowing like eryngium, alstroemeria, atrsantia etc, it is important that we treat them with hormones to prevent this. Gibberellic acid (GA) is the most commonly used PGR where yellowing occurs due to ethylene while Benzyl adenine (BA) is used where yellowing is as a result of apical dominance like in Lepidium.
o??Silver Thiosulfate (STS): Flowers that exhibit other types of ethylene sensitivities like some roses, gypsophila, alstroemeria, carnations etc, an STS is used to reduce their sensitivity to ethylene.
I hope this makes it easier for us as we decide on what product to adopt in our farms and why we should choose those particular products. The same way we invest heavily in growing flowers in terms of labor, chemicals and fertilizers, we need to take post-harvest processes seriously and invest in them too.
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