What is the correct procedure for the first type of citric acid treatment?

The procedure involving placing cut stems in citric acid solution at room temperature is correct because citric acid acts as a natural preservative and can help to prolong the life of cut flowers. The acidic environment created by the citric acid helps to lower the pH of the water, which can improve water uptake by the stems. This process is particularly effective in preventing bacterial growth and promoting healthy hydration of the plant tissues.

Using the citric acid solution at room temperature allows the stems to absorb the treatment without the stress that might come from extreme temperatures, ensuring that the flowers receive maximum benefits from the solution. This method effectively enhances the overall longevity and freshness of the floral arrangements.

In contrast, the other procedures either do not utilize citric acid effectively or might introduce conditions that are less ideal for the flowers, such as temperature shocks or improper hydration methods.