Answer: I really don't know the answer to your question! I've heard of people putting a pinch of sugar into a vase of cut flowers, but I don't know how roots would respond to sugar in water. My first guess would be that it wouldn't be helpful, and might harm the plants. Plant roots take water in through osmosis, and anything dissolved in the water might disrupt that process. (That's why high concentrations of soluble fertilizer harm roots--they in essence reverse the process of osmosis, drawing water out of the roots.) Also, remember that table sugar is sucrose, not glucose.
I can't give you a definite answer, but those are my thoughts. I hope they help.
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