The best temperature to maintain in the nutrient solution is about 72?F (22?C). This temperature is warm enough to keep the plant’s metabolic rate functioning at a fast pace. Cooler temperatures slow down the rate at which the roots function, limiting their ability to supply the upper parts with water and nutrients.
It is cool enough to hold large quantities of dissolved oxygen. At higher temperatures, the amount of oxygen in the water decreases (cold water holds more oxygen than hot water). The roots use oxygen. When they are oxygen starved, they weaken and are susceptible to attack by pathogens.
Cooler nutrient-water solution should be maintained in gardens in which the air temperature is high. The cool roots help the plants maintain health and vitality. The water also holds more dissolved oxygen, which is good for the roots.
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