If a plant's stomata are closed and no transpiration is occurring, then

The stomata are present on the plant body which are mainly regulated by the chemical balance (sugar level) inside the stomata's body. As, during the transpiration process the loss of excessive amount of water occurs which is required for the osmoregulation of the plants body. Now, when the stomata are mostly light sensitive and it loses it turgidity then the cells become much flattened and thus it closes to stop the process of transpiration. Which, brings about the increase of the water level or balance inside the plants body, which is required for better or proper mechanism. And, for that reason the requirement or need for more water molecules will end, as the plant roots will now stop absorbing any more water molecules from the soil.