Which process results in dropping of plant leaves, stem and flowers due to water loss?

Usually when a plant wilts, it is an indicative of lack of water or moisture . It also occurs due to the presence of some kind of toxin such as introduced by disease or poison. If the soil around the roots of a plant lacks water or the rate of loss of water is faster than the rate of absorption of water, the cells in the plant will contain less water and fail to support the plant. Therefore, it results in dropping of plant parts.