What causes a plant to wilt?

Answer 1

This is a loaded question. It can be due to micro or macronutrient deficiency, lack of water, too much sunlight, high salinity, infection, etc. The mechanical part of wilting is due to cells in the plant's leaves losing water due to the lowering of turgor pressure (essentially a lack of water causing the cells to deflate like a balloon losing air.)

Answer 2

ANSWER:There are many reasons that a plant wilts. Lack of water in the plant's cells (lower turgidity) reduces its ability to remain rigid or erect. Other reasons are diseases, bacteria or fungi that block or reduce the plants ability to transfer water through the body of the plant. Lack of rainfall or over-watering will saturate the soil and not allow the roots to receive oxygen. Another reason for wilt is high salinity which will draw water from the plant and shrink the cells.

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A plant can lose water through its leaves, especially if it loses wax on the leaf cuticle. The wax helps protect the leaf and prevent the loss of water.