It was noted that excess water can kill plants If water is n

It was noted that excess water can kill plants. If water is not toxic, and if all plants require water, then how can excess water kill plants What is actually killing the plant?

Solution

It is indeed noticed that excess of water can kill plants. It is very well known that water can freely diffuse through the cell wall and the plasma membrane according to the water potential of the cell and the matrix. If the water concentration inside the cell is low and matrix is high, the cells will experience hypertonicity with respect to the matrix. This will result in net inward movement of water by osmosis and cause the cells to swell up.

On the other hand, if the water content is high inside the cells and low outside the matrix, the cells will experience net hypotonicity with respect to the matrix. This will result in net outward movement of water by osomosis and cause the cells to shrink.

Thus, if the plant is provided with excess of water, the matrix will be highly diluted in nature and net inward movement of water will take place in the cells. This will cause the cells to swell up abruptly and consequently burst. Thus, although water is not toxic to plants, excess of water can eventually kill the plants due to osmotic inwards movement and consequent bursting of cells .