Transport in Plants — BIOLOGY STD 11 Science — Question

Wilting is the loss of turgidity of leaves and other soft aerial parts of a plant causing their drooping, folding and rolling. The symptoms of wilting are not shown by thick walled tissues. Therefore, they are less conspicuous in sclerophyllous plants. It is mainly of three types:

1. Incipient wilting.
2. Temporary wilting.
3. Permanent wilting.

Incipient wilting shows no external symptoms of wilting.
Differences between temporary and permanent wilting are as follows:

1. Temporary wilting is the temporary drooping down of leaves and young shoots due to loss of turgidity during noon. At this time the rate of transpiration is maximum. The rate of water absorption is less due to shrinkage of roots and depletion of water around the root hairs, lower leaves show wilting earlier than the upper ones. Whereas permanent wilting occurs when the soil is unable to meet the water requirement of plant.
2. Temporary wilting recovers as soon as water is replenished in the soil around root hair whereas permanent wilting cannot be recovered because cells do not regain their turgidity even in presence of plentiful water.
3. In temporary wilting plant regain its normal growth, whereas in permanent wilting plant eventually dies.