Question

Phytohormone connected with the closing of stomata is …………………

Answer 1

Stomata are the fine pores present on the leaves. These structures help in exchange of gases and are important for photosynthesis. The stomata are guarded by guard cells which regulate the opening and closing of it. It is regulated by a phytohormone which is an antitranspirant.

Complete answer:
As we have already discussed, the opening and closing of stomata is regulated by the guard cells. When the cells are turgid it opens and when they become flaccid, it closes. This closing and opening of stomata is due to the transpiration.

The plants absorb water from the soil and transpire through the stomata of the leaves. When the plants undergo excessive transpiration than the available water, the plant enters a state of stress. Abscisic acid hormone acts on the plant and stops the transpiration by closing the stomata. This prevents the plant from wilting. ABA is an antitranspirant hormone regulates the opening and closing of stomata

Additional Information: Abscisic acid hormone was discovered by Adicott in cotton balls. It also induces seed dormancy. It also reduces the cambial activity and accelerates abscission and senescence. This hormone also regulates the size of the organs. This hormone is essential for regulating the developmental processes in plants. It works antagonistically to gibberellins as it inhibits the seed germination.

Therefore the correct answer is Abscisic acid.

Note: ABA is also known as a stress hormone as it protects the plants during adverse conditions. The other plant hormones are:
Auxins- It is known as growth hormone.
Gibberellins regulate the developmental processes in plants.
Cytokinin promotes cell division.
Ethylene- It promotes ripening of fruits.