HORTICULTURE

Detailed explanation-1: -Among these, abscisic acid (ABA), is the best-known stress hormone that closes the stomata, although other phytohormones, such as jasmonic acid, brassinosteroids, cytokinins, or ethylene are also involved in the stomatal response to stresses.

Detailed explanation-2: -Abstract. Abscisic acid (ABA) is a stress hormone that accumulates under different abiotic and biotic stresses. A typical effect of ABA on leaves is to reduce transpirational water loss by closing stomata and parallelly defend against microbes by restricting their entry through stomatal pores.

Detailed explanation-3: -In angiosperms and gymnosperms (but not in ferns and lycopsids), ABA is the hormone that triggers closing of the stomata when soil water is insufficient to keep up with transpiration.