How does abscisic acid help plants form dormant buds?

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fern life cycle — plant development The life cycle of the fern. (1) Clusters (sori) of sporangia (spore cases) grow on the undersurface of mature fern leaves. (2) Released from its spore case, the haploid spore is carried to the ground, where it germinates into a tiny, usually heart-shaped, gametophyte (gamete-producing structure), anchored to the ground by rhizoids (rootlike projections). (3) Under moist conditions, mature sperm are released from the antheridia and swim to the egg-producing archegonia that have formed on the gametophyte's lower surface. (4) When fertilization occurs, a zygote forms and develops into an embryo within the archegonium. (5) The embryo eventually grows larger than the gametophyte and becomes a sporophyte.

In the context of plant development, abscisic acid is recognized as a dormancy hormone that helps regulate the transition into a resting state.1

When plants in temperate zones perceive environmental signals—such as shortening day lengths—they transmit inhibitory materials to the shoot apex to halt growth and initiate the formation of a resting bud. Abscisic acid is implicated in this response, acting as a growth-inhibiting substance that helps maintain the dormant state.1

The eventual resumption of growth, or budbreak, typically involves a shift in the hormonal balance within the plant. Specifically, the plant must overcome the influence of growth inhibitors like abscisic acid through the increased activity of growth-promoting hormones, such as gibberellins. While abscisic acid is central to inducing dormancy, the complex process of bud development and release is also influenced by other factors, including temperature changes and signaling molecules like cytokinins.1