From our perspective as Pistacia weinmannifolia, our dormancy cycle is not a period of simple rest but a complex, deeply ingrained survival strategy. It is a carefully orchestrated sequence of physiological and molecular events that allows us to withstand the harsh environmental conditions of our native habitats, such as the seasonal droughts and temperature fluctuations found in the rocky slopes and valleys of Southwest China. Our entire annual rhythm is built around this essential process.
As the long, warm days of summer begin to shorten and the nights grow cooler, we initiate our retreat. This first phase, endodormancy, is governed by an internal biological clock. We sense the changing photoperiod and decreasing temperatures, which trigger a cascade of hormonal changes. We actively produce growth inhibitors, most notably abscisic acid (ABA), which acts as a powerful signal to halt cell division and growth in our apical and cambial meristems. Simultaneously, we suppress the action of growth promoters like gibberellins. This is not a response to immediate cold but a proactive measure to ensure we do not resume growth during a transient warm period in autumn, which would be fatal. During this time, even if placed in ideal warm conditions, we will not break bud; the signal to awaken must come from within.
Once our internal requirements for chilling are satisfied—a specific cumulative exposure to low temperatures above freezing that effectively breaks endodormancy—we enter the ecodormancy phase. The internal biochemical block is lifted. Now, the factor preventing our growth is the external environment itself. We are poised and ready, our metabolic processes slowly gearing up, but we remain dormant because the conditions are still too cold for growth. Our bud scales remain tightly closed, protecting the delicate primordial leaves and flowers inside from frost desiccation and physical damage. We are in a state of quiescence, passively waiting for the environmental signal that spring has truly arrived.
The final trigger for our emergence is the sustained rise in soil and air temperatures in spring. This warmth is the catalyst that mobilizes our stored resources. Water and nutrients flow back into our buds, cell elongation begins, and the hormonal balance shifts decisively in favor of growth promoters. Gibberellins and cytokinins become dominant, directing the energy stored in our roots and stems to fuel the rapid expansion of new shoots, leaves, and inflorescences. The bud scales loosen, and the vibrant new growth bursts forth, marking the successful completion of our dormancy cycle and the beginning of a new season of photosynthesis and reproduction.
