Perry T O
Science. 1971 Jan 8;171(3966):29-36. doi: 10.1126/science.171.3966.29.
Early dormancy involves a number of phenomena: cessation of active growth, formation of terminal buds, formation of abscission layers in leaves, development of cold resistance, development of winter rest (a chilling requirement), and leaf fall. The buds of some tree species (or some races of a species) have a true rest or winter chilling requirement; usually the roots do not; perhaps the cambium does not. There is a wide range of genetic variation within and between species in response to photoperiod, winter chilling, water nutrients, and other environmental factors which affect the dormancy condition of plants. During the period of winter rest there are many metabolic and developmental processes going on in the buds and twigs. These processes include respiration, photosynthesis, some cell division, enzyme synthesis, production of growth stimulators, and dissipation of growth inhibitors. Dormancy of trees can be divided arbitrarily into three phases: early rest, winter rest, and after-rest. Each of these phases is marked by a distinct set of physiological processes. The transition between the three phases is gradual. Some processes of after-rest can proceed even though the winter chilling requirement (winter rest) of a tree has not been completed fully. Evidence from grafting experiments and chemical treatments to break winter rest, and studies of genetic variability indicate that the processes and phenomena of dormancy are at least partially independent of each other. Different buds and branches and other parts of the same plant may initiate dormancy, break dormancy, and renew vegetative growth independently. Initiation and cessation of dormancy can be triggered by a number of environmental variables: photoperiod, temperature, nutrition, water, an array of chemicals, and shock treatments. Dormancy regulation must either involve a variety of receptors or involve receptors that are responsive to a variety of stimuli. Unless dormancy is defined in a highly restricted sense (that is, possession of chilling requirement), it is hard to conceive of a single receptor or regulator that controls all of the phenomena of dormancy. A large number of genes are definitely involved and hence a large number of enzymes. The kinds of enzymes, their numbers, and their concentrations can be regulated by manipulating the environment.
生长活动停止、顶芽形成、叶片离层形成、抗寒能力发展、冬季休眠（需冷量）的形成以及落叶。一些树种（或一个树种的某些种群）的芽具有真正的休眠或冬季需冷量；通常根系没有；形成层可能也没有。物种内部和物种之间在对光周期、冬季低温、水分养分及其他影响植物休眠状态的环境因素的响应方面存在广泛的遗传变异。在冬季休眠期间，芽和嫩枝中会进行许多代谢和发育过程。这些过程包括呼吸作用、光合作用、一些细胞分裂、酶的合成、生长刺激物的产生以及生长抑制剂的消散。树木的休眠可任意分为三个阶段：早期休眠、冬季休眠和休眠解除后。每个阶段都有一组独特的生理过程作为标志。三个阶段之间的过渡是渐进的。即使树木的冬季需冷量（冬季休眠）尚未完全满足，休眠解除后的一些过程也可能会进行。嫁接实验、打破冬季休眠的化学处理以及遗传变异性研究的证据表明，休眠的过程和现象至少在一定程度上是相互独立的。同一植株的不同芽、枝条及其他部分可能会独立地开始休眠、打破休眠并恢复营养生长。休眠的开始和停止可由多种环境变量触发：光周期、温度、营养、水分、一系列化学物质以及冲击处理。休眠调节要么涉及多种受体，要么涉及对多种刺激有反应的受体。除非休眠被定义在非常狭义的范围内（即具有需冷量），否则很难设想有一个单一的受体或调节因子能控制所有的休眠现象。肯定涉及大量基因，因此也涉及大量酶。酶的种类、数量及其浓度可通过操纵环境来调节。
