Apical dominance is a phenomenon where the shoot tip, or apical meristem, of a plant suppresses the growth of lateral buds, or axillary meristems, below it. This means that the main stem grows taller and stronger than the lateral branches, resulting in a more upright plant form. The hormone responsible for apical dominance is auxin, which is produced by the apical meristem and moves downwards in the stem.
The suppression of lateral buds by the apical meristem is thought to be an adaptive mechanism that allows plants to grow tall and compete for sunlight in crowded environments. However, in some cases, such as in horticulture and agriculture, this growth habit may not be desirable. To promote branching and a more compact growth habit, gardeners and farmers can prune the apical meristem or apply a synthetic auxin to the lateral buds.
The process of branching in plants is regulated by a complex network of genes and hormones. In addition to auxin, cytokinins and strigolactones are also involved in the regulation of branching. Cytokinins promote the growth of lateral buds, while strigolactones inhibit their growth. The balance between these hormones determines the degree of branching in a plant.
The regulation of branching is important for plant architecture and productivity. In agriculture, crops with a more compact growth habit are preferred because they are easier to harvest and can be grown at higher densities, resulting in higher yields. In horticulture, pruning and training techniques are used to shape plants for aesthetic purposes and to control their size and form. Understanding the mechanisms of apical dominance and branching can help in the development of new varieties with desirable growth habits for different applications.