The Effect of the Apical Bud on the Growth of Lateral Buds on Subterranean Shoots

The influence of the apical bud on the growth of the lateral buds on subterranean shoots was studied in Stachys sieboldiiMig. and Helianthus rigidus(Gass.) Desv. Removing and damaging the apical parts of subterranean shoots or their treatment with 2% chlorocholine chloride shoot enhanced shoot branching. The response to light of the apical bud was invariably negative: the stolons, which came out or were extracted from the soil, grew back into the ground (negative phototropism). The response to light of lateral buds was autonomous and depended on the conditions of their initiation. The lateral buds developed in darkness manifested negative phototropism when withdrawn from the soil and exposed to the light, whereas the buds developed in the light showed positive phototropism. The author concludes that the concept of apical dominance, thoroughly studied in aboveground shoots, is also valid for subterranean shoots. However, in contrast to the former, in the latter case, the apical bud does not control the growth orientation of the lateral buds.