A morphological study of the development of the second inflorescences in strawberry (Fragaria x ananassa Duch.)

To clarify the timing of the differentiation of the first and second inflorescences in strawberry (Fragaria x ananassa Duch.), morphological changes on shoot apices during short day and low night temperature treatments were observed by scanning electron microscopy (SEM) and optical microscopy. Axillary buds just below the first inflorescence (axillary bud 1) became visible when sepal primordia of the primary flower were differentiated. By this time, other axillary buds had already developed. Axillary bud I developed four leaf primordia, and then a differentiated inflorescence at its summit. The phase transition of shoot apices from the vegetative to the reproductive phase may therefore trigger the differentiation of axillary bud I which is destined to develop into extension crowns.