Bushiness in Gerbera jamesonii: Abnormal shoot development during micropropagation

An abnormality, characterized by numerous leaves, short petioles and small laminae, which gives some cultivars of Gerbera jamesonii a bushy appearance , is known among the growers as "bushiness". It causes production losses up to 30% during micropropagation. In our study, bushiness was investigated b oth morphologically and anatomically in the Gerbera jamesonii cv. Rosabella (bushy) compared with the normal or non-bushy cv. Sunset. Three types of s hoots: the main shoot, adventitious and axillary shoots were investigated. Phenotypic changes were observed at the terminal region of the shoot: in ca se of bushiness it consisted of many apices in a linear arrangement on top of a short swollen stem. Nodes were not clearly distinguishable and no inte rnode elongation was observed. Anatomical analysis of longitudinal serial s ections of bushy shoots showed that the apical meristem and the axillary bu ds have the same potential for further development, i.e. axillary bud primo rdia are not inhibited, and develop right away. The process is repeated con tinuously and finally multi-apexing is installed.