[Growth of axillary buds of Salix babylonica L. and activity of phenylalanine ammonia-lyase].

In-vitro study of the growth of the axillary bud of a decapitated willow cutting gave the following results: 1. The intact and the decapitated willow cutting show a gradient of PAL (phenylalanine ammonia-lyase EC. 4.3.1.5) activity, which decreases from the apical part down to the base. 2. After decapitation of the cutting, a shift of PAL activity takes place 36 hr later at the section level. 3. A correlation between the growth of the axillary bud of the decapitated willow cutting and the PAL activity at the same level, within the stem as well as the leaf, has been demonstrated. In continuous red light (660 nm) apical dominance is lost after decapitation of the cutting.The highest leaf bud starts growing and replaces the cut-out apical bud. The PAL activity at that level first increases, then becomes stable.In continuous blue light (440 nm), apical dominance is maintained in spite of decapitation.The growth of the axillary bud is negligible and the PAL activity at that same level rapidly tends to zero.