In Pyrus
pyrifolia the type of cytokinin had high influence on the
formation of hyperhydrized plants while the concentration
had little influence. It was also reported by these authors that
synthetic phenylurea derivatives (CPPU and TDZ) produced
more hyperhydric shoots than adenine derivatives (BA and
kinetin) [20]. Therefore, cytokinin type and concentration
suitable for micropropagation of woody plants have to be
carefully optimized.