In Development of European Larch (larix decidua Mill.) Vegetaive Buds Induced by Plant Hormones

摘要

Effects of exogenously applied auxins and cytokinins on morphogenesis of European larch vegetative buds collectedfrom 40-year-old tree were investigated using plant tissue culture techniques. Explants were prepared as short segmentswith axillary buds cut from the current year twigs or one-year-old twigs and were cultivated on modified MS medium.Different variants of nutrient medium were featured by different content of phytohormones: abscisic acid, auxins (indole-3-acetic acid and 2,4-dichlorophenoxyacetic acid), cytokinins (kinetin and 6-benzylaminopurine) and gibberellin (gibberellicacid-3). Abscisic acid negatively affected organogenesis in larch vegetative buds. Negative effect of auxins on thedevelopment of basal needles was significant after larch buds were cultivated in vitro for 25 days but after 75 days the tendencywas observed that the number of explants with newly developing shoots increases with increasing concentration of auxins. Auxinsstrongly increased callus formation on larch explants. Cytokinins blocked elongation of needles and induced formation of long-shoot primordia (structures able to form new meristems and to develop adventitious buds). Positive effect of cytokinins on viabilityof larch buds was significant in dark-grown explants, while large amounts of cytokinins have decreased the viability of light-grownexplants (but less significantly). Gibberellin was able to promote the development of axial needles in the shoot apex zone.