Dry-matter partitioning between bulbs and leaves in plantlets of Lilium speciosum regenerated in vitro

Plantlets of Lilium speciosum regenerated in vitro consist of scales that may or may not bear a leaf. We studied the effects of several physical, nutritional and hormonal factors on dry-matter partitioning between bulbs and leaves. Both absolute bulb weight and relative bulb weight (bulb weight as a percentage of plant weight) were determined. High temperature, culture in the dark and high osmolarity promoted relative bulb weight. Day-length had no effect. Amongst the nutritional factors sucrose promoted relative bulb weight. High concentration of MS-nutrients caused an increase in bulb fresh weight only. Bulb formation was under control of abscisic acid (ABA): ABA added to the medium completely blocked leaf formation, whereas fluridone, an inhibitor of ABA-synthesis, inhibited bulb formation. Paclobutrazol (PP333) blocked leaf formation completely. The PP333-effect was reversed by gibberellins A4+7. Cytokinin (6-benzylaminopurine), auxin (indoleacetic acid), ethylene and methyl jasmonate had no effect.