Growth and flowering of Lemna paucicostata II. Role of growth regulators

Lemna paucicostata HEGELM., a short-day plant, can be induced to flower under long days by provision of cytokinins in the medium. Of several cytokinins tested, zeatin and 6-benzylaminopurine are the most potent. They are effective when added in a medium containing excess of iron and thus can bring about the same affect as EDDHA. Interestingly, when both EDDHA and a cytokinin are provided together, flowering occurs even in the medium containing normal level of iron. Other cytokinins such as SD 8339, kinetin and 6-(δ,δ-dimethylallylamino)-purine are also effective in medium containing a slightly higher level of ferric citrate. In contrast to cytokinins, indole-3-acetic acid and gibberellic acid are not only ineffective by themselves, but even nullify the inductive effect of cytokinins on flowering. Growth retardants such as CCC and abscisic acid have been found to inhibit flowering at high levels