Abstract
The objective of this study was to analyse the effect of seven kinds of plant growth regulators on the growth and enlargement of microtubers in yams (Dioscorea alata L.) . Microtubers from nodal stem segments were used in this investigation.
Among the growth regulators examined, 3-indoleacetic acid (IAA), kinetin, zeatin riboside (ZR), brassinosteroids (BRs) and methyl jasmonate (JA-Me) promoted growth and enlargement of microtubers. While gibberellic acid (GA3) and abscisic acid (ABA) exerted an inhibitory effect.
Closer examination revealed differences in the modes of actions. Growth was promoted with the increase in the concentration of ZR (0.1/1M-100μM), but it did not respond to an increase in IAA concentration from 1μM to 100μM. Both BRs and JA-Me exerted a beneficial effect on growth at lower concentrations.unlike at higher concentrations.
Both IAA and BRs stimulated root development whereas cytokinins promoted shoot growth, giving rise to shoots with long internodes. JA-Me did not significantly induce root and shoot growth.
These results indicate that microtubers of yam can be used in vitro bioassays of plant growth regulators. In other words, the new method applied in this study, “microtuber test”, is considered to be reliable enough to enable to detect the action of the endogenous growth substances, though the experiment can be performed in vitro.
