On the 28th
of March, the square was prepared according to the following table:
In our example the auxin IBA and the cytokinin BAP were used on a SP-0 medium.
Photos of the explants on the hormone square were taken on the 12th
of April, and I will now comment on the development that became apparent within
this time.
What can
soon be noticed is that the current stage of the plant development already
shows clear differences due to different hormone concentrations and
combinations.
Number 1
and 2 do not show any growth, in Nr. 3 little roots are visible, whereas Nr.4
shows clear formation of roots. This growing of roots is due to the well-known
effect of auxin (here IBA).
.JPG)
Number 5
and 9 also don’t show any growth, while in Nr. 13 some callus was formed. This
formation of callus due to only BAP and no combination with auxin also
makes sense since cytokinins stimulate cell division.
Though
without any cytokinin and only little auxin nothing happens and if there is no
auxin and only little cytokinin, nothing is growing either.
In Nr.8,
with 2 ppm of auxin and 0.02 ppm cytokinin, not only roots but also calluses are
forming.
.JPG)
The combination of as much auxin but a little more cytokinin (Nr.12) resulted
in callus and shoot formation.
Also Nr. 15
shows callus and shoots and looks similar to Nr. 12
Unfortunately
it seems that the formation of roots and shoots cannot be achieved with only one
mix of concentrations but a succession of different combinations would have to
happen. If first the shoots are generated and then the rooting should happen
there is the difficulty of having callus in between. Since callus between the vascular bundles of the stem and the vascular system of the roots reduces the ability
to take up nutrients and water, direct rooting of the shoots is desired.
