Feulgen staining
Ten roots from each hormonal treatment were ®xed in
96% ethanol:100% acetic acid (3:1, v:v) for at least 24 h.
The roots were then hydrolyzed in 1 n hydrochloric acid for
20 min, thoroughly rinsed in distilled water and incubated
in Schiff's reagent in the dark until sufficiently stained.
Staining was stopped by rinsing with 1 n KOH. Root
meristems in the tips (the last 4 mm) of the main and lateral
roots were counted. A root tip was considered responsive
when it contained at least one new lateral meristem. The
multi-initiation of lateral meristems, in responsive tips, was
evaluated by ranking the root tips according to the number
of lateral meristems. Alternatively, the average number of
lateral meristems per root tip was calculated. In each
experiment, 150±200 root tips (main roots plus laterals)
were analysed. Each experimental condition was repeated
twice.