Wheat coleoptile bioassay.
The light stress did not affect the wheat coleoptile elongation, while
the interaction “stress × harvest time × concentration” was
significant at the 0.05 probability level (Table 2). Extract
concentration explained much of the inhibitory activity, contributing
for 55.5% on variance.
Wheat coleoptile’s inhibition was marked for all the extracts (Fig. 4),
with a high contribution of extract concentration. On the average of all
treatments, in fact, 800 ppm reduced by 69% coleoptile’s elongation,
compared to 46 and 31% of 400 and 200 ppm, respectively. Moreover,
April harvest exerted a higher allelopathic activity compared to
January, inhibiting by 64% vs . 33% on the average of all
treatments. The light stress condition in the April harvest showed the
best results, with values of 91, 77 and 46% at 800, 400 and 200 ppm,
respectively, compared to 85, 54 and 33% of Control.