Tomatiet al. (1988) reported
that giberline which is incorporated to the compost and
then to soil by the earthworm causes increased plant height
and provides favorable photosynthesis condition for the
plant. From the other hand, organic acids which are exerted
from the worm body, act as plant growth inducers in such a
way that they have positive role in seed germination, root
growth and plant tissue consistency (Kale 1998).