INCREASED MASS-PRODUCTION OF VERONICA-ARVENSIS GROWN ON A SLOWLY ROTATING CLINOSTAT

Morphometric analyses were made on 45-day-oId plants of Veronica arvensis grown from seed on a horizontal rotator (slow clinostat; 1 rpm) or on a vertical, equally slow rotator (control). During this period and for the clinorotated plants, dry weight of the hypocotyl and roots increased by 40% compared with the control, due to a higher production of secondary roots. The weight of the epicotyl, stem and leaves increased by only 10%. This increase was the consequence of a faster plastochronic activity and of an increase in the length of leaves, although their shape was not modified. Ethylene production was found to be higher in the rotated samples. When the increase of biomass on the clinostat was taken into account, the content of ethylene was equivalent to that of the control. From the results of these experiments it is concluded that the effects registered on plant morphogenesis after clinorotation are due to disturbances in graviperception.