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

Morphometric analyses were made on 45-day-oId plants of Veronica arven sis 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 in creased by 40% compared with the control, due to a higher production o f secondary roots. The weight of the epicotyl, stem and leaves increas ed by only 10%. This increase was the consequence of a faster plastoch ronic activity and of an increase in the length of leaves, although th eir 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 tha t of the control. From the results of these experiments it is conclude d that the effects registered on plant morphogenesis after clinorotati on are due to disturbances in graviperception.