Colchicine-light effects on growth and mitotic behaviour in germinating lettuce achenes.

Root and shoot growth were severely suppressed in colchicine-pretreated lettuce achenes germinated in the dark and under illumination of 150 lux. Abnormal nuclear morphology rather than normal-appearing restitution nuclei was evident in these drug-pretreated achenes, there being no evidence of normal mitotic behaviour or cytokinetic activity in the root and shoot tissues examined. Root extension and lateral root meristem differentiation were evident in colchicine-pretreated achenes germinated under an illumination of 3000 lux, normal-appearing anaphase figures and cytokinetic activity being evident in both the primary root apices and lateral root meristems. Thus, the growth and mitotic behaviour of germinating colchicine-pretreated lettuce achenes were observed to be influenced significantly by the environmental light intensity in which germination occurred.