FORMATION AND GROWTH OF ROOTS IN CARNATION CUTTINGS - INFLUENCE OF COLD-STORAGE PERIOD AND AUXIN TREATMENT

The time course of the formation and longitudinal growth of the roots was determined by measuring the number of roots per plant and their av erage length, respectively at different time periods after planting of cuttings. The study was carried out in fresh and cold stored cuttings from two carnation cultivars ('Solar' and 'Master'). The duration of the storage period and auxin treatment modified the rooting process, s uch effects on root formation frequently being different from those on root growth. Long storage periods (8, 12 weeks) reduced the rates of root formation and growth and delayed the formation in 'Solar' cutting s. In 'Master' cuttings, the rates varied with the highest values bein g observed after 2 and 12 weeks of storage. Auxin treatment to fresh c uttings was as effective as storage for 2 weeks in stimulating rooting in both cultivars. As a rule, and irrespective of the storage period, auxin treatment brought forward and increased the rate of root format ion and growth in both cultivars except the rate of root formation in 'Master'. These results suggest that some changes occur in the endogen ous auxin concentration and auxin sensitivity during cold storage, whi ch could be responsible for differently modifying the distinct phases of the rooting process, and that the cuttings' requirement of auxin di ffer in each phase depending on the cultivar. (C) 1998 Published by El sevier Science B.V.