Effect of Anatomical Structure of Shoots in Different Flowering Phase on Rhizogenesis of Once-blooming Roses

Abstract

The research was conducted on five once-blooming different origin historical roses. The aims were establishing differences in the anatomical structure of shoots taken in four maturity stages and their natural ability to roots creating. There were hypothesized, that the changes in anatomical structure occur in the time of flowering and may affect the ability of rhizogenesis. Single node one leaf cuttings of chosen cultivars were cut from shoots in four maturity phases: flower buds closed, all flowers open, just after and 7-14 days after petal fall. The cuttings were planted in multipot trays in peat substrate without using rooting stimulators. The anatomical structure of shoots in the place of rhizogenesis were observed, the width of xylem layer and cambial zone, diameter of vascular cells were measured. The percentage of rooted cuttings and forming only a callus were counted. Adventitious roots appeared probably in the cambium zone, pith rays, and also in the zone of phloem and pericycle. The anatomic structure of shoots changes during the period of flowering and influences rooting percentage and the percent of cuttings which developed callus only. The width of the cambium layer of shoots influences the width of the wood layer in all cultivars. The rise of width of cambium tissue have an effect of increase of percentage of cuttings forming a callus only in ‘Hurdals’ and ‘Maiden’s Blush’. The width of the cambium layer in shoots enlarges during full blooming in four of the studied cultivars (‘Hurdals’, ‘Maiden’s Blush’, ‘Mousseuse Rouge’, ‘Semiplena’) and in one it stays at the same level for the whole duration of the experiment (‘Duchesse d’Angoulême’). The specifying in practice the period of taking rose cuttings, individual properties of cultivars and phenological phase of shoot should be taken into consideration.