The Impact of Seasonal Changes in Plant Tissue on Rhizogenesis of Stem Cuttings of Once Blooming Roses

Abstract

The majority of old and long-to-root roses are enough frost resistant to grow on their own roots in moderate and cool climates. The most often used method of rose propagation are single node stem cuttings derived from blooming shoots. The long duration of rhizogenesis exposes cuttings to stress conditions and precocious ageing processes, which result in a low rooting percentage. It was hypothesized that in the short season of flowering the amount of nutrients in shoots of stock plants changes, thus affecting the process of rhizogenesis, as well as a condition of rooted cuttings, which may be estimated by the contents of the biologically active components. The shoots of four rose cultivars were cut in four phenological stages: flower buds closed, flowers opened, just after petal shedding and 7-14 days after petal fall. The rooting percentage were counted after 10 weeks of rooting. The evaluation of plant material were carried out before and after rooting, including: soluble proteins, chlorophyll a and b, carotenoids, polyphenolic acids, reducing and total soluble carbohydrates. The research revealed variability, characteristic for each examined cultivar, in the contents of the biologically active compounds, both before and after rooting, in cuttings harvested from stock plants in successive phases of development. Decrease in pigment contents in leaves of rooted cuttings may suggest a progressing senescence, both during propagation and later in a vegetative season. The cuttings of 'Mousseuse Rouge' rooted similarly when harvested in each of the phenological phases (53.8-67.5%). For other cultivars the highest rooting percentage was obtained for cuttings harvested from shoots with closed flower buds: ('Hurdals' 47.5%, 'Maiden's Blush' 55.0%, 'Semiplena' 67.5%). In these cultivars a relationship between rooting percentage and changes in the contents of pigments, sugars or/and polyphenolic acids in successive phenological phases was shown.

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

“…So far, morphological and anatomical diversification of cultivars has been shown by studies conducted on pillar roses (Delinschi et al, 2009a, b). Moreover, in various phases of development of shoots during flowering, changes were shown in the content of chlorophyll a and b, carotenoids, proteins and carbohydrates, which affected the rooting of historical roses (Monder et al, 2016).…”

“…in 'Hurdals'. Changes were shown in the content of biologically active components (proteins, chlorophyll a and b, carotenoids, polyphenolic acids) in consecutive phenological phases of shoots and the influence of the changes on rhizogenesis of once-blooming historical roses suggests a diversification in the pace of this process in the studied rose cultivars (Monder et al, 2016).…”

“…The cuttings of D of 'Hurdals' did not root and those of 'Maiden's Blush' had a lower rooting percentage. The reason for that may also be the fastadvancing process of aging (Monder et al, 2016) e.g. in 'Hurdals'.…”

“…The high vitality and frost resistance of historical roses indicate on possibility their cultivation on own roots and economically favourable methods of propagation by stem cuttings. However, the cuttings of historical roses rooted in long period of time (Moroz 2006;Monder at al., 2014;Monder et al, 2016), whereas the efficiency of rooting and quality of a cutting is an integral production factor (Blythe et al 2007). In nursery practice, the cuttings are cut from flowering shots in various terms without differentiation of phenology phase.…”