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 coolclimates. The most often used method of rose propagation are single node stem cuttings derived from blooming shoots. Thelong duration of rhizogenesis exposes cuttings to stress conditions and precocious ageing processes, which result in a lowrooting percentage. It was hypothesized that in the short season of flowering the amount of nutrients in shoots of stock plantschanges, thus affecting the process of rhizogenesis, as well as a condition of rooted cuttings, which may be estimated by thecontents of the biologically active components. The shoots of four rose cultivars were cut in four phenological stages: flowerbuds closed, flowers opened, just after petal shedding and 7-14 days after petal fall. The rooting percentage were counted after10 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 revealedvariability, characteristic for each examined cultivar, in the contents of the biologically active compounds, both before and afterrooting, in cuttings harvested from stock plants in successive phases of development. Decrease in pigment contents in leaves ofrooted 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 thehighest 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 thecontents of pigments, sugars or/and polyphenolic acids in successive phenological phases was shown.