Response of Rambler Roses to Changing Climate Conditions in Urbanized Areas of the European Lowlands

Climate change affects the possibility of crop production and yield and disrupting the maintenance of crop biodiversity, including ornamentals. Warsaw is located in a temperate zone with mixed continental and oceanic climate influences. This research examines the response of once-blooming rambler roses to changing climate conditions in connection with their frost resistance and ornamental value. The 15 selected rambler rose cultivars were observed in the years 2000–2016 in the Polish Academy of Sciences Botanical Garden—Center for Biological Diversity Conservation in Powsin. Damage to shrubs caused by frost, the timing of bud break, leaf development, and initial, full, and final flowering were recorded. We show that changes in phenology and frost damage were the effect of weather conditions in the autumn–winter–spring period. Frost damage influenced the flowering and growth of plants in different ways, depending on the extent of required pruning. The cultivars most highly tolerant to frost damage were: “Lykkefund”, “Polstjårnan”, and “Semiplena”. During the final years (2014–2016), due to mild winters, all of the studied rose cultivars could be used for a wider range of applications than previously (2000–2006 and 2009–2013). Their reintroduction helped to maintain biodiversity of old cultivars, which makes these roses a proposal for the lowlands of Central Europe

Trends in the Phenology of Climber Roses under Changing Climate Conditions in the Mazovia Lowland in Central Europe

The genetic pool of valuable old ornamental cultivars and their in situ maintenance is threated by climate change. Meanwhile, ornamental plants like roses make up an important share of both gardens and urban green spaces, where they are particularly vulnerable to multi-stress growth conditions. The aim of this research was to evaluate the effect of changing climatic conditions on growth and flowering of 11 historic climber roses through long-term studies (2000–2017) conducted in Central Europe. The evaluation of plants consisted of assessment of frost damage and the timing of early phenological stages (starting of bud break, leaf unfolding), as well as gathering data on the beginning, fullness, and end of flowering and its abundance. Frost damage was not observed in any year only in ‘Mme Plantier’ and did not occur for any cultivar after the winter in the years 2007, 2008, and 2014. Only a little damage to one-year shoots was recorded after the winter in the years 2015–2017. Frost damage to ‘Alberic Barbier’, ‘Albertine’, ‘Chaplin’s Pink Climber’, ‘Orange Triumph clg’, and ‘Venusta Pendula’ led to pruning to ground level in every year excluding those listed above. Frost damage of once-blooming roses limited their flowering; however, the many-year datasets showed a trend for decreased frost damage and improved abundance of flowering, and these results can be interpreted as a response to the increase of average air temperature. The timing of bud breaking and leaf development in all climber roses was strictly correlated with average air temperature in the dormancy period. The reactions of climber roses to weather conditions confirmed the influence of climatic changes on ornamental crop plants in Central Europe, introducing the potential possibility for the wider application of climber roses, but without certainty of flowering every year

Preparations of plant origin enhance carbohydrate content in plant tissues of rooted cuttings of rambler roses: Rosa beggeriana ‘Polstjärnan’ and Rosa helenae ‘Semiplena’

During rhizogenesis, carbohydrates are an important source of energy for the plant tissues. It has been hypothesised that phenological phase of the shoot plays a major role in plant's response to rooting stimulants and affects the cuttings’ carbohydrate content. Therefore, the purpose of this study was to evaluate the impact of phenological phase of the shoots and the use of rooting stimulants of plant origin on the relationship between rooting abilities and the carbohydrate content in leaves and stems of cuttings. Single-node stem cuttings of Rosa beggeriana ‘Polstjärnan’ and Rosa helenae ‘Semiplena’ were harvested from shoots in four phenological stages: flower buds closed (P1), flowers open (P2), immediately after petal shedding (P3), and 7–14 days after petal fall (P4). The following rooting enhancers were used: 0.4% indole butyric acid (IBA) (Ukorzeniacz Aaqua); 0.2% naphthalene acetic acid (NAA) (Ukorzeniacz Baqua); Bio Rhizotonic; and Root Juice™; Bio Roots. Controls included untreated cuttings. The contents of reducing and total soluble carbohydrates in leaves and shoots were estimated before and after rooting. The rooting percentage and rooting degree were determined. A relatively high or moderate natural rooting ability without any treatment were shown by R. beggeriana ‘Polstjärnan’ in 63.8%–87.5% and by R. helenae ‘Semiplena’ in 41.3%–72.5% cuttings. IBA and NAA decreased the mean rooting percentage in ‘Polstjärnan’, but increased it for P4 cuttings in ‘Semiplena’. None of the preparations had any impact on the degree of rooting. The mean level of total soluble and reducing sugars in leaves and stems of cuttings before rooting was lower than that of after root formation. The preparations of plant origin positively affected rhizogenesis and sugar contents in plant tissues, but their effect depended on shoot's phenological phase and cultivar. Plant origin preparations may successfully replace those containing IBA or NAA

The Pivotal Role of Phenological Stages Enhanced by Plant Origin Preparations in the Process of Rhizogenesis of Rosa ‘Hurdal’ Stem Cuttings

Some biostimulants, including plant origin preparations, act similarly to plant growth regulators. Moreover, the supplementation of known and unknown rooting cofactors can stimulate rhizogenesis in cuttings. The aim of this research was to assess the response of difficult-to-root and long-rooting stem cuttings of the once-blooming old variety Rosa ‘Hurdal’ to preparations of plant origin. The hypothesis was that the plant origin preparations could enhance rooting processes by inhibiting chlorophyll a/b degradation in leaves and postponing leaf senescence, simultaneously increasing the quality of cuttings. The one-bud stem cuttings were made in four phenological stages: (H1) flower buds closed, (H2) open flowers, (H3) just after petal fall, and (H4) 7–14 days after petal shedding. They were treated with either standard commercial powder preparations containing 0.4% indole-3-butyric acid (IBA) or 0.2% 1-naphthalene acetic acid (NAA) as well as with commercial plant origin preparations that this work will henceforth refer to as: Algae Extract, Organic Preparation, and Plant Extract. The cuttings were evaluated after 12 weeks of rooting them in two substrates: peat–perlite and peat–sand (v:v; 1:1). Mean root percentages for both substrates were noted after preparation from stage H1 (74.5%), H2 (59.5%), H3 (50.8%) shoots. The H4 cuttings did not root at all and were not considered further. The means for all phenology stages together were the highest by the use of 0.6% Algae Extract, 0.012% and 0.02% Organic Preparation, and 0.2% and 0.4% Plant Extract. The lowest means were reported for the control cuttings as well as NAA and IBA treatment. Plant origin preparations encouraged growth parameters but did not unequivocally inhibit the decrease of chlorophyll content in the cuttings’ leaves. The percentage of cuttings that rooted in both rooting substrates was determined by the quality of the cuttings as well as the chlorophyll a/b and soluble protein content in the leaves

The Pivotal Role of Phenological Stages Enhanced by Plant Origin Preparations in the Process of Rhizogenesis of Rosa ‘Hurdal’ Stem Cuttings

Some biostimulants, including plant origin preparations, act similarly to plant growth regulators. Moreover, the supplementation of known and unknown rooting cofactors can stimulate rhizogenesis in cuttings. The aim of this research was to assess the response of difficult-to-root and long-rooting stem cuttings of the once-blooming old variety Rosa ‘Hurdal’ to preparations of plant origin. The hypothesis was that the plant origin preparations could enhance rooting processes by inhibiting chlorophyll a/b degradation in leaves and postponing leaf senescence, simultaneously increasing the quality of cuttings. The one-bud stem cuttings were made in four phenological stages: (H1) flower buds closed, (H2) open flowers, (H3) just after petal fall, and (H4) 7–14 days after petal shedding. They were treated with either standard commercial powder preparations containing 0.4% indole-3-butyric acid (IBA) or 0.2% 1-naphthalene acetic acid (NAA) as well as with commercial plant origin preparations that this work will henceforth refer to as: Algae Extract, Organic Preparation, and Plant Extract. The cuttings were evaluated after 12 weeks of rooting them in two substrates: peat–perlite and peat–sand (v:v; 1:1). Mean root percentages for both substrates were noted after preparation from stage H1 (74.5%), H2 (59.5%), H3 (50.8%) shoots. The H4 cuttings did not root at all and were not considered further. The means for all phenology stages together were the highest by the use of 0.6% Algae Extract, 0.012% and 0.02% Organic Preparation, and 0.2% and 0.4% Plant Extract. The lowest means were reported for the control cuttings as well as NAA and IBA treatment. Plant origin preparations encouraged growth parameters but did not unequivocally inhibit the decrease of chlorophyll content in the cuttings’ leaves. The percentage of cuttings that rooted in both rooting substrates was determined by the quality of the cuttings as well as the chlorophyll a/b and soluble protein content in the leaves

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

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