Scion-rootstock relationships in hybrid tea cut roses on Rosa canina 'Inermis'.

In 2 successive years, 11-month-old cut rose clones grown in greenhouses were uprooted in December. Highly significant correlations occurred between the girth at the graft union and the root weight or the number of bottom-breaks, between the root weight and the number of bottom-breaks, and between the number of bottom-breaks and the number of harvested shoots. Plant vigour in clones was mainly determined by the scion. Rootstock-scion relations in rose were similar to those in apples and cherries. The equilibrium between aerial and underground parts in composite plants is discussed. Breeding of rose rootstocks that promote scion vigour under various glasshouse conditions is recommended. (Abstract retrieved from CAB Abstracts by CABI’s permission

Hybrid tea-roses under controlled light conditions. 2. Flowering of seedlings as dependent on the level of irradiance.

Under the experimental conditions described in the preceding abstract, mortality increased with decreasing light intensities. The percentage of flowering seedlings increased and that of aborting ones decreased with irradiance. For the populations studied, no genotype-environment interactions for the percentages of flowering seedlings occurred. A selection procedure for roses with a low light requirement for flowering is considered. (Abstract retrieved from CAB Abstracts by CABI’s permission

Hybrid tea-roses under controlled light conditions. I. The effect of the level of irradiance on the growth and development of seedlings.

As a basis for breeding cvs adapted to flowering in winter light conditions, the growth of hybrid tea rose seedlings under controlled conditions was studied. Irradiance varied from 4-24 W/m2, day length was 8 h, temperature 21 deg C. Like cvs, the seedlings sometimes aborted the flower bud at low light intensity. With increasing irradiances, the following phenomena were observed: the juvenile period of the seedlings shortened; plants were longer at bud formation, at first flowering and at flower bud abortion; leaf area and the number of petals increased. Leaf number was constant at all irradiances. Flowering seedlings were smaller at bud formation, but taller at actual flowering than blind ones. Blind seedlings had fewer leaves with a smaller area. (Abstract retrieved from CAB Abstracts by CABI’s permission

Hybrid tea-roses under controlled light conditions. 4. Combining ability analysis of variance for percentage of flowering in F1 populations.

F1 populations of the hybrid tea-roses Sonia, Baccara, Ilona, Prominent and Zorina were grown in a growth room under 8 W/m2 at 20 deg C with an 8 h day. The inheritance of flowering ability under low irradiance was mainly controlled by additive gene action. Prominent and Zorina had a good general combining ability for flowering under low irradiance. [For part 3 see HcA 49, 5235]. (Abstract retrieved from CAB Abstracts by CABI’s permission

Hybrid tea-roses under controlled light conditions. 3. Flower and blind shoot production in the glasshouse of seedlings selected for flowering or flower bud abortion at low irradiances in a growth room.

Seedlings of hybrid tea roses, previously selected in a growth room for flowering or flower bud abortion at low light intensities were grown in a greenhouse for periods of at least 14 months. Previously flowering seedlings whether grown on their own roots or on a rootstock yielded more flowers, particularly in winter, than previously aborting ones. This was due to a lower percentage of blind shoots and a tendency to produce more shoots. It was shown that selection for better winter performance under glass could be made in young seedlings. [For part 2 see HcA 48, 7528.] (Abstract retrieved from CAB Abstracts by CABI’s permission

The vigour of glasshouse roses : scion - rootstock relationships : effects of phenotypic and genotypic variation

Glasshouse roses commonly are combination plants, consisting of a scion variety and a rootstock of different genotypes. In this study, various environmental and genotypic factors have been investigated that influence the vigour of rootstocks and scion varieties, separately and in graft combination.In a field crop of Edelcanina (selections of R.canina L.) rootstock plants, significant phenotypic variation occurred for all plant characters investigated. Nurserymen partly disguise variation by grading the rootstock plants by standard classes for the diameter of the root collar. Even amongst plants of the same diameter (8-12 mm), both between and within batches of 'Inermis' of different provenance, significant variation occurred in branching of the roots, in the number of shoots, in the number of bottom-breaks and in the root collar diameter.The effect of the plant density, as a possible source of variation, was investigated by growing 'Inermis' rootstock seedlings at nine plant densities between 30 and 190 plants per m 2. As density increased, the root collar diameter of one-season-old stocks decreased; the distribution of plants over diameter classes shifted from a majority of thick (>10 mm) to one of thin (≤6 mm) stocks; interplant variation for root collar diameter increased; biomass increased to a maximum at a density of 170 plants per m 2. Density significantly affected the expression of plant characters. Hence, as density increased, shoot number per plant decreased, shoots became longer and lighter, the root system became lighter and less well-branched, and the shoot/root (fresh) weight ratio decreased. Density did not affect the percentage of plants with crooked root collars. Phenotypic variation of plant characters of 'Inermis' is mainly attributed to variation in plant age and in plant-to-plant distance in the seedling field.The diameter of the root collar of stocks at grafting had significant influence on the subsequent growth of 'Sonia' combination plants in the glasshouse. As the root collar diameter of the Edelcaninas 'Inermis'. 'Brögs Stachellose' and 'Pollmers' increased from 3 to about 15 min, the primary shoots of 'Sonia' were longer. bottom-breaks emerged earlier and yield measured in terms of the number. weight and length of shoots, increased. After 12 months. the absolute fresh weight of the roots of thick stocks was greatest. but the increase in weight of thin stocks was much larger (20 fold) than of thick ones (2-5 fold). The shoot/root (fresh) weight ratio in 12- month-old plants was not affected by the original stock diameter. but 'Brögs Stachellose' induced higher ratios than 'Inermis' or 'Pollmers'.Scion-rootstock relationships were studied by comparing the growth and development of own-rooted Hybrid Tea rose seedlings in the first year. with those of their clones grafted on 'Inermis' in the second year. Allowing for differences in level, the growth and development of Hybrid Tea seedlings generally agreed with those of their clones. The numbers of bottom-breaks and of harvested shoots of seedlings and clones were not affected by scionrootstock interaction. As the vigour of scion genotypes increased, the quiescent axillary buds of scions sprouted sooner after grafting. while more bottombreaks emerged in an earlier stage; over a 12-month period shoot yield was higher. and root weight of the stocks increased. The value set in practice on a high number of bottom- breaks as a basis for high flower production was confirmed. Breeders are recommended to use the number of bottom-breaks and the shoot yield in own-rooted seedlings as a predictor of the shoot yield of future cultivars.In clones of weak Hybrid Tea cut rose seedlings, the rootstock 'Inermis' promoted the vigour of combination plants but. as the original seedling had been more vigorous. increase of the vigour of combination plants on *Inermis' was smaller. In combination plants of various scion varieties grafted on one type of stock, the vigour is controlled by the scion variety rather than by the stock. The high cultural value attached to R.canina 'Inermis' as a rootstock. does not seem justified. A major component of the vigour of scion varieties is their branching capacity. Since branching capacity depends on degree of correlative inhibition, the ratio of auxins synthesized in the shoot and cytokinins produced in the root, is supposed to be the controlling mechanism of axillary bud-break. The lead in growth of vigorous over weak scion genotypes. is likely owing to a larger leaf area per plant as a result of earlier sprouting of more axillary buds after grafting or shoot harvest.To investigate the possibility of (undesired) hybridization in Edelcanina rootstocks, first the genotypic variation of 'Inermis' was studied as to characters and adventitious root formation of individual rootstock plants. After 6 months in the glasshouse, originally uniform (8-12 mm) 'Inermis' stocks appeared to differ in internode length, number of leaflets per leaf and the leaf area. In 23-day-old softwood cuttings of different genotypes, significant genotypic variation occurred for the time of axillary bud-break, axillary sprout length and weight of adventitious roots. Between rootstock clones, the root weight of cuttings was correlated with: number of leaflets per leaf, leaf area, and days to axillary bud-break.Subsequently, genotypic variation in R.canina 'Inermis' and 'Brögs Stachellose' was studied as variation in the growth and development of 'Sonia', grafted on clones of these stocks. Owing to different induction of vigour, 'Sonia' combination plants varied for: the date of emergence of the first and second bottom-break, the number of bottom-breaks, and the number of 'Sonia' shoots harvested after 12 months. Correlations between the root weight and the diameter of the graft union were significant for both 'Inermis' and 'Brögs Stachellose' clones. Graft unions of 'Brögs Stachellose' were always thicker than 'Inermis' of equivalent root weight. Genotypic variation of Edelcanina selections is attributed to hybridization with other Edelcaninas or other species. Finally, the effect of root clones of Hybrid Tea rose seedlings, pre-selected for vigour, was studied in 'Sonia' combination plants. For that purpose a complete Hybrid Tea rose seedling population was studied. In that population, the shoot yield of 8-month-old, own-rooted seedlings was negatively correlated with the time from seed germination to first flowering (juvenile period). The shoot yield of 12-month-old 'Sonia', grafted on root clones of low or high yielding Hybrid Tea seedlings, was positively correlated with both the yield of the original Hybrid Tea seedlings, and with the root weight of the clonal Hybrid Tea stocks.In all experiments the shoot yield of 'Sonia' combination plants was positively correlated with the number of bottom-breaks per plant per rootstock. It was generally found that as rootstock clones induced a first bottom-break earlier, the second bottom- break emerged earlier as well. Furthermore, 'early' rootstock clones induced more bottom- breaks and more shoots per 'Sonia' plant than 'late' clones. The diameter of bottom-breaks at pinching, was not-significantly correlated with the number of harvested shoots of a clone. The vigour of rose genotypes appears to be an inherent character. that is expressed in both the aerial and subsoil parts. In combination plants, the vigour of the rootstock genotype is transmitted to the scion variety.A major effect of vigorous rose rootstocks is an increased branching capacity of the scion variety, visible as earlier and more profuse axillary budbreak in all stages of plant development. Owing to induction of a larger branching capacity, scion varieties on vigorous stocks have a larger photosynthetically active area than those on weak stocks at an early stage of plant development. This results in a lead in growth. Main differences in the vigour of rootstocks are attributed to endogenous hormone action, a concept in which rootstocks are supposed to differ for cytokinin synthesis. A model of the vigour of combination plants, based on additive vigour of scion variety and the rootstock, derived from endogenous hormone action, is tentatively proposed.Edelcaninas generally induce mediocre vigour. show genotypic variation for yield and are too large plants for most artificial substrates. Because Edelcaninas generally are recalcitrant to vegetative propagation. they are unsuitable as clonal stocks. Also. because healthy Edelcanina stocks can only be produced in fields that are chemically disinfected, the important role of these stocks for the glasshouse culture seems to be finished. If. despite these disadvantages Edelcaninas are yet to be improved by breeding. at short notice genotypic variation may be stabilized by selecting good-looking mother bushes, to be planted in monoclonal seed gardens. At long term. such seed gardens may be established with mother bushes of which the (seedling) offspring has been thoroughly tested for a range of characters.For the modern cut rose culture in artificial substrates. clonal stocks should he given preference over seedlings. Populations for the selection of clonal stocks may arise from cross-breeding or genetic modification. Preliminary selection for rootstock vigour may be carried out on the basis of number of shoots and/or shoot length of individual genotypes. Vigorous genotypes are likely to occur among individuals with a short juvenile phase. Selection for rootstock genotypes that induce a high shoot/root (fresh) weight ratio at the same vigour of combination plants. should be an aim. The management of combination plants on vigorous stocks is discussed. In weighing pros and cons of the use of self-rooted cultivars and those on a vigorous rootstock. preference is given to the latter

The impact of information provision on agglomeration bonus performance : an experimental study on local networks

This research was funded by the European Investment Bank (EIB) under the EIB-University Research Action ProgrammeThe agglomeration bonus is an incentive mechanism to induce adjacent landowners to spatially coordinate their land use for the delivery of ecosystem services from farmland. This paper uses laboratory experiments to explore the performance of the agglomeration bonus in achieving the socially optimal land management configuration in a local network environment where the information available to subjects varies and the strategic setting is unfavorable for efficient coordination. The experiments indicate that if subjects are informed about both their direct and indirect neighbors' actions, they are more likely to produce the socially optimal configuration. Thus effectiveness of the policy can be improved by implementing information dissemination exercises among landowners. However given the adverse strategic setting, increased game experience leads to coordination failure and optimal land choices only at the localized level independent of the information available to subjects. Thus success of the agglomeration bonus scheme on real landscapes will have to take account of the roles of both information and experience on participant behavior.PostprintPeer reviewe

The impact of walking impairment, cardiovascular risk factors, and comorbidity on quality of life in patients with intermittent claudication

AbstractObjective: The objective of this study was to assess the impact of walking impairment, cardiovascular risk factors, and comorbidity on quality of life (QOL) in patients with intermittent claudication (IC). Material and Methods: The prospective observational study was conducted in the setting of a vascular outpatient department of a teaching hospital. QOL was assessed in 200 consecutive patients with IC, with a reduced version of the World Health Organization Quality of Life Assessment Instrument-100. The reduced instrument assesses 17 facets of QOL within five domains (Physical and Psychological Health, Level of Independence, Social Relationships, and Environment). Age, gender, degree of IC, risk factors, comorbidity, as recommended by the Society for Vascular Surgery/North American Chapter of the International Society for Cardiovascular Surgery (SVS/ISCVS), and the presence of back, hip, or knee symptoms were analyzed as possible predictors of QOL. Multiple regression analyses were run with each of the QOL facets and domains as dependent variable. A probability value of less than .05 was considered to be statistically significant. Results: Male gender was found to be a predictor of better scores for Energy and Fatigue and for Sleep and Rest. Women had more Negative Feelings. The presence of back, hip, or knee symptoms was a significant predictive value for many aspects of QOL. With more concomitant diseases, patients had lower scores on the facets of Overall QOL and General Health and of Energy and Fatigue and showed more dependence on medication and treatments. The degree of IC, as expressed in the SVS/ISCVS classification, was a statistically significant predictor of QOL on the domain Level of Independence and its facets Mobility, Activities of Daily Living, and Working Capacity and the facets Pain and Discomfort, Sexual Activity, and Transport. Hypertension was the second most important single predictor of QOL in patients with IC. Conclusion: QOL in patients with IC is only partially determined by the severity of walking limitation as expressed in the SVS/ISCVS classification. The significant impact of cardiovascular risk factors and comorbidity and the presence of back, hip, or knee symptoms on QOL should be recognized and taken into account in the treatment policy. (J Vasc Surg 2002;36:94-9.