Primula Vulgaris Research Articles

In vitro regeneration in Primula ssp. via organogenesis

Culturing pedicle segments of primroses on a medium supplemented with 2,4-dichlorophenoxyacetic acid (2, 4-D) and thidiazuron (TDZ) resulted in callus induction rates of about 80%. The highest shoot regeneration rate (1.8 shoots per explant; mean of ten genotypes) was achieved with the combination of 2.0 mg/l 2, 4-D and 2.0 mg/l TDZ. Culture on a medium containing a high concentration of nitrate (for example, B5 medium) negatively affected the survival of regenerated shoots of one genotype, Gelb IV 48, probably due to an increase in the pH value of the medium. Consequently, the highest efficiency was obtained using a basal medium containing half-strength Murashige and Skoog macroelements. A protocol to regenerate shoots of Primula vulgaris and P. elatior is described.

Flower formation in Primula vulgaris is affected by temperature, photoperiod and daily light integral

Primula vulgaris ‘Dania Lemon Yellow’ was grown at photoperiods of 8, 11 and 14 h, daily light integrals (DLIs) of 2, 10 and 18 mol m −2 per day, and temperatures of 8, 12, 16 and 20 °C from transplant (30 days from seeding). Time to flower initiation varied from 28 to 201 days from transplant. Fastest flower initiation as determined by regression analysis occurred at 14 h photoperiod, 11 mol m −2 per day and 13 °C. No correlation between plant size and flower initiation could be identified. At the time of flower initiation, leaf number varied from 6 to 26. Leaf unfolding rate was not affected by photoperiod but increased as a linear function of temperature and DLI (leaves per day=0.01114(°C)+0.007627(DLI). Maximum leaf unfolding rate was 0.36 leaves per day at 20 °C and 18 mol m −2 per day. The length of the longest plant leaf at 8 weeks varied from 4.2 to 9.7 cm. In general, plants at a more advanced flower development stage after 8 weeks had the greater leaf lengths. After 8 weeks of experimental conditions, plants were moved to a common environment (11 h photoperiod, 10 mol m −2 per day and 16 °C). By week 15, the longest plant leaf length varied from 7.4 to 10.5 cm. Although there was a significant trend for longer leaves with a higher initial temperature, leaf size was proportional to overall plant size at all growing conditions. Average number of side shoots decreased from 7 at 8 and 12 °C, to 5 at 16 and 20 °C. The largest number of flowers and buds at termination was more than 100 for plants initially grown at 20 °C and 18 mol m −2 per day. First flower color was recorded after 25–35 days in the common environment for plants initially at 14 h, 10 or 18 mol m −2 per day, and 12 or 16 °C. Less than 35 days was also sufficient for flower color in Primula first grown at 8 °C, 14 h and 10 or 18 mol m −2 per day.

Temporal changes (1986–1999) in populations of primrose ( Primula vulgaris Huds.) in an agricultural landscape and implications for conservation

In Belgium, Primula vulgaris is a rare and declining species. Its fate is bound up with the ever-changing agricultural landscape in northwestern Belgium and analysis of historical data showed a shrinking distribution area during the last decades. Contrary to the situation in England and France, most of the populations are situated in small landscape elements in the agricultural landscape and not in woodland. The population size distribution is skewed to very small populations (<10 individuals) with few younger life stages in small populations, higher proportions of older adults and unequal flower morph numbers. The changes in several population traits during a 13-year interval are correlated with initial population status, indicating that small populations tend to be more prone to extinction than larger ones. Small remnant woodland patches may be seen as ‘safe sites’: in this environment population sizes were more or less stable during the 13-year period whereas populations in ditches around arable fields were particularly susceptible to decline. Under current conditions, the long term survival of the species in small landscape elements is highly critical unless land use practices change drastically in the near future. The minimum viable populations concept and management of small landscape elements are discussed.

Changes in pin-thrum ratios in populations of the heterostyle Primula vulgaris Huds.: Does imbalance affect population persistence?

Summary The heterostyle Primula vulgaris is a rare and declining species in Northern Belgium; its presence is restricted to a limited number of small landscape elements in a matrix of intensively managed agricultural land. In 1986 and 1999 we recorded numbers of pin-thrum flower morphs in respectively 34 and 89 populations. No structural imbalance in flower morph numbers was found, but imbalances were significantly larger in small populations. Moreover, relative imbalance also increased between 1986 and 1999. Population persistence however, was not correlated with morph imbalance: changes in population size between the two survey periods did not depend on initial flower morph imbalance. Results are compared with other heterostyly-related population research in Primula species and the relative importance of deterministic and stochastic processes for population persistence are discussed. To conclude, the introduction of missing morphs into relic populations with only pin or thrum plants is suggested to reduce pollinator-limited seed set.

Spectral filters for the control of Botrytis cinerea

SummaryExperiments performed in vitro examined the sporulation of Botrytis cinerea (grey mould) under different spectral distributions. Eighty‐three isolates, taken from plants of primula (Primula vulgaris) at different locations throughout the UK, were incubated in the dark, with visible light only and visible plus near‐ultraviolet (nUV) light. On average, compared to isolates not exposed to nUV, sporulation was increased 54‐fold following illumination with nUV light. No isolates showed complete insensitivity to near ultraviolet. New polyethylene materials with different optical properties were then tested on two typical isolates. A film which removed nUV up to 405 nm, compared to a film with nUV absorption up to 384 nm, resulted in the lowest production of conidia (by 5‐fold). The former film was used to clad horticultural polyethylene tunnels in which crops of P. vulgaris and strawberry were grown for two seasons and the incidence of B. cinerea assessed throughout the growth of the crops. The incidence of infection on the P. vulgaris and strawberries was reduced by c. 50% and c. 26% respectively with the nUV blocking film compared to a standard film. The results are discussed in terms of the potential of spectral filters as a novel means of grey mould control in greenhouse‐produced crops.

Glechoma hederaceaL. (Nepeta glechomaBenth.,N. hederacea(L.) Trev.)

A polycarpic, aromatic, often purplish, softly hairy or nearly glabrous perennial herb. Flowering shoots 10–30 (–60) cm long, square in section and ascending or erect. Non-flowering stems also square in section, creeping and rooting at many, but not all, nodes. Leaf laminae 4–35 (–80) × 6–40 (–80) mm, reniform to ovate–cordate, obtuse or subacute and coarsely crenate. Petioles highly variable in length from 10 mm in grassland to over 200 mm in woodland with dense canopy cover and dense ground vegetation. Bracteoles 1–1.5 mm, shortly hispid or pubescent. Flowers zygomorphic and hypogynous, borne in few (2–5)-flowered secund axillary whorls, the bracts not differing from the foliage leaves. Calyx tubular or tubular-campanulate, 15-veined, not gibbous at base, and somewhat two-lipped. Upper lip of the corolla flat with three triangular acuminate teeth that are 0.2–0.3 times as long as the tube. Lower lip with two teeth. Corolla tube narrowly obconical, straight and hairy within at the base of lower lip. Corolla (6–) 15–22 (–25) mm, usually blue–violet with purple spots on the lower lip; rarely pink or white. Stamens four, two long and two short, borne on corolla tube and lying below upper lip; anther cells at right angles to each other, each opening by a separate slit. Ovary four-celled and deeply four-lobed, each cell with one ovule. Style gynobasic, its branches equal. Hermaphrodite and male-sterile forms of flowers occur, the latter usually with smaller corollas than hermaphrodite flowers, and much-reduced, pollen-less stamens that are often included in the corolla tube. Clones usually bear either only hermaphrodite or only male-sterile flowers, but in rare cases both types are found on the same individual (Price 1991). Each flower produces a maximum of four obovoid, slightly angled, smooth nutlets with a mean air-dry mass of 0.69 mg (n = 100). Each is slightly angled owing to pressure exerted by the adjacent developing nutlets before dispersal, and each bears a grey protuberance which may be an elaiosome. The dimensions of the seed are 1.9 × 1.1 mm. Glechoma serbica Halacsy & Wettst., which has been recorded in former Jugoslavia, is probably an ecological modification of G. hederacea (Fl. Eur. 3). The southern counterpart of G. hederacea in Europe is ssp. hirsuta (Waldst. & Kit.) F. Hermann, sometimes referred to as G. hirsuta (Elias 1979, 1983). This has denser and longer hairs and longer calyx teeth than G. hederacea, and the corolla is pale blue. It has been recorded in Albania, Austria, Bulgaria, the Czech Republic, Greece, Hungary, Italy, former Jugoslavia, Poland, Rumania, central and south-west Russia, Sardinia and Sicily (Fl. Eur. 3). Intermediates, which are presumably hybrids between G. hederacea and G. hirsuta, sometimes occur (Fl. Eur. 3). In eastern Asia a more or less distinct, short-pubescent race occurs that is called ssp. grandis (A. Gray) Hara [also var. grandis A. Gray and var. longituba (Nakai) Kuprian] (Hulten 1971). In North America the variety micrantha Moricand [or var. parviflora (Benth.) House] is distinguished (Hulten 1971).

Selection for seed set capacity uncorrelated with flower heteromorphism in Primula vulgaris Hudson

Within-line pollinations were used when measuring the seed set of plants from seven early generation inbred lines of Primula vulgaris. One high seed setting plant and one low seed setting one were selected from each line and the seed set was evaluated on the offspring from selfings and within-line pollinations of these plants. Regression of offspring on parents for seed set was studied. The slope was estimated to be 0.17 ± 0.08, equivalent to an estimated heritability of around 34%. No significant differences in the slope of regression between the two reproduction methods (selfings or within-line pollinations) were detected. The realized improvement through one cycle of selection of high seed setting single plants in this early generation inbred material of P. vulgaris was 23.7%. Analysis of the seed set of within-line pollinated clones from late generation inbred lines of P. vulgaris revealed that only limited within-line variation remained after removal of the effects of the heteromorphic incompatibility system. It was concluded that selection of high seed setting single plants during early generations of inbreeding is efficient for improvement of seed set in future inbred lines of P. vulgaris to be used for hybrid seed production.

Factors affecting floral herbivory in a limestone grassland

The amount of herbivore damage to the petals of 41 species of herbaceous plant was surveyed from April to September in a limestone grassland in central England. Damage was recorded as the percentage of the petal area removed. Most damage was caused by invertebrates, particularly slugs. The amount of invertebrate damage differed significantly between plant species and with time of year. The mean damage across all species was only 2 %, ranging from an average of 0 % in Galium sterneri to 8 % in Primula vulgaris. In most species, less than a quarter of flowers received any damage, so those that were damaged were often severely affected. Species flowering early or late in the season received more damage, possibly because of greater slug activity. Hypotheses to explain the inter-specific variation in the amount of herbivory were examined by testing for correlations with a range of plant variables. No correlations with flower-stem length, flower-stem thickness or the longevity of flowers were apparent. The amount of petal damage correlated strongly with flower size and petal thickness. This appeared to result from the prevalence of large-flowered species early and late in the season rather than from a preference for flower size and petal thickness per se. The evolutionary significance of floral herbivory is discussed.

Immediate skin and mucosal symptoms from pot plants and vegetables in gardeners and greenhouse workers.

Short-lived occupational skin symptoms of irritant or urticarial nature were commonly reported among 253 attendants in a clinical study on occupational dermatitis in Danish gardeners and greenhouse workers. Aimed prick or scratch-patch testing for immediate skin and mucosal symptoms was performed in 105 persons with plants as is. 35 persons (33%) had at least 1 positive reaction and a family history of, or personal, atopy was significantly more prevalent among these compared to attendants with negative reactions. Positive histamine release tests made immunologic etiology probable in Schlumbergera cacti, Stephanotis floribunda, Euphorbia pulcherrima and Gerbera reactions. Other new species implicated in immediate-type reactions included Ficus pumila, Gardenia jasminoides, Hibiscus rosa-sinensis, Campanula, Columnea, Epipremnum aureum, Pelargonium and Primula vulgaris. Because of the high prevalence of short-lived skin symptoms and because contact urticaria may present itself as a dermatitis, it is recommended that one supplement patch tests with tests for immediate reactions.

Variation in the demography of a woodland understorey herb (Primula vulgaris) along the forest regeneration cycle: projection matrix analysis

1 Gaps in the forest canopy allow establishment of many understorey species. As gaps close, their demographic behaviour is affected by changing environmental conditions. A demographic analysis of Primula vulgaris populations in forest patches with varying canopy openness was carried out to investigate the effect of forest canopy dynamics on the demography of this forest understorey herb. 2 Eight P. vulgaris populations across a range of light conditions were studied in three deciduous temperate forests in Britain. Demographic data were collected in each population during summer 1992, 1993 and 1994, and stage‐based population projection matrices were built to describe their demography for two growth periods (1992–93 and 1993–94). 3 Population growth rate (λ) varied from 0.97 to 1.98 in 1992–93, and from 0.88 to 1.23 in 1993–94. There was a significant positive correlation between λ and diffuse light for the two periods studied: generally, population growth rate was lower in darker patches, implying that populations decline as the canopy closes. Lower λ‐values in 1993–94 were the result of increased mortality and decreased fecundity compared to 1992–93. In most cases the observed population structures were significantly different from the calculated stable‐stage distributions. 4 Sensitivity analysis showed that λ was most sensitive to changes in matrix transitions that corresponded to growth from small to adult stages, especially those that implied fast growth. Elasticity analysis revealed that the contribution of fecundity elements to λ was small, but populations in brighter patches showed comparatively higher fecundity elasticities than populations under the closed canopy. High elasticities corresponded to the entries that implied growth (especially in brighter patches) or persistence in adult categories (predominantly in darker patches). 5 The observed variation in the demography of P. vulgaris in different patches along the forest regeneration cycle stresses the importance of studying the variation in plant population dynamics across the range of habitat patches in which the plant naturally occurs.

An Integrated Model of Demography, Patch Dynamics and Seed Dispersal in a Woodland Herb, Primula vulgaris

Primula vulgaris is a woodland herb often associated with canopy gaps. The canopy regeneration cycle results in a permanently changing environment which confers a dynamic character to the overall system of P. vulgaris populations inhabiting a forest. In order to describe the dynamics of this spatially structured population, we built a matrix model that incorporates both the spatio-temporal variation in its population dynamics and the dynamics of the forest habitat given by the opening and closure of canopy gaps. To build the model, we combined empirical data on 1) the demography of populations in various forest patches and 2) canopy closure rate. We then used the model to test the effect of disturbance rate and long-distance (i.e., off-patch) seed dispersal on overall population dynamics. Simulation results suggest that overall population growth rate of P. vulgaris would be enhanced by high gap opening rates, as this would increase the relative frequency of clearings, where population growth rate is maximal. Our analysis also predicts a negative effect of long-distance seed dispersal on overall population dynamics, since seeds dispersing out of occupied patches would have a high probability of landing in closed canopy patches. These results are an example of the costs of long-distance seed dispersal on overall population dynamics. Finally, the potential role of long-distance seed dispersal in the colonization of newly opened gaps is discussed.

A Metapopulation Model for Primula Vulgaris, A Temperate Forest Understorey Herb

1 We suggest that Primula vulgaris in woodland habitats may form metapopulations: colonization is associated with the opening of canopy gaps and local populations become extinct as the canopy closes. The metapopulation is seen as a permanently changing system in which colonizations and extinctions are constantly occurring, coupled with forest canopy dynamics. 2 To describe metapopulation dynamics we use a Markovian model that incorporates the different stages through which local populations pass; we calculate the transition probabilities among those stages and estimate colonization and extinction rates. We combine empirical information on the demography of local populations and the dynamics of the forest mosaic in the model and use it to explore the effect of seed dispersal, fd (i.e. the fraction of seeds dispersing out of populations) and forest disturbance rate, k, on metapopulation growth rate, XM (i.e. the rate at which the number of populations in the metapopulation increases or decreases). 3 Increasing either fd or k has a positive effect on the projected metapopulation growth rate: higher disturbance rates increase the frequency of newly opened gaps in the environment and higher seed dispersal levels increase the probability of gap colonization. 4 Metapopulation growth rate is also affected by a number of other variables. It declines when time to local population extinction decreases and when fecundity is lower. The latter emphasizes that sufficient seeds must be available for dispersal to ensure gap colonization. 5 Stable patch/population-type distributions given different parameter values were obtained as the right eigen-vectors of metapopulation matrices. The proportion of forest patches occupied by P. vulgaris populations at equilibrium would be expected to be negligible under low k andfd values. 6 Metapopulation structure may break down under high disturbance rates because P. vulgaris local populations may never go extinct and thus seed dispersal would not play a major role in local population re-establishment.

Genetic control of seed set linked and unlinked to flower heteromorphism in inbred lines of Primula vulgaris Hudson

Analyses of a 12 × 12 diallel cross among inbred lines of Primula vulgaris disclosed considerable genetic variation for seed set, with differences between floral morphs accounting for 37.3% of the total variation. The differences between morphs agree with those reported elsewhere, with intra-thrum crosses being almost sterile, and intra-pin crosses relatively fertile. Inter-morph crosses produced higher seed yield when the thrum morph was used as the maternal parent. Results further showed that significant genetic effects, explaining 25.2% of the total variation, remained when the effects of the heteromorphic incompatibility system had been removed. Analysis revealed that these effects are due mainly to additive genetic differences between the lines and reciprocal general effects. A factorial analysis of the data indicated that differences in seed set capacity occurred only when the lines were evaluated as females. Seed set from within-line and between-line pollinations were highly positively correlated. These results suggest that selection for within-line fertility during inbreeding of parental lines could be an efficient method for improving seed setting in future inbred lines of P. Vulgaris for hybrid sedd production.

Flowering in Primula as Affected by Day and Night Temperatures

The growth of Primula vulgaris Huds. `Dania Lemon Yellow' and `Blue Danova' was evaluated for plants grown at day/night temperature differences of 9, 3, 0, –3 or –9°C. The day temperature was maintained for the duration of the 16-hour photoperiod and the day and night temperatures were selected to provide an average daily temperature of 16°C. The plants were grown at the specific temperatures starting 8 weeks from seeding until flowering. Total daily irradiance was 12 mol·d–1·m–2. Time for visible flower bud, flower color and first open flower was recorded. Plant height and flower bud number were determined at the termination of the experiment. `Dania Lemon Yellow' plants grown with a positive or negative difference of 9°C were significantly (P &lt; 0.05) later in reaching a visible bud stage. There were no differences however, in the number of days required for flower color or first open flower for `Dania Lemon Yellow'. Plants of `Blue Danova' showed a significant difference only in the number of days required for flowering. The plants grown with a positive or zero difference between day and night required on average 2 more days to reach the stage of first open flower. There were no significant differences in plant height or flower bud number in `Dania Lemon Yellow' or `Blue Danova'.

Stylar peroxidases and heteromorphic incompatibility reactions inPrimula acaulisHill («thrum» morph)

SUMMARYIn non-, self- and cross-pollinated styles of Primula acaulis «thrum» morph, the distribution of apoplastic peroxidase activity has been investigated, by means of the cytochemical treatment with diaminobenzidine. Apoplastic peroxidase activity was detected throughout the transmitting tract (at the «neck» region level) in non- and self-pollinated styles. The enzyme has been related to the predisposition of incompatible pollen tube rejection, no appreciable differences in enzyme distribution having been found between non- and self-pollinated styles since, in this morph, incompatible pollen tubes hardly ever reach the stylar neck. Compatible intermorph pollination caused the disappearance of apoplastic peroxidase activity in the central portion of the transmitting tract, where pollen tubes elongated, utilizing the reserves of the stylar cells, which appeared highly degenerate. Stylar apoplastic peroxidases seem then to play a role in heteromorphic incompatibility responses.

Spatial Variation in the Seed Ecology of a Woodland Herb (Primula vulgaris) in Relation to Light Environment

Patches of Primula vulgaris occur across a range of light conditions within forests. To understand how light affects the stages of the life cycle involved in reproduction and recruitment, several fecundity-related variables (flower and capsule production, seed set, seed germination and seedling establishment) were studied in eight populations across a range of light conditions. The mean number of seeds per plant varied greatly, from seven to 136, and the percentage of seedling establishment varied from 0.4 to 17.2%. These variables, as well as the number of flowers per plant and fecundity, were positively correlated with the light conditions. Primula vulgaris populations establish in newly opened gaps. How this species colonizes new clearings was investigated by looking at seed survival in the soil and seed removal by potential dispersers, in particular rodents and ants. After 14 months in the greenhouse, only three P. vulgaris seedlings were observed germinating from 200 soil samples taken from two populations. Germination of retrieved seeds from buried samples was generally lower than 10%. This suggests that only a small number of seeds remain viable in the soil for long periods of time. Seed removal was high in the populations studied (more than 70% in 10 days). Rodents harvested a greater proportion of seeds than ants. Seed dispersal by ants is known to occur within short distances but rodents may be long-distance dispersers, which may be important for the long-term persistence of P. vulgaris in a site because it allows seeds to reach newly opened gaps.

Peronospora oerteliana . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Peronospora oerteliana . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Primula acaulis, P. algida, P. elatior, P. juliae, P. officinalis, P. veris, P. vulgaris . DISEASE: Downy mildew of Primula species. GEOGRAPHICAL DISTRIBUTION: Asia-Temperate: Kazakhstan. Europe: Czechoslovakia, Denmark, Eire, France, Germany, Poland, Romania, Sweden, Switzerland, Yugoslavia, UK (England, Scotland). TRANSMISSION: By conidia which are dispersed by wind or rain-splash. The role of oospores in disease transmission is unknown, but they may have a perennating function.

Protein Concentration and Vigor of Imbibed Density-separated Primula Seed

Seeds of Primula acaulis (L.) J. Hill `Dukaat Helderrose' were imbibed for 48 h at 18C, and Maltrin 600 solution was used to separate them into density classes of 1.10, 1.12, 1.14, 1.16, and 1.18 g·cm-3. Seeds were rinsed, air-dried for 48 h at 22C, and germinated at 18C; 80% were separated into density classes between 1.16 and 1.18 g·cm-3. Percentages of germination and high-vigor seedlings were significantly greater for seeds with densities &gt;1.14 g·cm-3. Soluble protein concentration increased with density, whereas insoluble protein concentration was unchanged. Distinct protein groups with estimated molecular weights of ≈50, 33, and 25 kDa were present in the protein profile of nonseparated imbibed seed. These proteins were most abundant at densities ≥1.16 g·cm-3. The 25-kDa protein was present only in higher density seed. Presence of an additional 14-kDa protein was noted in the insoluble protein profile. Certain proteins in the soluble protein fraction maybe used to test for seed vigor.

FLOWER INITIATION AND DEVELOPMENT OF PRIMULA GROWN AT INCREASED ROOT-ZONE TEMPERATURE

Plants of Primula malacoides Franch `Prima Carmine Red' and Primula vulgaris Huds. `Danova Lemon Yellow' were grown for 5 weeks after transplant in root growth chambers maintained at 16, 20 or 24C. Germination and seedling development occurred at 16C, 16 hours photoperiod and 5.8 mol· day-1m-2 (100 μmol· s-1m-2). The location for the root growth chambers and the continued plant development after the root temperature treatment was a greenhouse at 15 ± 3C and 16 hours at an average 5.8 mol· day-1m-2. Both flower initiation and flowering were first recorded for P. malacoides plants grown in the root growth chamber at 16C. The observed time from transplant to flower initiation was 28 days and to the first open flower 76 ± 5 days for the plants grown with 16C root zones. The number of leaves and shoots on P. malacoides plants showed an increasing nonsignificant trend with increasing root temperature. P. vulgaris may respond differently than P. malacoides to increased root temperature.

THE CONTROL OF PRIMULA FLOWER INITIATION BY TEMPERATURE, PHOTOPERIOD, AND DAILY IRRADIANCE

The number of days required for flower initiation (FI) in Primula vulgaris Huds. `Dania Lemon Yellow' was determined under growing conditions in the ranges of 8 to 20C, 8 to 14 hours photoperiod (PP) and 2 to 18 mol· day-1m-2 photosynthetic photon flux. Germination and early seedling development occurred at 16C, 11 hours PP and 10 mol· day-1m-2. The environment was changed four weeks after seeding to the experimental conditions and the study initiated. FI was defined to have occurred when the first change from a vegetative to a reproductive meristem was detected using scanning electron microscopy. The observed number of days from transplant to FI varied from an average 201 days at 8C, 8 hours PP and 2 mol· day-1m-2 to 28 days at 16C, 14 hours PP and 10 mol· day-1m-2. Based on the functional relationship developed to describe the interactions among temperature, PP and PPF, the optimum conditions within the studied ranges for fastest primula FI were 13C, 14 hour PP and 11 mol· day-1m-2.