Effect Of Vernalization Research Articles

Comprehensive transcriptome analysis of faba bean in response to vernalization.

This study unravels the transcriptional response of a highly productive faba bean cultivar under vernalization treatment. Faba bean (Vicia faba L.) is a member of the Leguminosae family and an important food crop worldwide providing valuable nutrients for humans. However, genome-wide studies and comprehensive sequencing resources of faba bean remain limited. Vernalization is crucial for enhanced yields in a number of winter-sown crops. However, the effects of vernalization on faba bean remain unknown. In this study, we generated a high-quality transcriptome assembly and functional annotation source for vernalized faba bean (Vicia faba L.) cv. Tongxian-2, a domesticated cultivar from southern China. A total of 369.9million clean Illumina paired-end RNA-Seq reads were generated, and the transcriptome was assembled into 68,683 unigene sequences, with an average length of 1018 bp and an N50 of 1652 bp. Comprehensive functional annotation provided putative functional descriptions for more than 70% of the faba bean transcripts. We annotated a total of 1560 faba bean transcripts encoding transcription factors (TFs) belonging to 55 distinct TF families. The bHLH (168 transcripts), ERF (123 transcripts) and WRKY (105 transcripts) contained the largest number of TFs in response to vernalization. Genome-wide transcript changes comparing vernalized and unvernalized seedlings were investigated using bioinformatics approaches, which revealed a strong repression of photosynthesis and carbon metabolism, while genes participating in 'response to stress' were significantly induced. We also specifically identified vernalization-induced twenty-two 'pollen-pistil interaction' genes. A detailed functional annotation and expression profile analyses unveiled a number of protein kinases, which were specifically induced in vernalized seedlings. We also identified a total of 6852 simple sequence repeats (SSRs) in 6552 transcripts, representing a valuable genomic molecular marker resource for faba bean. In summary, this study provides new insights into the vernalization process in this economically valuable crop. The transcriptome data obtained provides us with a valuable candidate gene resource for future functional and molecular breeding studies. These data will contribute to the genome annotation for ensuing genome projects.

Photosynthesis in Ranunculus asiaticus L.: The Influence of the Hybrid and the Preparation Procedure of Tuberous Roots.

Ranunculus asiaticus L. is a quantitative long-day geophyte, grown in a cold greenhouse for cut flowers and potted plants. Flowering in ranunculus is a complex process, strongly steered by temperature and photoperiodism. Vernalization of rehydrated tuberous roots anticipate sprouting and leaf rosette formation and flowering. It is known that the time for flowering and the sensitivity to cold treatment, in terms of flowering anticipation, varies in numerous hybrids, while no information seems to be available on the influence of hybrids and on the vernalization on the photosynthetic process and primary metabolite profiling. We investigated the influence of two ranunculus hybrids, MDR and MBO, and two preparation procedures of tuberous roots, only rehydration (Control, C) and rehydration followed by vernalization (V), on the photosynthesis and photochemistry of plants grown in a climatic chamber, under a controlled environment. In addition, in MBO plants, in which the vernalization showed the main effects, carbohydrate, amino acid and protein levels were also investigated. In control plants, the response of leaf photosynthesis, to increasing white light, revealed higher photosynthetic activity in MDR than in MBO. The quantum yield of PSII (ϕPSII), electron transport rate (ETR) and non-photochemical quenching (NPQ) did not differ between the two hybrids. The maximal photochemical efficiency (Fv/Fm) was higher in MBO than in MDR and showed a decrease in both hybrids after vernalization. The preparation treatment of propagation material affected the light response of photosynthesis in the two hybrids differently, which increased in plants from vernalized tuberous roots, compared to those from only rehydrated in MBO and decreased in MDR, in accordance to the effects of vernalization observed in leaf photosynthetic pigments. In MBO vernalized tuberous roots, starch was rapidly degraded, and the carbon skeletons used to synthesize amino acids. Control plants of MBO, developed more leaves than those of MDR and a consequent larger plant leaf area. Compared to only rehydration, vernalization of rehydrated tuberous roots increased the plant leaf area in both the hybrids. Compared to the control, vernalized tuberous roots of MBO showed higher concentrations of sucrose and free amino acids, which could act as a long-distance signal promoting floral transition in young leaf primordia.

Interactive effects of multiple vernalization (Vrn-1)- and photoperiod (Ppd-1)-related genes on the growth habit of bread wheat and their association with heading and flowering time

BackgroundThe precise identification of Winterness/Springness (growth habit) for bread wheat, which is determined by genes involved in vernalization and photoperiod, will contribute to the effective utilization of bread wheat varieties. Here, 198 varieties from the Yellow and Huai wheat production region (YHW) in China were collected to identify their vernalization (Vrn-1) and photoperiod (Ppd-1) gene composition via a series of functional markers and their association with vernalization and photoperiod requirements at three locations during two years of experiments. The growth habits were measured during the spring sowing season.ResultsThe results showed that the semi-winter varieties (grades1–4) were most prevalent in the population. The relative effects of single Vrn alleles on the growth period, such as heading date (HD) and/or flowering date (FD), were as follows: Vrn-B1b > Vrn-B1a > Vrn-D1b > Vrn-D1a > vrn-D1 = vrn-B1. The interactive effects of Vrn-B1 and Vrn-D1 on HD and FD were identical to those of Vrn-B1b. Approximately 35.3% of the cultivars carried Ppd-B1a (photoperiod-insensitive) and exhibited the earliest HD and FD. The Ppd-D1a-insensitive allele (Hapl II) was carried by just 0.5% of the varieties; however, the other two sensitive alleles were present at a higher frequency, and their effects were slightly weaker than those of Ppd-B1a. In addition, strong interactive effects between Ppd-B1 and Ppd-D1 were detected. In terms of mean values among various genotypes, the effects followed the order of Vrn-1 > Ppd-1.ConclusionsAccording to the results of ANOVA and least significant range (LSR) tests, we can conclude that Vrn-1 rather than Ppd-1 played a major role in controlling vernalization and photoperiod responses in this region. This research will be helpful for precisely characterizing and evaluating the HD, FD and even growth habit of varieties in the YHW at molecular levels.

Genetic dissection of flowering time in Brassica rapa responses to temperature and photoperiod

The Brassica rapa (B. rapa) species displays enormous phenotypic diversity, with leafy vegetables, storage root vegetables and oil crops. These different crops all have different flowering time, which determine their growing season and cultivation area. Little is known about the effects of diverse temperature and day-lengths on flowering time QTL associated with FLC paralogues. We phenotyped the flowering time of a doubled haploid population, established from a cross between Yellow sarson and Pak choi under diverse environmental conditions. We identified flowering-time QTL (fQTL) in different photoperiod and temperature regimes in the greenhouse, and studied their colocation with known flowering time genes. As several fQTL colocalized with FLC paralogues, we studied the expression patterns of four FLC paralogues during the course of vernalization in parental lines. Under all environmental conditions tested the major fQTL that mapped to the BrFLC2_A02 locus was detected, however its effect decreased when plants were grown at low temperatures. Another fQTL that mapped to the FLC paralogue, BrFLC5_A03 was also identified under all tested environments, while no fQTL colocated with BrFLC1_A10 or BrFLC3_A03. Furthermore, the vernalization treatment decreased expression of all BrFLC paralogues in the parental lines, and showed the lowest transcript level after 28 days of vernalization. Transcript abundance stayed low after returning the plants for seven days to normal growth temperature. Interestingly, transcript abundance of BrFLC3_A03 and BrFLC5_A03 was repressed much stronger and already reached lowest levels after 14d in the early-flowering type YS-143. This study improves understanding of the effects of daylength and vernalization on flowering time in B. rapa and the role of the different BrFLC paralogues therein.

Effect of vernalization on tuberization and flowering in the Tibetan turnip is associated with changes in the expression of FLC homologues

The turnip (Brassica rapa var. rapa) is a biennial crop that is planted in late summer/early fall and forms fleshy tubers for food in temperate regions. The harvested tubers then overwinter and are planted again the next spring for flowering and seeds. FLOWERING LOCUS C (FLC) is a MADS-box transcription factor that acts as a major repressor of floral transition by suppressing the flowering promoters FT and SOC1. Here we show that vernalization effectively represses tuber formation and promotes flowering in Tibetan turnip. We functionally characterized four FLC homologues (BrrFLC1, FLC2, FLC3, and FLC5), and found that BrrFLC2 and BrrFLC1 play a major role in repressing flowering in turnip and in transgenic Arabidopsis. In contrast, tuber formation was correlated with BrrFLC1 expression in the hypocotyl and was repressed under cold treatment following the quantitative downregulation of BrrFLC1. Grafting experiments of non-vernalized and vernalized turnips revealed that vernalization independently suppressed tuberization in the tuber or hypocotyl of the rootstock or scion, which occurred in parallel with the reduction in BrrFLC1 activity. Together, our results demonstrate that the Tibetan turnip is highly responsive to cold exposure, which is associated with the expression levels of BrrFLC genes.

Effect of vernalization on flowering and true seed production behaviour of garlic (Allium sativum) under North Indian Plains

The effect of vernalization on reproductive potential of garlic (Allium sativum L.) especially on flowering and its true seed production behaviour which includes bolting behaviour, scape colour, flower colour, bulbil colour, number of bulbils per umbel, scape length and number of seeds per umbel were studied under North Indian Plain conditions. The thirteen ‘seed producing’ garlic genotypes which produce true seed under USA (long day) conditions were used in the present study and were given vernalization treatment at 4oC for two months before sowing. In control treatment, garlic bulbs were kept at room temperature before sowing. The vernalization of garlic bulbs at 4oC (for two months) resulted in bolting, umbel formation and true seed production in nine genotypes, whereas non-vernalized did not result into bolting, i.e. no true seed production was observed. Out of nine true seed producing garlic genotypes, the maximum seed setting was observed in genotypes 5366, 5351 and 5477 having values of 20.0, 18.0 and 13.0 seeds per umbel. The seed received from these genotypes were further sown but they did not germinated. These genotypes can be used in breeding programme, if these are sown under long day conditions. The highly significant and positive correlation was observed between number of seeds per umbel and scape length (r= 0.99); significant and positive correlation for number of seeds per umbel and number of bulbils per umbel (r=0.58); significant and positive correlation for number of bulbils per umbel and scape length (r=0.61). It was and also observed that when vernalization treatment was given to the 13 different genotypes of the garlic; out of them, nine complete genotypes produce flowers and after bulbil removal process resulted in true seed production. True seed production in garlic has the practical significance as it generates genetic variation which can be exploited in garlic breeding.

春化および日長条件がテンサイの抽苔・開花に及ぼす影響 : 幼苗からの採種に必要な春化日数の検討(平成23年度年次講演会一般講演)

春化および日長条件がテンサイの抽苔・開花に及ぼす影響 : 幼苗からの採種に必要な春化日数の検討(平成23年度年次講演会一般講演)

Research of influence of contrasting trophic conditions of vernalization on the mitotic activity of meristems, growth and development of winter wheat

The work is devoted to the most important physiological and selective sign of winter soft wheat Triticum aestivum L. – vernalization.Aim. The main aim of the work was the study of trophic factor influence on the effectiveness of vernalization process.Methods. In experiments were used the varieties of winter wheat – Statna and Doridna. The contrasting conditions of trophic support were created by vernalization on integral seeds (control) and isolated buds (experiment) adding water and 3-% solution of saccharose during 45 days at temperature 3±1°С. In experiments there was studied the influence of contrasting trophic conditions of vernalization on the mitotic activity of root meristems of vernalized sprouts, their growth reaction and rates of ontogenetic development of plants, cultivated from vernalized sprouts. All experiments were carried out under conditions of vegetative experiment in factorostatic chamber of the department of physiology and biochemistry of plants and microorganisms of Kharkiv national university, named after V.N. Karazin.Results. According to the results of researches, it was established that the growth reaction of sprouts at vernalization depends on their variety specific characteristics and on trophic factors presence. It was demonstrated that 3% solution of saccharose at vernalization stimulates proliferative activity of root meristems of both winter wheat varieties but doesn’t influences the parameter – duration of mitosis phases. The presence of trophic factors in sprouts at vernalization conditions the speed of phenophases passage and transfer to generative development of both winter wheat varieties. The vernalized sprouts of Doridna variety are characterized with higher parameters of mitotic activity of root apical meristems, accumulation of biomass of sprouts at vernalization influence and longer vegetative period comparing with Statna.Conclusion. The trophic conditions of vernalization process cause proliferative activity of meristems, growth reaction of sprouts and speed of transfer to generative development that is effectiveness of vernalization

Maternal vernalization and vernalization-pathway genes influence progeny seed germination.

Different life stages frequently respond to the same environmental cue to regulate development so that each life stage is matched to its appropriate season. We investigated how independently each life stage can respond to shared environmental cues, focusing on vernalization, in Arabidopsis thaliana plants. We first tested whether effects of rosette vernalization persisted to influence seed germination. To test whether genes in the vernalization flowering pathway also influence germination, we assessed germination of functional and nonfunctional alleles of these genes and measured their level of expression at different life stages in response to rosette vernalization. Rosette vernalization increased seed germination in diverse ecotypes. Genes in the vernalization flowering pathway also influenced seed germination. In the Columbia accession, functional alleles of most of these genes opposed the germination response observed in the ecotypes. Some genes influenced germination in a manner consistent with their known effects on FLOWERING LOCUS C gene regulation during the transition to flowering. Others did not, suggesting functional divergence across life stages. Despite persistent effects of environmental conditions across life stages, and despite pleiotropy of genes that affect both flowering and germination, the function of these genes can differ across life stages, potentially mitigating pleiotropic constraints and enabling independent environmental regulation of different life stages.

Identification of Earliness Per Se Flowering Time Locus in Spring Wheat through a Genome‐Wide Association Study

Identification of earliness per se (Eps) flowering time loci in spring wheat are troublesome due to confounding effects of vernalization and photoperiod responses. The Wheat Association Mapping Initiative panel of 287 elite lines was assessed to identify genomic regions associated with Eps and to understand the effects of vernalization and photoperiod treatments in spring wheat. The panel was grown under field conditions with four different treatments: (i) vernalization, where 1‐d germinated seeds were kept at 4°C for 6 to 8 wk; (ii) extended photoperiod treatment, from seedling emergence to 10 d after anthesis in the field; (iii) treatments (i) and (ii) in combination; and (iv) a control treatment without either (i) or (ii). The combined vernalization and photoperiod treatments had the greatest effect in advancing the flowering time (4 d). Genome‐wide association study in this panel on treatment (iii) detected a locus for Eps in chromosome 1D at 163 to 167 cM. An analysis of the flowering time data on this panel from 19 international environments did not show the presence of Eps in chromosome 1D, indicating the possible masking effect of vernalization and photoperiod genes. This study also validated the diagnostic marker—a transcription factor in the circadian clock input pathway called Triticum aestivum EARLY FLOWERING 3—that is associated with Eps in chromosome 1D and can be used for marker‐assisted selection.

Flowering pathway is regulated by bulb size in Lilium longiflorum (Easter lily).

Lilium longiflorum (Easter lily) vegetative propagation occurs through production of underground bulbs containing apical and axillary meristems. In addition, sexual reproduction is achieved by flowering of elongated shoots above the bulb. It is generally accepted that L.longiflorum has an obligatory requirement for vernalisation and that long day (LD) regime hastens flowering. However, the effect of bulb size and origin, with respect to axillary or apical meristems on flowering, as well as the interactions between these meristems are largely unknown. The aim of this study was to explore the effect of bulb size, vernalisation and photoperiod on L.longiflorum flowering. To this end, we applied vernalisation and photoperiod treatments to the different bulb sizes and used a system of constant ambient temperature of 25°C, above vernalisation spectrum, to avoid cold-dependent floral induction during plant growth. Vernalisation and LD hasten flowering in all bulbs. Large, non-vernalised bulbs invariably remained at a vegetative stage. However, small non-vernalised bulbs flowered under LD conditions. These results demonstrate for the first time that cold exposure is not an obligatory prerequisite for L.longiflorum flowering, and that an alternative flowering pathway can bypass vernalisation in small bulbs. We suggest that apical dominance interactions determine the distinct flowering pathways of the apical and axillary meristems. Similar floral induction is achieved in propagated bulblets from scaling. These innovative findings in the field of geophyte floral induction represent valuable applicative knowledge for lily production.

Effect of plant age and vernalization on bolting, plant growth and enzyme activity of garlic (Allium sativum L.)

In many bulbous plant species that require vernalization, including garlic, the age of the plant and a period of low temperature are important for complete vernalization. However, the response of garlic to vernalization treatment, which regulates development, remains poorly understood. In this study, the effects of vernalization and plant age on garlic growth and development were assessed. Garlic cultivar cv. G064 (bolting type), which is widely cultivated in China, was grown in a plastic tunnel for three different durations (A65, A45 or A25: 65, 45 or 25 days after planting) and then exposed to four vernalization temperatures [T5–0: 5°C/0°C, T10–5: 10°C/5°C, T15–10: 15°C/10°C, T20–15: 20°C/15°C (day/night)] for 40 days in growth chambers. To evaluate the bolting rate, plant growth, and endogenous physiological indexes, leaf and pseudostem samples were taken from all plants after 20 days of treatment and from A25 plants after 40 days of treatment. The results indicate that the response to vernalization varied among garlic plants of different ages, although the patterns were similar among the treatments. In general, vernalization treatment significantly increased the bolting rate in plants at all ages tested, with the youngest plants having the highest bolting rates at 10°C/5°C (28.6%, 40.1% and 50.0% for the A65, A45, and A25 plants, respectively), inhibited vegetative growth (with reductions in plant height observed in all plants except for A65 plants, pseudostem diameter, and green leaf number, especially for the T5–10 treatment) and promoted peroxidase (E.C. 1.15.1.7) and superoxide dismutase (E.C. 1.15.1.1) activities compared with the results observed in the control. The lowest temperature induced the strongest enhancing effect. It seems that a curved parabolic relationship might exist between the vernalization conditions and successful vernalization. Furthermore, the regulation of growth and bolting of plants requiring green-plant vernalization is achievable through the control of plant age (sowing dates) and growth temperature.

Effects of Vernalization, Temperature, and Soil Drying Periods on the Growth and Yield of Chinese Cabbage

Abstract: This study was carried out to determine the effects of vernalization, temperature, and soil water deficit (SD) on mesoph yll cells, growth, and yield of Chinese cabbage ( Brassica campestris L). The palisade parenchyma and spongy tissues of Chinese cabbage were observed under full irrigation and two weeks of SD treatment. These cells were severely collapsed by four weeks SD treatment. The SD treatment had the greatest influence on the growth of Chinese cabbage among the tested treatment factors (vernalization, temperature, and SD), growth significantly decreased by severe drought treatment (four weeks SD treatment). In addition, the relative growth rate, unit leaf rate, leaf area ratio, specific leaf area, and leaf weight ratio were si gnificantly affected by SD treatment; however, other individual factors and their combined treatments did not influence the analyzed growth parameters. The yield under vernalization after high temperature and full irrigation treatments was 3,056 kg/10 a, which was the greatest among all the tested treatments, while four-week SD treatment significantly reduced the yield. Head formation of Chinese cabbage was not altered under SD treatment, and vernalization treatments did not induce bolting. Our results indicat ed that collapsing mesophyll cells and reduced growth and yield were induced by SD treatment. Thus we suggest that optimal irrigation system should be install to avoid or overcome crippling drought conditions in the open field.Additional key words:

Harvest date, post-harvest vernalization and regrowth temperature affect flower bud induction in Russian dandelion (Taraxacum kok-saghyz)

Hodgson-Kratky, K. M. J., Demers, M. N. K., Stoffyn, O. M. and Wolyn, D. J. 2015. Harvest date, post-harvest vernalization and regrowth temperature affect flower bud induction in Russian dandelion (Taraxacum kok-saghyz). Can. J. Plant Sci. 95: 1221–1228. Russian dandelion (Taraxacum kok-sagyz Rodin; TKS) is a promising candidate for introducing natural rubber production into North America; however, a comprehensive analysis of factors that influence flowering is essential for efficient breeding and crop development. The objectives of this study were to determine the effects of fall harvest date (early September, October and November), post-harvest vernalization (0, 4 and 8 wk at 4°C), and greenhouse regrowth temperature [15/13°C or 21/18°C (day/night)] on flower induction. The vernalization requirements (0, 4, 8 and 12 wk at 4°C) to reflower TKS plants were also examined in controlled environments at 21/18°C. Plants harvested in September or October required 4 wk of vernalization and growth at 15/13°C to maximize the percentage of plants with flower buds and minimize the time for flower bud appearance. Those harvested in November flowered quickly and at high frequency with no vernalization and regrowth at 21/18°C. Vernalization was not essential to re-induce flowering; 80–100% of plants flowered regardless of treatment. Various combinations of harvest dates, vernalization periods and regrowth temperatures can be used to maximize flowering in TKS and have a positive impact on germplasm development.

Effects of vernalization on flowering ofDianthus barbatus

Effects of vernalization on flowering ofDianthus barbatus

Allelic variation and differential expression of VRN‐A1 in durum wheat genotypes varying in the vernalization response

AbstractThe purpose of this research was to study the effect of vernalization on flowering time in thirty accessions of Triticum turgidum spp. durum. To this end, screening of allelic variation at VRN‐1 loci was carried out using PCR‐based markers and DNA sequencing, and gene expression analysis was performed in two and four developmental stages, with and without cold treatment. In non‐vernalized plants, average days to flowering ranged from 34 to 99 days and only one accession was observed to remain at the vegetative stage. Three accessions were found to accelerate flowering after cold treatment. At VRN‐A1 locus, three alleles previously characterized, Vrn‐A1b, Vrn‐A1c and vrn‐A1, were detected. No polymorphisms at VRN‐B1 locus were observed. The differences in vernalization response among the genotypes studied could be explained by allelic variation and VRN‐A1 transcript levels. Variability in flowering time and sensitivity to vernalization in a collection of durum wheat, both potentially useful to the development of new varieties, were observed. This information is key to directing breeding cultivars for adaptation.

Genetic variation in the flowering and yield formation of timothy (Phleum pratense L.) accessions after different photoperiod and vernalization treatments.

Timothy is a perennial forage grass grown commonly in Boreal regions. This study explored the effect of vernalization and photoperiod (PP) on flowering and growth characteristics and how this related to changes in expression of three flowering related genes in accessions from different geographic origin. Large variation was found in accessions in their vernalization and PP responses. In southern accessions vernalization response or requirement was not observed, the heading date remained unchanged, and plants flowered without vernalization. On the contrary, northern types had obligatory requirement for vernalization and long PP, but the tiller elongation did not require vernalization at 16-h PP. Longer vernalization or PP treatments reduced the genotypical differences in flowering. Moreover, the vernalization saturation progressed stepwise from main tiller to lateral tillers, and this process was more synchronized in southern accessions. The expression of PpVRN1 was associated with vernalization while PpVRN3 accumulated at long PP. A crucial role for PpVRN3 in the transition to flowering was supported as in southern accession the transcript accumulated in non-vernalized plants after transfer to 16-h PP, and the apices transformed to generative stage. Differences in vernalization requirements were associated with variation in expression levels of PpVRN1 and PpVRN3, with higher expression levels in southern type. Most divergent transcript accumulation of PpMADS10 was found under different vernalization conditions. These differences between accessions can be translated into agronomic traits, such as the tiller composition of canopy, which affects the forage yield. The southern types, with minimal vernalization response, have fast re-growth ability and rapidly decreasing nutritive value, whereas northern types grow slowly and have better quality. This information can be utilized in breeding for new cultivars for longer growing seasons at high latitudes.

Observations on the development of plants. XV. Effect of CCC, gibberellin and vernalization on the development of Salvia pratensis sown at various dates

Observations on the development of plants. XV. Effect of CCC, gibberellin and vernalization on the development of Salvia pratensis sown at various dates

English

In the production of parsley ( Petroselinum crispum ) seeds is recommended the cultivation in locations of low temperatures to permit the emission of floral stalk. The study aimed to verify the effect of vernalization on floral induction, production and quality of parsley seeds. Ten plants of three cultivars (Caipira, Chacareira and Lisa Grande Portuguesa (O. Enke)) grown in pots for six months were submitted to vernalization at 5 °C for 0, 15, 30 and 45 days. After treatment, the plants were transferred to greenhouse and evaluated for period and flowering percentage, seed yield per plant and seed quality. The seed quality was evaluated by weight of a thousand seeds, germination (percentages of normal and abnormal seedlings, dormant and dead seeds), first count of germination, accelerated aging, dormancy after accelerated aging, seedling emergence in the field and seed water content before and after accelerated aging. It was concluded that the vernalization does not promotes floral induction and production of parsley seeds. For Lisa Grande Portuguesa (O. Enke) cultivar, the vernalization of the plant for 30 days enables the production of seed with high germination and vigor. Parsley seeds dormancy can be caused by plants vernalization periods between 30 and 45 days depending on the cultivar, followed by the exposure of the seeds to the conditions of high temperature and relative humidity of the air (41 °C/100%, UR/72 h).

Studies on the flowering biology of red sorrel (Rumex acetosella) ramets from lowbush blueberry (Vaccinium angustifolium) fields in Nova Scotia, Canada

Red sorrel (Rumex acetosella L.) is a ramet-producing herbaceous creeping perennial species commonly found as a weed in commercially managed lowbush blueberry (Vaccinium angustifolium Aiton) fields in Nova Scotia, Canada. Flowering and seed production occur primarily in overwintering ramets of this species, indicating a potential vernalization requirement for flowering. This study was therefore initiated to examine the role of vernalization, photoperiod, and pre-vernalization stimulus on ramet flowering. Red sorrel ramets propagated from creeping roots and seeds collected from established red sorrel populations in lowbush blueberry had an obligate requirement for vernalization to flower. Ramet populations maintained under pre- and post-vernalization photoperiods of 16 h flowered following 12 weeks of vernalization at 4 ± 0.1 °C, whereas those maintained under constant 16, 14, or 8 h photoperiods without vernalization did not flower. Vernalization for 10 weeks maximized, but did not saturate, the flowering response. Pre-vernalization photoperiod affected flowering response, with increased flowering frequency observed in ramet populations exposed to decreasing, rather than constant, photoperiod prior to vernalization. This study represents the first attempt to determine the combined effects of vernalization and photoperiod on red sorrel flowering, and the results provide a benchmark for the future study of flowering and sexual reproduction in this economically important perennial weed species.