Floral Bud Formation Research Articles

Average daily temperature controls floral bud formation rate, callose deposition and flower development of Hydrangea macrophylla ‘Early Blue’

ABSTRACT Hydrangea macrophylla ‘Early Blue’ was exposed to six different day (DT) and night (NT) and average daily temperatures (ADT) during flower bud formation (DT/NT°C: 12/12, 17/12, 17/17, 22/12, 22/17, 22/22). The aim was to evaluate the effect of ADT and DT/NT on the rate of bud formation and forcing time after a period of chilling. Furthermore, the role of callose in dormancy induction and release during cold storage was investigated. ADT ≤ 17°C accelerated flower bud formation irrespective of DT and NT compared to an ADT > 17°C. Floral buds developed at ADT 17°C contained significantly lower level of callose compared to buds from the higher ADT regimes (ADT >17°C). After 6 weeks of chilling (10°C) the callose level was decreased to a similar level irrespective of the DT/NT regime during floral bud formation and/or floral stage at the start of the chilling treatment. We conclude that callose may play an important role in the dormancy release of H. macrophylla. However, floral buds do not have to be fully developed to remove the callose in response to chilling and no clear relationship was found between the levels of callose after chilling and forcing time.

LhANS-rr1, LhDFR, and LhMYB114 Regulate Anthocyanin Biosynthesis in Flower Buds of Lilium 'Siberia'.

The bulb formation of Lilium is affected by many physiological and biochemical phenomena, including flower bud differentiation, starch and sucrose accumulation, photoperiod, carbon fixation, plant hormone transduction, etc. The transcriptome analysis of flower buds of Lilium hybrid 'Siberia' at different maturity stages showed that floral bud formation is associated with the accumulation of anthocyanins. The results of HPLC-MS showed that cyanidin is the major anthocyanin found in Lilium 'Siberia'. Transcriptome KEGG enrichment analysis and qRT-PCR validation showed that two genes related to flavonoid biosynthesis (LhANS-rr1 and LhDFR) were significantly up-regulated. The functional analysis of differential genes revealed that LhMYB114 was directly related to anthocyanin accumulation among 19 MYB transcription factors. Furthermore, the qRT-PCR results suggested that their expression patterns were very similar at different developmental stages of the lily bulbs. Virus-induced gene silencing (VIGS) revealed that down-regulation of LhANS-rr1, LhDFR, and LhMYB114 could directly lead to a decrease in anthocyanin accumulation, turning the purple phenotype into a white color. Moreover, this is the first report to reveal that LhMYB114 can regulate anthocyanin accumulation at the mature stage of lily bulbs. The accumulation of anthocyanins is an important sign of lily maturity. Therefore, these findings have laid a solid theoretical foundation for further discussion on lily bulb development in the future.

Transcriptome analysis of floral bud development and function analysis of a novel CO gene in Paeonia × lemoinei ‘High Noon’

Paeonia × lemoinei 'High Noon' is one of the most important cultivars in tree peony (Paeonia sect. Moutan), a traditional horticultural plant in China, with a re-blooming characteristic which was quite different from other cultivars. So, the genetic resources in 'High Noon' were incredibly valuable in flowering-time-modified molecular breeding in tree peony. However, the molecular mechanism underlying the floral bud formation of 'High Noon' was not clear yet. To explore the molecular mechanism in this process, the transcriptomes of three stages during floral bud development were deeply analyzed in this study. As a result, a total of 5816 differentially expressed genes (DEGs) were identified between the three developmental stages, and pathways including ''DNA replication'', ''metabolic pathways'', ''circadian rhythm'', and ''plant hormone signal transduction'' were mostly enriched in the functional enrichment and expression pattern analysis. Furthermore, a total of 584 genes related to the photoperiod pathway were further identified and a novel CO homolog gene PlCO was identified to be a stable hydrophilic protein, which contained both CCT domain and B-box domain. Over-expression of PlCO in Arabidopsis resulted in early flowering, which suggested a promotion role of flowering. The PlCO protein localized in nucleus and possessed a transcription activity ability, which implied that PlCO might function as a transcription factor. The transcriptome analysis revealed pathways involved in floral bud development in tree peony and provided new insight into the regulatory network underlying the floral bud development. The gene identification in 'High Noon' provided new valuable candidate genes for flowering-time-modified molecular breeding in tree peony.

Proteomic differences in apple spur buds from high and non-cropping trees during floral initiation

The cropping behavior of biennial apple (Malus ×domestica Borkh.) cultivars is irregular and often follows a biennial bearing pattern with ‘On’ years (high crop load and inhibited floral bud formation) followed by ‘Off’ years (little crop load and a promoted formation of floral buds). To study proteomic differences between floral and vegetative buds, trees of the strongly alternating cultivar ‘Fuji’ and the regular bearing cultivar ‘Gala’ were either completely thinned or not thinned at full bloom to establish two cropping treatments with no (‘Off’) or a high (‘On’) crop load, respectively. Student's t-Tests indicated significant differences of protein profiles in buds from 2-year old spurs from both treatments at each sampling date. Abundance patterns of protein clusters coincided with the onset of floral bud initiation and were most noticeable in buds from ‘On’ trees with a decreased abundance of key enzymes of the phenylpropanoid and flavonoid pathways and an increased abundance of histone deacetylase and ferritins. Furthermore, an increased abundance of proteins involved in histone and DNA methylation was found in the buds from ‘Off’ trees. This study presents the first large-scale, label-free proteomic profiling of floral and vegetative apple buds during the period of floral bud initiation. SignificanceAlthough several studies exist that address the complex developmental processes associated with the formation of floral buds in apple (Malus ×domestica Borkh.) at transcriptomic level, no data is available for explaining the difference between floral and vegetative buds or biennial and regular bearing cultivars on a proteomic level. This study presents the first large-scale, label-free proteomic profiling of floral and vegetative apple buds from the two cultivars ‘Fuji’ and ‘Royal Gala’ during the period of floral bud initiation and renders possible the development of suitable biomarkers for biennial bearing in apple.

Gibberellin Induced Transcriptome Profiles Reveal Gene Regulation of Loquat Flowering

Flowering is an integral part of the life cycle of flowering plants, which is essential for plant survival and crop production. Most woody fruit trees such as apples and pears bloom in spring, but loquat blooms in autumn and winter. Gibberellin (GA) plays a key role in the regulation of plant flower formation. In this study, we sprayed loquat plants with exogenous GA3, which resulted in vigorous vegetative growth rather than floral bud formation. We then performed a comprehensive RNA-seq analysis on GA3-treated and control-treated leaves and buds over three time periods to observe the effects of exogenous GA3 application on floral initiation and development. The results showed that 111 differentially expressed genes (DEGs) and 563 DEGs were down-regulated, and 151 DEGs and 506 DEGs were up-regulated in buds and leaves, respectively, upon treatment with GA3. Among those that are homologs of the DELLA-mediated GA signal pathway genes, some may be involved in the positive regulation of flower development, including EjWRKY75, EjFT, EjSOC1, EjAGL24, EjSPL, EjLFY, EjFUL, and EjAP1; while some may be involved in the negative regulation of flower development, including EjDELLA, EjMYC3, EjWRKY12, and EjWRKY13. Finally, by analyzing the co-expression of DEGs and key floral genes EjSOC1s, EjLFYs, EjFULs, EjAP1s, 330 candidate genes that may be involved in the regulation of loquat flowering were screened. These genes belong to 74 gene families, including Cyclin_C, Histone, Kinesin, Lipase_GDSL, MYB, P450, Pkinase, Tubulin, and ZF-HD_dimer gene families. These findings provide new insights into the regulation mechanism of loquat flowering.

Identification and characterization of miRNAs associated with sterile flower buds in the tea plant based on small RNA sequencing

BackgroundmiRNAs are a type of conserved, small RNA molecule that regulate gene expression and play an important role in the growth and development of plants. miRNAs are involved in seed germination, root development, shoot apical meristem maintenance, leaf development, and flower development by regulating various target genes. However, the role of miRNAs in the mechanism of tea plant flower sterility remains unclear. Therefore, we performed miRNA sequencing on the flowers of fertile male parents, female parents, and sterile offspring.ResultsA total of 55 known miRNAs and 90 unknown miRNAs were identified. In the infertile progeny, 37 miRNAs were differentially expressed; 18 were up-regulated and 19 were down-regulated. miR156, miR157, miR164, miR167, miR169, miR2111 and miR396 family members were down-regulated, and miR160, miR172 and miR319 family members were up-regulated. Moreover, we predicted that the 37 differentially expressed miRNAs target a total of 363 genes, which were enriched in 31 biological functions. We predicted that miR156 targets 142 genes, including ATD1A, SPL, ACA1, ACA2, CKB22 and MADS2.ConclusionWe detected a large number of differentially expressed miRNAs in the sterile tea plant flowers, and their target genes were involved in complex biological processes. Among these miRNAs, the down-regulation of miR156 may be one of the factor in the formation of sterile floral buds in tea plants.

Comparative Transcriptomic Analysis of Differentially Expressed Transcripts Associated with Flowering Time of Loquat (Eriobotya japonica Lindl.)

Flowering is an important phenophase of plant species, however, knowledge about the regulatory mechanism controlling flowering cues in loquat is limited. To identify candidate genes regulating flowering time in loquat, we used RNA-Seq technology to conduct a comparative transcriptome analysis of differentiating apical buds collected from the early-flowering variety ‘Baiyu’ and the late-flowering variety ‘Huoju’. A total of 28,842 differentially expressed transcripts (DETs) were identified. Of these, 42 DETs controlled flowering time while 17 other DETs were associated with the ABA signaling pathway. Compared with those in ‘Huoju’, EjFT, EjFY, EjFLK, and EjCAL1-like were significantly upregulated in ‘Baiyu’. Moreover, transcripts of the ABA 8′-hydroxylases (EjABH2, EjABH4, and EjABH4-like2), the ABA receptors (EjPYL4/8), and the bZIP transcription factor EjABI5-like were upregulated in ‘Baiyu’ compared with ‘Huoju’. Hence, they might regulate loquat flowering time. There was no significant difference between ‘Baiyu’ and ‘Huoju’ in terms of IAA content. However, the ABA content was about ten-fold higher in the apical buds of ‘Baiyu’ than in those of ‘Huoju’. The ABA:IAA ratio sharply rose and attained a peak during bud differentiation. Thus, ABA is vital in regulating floral bud formation in loquat. The results of the present study help clarify gene transcription during loquat flowering.

K+ ions improve hydraulic conductance of grapevine shoots for sucrose loading aimed at manipulation of vine carbohydrate reserves

Introduction – Poor fruitfulness of subtropical table grapevines can reflect a low carbohydrate (CHO) status of the plant during floral bud formation and fruit development. CHO reserves can ameliorate poor fruitfulness. Such supplementation can be achieved by sucrose injection into the grapevine trunk; however, poor hydraulic conductance of stem tissues limits the success of this procedure. The objective of this study was to evaluate the co-addition of KCl to the sucrose solution to improve the hydraulic conductivity of grapevine shoots. Materials and methods – The hydraulic conductance of 15 cm long current season cane cuttings was assessed under a pressure gradient of 7.84 kPa during perfusion with water, KCl (1 to 50 mM) and sucrose solutions (2.5%, 5% and 7.5% w/v) in 0 and 10 mM KCl. Experiments were conducted over both short (about 2 hours) and long (about 78 hours) term. Additionally, transpiration of dye solutions enabled estimation of direct xylem conduits was undertaken. Results and discussion – Hydraulic conductance increased by about 20% with perfusion of ≥10 mM KCl compared to water, with the effect reversible and repeatable. Sucrose solutions caused a decrease in conductance relative to water. Co-addition of KCl mitigated the sucrose-mediated decrease in conductance. There was no evidence of physical vessel blockage such as tyloses or microbiota. Conclusion – The results are consistent with the hypothesis that cations cause shrinkage of pectins, increasing the conductance of pit membranes.

Cerium (Ce) Affects the Phenological Cycle and the Quality of Tulip (Tulipa gesneriana L.)

Objective: To study the effect of Ce applied in a nutrient solution during the productive cycle, on the duration of the phases of the phenological cycle of tulip cv. Jan van Nes. Design/Methodology/Approach: Commercial bulbs (caliber 12+) were planted under shade cloth conditions during the autumn-winter period. The levels of Ce used were 5, 15 and 15 µM from CeCl3 7H2O; Ce was applied in the nutrient solution from the first day of the sowing, apart from the control without its application. Results: The different concentrations of Ce bulb sprouting. The low concentration of Ce (5 ?M) promoted the early formation of floral buds and their coloration. Hence, the application of 5 ?M Ce advances flowering of the tulip without exhibiting changes in the period of time to reach senescence. When 25 ?M Ce were applied, the opposite effects were observed. The duration of the flower was not significantly affected by the treatments. Study Limitations/Implications: This study was made only in one cultivar of tulip. Findings/Conclusions: The application of 5 µM of Ce had a positive effect in the tulip cycle, by stimulating bulb sprouting, the formation of the floral bud, the coloration, and the advance of the flowering cycle

Seasonal response of night-breaking on floral bud formation in red pitaya (Hylocereus sp.) in a noninductive period

Off-season flowering in red pitaya (Hylocereus sp.) can be achieved by night-breaking (NB) with artificial light in a noninductive season. To ensure abundant flowering, 4–6 h of NB is applied and often resulted in over flowering. This study compared the effects of four NB durations (4 h [2200–0200HR], 2 h [2300–0100HR], 1 h [2330–0030HR], and 0.5 h [2345–0015HR]) on floral bud formation in late autumn and early spring. In late autumn, the accumulated number of flowering shoots (FStotal) increased as the NB duration increased and 0.5 h was not sufficient to force 50 % of shoots flowering. The number of days to 50 % of the shoots flowering (FS50 %) was 35 for 1−4 h NB duration treatments. In late spring, the shoots were more responsive to the NB treatment and the duration effect on FStotal was less distinct; however, days to FS50 % decreased as the NB duration increased, and the shortest was 28 days in the 4-h treatment. Therefore, for obtaining shortest days to FS50 %, we suggest that the NB duration in late autumn and early spring should be 1 and 4 h, respectively. Thinning out the new sprouting are also in off-season production in early spring.

Genome-wide identification and expression analysis of flowering-related genes reveal putative floral induction and differentiation mechanisms in tea plant (Camellia sinensis)

The tea leaf is economically important, while reproductive growth reduce tea output. However, little is known about flowering mechanisms in tea plants. Here, we determined the approximate times of floral induction, floral transition and floral organ differentiation by morphological observation. We identified 401 and 356 flowering-related genes from the genomes of Camellia sinensis var. sinensis and Camellia sinensis var. assamica, respectively. Then, we compared the expression profiles of flowering-related genes in floriferous and oliganthous cultivars, the result showed that PRR7, GI, GID1B and GID1C expression is correlated with the floral induction; LFY, PNF and PNY expression was correlated with floral bud formation. Transcriptome analysis also showed that GI, PRR7 and GID1 were correlated with stress-induced flowering. Thus, we proposed putative mechanisms of flowering in tea plants. This study provides new insights into flowering and a theoretical basis for balancing vegetative and reproductive growth in tea plants and other economical plants.

Transcriptome profiling of the fertile parent and sterile hybrid in tea plant flower buds

BackgroundThe tea plant is a crucial economic crop. The floral organ development consumes a large amount of nutrients, which affects the leaf yield. To understand the mechanism by which the tea plant produces sterile floral buds, we obtained a sterile tea plant by artificial hybridization. RNA-sequencing based transcriptome analysis was implemented in three samples to determine the differentially expressed genes (DEGs) related to flower development.ResultsIn this study, a total of 1991 DEGs were identified; 1057 genes were up-regulated and 934 genes were down-regulated in sterile hybrid floral buds. These were mainly distributed in the regulation of biological and metabolic processes. Significantly, auxin biosynthesis genes YUCCA, AUX1 and PIN were dramatically down-regulated, and ARF gene was up-regulated in the sterile hybrid floral buds, and flower development-related genes AP1, AP2 and SPL were changed. A total of 12 energy transfer-related genes were significantly decreased. Furthermore, the expression of 11 transcription factor genes was significantly different.ConclusionThe transcriptome analysis suggested that the production of sterile floral buds is a complex bioprocess, and that low auxin-related gene levels result in the formation of sterile floral buds in the tea plant.

Effect of thidiazuron on morphological and flowering characteristics of Dendrobium ‘Sunya Sunshine’ potted plants

ABSTRACTDendrobium is a kind of popular orchid with long display life of flowers. Since it has a long vegetative period to flowering, it is necessary to develop methods to promote flowering. The effects of thidiazuron (TDZ) on flowering and the morphological characteristics of the Dendrobium ‘Sunya Sunshine’ were investigated. One-year-old and uniform height potted plants were used. Plants were spayed and root irrigated with the same amount of TDZ solution in different concentration treatments. The results showed that TDZ promoted the emergence of new shoots, but it did not affect plant morphology, such as the stem height, stem diameter, leaf size. TDZ application of 30 mg·L−1 increased the floral bud formation rate to 87.1%, increased inflorescence number and stalk thickness, but it also decreased the flower number per inflorescence and flower size, and shortened the flowering duration. This study indicated that TDZ could promote flowering, and the optimum concentration of the TDZ solution was 30 mg·L−1.

THE DETECTION OF THE TIME OF CONVERSION FROM VEGETATIVE TO REPRODUCTIVE GROWTH IN Swainsona formosa (FABACEAE)

The induction of chromosome doubling using antimitotic chemical will only be effective when the substance is applied at vegetative growth phase, as it works only during mitotic division within cells of actively growing tissues. Therefore, this investigation was carried out to determine the precise conversion time from vegetative into reproductive growth stage, that in turn can be used as a reliable reference for the application of antimitotic chemicals in doubling the chromosome number in Swainsona formosa. The conversion from vegetative to reproductive growth in Swainsona formosa was successfully determined with particular emphasis on the effect of different photoperiods. Although photoperiod affected the time required for first flower initiation, the number of nodes before the plant entering the reproductive stage was not affected by photoperiod and presumed to be set genetically. It was found that under artificial photoperiods of 16, 12 and 8 hours the 12th and 11th nodes were the critical nodes for the main and side stems, respectively. Meanwhile the 10th and 8th nodes were found to be critical for main and side stems of plants grown under natural photoperiods ranging from 12 to 16 hours during their life cycle. Histological examination indicated that when the plants were grown under 12 – 16 hours photoperiods the first floral bud formation was initiated within 56 – 60 days after germination, thus this period was considered as the critical time for the conversion from vegetative to reproductive growth in S. formosa.
 
 Keywords: Sturt’s desert pea, legume, ornamental plant, plant breeding.

Gibberellic Acid Signaling Is Required to Induce Flowering of Chrysanthemums Grown under Both Short and Long Days.

Flower bud formation and flowering in chrysanthemums occur under short day conditions (SD), but the molecular basis for the switch to reproductive growth is less well understood than in model plants. Here, a spontaneous mutant able to flower under long days is described. In an attempt to reveal the pathway(s) involved in the formation of flower buds under contrasting daylengths, transcriptome sequencing was carried out in plants grown both under SD and long day conditions (LD). A number of differentially transcribed genes involved in the various known flowering pathways were identified. Both circadian clock genes and Chrysanthemum FLOWERING LOCUS T Like3 (CmFTL3) were up-regulated under SD, thereby inducing floral bud formation and flowering. The gibberellin (GA) signaling pathway-related genes Gibberellin 20-oxidase (GA20ox) and Gibberellin receptor (GID1) were up-regulated in the mutant under LD, while the catabolic genes Gibberellin 2-oxidase (GA2ox) and GA-INSENSITIVE (GAI) were down-regulated, thereby inducing the transcription of SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1) and LEAFY (LFY). The GA content of the leaf was higher in the mutant than in the wild type (WT) under LD and SD, and the mutant has more branching than WT plants under LD or SD. When treated with GA, the mutant flowered earlier under both SD and LD relative to WT, but there was no detectable phenotype difference between the two lines. The indication was that the photoperiod pathway majorly regulates flower bud formation and flowering time in chrysanthemums under SD. The GA signaling pathway only plays a subsidiary role for flowering. However, the GA signaling pathway predominated for flowering under LD.

Biological Characteristics and Vegetative Propagation of a New Camellia Cultivar Maozi

Camellia flowers are highly prized for their beauty worldwide and are strongly symbolic in many cultures. A new interspecific hybrid cultivar, Camellia ‘Maozi’, generated by crossing Camellia pubipetala with C. japonica ‘Dahong Mudan’, exhibits strong hybrid vigor and has small flowers with a rare light tone of purple. In southwest China with a subtropical monsoon climate, young Camellia ‘Maozi’ trees flush shoots three times in spring, summer, and autumn, with an average annual growth of 12.9 cm. Adult trees flush once a year. Floral bud formation occurs in late April and early May. Camellia ‘Maozi’ flowers are sterile with no fruits and seeds produced. While an individual flower wilts 4–8 days after opening, the blossom can last 1–3 months. Frost damage can be found in young leaves when temperature drops to 4–7 °C. Under direct sunlight with temperatures of 37–39 °C lasting for more than 2 days, young leaves can turn yellow on their edges. Its primary diseases include sooty mold, shoot tip blight, and peony leaf tip blight. Its primary insect pests are tea green leafhopper (Jacobiasca formosana) and tea aphid (Toxoptera aurantii). Rooting of stem cuttings occurs directly from stems, mostly without callus development. Two hours of treatment with 500 mg·L−1 indole-3-butyric acid and rooting in a mix of latosolic red soil and vermiculite (2:1 v/v) resulted in high rooting rate and quality of aboveground growth. Grafting can be carried out from May to September, while survival rate and new shoot length are highest in July. The most compatible rootstock is C. oleifera, followed by C. polyodonta. The results of this study are of value for understanding the reproductive biology of Camellia ‘Maozi’ and further disseminating it as a new cultivar for camellia collection.

Antagonistic action of blue and red light on shoot elongation in petunia depends on gibberellin, but the effects on flowering are not generally linked to gibberellin

Plant morphology and flowering are influenced by light quality, but responses vary between species. Here we investigated effects of irradiance (70 or 150μmolm−2s−1) of red (R) and blue (B) compared to white (W) light, provided by light emitting diodes, on growth and flowering in petunia. R light inhibited shoot elongation, but opposite to commonly observed, B light greatly enhanced shoot elongation. Consistent with this, bioactive gibberellins (GA1, GA4) showed higher and lower levels under B and R light, respectively, and GA3 application induced elongation in uniconazole-treated plants, although delayed in R. Inhibited shoot elongation under RB treatment in spite of higher GA level compared to R only, supports that R light inhibits elongation growth, and indicates negative effect of R light on GA signaling. Floral bud formation and flowering occurred earlier under B compared to W light. Whereas no floral buds were observed under low R irradiance, high R irradiance and temporal switching to B light during long-term low R irradiance induced floral development. Except slight trends of promoting effect of the highest GA3 level and delay in uniconazole-response under B light, lack of flowering under low R irradiance was not significantly affected by uniconazole or GA3 application. In conclusion, B and R light are strong signals enhancing and inhibiting shoot elongation, respectively, through modulation of GA content. B light is a strong signal in floral bud formation, whereas effect of R light depends on irradiance, indicating existence of an energy/photosynthesis-related floral pathway in petunia. Although light quality affects flowering and main shoot elongation, these responses do probably not correlate with each other through GA synthesis.

Seed development of arrowleaf, balansa, gland and Persian clover

The development process from floral bud formation to seed maturity of four top flowering annual clovers was quantified from a field experiment across 10 sowing dates at Lincoln University, Canterbury, New Zealand. For each species, a numeric reproductive scale was created as a field guide to document morphological changes as the bud progresses through reproductive development. The duration from bud visible to open flower was 341 °C days for 'Cefalu' arrowleaf, 215 °C days for 'Bolta' balansa, 196 °C days for 'Prima' gland and 186 °C days for 'Mihi' Persian clover. The inflorescence then required a further 274-689 °C days, 185 °C days , 256 °C days and 425 °C days for each respective species to reach physiological maturity. This was indicated when 50% of seeds had turned red/brown for 'Cefalu' arrowleaf, 100% pods turned yellow for 'Bolta' balansa, 100% of seeds were yellow and hard for 'Prima' gland, and pods turned brown with the first sign of colour change in seeds for 'Mihi' Persian clover. These results can be used to facilitate on farm decision making in relation to grazing management or seed set for subsequent regeneration. Keywords: floral development chart, harvest maturity, peak flowering, pollination, seed filling, thermal time, Trifolium vesiculosum, T. michelianum, T. glanduliferum, T. resupinatum

Effect of Day-length Extension Treatment Using LED on Growth and Flowering of Freesia hybrid ‘Yvonne’

본 연구는 프리지아 '이본느'를 가지고 매일 오후 5시에서 8시까지 150일 동안 LED(청색, 녹색, 적색, 청색:녹색:적색 혼합)광과 백열등, 메탈할라이드등으로 보광을 함으로써, 꽃눈분화 이후부터 개화가 완전히 종료될 때까지 광질에 따른 장일처리가 프리지아의 생육 및 개화에 미치는 영향을 알아보기 위하여 수행되었다. 엽분열기부터 화뢰형성기까지 초장은 광원별 장일처리에 의해 큰 변화는 없었고 엽수는 메탈할라이드등 처리에서 감소하는 경향이었으나 화뢰 발달기 때 엽 내 엽록소 함량은 메탈할라이드등에서 가장 높았다. LED 청색광과 녹색광에서 개화기가 빨랐는데 특히 녹색광 처리에서 가장 빨라 무처리와 메탈할라이드등에 비해 6-8일 정도 단축되었다. 포장 내 개화기간은 LED 적색광에서 가장 짧아 일시 수확에는 효과적이었다. 메탈할라이드 등에서 절화중, 소화의 길이와 폭 등 절화특성이 우수하였다. 구근의 특성을 조사한 결과 LED 적색광에서는 구폭과 구중이, 백열등 처리에서는 구고와 구중이 감소하였고, 구근 내 전분함량은 모든 시험구 사이에 특별한 차이가 없었다. 결과적으로 개화촉진은 LED 녹색등에서 효과적이었고 개화품질은 메탈할라이드등 처리에서 우수하였다. The aim of this study was to determine the effect of day-length extension treatment using LED lighting (blue, green, red, or 3 mixed) on vegetative growth and flowering of freesia 'Yvonne', in comparison to that using glow lamps and metal halide lamps. Lighting treatments were imposed from 5 PM to 8 PM for 150 days from after flower bud differentiation to flowering end. For the period from leaf emergence to floral bud formation, no light source affected plant height but the number of leaves was decreased by the metal halide lamp. The highest SPAD value in the flower bud developing period occurred in the metal halide lamp treatment. The time of flowering was advanced by blue or green LED treatment compared to the no lighting control. The green LED lighting advanced flowering by 6 and 8 days compared to no lighting and metal halide lamp treatment, respectively. The blooming period tended to be shortened by the red LED treatment. As for the flower characteristics of 'Yvonne', floret length and width, and the weight of cut flowers were highest in the metal halide lamp treatment. Red LED decreased corm width and weight of 'Yvonne' while glow lamp decreased height and weight. Starch contents in corm were not influenced by the lighting source. Our results indicate that the green LED lighting advanced the time of flowering and the metal halide lamp was good for cut-flower quality.

Producción de semillas de Araucaria araucana (Molina) K. Koch durante 15 años en diferentes poblaciones del Parque Nacional Lanín (Neuquén-Argentina)

Ecología Austral, 24:265-275 (2014)Seed production studies on tree species are important for science and for forest management. The objective of this work was to study the long term seed production of araucaria (Araucaria araucana), which are a valuable food for humans, at populations located at different aspect, altitude and with variations on forest structure and composition. Cones were counted at seven populations in Lanín National Park, Neuquén Province, Argentina for 15 years (2000 to 2014), estimating seeds and cones per tree, per hectare and per population. Peaks in seed production occurred in 2000, 2007 and 2013, while seed crops were low during 2005, 2008, 2012 and 2014. Mean cones per tree was 19 (range: 1-62) with 56 fold variation among years. Mean seeds per tree was 2372 (range: 61-9287) with 152 fold variation among years. The greater temporal variation in seed production in relation to cones was due to a significant increase in seeds per cone during mast years. Mean cones, individual seeds and kilograms of seeds per hectare were 685, 89394 and 273, respectively. Dense and pure Araucaria forests and those mixed with lenga (Nothofagus pumilio) were at least 2.5 and 1.5 fold more productive than the rest of forest types. Cones per tree differed significantly among sites and were related mainly with sun exposure. However, this effect varied according to the class productive year and the observed pattern may be related with the floral bud formation associated with drought. Araucaria showed a synchronous reproduction between trees and populations at regional scale, with a greater temporal variability than spatial variation between populations. These results could be important for conservation planning of these forests in Argentina and Chile against the threats posed by increased seed gathering pressure and by the presence of exotic invasive granivores.