Dahlia Doctor Research Library: Tissue Culture, Meristem Culture, and Clean Stock in Dahlias

A Curated Knowledge Card Collection

Copyright © 2026 by Steve K. Lloyd
All Rights Reserved

Dahlia growers rarely think of tissue culture as their concern. The equipment is specialized, the terminology is unfamiliar, and the procedures belong to laboratories, not garden sheds. But the outcomes of dahlia tissue culture research reach every grower who has ever received a cutting from a collected variety, planted tubers from a heritage stock, or tried to recover a beloved plant from a virus-infected clump.

Tissue culture in dahlias has developed along three intersecting lines. The first is clean-stock production: using meristem-tip culture and related techniques to recover pathogen-free plants from infected material. The second is micropropagation: multiplying dahlia stock rapidly in vitro using defined culture media, plant growth regulators, and explant types. The third is germplasm conservation: slowing the growth of in vitro cultures to hold dahlia genetic material in storage without repeated subculturing or risk of field loss.

All three lines of work are present in this collection. The selected Knowledge Cards span from a 1975 practitioner report on home-environment meristem-tip culture to a 2025 micropropagation study evaluating growth regulator combinations. Between those endpoints, the research covers DMV elimination by meristem culture, electrotherapy, and chemotherapy; cytokinin and auxin effects on shoot multiplication and rooting; explant source differences; liquid-medium culture; regeneration from leaf and stem tissue; and in vitro storage under growth-retarding conditions.

For most dahlia growers, the practical takeaway is a clear one: the clean-stock question is not simply about whether a laboratory can eliminate a virus. It is about whether a reliable procedure exists, what that procedure requires, how often it succeeds, and what comes after. This collection answers those questions from the primary research record.

Each post in this series presents a curated set of Dahlia Doctor Knowledge Cards organized around a specific research topic. A Knowledge Card summarizes one scientific or technical source using a consistent structure: study system, experimental context, experimental design, key results, mechanistic insight, practical guidance, and why the source matters to dahlia growers and researchers. These summaries represent original interpretive work. They are intended as a research guide, not a substitute for reading the original papers. Each citation title links to a Google Scholar search for that source, opening in a new tab, to help you locate the original publication independently.

Each Knowledge Card appears once in this collection, placed in the topic cluster where it contributes most directly. Some sources are relevant to more than one cluster; placement reflects primary emphasis rather than exclusive relevance. KC-0070, which documents a dahlia-specific meristem-tip culture procedure developed explicitly for virus recovery, anchors the opening cluster on clean-stock framing; its detailed procedural content also informs the micropropagation cluster that follows. KC-0781 and KC-0875, both from the same research group working on in vitro conservation, are retained as separate records because they report distinct experimental variables: KC-0875 evaluates growth retardants and sucrose effects, while KC-0781 addresses MS salt strength and enclosure type.

Publication Type

Technical Report

Full Citation

Weland, G. G. (1975). Meristem tip culture. Dahlia Reporter, Fall 1975.

Study System

Dahlia meristem-tip propagules taken from axillary shoot tips of virus-symptomatic dahlia stock and cultured under home-environment conditions.

Experimental Context

The report documents a dahlia meristem-tip culture procedure developed to recover symptomless dahlia stock from plants expressing virus symptoms. The procedure was presented as a home-environment adaptation of earlier dahlia meristem-tip culture work, with added emphasis on rooting in culture rather than grafting onto seedling rootstock.

Experimental Design

Shoot-tip blocks were removed from dahlia canes, held in antioxidant solution, surface-treated with surfactant and hypochlorite sterilant, rinsed, and dissected under a binocular microscope. Propagules consisting of the meristem-tip region with small associated tissue and usually one or two leaf primordia were placed on a nutrient medium based on modified mineral salts with sucrose, thiamine, inositol, tyrosine, kinetin, indole-3-acetic acid, and agar. Cultures were held under artificial light and controlled temperature. After initial growth and a dormancy-like pause, propagules were recultured onto media with reduced kinetin levels to encourage rooting. Rooted and unrooted explants were moved through rooting medium, high-humidity hardening, pot culture, greenhouse growth, stock increase, and visual or proposed indexing evaluation.

Key Results

An initial workshop-derived attempt placed 24 dahlia meristem tips in culture, recovered 8 cultures, grew 3 to grafting size, and lost all propagules after grafting or regrafting failure. The later home-environment programs recovered 83 plants from 63 varieties, including 35 plants from 26 varieties in the first program and 48 plants from 37 varieties in the second program. Reculturing on reduced-kinetin medium produced roots on approximately 35 percent of treated propagules. The report states that the described reference program could be expected to produce 8 to 15 percent overall success over 2 to 3 years. Three recovered varieties were discarded at the transplant stage as possibly diseased based on visual symptoms. The report states that no state or national certification program for dahlias was available and that recovered stock required indexing or multi-season isolated observation before being treated as pathogen-free.

Mechanistic Insight

The procedure is based on the source's statement that virus is not equally distributed within an infected plant and that rapidly growing shoot tips have a better chance of being free of virus pathogens than older tissue. Smaller propagules were described as having a better probability of being virus-free but a lower probability of surviving in culture. The meristem-tip propagule was described as a compromise that includes the shoot-tip region, adjacent cells, sub-jacent tissue, and usually early leaf primordia. Rooting response was linked to altered growth-regulator balance, with reduced kinetin used after initial culture and the source stating that the best rooting relationship between kinetin and auxin had not been definitely established.

Practical Guidance

Use vegetative axillary shoot tips rather than shoots that have already formed flower buds when possible. Excise small shoot-tip blocks, keep them moist in antioxidant solution, surface-sterilize before dissection, remove leaves and primordial leaves without damaging the meristematic dome, and transfer very small propagules aseptically to prepared culture tubes. Monitor cultures daily for contamination. Transfer propagules after the first growth phase to reduced-kinetin medium to encourage rooting. Treat unrooted explants like delicate green cuttings rather than relying on seedling grafting. Harden explants gradually under high humidity and increasing light before greenhouse growth. Grow recovered stock in isolation for two or preferably three full seasons, or use an indexing method, before assuming freedom from virus.

Why This Source Matters

This 1975 practitioner report is the oldest primary source in this collection and one of the few to document dahlia meristem-tip culture from an explicitly dahlia-grower perspective rather than a laboratory one. The procedure described was developed under home-environment conditions, not a commercial tissue-culture facility, which makes its success rates — 8 to 15 percent overall over two to three years — a meaningful baseline for what the technique can realistically achieve outside a research laboratory. The emphasis on post-recovery isolation and indexing is also notable: even in 1975, the author recognized that a plant that emerges from meristem culture symptom-free is not necessarily pathogen-free, and that multi-season observation or formal indexing is required before recovered stock can be treated as clean. That caution remains as relevant today as it was fifty years ago.

Publication Type

Experimental Research Article

Full Citation

Šedivá, J., Novák, P., Kaňka, J., & Laxa, J. (2006). Micropropagation, detection and elimination of DMV in the Czech collection of Dahlia. Acta Horticulturae, 725, 495–498.

Study System

Dahlia pinnata cultivars from a Czech dahlia collection; stem segments with terminal and axillary buds; in vitro dahlia cultures; apical meristems from DMV-infected cultivars.

Experimental Context

In vitro propagation and meristem-tip culture were tested for production of DMV-free dahlia plants. Cytokinin treatment, sampling time of primary explants, meristem-tip size, meristem regeneration, and DMV detection were included.

Experimental Design

Primary stem explants were placed on MS medium supplemented with 0.5 mg L-1 zeatin or 0.5 mg L-1 BA, myo-inositol, sucrose, vitamins, and agar. Cultures were maintained at 22 ± 2°C under a 16-hour photoperiod. Stem apical meristems measuring 0.4–0.5 mm or 0.9–1.0 mm were excised from seven infected cultivars grown in vitro and cultured on MS medium with 0.5 mg L-1 zeatin. DMV was detected using real-time PCR and conventional PCR.

Key Results

Primary explants initiated shoot growth after five weeks. Higher regeneration capacity and lower contamination were reported on MS medium with zeatin in May. New shoots were obtained on the same medium. Meristem regeneration and DMV elimination depended on meristem-tip size. DMV elimination was 50% from 0.4–0.5 mm meristems and 9% from 0.9–1.0 mm meristems.

Mechanistic Insight

Smaller meristem-tip size increased the effectiveness of meristem culture for DMV elimination while affecting regeneration. PCR-based assays were used to confirm DMV status after culture.

Practical Guidance

MS medium with 0.5 mg L-1 zeatin supported regeneration of primary explants and meristem-derived shoots. Smaller meristem tips provided higher DMV elimination than larger meristem tips in this study.

Why This Source Matters

This study provides the clearest quantitative evidence in this collection for the size-elimination relationship in dahlia meristem-tip culture: excising smaller meristems (0.4–0.5 mm) produced DMV elimination in 50 percent of tested plants, while larger meristems (0.9–1.0 mm) produced elimination in only 9 percent. That fivefold difference is the central practical finding. The study also introduces PCR-based confirmation as the detection standard, moving beyond the visual symptom assessment described in KC-0070 and establishing a post-culture verification step that is now the laboratory norm. The seasonal effect — higher regeneration and lower contamination from May explants — adds a practical variable that growers and tissue culture practitioners working with dahlia collections should consider when planning meristem-tip work.

Publication Type

Journal Article

Full Citation

Nerway, Z. A. A., Duhoky, M. M. S., & Kassim, N. A. (2020). In vitro elimination of Dahlia mosaic virus by using meristem culture, electrotherapy and chemotherapy. Iraqi Journal of Agricultural Sciences, 51(2), 665–674.

Study System

Dahlia variabilis infected with Dahlia mosaic virus.

Experimental Context

In vitro virus elimination for clean propagation.

Experimental Design

Meristem tip culture; electrotherapy at 15–35 mA for 10–20 minutes; chemotherapy with acyclovir and salicylic acid; DAS-ELISA confirmation of DMV elimination.

Key Results

Meristem culture achieved 100% DMV elimination. Electrotherapy achieved up to 85% elimination. Chemotherapy achieved up to 100% elimination with salicylic acid, but with plant survival trade-offs at higher doses.

Mechanistic Insight

Virus exclusion in meristem culture operates through the absence of functional vascular tissue in the smallest shoot apex tissues and the rapid cell division that may outpace viral replication. Electrotherapy and chemotherapy are intended to suppress virus survival or replication through different routes, while the survival trade-offs at higher chemotherapy doses indicate that the treatments can also affect host tissue.

Practical Guidance

Meristem culture alone achieved complete DMV elimination in this study and remains the most reliable method when propagule survival is the priority. Electrotherapy and optimized chemotherapy with salicylic acid offer alternatives that may reduce the precision required for very small meristem excision but require careful dose calibration to avoid plant losses. DAS-ELISA confirmation after treatment is essential before treating recovered material as virus-free.

Why This Source Matters

This is the most methodologically comprehensive DMV elimination study in this collection, comparing three distinct approaches — meristem culture, electrotherapy, and chemotherapy — within the same experimental framework and confirming outcomes with ELISA. The 100% elimination rate from meristem culture provides a benchmark against which the other methods can be evaluated. The electrotherapy and chemotherapy data are also useful because they offer alternative pathways for practitioners who lack the dissection precision required to excise consistently small meristems. Taken together, the three-method comparison gives the reader a clearer picture of the available options and their trade-offs than any single-method study can provide.

Publication Type

Journal Article

Full Citation

Ibrahim, M. A., & Daraj, I. A. (2015). Micropropagation of dahlia plants Dahlia variabilis Wild (Desf.): Effect of explant and plant growth regulators on shoot regeneration and growth. Advances in Agriculture & Botanics, 7(1), 1–6.

Study System

Dahlia variabilis.

Experimental Context

In vitro tissue culture evaluation of explant type and growth regulator combinations.

Experimental Design

Shoot tip, hypocotyl, cotyledon, nodal, and root explants cultured on MS media with BA, NAA, and IBA under controlled conditions.

Key Results

Shoot tip explants and BA plus NAA at 2.0 plus 2.0 mg L-1 gave the highest shoot regeneration. Optimal rooting was achieved with 0.6 mg L-1 IBA. Acclimatization success reached 100 percent.

Mechanistic Insight

Cytokinin-auxin balance and meristematic activity determine shoot organogenesis and rooting efficiency. Shoot tip explants retain greater organogenic competence than hypocotyl, cotyledon, or root tissue, and respond more strongly to the cytokinin-dominant conditions that promote axillary shoot proliferation.

Practical Guidance

Shoot tip explants on MS medium with BA plus NAA at 2.0 plus 2.0 mg L-1 are recommended for shoot regeneration. Rooting is most efficient with IBA at 0.6 mg L-1. Post-transfer acclimatization under the conditions tested was reliable.

Why This Source Matters

This study provides a direct comparison of five explant types under the same culture conditions, establishing that shoot tips outperform hypocotyl, cotyledon, nodal, and root explants for shoot regeneration in Dahlia variabilis. That comparison is more useful than single-explant studies because it controls for medium and hormone variables and isolates the explant source as the primary factor. The 100 percent acclimatization success rate also suggests that the protocol described is robust enough to support reliable transfer from in vitro to ex vitro conditions, a step that often produces significant losses in other ornamental species.

Publication Type

Journal Article

Full Citation

Marcinek, B., Parzymies, M., Poniewozik, M., Kozak, D., & Durlak, W. (2019). The influence of growth regulators on dahlia propagation in tissue culture and acclimatization of plants in ex vitro conditions. Acta Scientiarum Polonorum Hortorum Cultus, 18(5), 49–61.

Study System

Dahlia cultorum 'Pirat'.

Experimental Context

In vitro micropropagation with ex vitro acclimatization and field evaluation.

Experimental Design

Factorial cytokinin and gibberellic acid treatments on shoot tip and nodal explants with downstream rooting and field performance assessment.

Key Results

Benzyladenine maximized shoot multiplication. Gibberellic acid enhanced elongation. Kinetin and 2iP improved ex vitro survival and field vigor.

Mechanistic Insight

Cytokinin identity modulates axillary activation versus elongation and determines later rooting and acclimatization outcomes. Cytokinin carryover effects from in vitro culture influence ex vitro rooting capacity and subsequent field performance, so the choice of cytokinin affects not only what happens in the culture vessel but what the recovered plant does after transfer.

Practical Guidance

Low BA for multiplication, GA3 for elongation, and kinetin in the final culture cycle to improve acclimatization and field performance.

Why This Source Matters

This study is one of the few in this collection to follow in vitro-propagated dahlia plants through to field performance rather than stopping at the rooting or acclimatization stage. The finding that cytokinin identity in the final culture cycle affects downstream field vigor — not only in vitro shoot multiplication — means that the choice of growth regulator cannot be evaluated on in vitro metrics alone. That downstream-performance perspective is directly relevant to anyone using tissue culture for clean-stock multiplication in a system where field or greenhouse productivity after transfer matters.

Publication Type

Experimental Research Article

Full Citation

Salman, M. A., Hamad, M. S., & Al-Ahmer, S. M. (2010). In vitro propagation of Dahlia variabilis. Al-Anbar Journal of Agricultural Sciences, 8(1), 148–161.

Study System

Dahlia variabilis hybrid plant material from greenhouse-grown potted plants, using apical shoot tips and single-node stem cuttings as explants.

Experimental Context

In vitro propagation experiments using modified MS medium, controlled incubation at 25 ± 2°C, 16 hours light and 8 hours dark, and four-week culture intervals for treatment evaluation.

Experimental Design

Experiments tested explant type, cytokinin type and concentration, BA and IAA combinations, adenine sulphate concentrations, aqueous and alcoholic Johnson grass seed extracts from immature and mature seed stages, auxin type and concentration for rooting, sucrose concentration in half-strength MS medium with IBA, and acclimatization in loam and peat moss.

Key Results

Apical shoot tips and single-node explants cultured on hormone-free MS medium gave 100 percent response. MS medium with 2 µM BA and 2 µM IAA produced 4.00 shoots per explant. Addition of 60 mg/L adenine sulphate increased shoot production to 6.80 shoots per explant with shoot length of 7.27 cm. Half-strength MS medium with 45 g/L sucrose and 3 µM IBA gave 100 percent rooting, 8.00 roots per shoot, and 10.40 cm root length. Acclimatization in 1:1 loam and peat moss under controlled humidity gave 100 percent survival.

Mechanistic Insight

The discussion attributes reduced response on cytokinin-containing initiation medium to possible high endogenous cytokinin content in dahlia explants associated with tuberous storage roots. Shoot multiplication is discussed in relation to auxin-cytokinin balance and release of buds from apical dominance. Adenine sulphate effects are attributed to a nitrogenous base or organic nitrogen source and possible indirect stimulation of cell division and vascular tissue formation. IBA rooting response is attributed to relatively high stability against auxin-degrading enzymes.

Practical Guidance

Hormone-free MS medium for initiation; MS medium with 2 µM BA and 2 µM IAA plus 60 mg/L adenine sulphate for shoot multiplication; half-strength MS medium with 45 g/L sucrose and 3 µM IBA for rooting; 1:1 loam and peat moss under controlled humidity for acclimatization.

Why This Source Matters

This study is the most systematically staged propagation protocol in this collection, stepping through initiation, multiplication, rooting, and acclimatization as sequential experiments rather than as a single combined evaluation. The adenine sulphate finding — that adding an organic nitrogen supplement to a BA plus IAA medium nearly doubled shoot production per explant — is an underappreciated detail in the dahlia micropropagation literature and a practically testable variable for laboratories working to optimize multiplication rates. The hypothesis about high endogenous cytokinin content from tuberous storage roots is also a useful mechanistic note, offering a possible explanation for why hormone-free medium works well for initiation in dahlia when other species require exogenous cytokinin at that stage.

Publication Type

Journal Article

Full Citation

Rudiyanto, Wulansari, A., Maulana, E., Solin, N. W. N. M., & Yulianti, F. (2025). In vitro propagation of Dahlia sp. using different types of explants and plant growth regulators (PGR). Comunicata Scientiae, 16, Article e4330.

Study System

Dahlia sp. cultured in vitro.

Experimental Context

Controlled tissue culture evaluation of explant type and plant growth regulators.

Experimental Design

Completely randomized factorial design testing explant type and cytokinin-auxin combinations.

Key Results

1 mg/L 2-iP plus 1 mg/L NAA with middle nodes maximized shoot, root, and biomass metrics.

Mechanistic Insight

PGR interactions regulate cell division and organ formation through cytokinin-auxin balance. Middle node explants retain sufficient meristematic competence to respond to the tested regulator combinations more efficiently than other explant types under these conditions.

Practical Guidance

Use 2-iP plus NAA with middle nodes for optimal micropropagation outcomes under the conditions described.

Why This Source Matters

As the most recent source in this collection, published in 2025, this study confirms that the core cytokinin-auxin balance principle governing dahlia micropropagation continues to hold across new experimental designs and newer dahlia material. Its inclusion of 2-iP — a cytokinin less commonly tested in dahlia than BA, zeatin, or kinetin — alongside NAA also adds a data point that extends the regulator comparison available in this cluster. Read alongside KC-0239, KC-0415, and KC-0929, it reinforces the consistent finding that no single growth regulator combination dominates across all explant types and cultivars; the specific cytokinin, auxin, and explant source combination must be evaluated together.

Publication Type

Journal Article

Full Citation

Otani, Y., Endo, C., Chin, D. P., & Mii, M. (2013). Highly efficient system for plant regeneration from leaf and stem explants in dahlia. Plant Biotechnology, 30(2), 141–146.

Study System

Dahlia x pinnata, multiple cultivars.

Experimental Context

In vitro development of a high-efficiency regeneration system from vegetative explants.

Experimental Design

Leaf and stem explant culture on MS medium with cytokinins; MSP induction; hormone-free regeneration; statistical analysis.

Key Results

TDZ at 10 mg L-1 induced stable meristematic sector proliferation (MSP) and high-frequency shoot regeneration. Regenerated plants were phenotypically normal.

Mechanistic Insight

TDZ-driven cytokinin effects enable long-term meristematic competence and controlled shoot differentiation. Unlike many cytokinin treatments that drive rapid organogenesis followed by declining competence, TDZ-induced MSP maintains a stable meristematic state from which shoot regeneration can proceed reliably over time.

Practical Guidance

This protocol enables reliable micropropagation and a basis for genetic transformation work in dahlia. The TDZ-induced MSP system is particularly relevant where high-frequency shoot regeneration from non-meristematic tissue is needed and where conventional shoot-tip culture is constrained by source material availability.

Why This Source Matters

This study is the most technically advanced regeneration protocol in this collection and the one most directly relevant to genetic improvement and transformation work in dahlia. The ability to generate large numbers of shoots from leaf and stem tissue — rather than relying on shoot tips or axillary buds — substantially expands the propagation base available for a given genotype. The demonstration that TDZ-induced MSP produces phenotypically normal regenerants is also practically significant: somaclonal variation is a documented risk in tissue culture, and this study's phenotypic normality data provide meaningful reassurance for applications where genetic fidelity matters.

Publication Type

Journal Article

Full Citation

Fatima, B., Usman, M., Ashraf, T., Waseem, R., & Ali, M. A. (2007). In vitro shoot regeneration from cotyledon and hypocotyl explants of dahlia cultivars. Pakistan Journal of Agricultural Sciences, 44(2), 312–316.

Study System

Dahlia cultivars 'Double Decorative' and 'Double Giant'.

Experimental Context

In vitro tissue culture system using seed-derived explants.

Experimental Design

MS medium with NAA plus BA or BA plus IAA; completely randomized design; three replications.

Key Results

Maximum callus and shoot regeneration occurred with 3 mg L-1 NAA plus 3 mg L-1 BA.

Mechanistic Insight

Auxin-cytokinin balance drives indirect organogenesis in dahlia explants, while some hormone combinations inhibit rooting. Callus formation at relatively high hormone concentrations precedes shoot differentiation in this system, in contrast to the direct organogenesis seen in shoot-tip-based protocols.

Practical Guidance

Useful for dahlia tissue culture and regeneration work, especially where indirect organogenesis or somaclonal variation studies are relevant. Not a primary path for routine clean-stock propagation, where direct organogenesis from shoot-tip explants is more reliable.

Why This Source Matters

This study is the only one in this collection to use seed-derived cotyledon and hypocotyl explants rather than vegetative material, opening a propagation pathway that is independent of the vegetative stock. For breeders working with known seed crosses, that independence is useful: the protocol allows regeneration from specific genetic material at the seedling stage without requiring an established in vitro vegetative line. The indirect organogenesis pathway described — callus formation followed by shoot differentiation — also serves as a reference point for understanding how IAA and BA interact differently in non-meristematic dahlia tissue compared with the shoot-tip and nodal systems described elsewhere in this collection.

Publication Type

Journal Article

Full Citation

Hernández Pérez, F., & Mejía Muñoz, J. M. (1994). Micropropagación de dalia (Dahlia variabilis Cav.) [Dahlia (Dahlia variabilis Cav.) micropropagation]. Revista Chapingo. Serie Horticultura, (1), 63–66.

Study System

Dahlia variabilis Cav.; vegetative apices and floral buds cultured in vitro.

Experimental Context

In vitro micropropagation using MS medium with IAA and BAP combinations.

Experimental Design

Completely randomized design; 12 hormone combinations for apices; 6 for floral buds; 12 replicates per treatment; variables: shoot length, rooting, pigmentation, callus.

Key Results

Floral buds can redifferentiate into vegetative shoots. Best shoot growth occurred with 0.1 mg L-1 IAA. Rooting was higher without BAP. BAP increased pigmentation.

Mechanistic Insight

IAA promotes elongation and rooting. BAP inhibits rooting and enhances pigmentation. Floral buds show developmental plasticity, retaining the capacity to redifferentiate into vegetative shoots under appropriate cytokinin and auxin conditions.

Practical Guidance

Avoid BAP for rooting; include BAP for pigmentation. For routine multiplication, vegetative apices with low IAA are preferable; floral bud explants can serve as a supplementary source where vegetative material is limited.

Why This Source Matters

The floral bud redifferentiation finding is the most distinctive contribution of this study and the primary reason it is included in this cluster. Demonstrating that floral buds can be diverted from reproductive development into vegetative shoot formation under in vitro conditions is a useful practical observation for breeders and collectors who wish to initiate tissue culture from plants already past the vegetative stage. The study also documents a straightforward and consistent outcome — that BAP simultaneously inhibits rooting and increases pigmentation — that adds to the functional understanding of cytokinin effects in dahlia culture built across this collection.

Publication Type

Experimental Research Article

Full Citation

Shivayogeppa, G., Adiga, J. D., Prabhuling, G., Reddy, B. S., Natraj, S. K., & Prashanth, S. J. (2009). In vitro conservation studies in dahlia (Dahlia variabilis L.). Asian Journal of Horticulture, 4(2), 470–472.

Study System

Micro-shoot cultures of dahlia (Dahlia variabilis L.).

Experimental Context

In vitro conservation study evaluating growth and storability of dahlia micro-shoots on MS basal medium supplemented with maleic hydrazide, sucrose, or alar.

Experimental Design

Shoot tips of 0.3 to 0.5 mm were excised from young actively growing plant parts, surface-treated, rinsed, and inoculated onto prepared MS basal media. Media treatments included maleic hydrazide at 0, 10, 20, 30, and 40 mg per litre; sucrose at 0, 0.5, 1.0, 3.0, and 5.0 percent; and alar at 0, 10, 20, 30, and 40 mg per litre. Cultures were incubated at 25 ± 2°C under a 16:8 light-dark cycle. Recorded variables included days to bud sprouting, multiple shoots produced during storage, shoot length at the end of storage, culture storage period, and percent recovery.

Key Results

Maleic hydrazide at 40 mg per litre delayed bud sprouting to 27.50 days and gave the longest culture storage period at 134.00 days, with 83.00 percent recovery. Sucrose-free medium produced the longest storage period among sucrose treatments at 131.00 days and 93.00 percent recovery, while 3.0 percent sucrose produced the highest number of multiple shoots during storage. Alar at 40 mg per litre delayed bud sprouting to 22.70 days, gave the longest storage period among alar treatments at 129.00 days, and produced 91.00 percent recovery.

Mechanistic Insight

Delayed explant sprouting was associated with longer culture storage period. The effectiveness of 40 mg per litre maleic hydrazide is attributed to delayed bud sprouting, which may have resulted from delayed exploitation of available nutrients in the cultures.

Practical Guidance

MS medium supplemented with 40 mg per litre maleic hydrazide was identified as the best treatment for storability of in vitro dahlia cultures. Sucrose-free medium is an effective alternative for extended storage with high recovery.

Why This Source Matters

This study is the primary in vitro conservation reference in this collection, providing systematic quantitative data on the effects of three growth-suppressing treatments on dahlia micro-shoot storability. The 134-day storage period achieved with maleic hydrazide at 40 mg per litre represents a practical conservation window of roughly four months — long enough to be useful for collection management, short enough to require periodic subculture. The high recovery rates under sucrose-free medium (93 percent) are also notable: the absence of a carbon source, rather than the presence of a growth retardant, can itself prolong culture viability, apparently by simply slowing metabolic activity. Together, these findings establish that in vitro conservation of dahlia does not require expensive cryopreservation technology to be practical.

Publication Type

Conference Proceedings Article

Full Citation

Shivayogeppa, G., Dinakar Adiga, J., Prabhuling, G., Reddy, B. S., & Sathyanarayana, B. N. (2008b). Strategies for in vitro conservation of dahlia (Dahlia variabilis L.). Acta Horticulturae, 865, 393–396.

Study System

Dahlia variabilis L. micro-shoot cultures.

Experimental Context

In vitro germplasm conservation through manipulation of sucrose concentration, MS salt strength, and enclosure type.

Experimental Design

Shoot tips cultured on MS medium with varying sucrose levels, MS salt strengths, and enclosure types; measured bud sprouting time, shoot length, storage duration, and recovery.

Key Results

Zero percent sucrose and quarter-strength MS delayed bud sprouting and extended storage up to 131 days. Polypropylene caps achieved the highest recovery at 95 percent.

Mechanistic Insight

Reduced carbon and nutrient supply slow growth and extend storage. Enclosure type affects culture microenvironment and viability by influencing gas exchange, humidity, and culture headspace composition.

Practical Guidance

Use MS medium without sucrose or reduced salt strength and polypropylene caps for improved in vitro storage of dahlia.

Why This Source Matters

This companion study from the same research group addresses variables that KC-0875 does not: MS salt strength and enclosure type. The finding that polypropylene caps achieved 95 percent recovery — the highest recovery rate in either study — points to the culture microenvironment as a meaningful variable that is often overlooked in protocol optimization. The convergence between KC-0781 and KC-0875 on the utility of sucrose-free or carbon-restricted medium for extended storage also strengthens confidence in that finding across two separate experimental series. Together, the two records cover the main levers available for slow-growth conservation of dahlia micro-shoots: growth retardants, carbon supply, nutrient concentration, and physical enclosure.

The twelve Knowledge Cards in this collection cover a span of fifty years of dahlia tissue culture research, from Weland's 1975 home-environment meristem-tip procedure to Wulansari and colleagues' 2025 growth regulator evaluation. Across that span, some things have changed substantially and some have not.

What has changed: the tools for confirming virus-free status have advanced from visual symptom assessment to PCR-based molecular detection, and the culture media and growth regulator options available to practitioners have expanded considerably. The ability to regenerate plants from leaf and stem tissue rather than only from shoot-tip meristems has also opened new possibilities for propagation and genetic work.

What has not changed: the core principle that the smallest accessible meristem offers the best chance of virus exclusion, while also posing the greatest challenge for successful regeneration. The tension between those two variables — smaller is cleaner, but harder to culture — was present in 1975 and remains the central technical challenge of meristem-tip culture for clean-stock production in 2025.

The conservation findings add a practical dimension that complements the propagation work. Growth retardants, carbon restriction, and enclosure type can hold dahlia micro-shoot cultures viable for up to 134 days at high recovery rates, without cryopreservation. For dahlia collections that need to maintain genetic diversity across many cultivars without continuous subculturing, that window is meaningful.

What the collection does not contain is a complete commercial protocol. The studies collected here represent different species, cultivars, growth regulator combinations, laboratory conditions, and experimental goals. No single paper defines a universal dahlia tissue culture procedure, and the variation across studies is evidence that dahlia responses to in vitro conditions are cultivar-sensitive enough that protocols developed in one context may need adjustment in another.

The Knowledge Card summaries in this collection were written by the author based on direct reading of the cited sources. AI tools assisted with retrieval, formatting, and assembly of this collection from the Dahlia Doctor research archive. All curatorial decisions, source selection, topic organization, and editorial framing, were made by the author.