Dahlia Doctor Research Library: Micronutrient Nutrition and Deficiency Diagnosis

A Dahlia Doctor Research Library Collection 

Copyright © 2026 by Steve K. Lloyd
All Rights Reserved

Visual deficiency symptoms are where most growers start, and they are a reasonable starting point. Yellowing between the veins, marginal leaf scorch, stunted growing tips, pale new growth: each of these is a signal. But micronutrient and secondary-nutrient disorders are among the most commonly misread problems in ornamental crop production, and dahlias are no exception. A symptom that looks like iron chlorosis can reflect manganese competition, pH-driven lock-up, or excess phosphorus suppressing iron availability in the root zone. What appears to be magnesium deficiency may be a consequence of high potassium suppressing magnesium uptake. Boron deficiency can present similarly to calcium deficiency, because the two nutrients interact directly at the cell wall level.

This collection gathers research on how dahlia and closely related ornamental crops respond to micronutrient and secondary-nutrient supply, what normal tissue mineral concentrations look like in productive dahlia plants, and what foliar correction with zinc, iron, boron, calcium, potassium sulfate, and ascorbic acid has produced in experimental settings. Three non-dahlia review sources are included to supply the physiological and mechanistic framework that smaller dahlia-specific trials cannot provide on their own. Without that framework, the trial results are harder to interpret correctly.

This collection is a companion to Dahlia Nutrient Management and Soil Fertility, which covers macronutrient programs, organic matter, integrated fertility management, and broad fertilization strategies. The focus here is narrower: nutrient disorder recognition, deficiency diagnosis, tissue mineral status, and micronutrient and secondary-nutrient correction. General NPK fertility programs, compost and organic amendment strategies, and tuber disease pathology are outside the scope of this collection.

One diagnostic caution worth naming directly: mineral composition data from dahlia storage roots does not translate straightforwardly into field deficiency diagnosis. Tubers that collapse or fail to develop correctly sometimes show unusual mineral profiles, but disordered mineral accumulation in storage tissue is not the same problem as an in-season foliar deficiency. Growers should be cautious about treating storage-organ mineral data as a guide to in-season correction decisions.

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 or direct source link, opening in a new tab when possible, 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-0693 (Barnes et al., 2015), KC-0140 (Kashif et al., 2014), and KC-0134 (Hamayl et al., 2016) have appeared in previous Dahlia Doctor Research Library collections. KC-0693 (Barnes et al., 2015) and KC-0140 (Kashif et al., 2014) were used in Dahlia Nutrient Management and Soil Fertility. KC-0134 (Hamayl et al., 2016) was used in both Dahlia Nutrient Management and Soil Fertility and in Dahlia Cut Flower Production and Harvest Quality. Each of the three cards appears here in a narrower and more specific role: KC-0693 (Barnes et al., 2015) as the foundational dahlia deficiency-diagnosis card, KC-0140 (Kashif et al., 2014) as direct evidence on foliar macro- and micronutrient formulation effects, and KC-0134 (Hamayl et al., 2016) focused on calcium borate, potassium sulfate, and secondary-nutrient interaction rather than on yield or cut-flower quality optimization.

KC-0112 (Mills-Ibibofori et al., 2019) is a dahlia-including source. Dahlia is one of three ornamental species studied. The findings are not dahlia-exclusive, and species differences should be considered when applying results directly to dahlia production. This card is included for its documentation of dahlia leaf mineral content, soil silica levels, and transpiration responses under two irrigation regimes, which provide context for interpreting mineral-profile data in potted ornamental greenhouse settings.

KC-0664 (Fageria, 2001), KC-0667 (Grzebisz et al., 2022), and KC-0678 (Ya-Lin et al., 2018) are non-dahlia support sources. None carries dahlia-specific claims on its own. They are included to supply the mechanistic and physiological framework for understanding nutrient interactions, secondary-nutrient roles in root function and nitrogen efficiency, and boron-calcium cell wall chemistry. They are identified as non-dahlia support in their Study System fields.

KC-0984 (Saxena, 2023) is a master's thesis, not a peer-reviewed journal article. The study was conducted at a single field location in Western Uttar Pradesh, India, during one season from 2022 to 2023. Results should be read as site-specific and preliminary rather than as broadly generalized conclusions. The Google Scholar search for this thesis may not return the full text directly. Researchers may find the document through Shodhganga, the Indian national thesis and dissertation repository, or through the Sardar Vallabhbhai Patel University of Agriculture and Technology library.

KC-0966 (Martínez-Damián et al., 2025) is a Spanish-language article published in Revista Mexicana de Ciencias Agrícolas in 2025. The English translation of the title is provided in brackets in the KC heading. The mineral concentration data reported for Yaretzi ligulate flowers and tuberous roots represent one variety under specific production conditions at Universidad Autónoma Chapingo and should be read as a variety-specific documented reference, not as universal norms for dahlia tissue mineral content.

A related Knowledge Card, KC-0418 (Van Leeuwen & Trompert, 2005), which documents tuber mineral composition in the context of tuber collapse, is not included in this collection. It is relevant background for understanding how storage-tissue mineral data can become a diagnostic trap, but tuber collapse and structural root disorders are outside the scope of a collection focused on micronutrient nutrition and deficiency diagnosis.

Publication Type

Conference Proceedings Paper

Full Citation

Barnes, J., Whipker, B., McCall, I., & Frantz, J. (2015). Characterization of nutrient disorders of Dahlia × hybrida 'Maxi Morelia'. Acta Horticulturae, (1062), 39–48.

Study System

Dahlia × hybrida 'Maxi Morelia' grown in greenhouse silica-sand soilless culture under controlled nutrient omission and toxicity conditions.

Experimental Context

Greenhouse silica-sand culture nutrient omission and toxicity system designed to isolate element-specific deficiency and toxicity responses in dahlia under controlled production conditions.

Experimental Design

Single-element omission treatments plus a boron toxicity treatment applied using a modified Hoagland's solution with weekly solution replacement. Photographic symptom documentation was carried out throughout the trial. Foliar tissue analysis used CHN and ICP-OES methods.

Key Results

Element-specific deficiency symptomology was documented for multiple nutrients. Significant dry mass reductions were recorded for several nutrient-omission treatments. Critical tissue concentrations were established at the point of first visible symptom appearance. Copper and molybdenum deficiencies were asymptomatic despite reduced tissue levels under the trial conditions.

Mechanistic Insight

Symptom expression reflects nutrient mobility and physiological role within the plant. Sap responses distinguished mobile from immobile nutrient deficiencies in this system. Boron toxicity produced characteristic marginal necrosis. The omission design isolated element-specific responses in a way that field-grown plants under mixed fertility conditions do not allow.

Practical Guidance

The study provides visual diagnostic standards and critical tissue concentration benchmarks for dahlia in controlled greenhouse production. These benchmarks can support interpretation of leaf tissue analysis results in commercial and research settings where visual symptom identification alone is insufficient.

Why This Source Matters

Defines element-specific deficiency symptoms and critical tissue concentration thresholds for dahlia in a controlled soilless production system. This is the most direct published reference for nutrient disorder diagnosis and tissue benchmarking in dahlia, and the anchor card for this collection's diagnostic framework.

Publication Type

Review Article

Full Citation

Fageria, V. D. (2001). Nutrient interactions in crop plants. Journal of Plant Nutrition, 24(8), 1269–1290.

Study System

Annual crop plants across multiple species grown in soil and nutrient solution systems. Non-dahlia support source.

Experimental Context

Synthesis of published studies examining how supply of one nutrient alters uptake, utilization, and physiological effects of other macro- and micronutrients under varying soil, solution, and environmental conditions.

Experimental Design

Narrative review of experimental evidence from field, pot, and solution culture studies addressing nutrient pair and multi-nutrient interactions, including synergistic, antagonistic, and neutral responses, across a wide range of crop species and soil conditions.

Key Results

Nutrient interactions are common and can be synergistic, antagonistic, or neutral depending on concentrations, ratios, soil pH, plant species, and environmental factors. Excess of one nutrient often reduces uptake of others through competitive absorption, changes in rhizosphere chemistry, or internal metabolic effects. High phosphorus supply can induce zinc and iron deficiency symptoms. High potassium can antagonize calcium and magnesium uptake. Calcium influences uptake of multiple macro- and micronutrients. Manganese interactions with iron, calcium, and silicon affect toxicity and deficiency responses in sensitive species. Balanced nutrient supply is consistently associated with improved growth and yield across the reviewed evidence.

Mechanistic Insight

Interactions occur at root surfaces and within plants through chemical complexation, precipitation, competition for transport sites, membrane-level ion competition, and metabolic regulation. Nutrient form, soil pH, redox conditions, and internal nutrient ratios alter availability, transport, and physiological function, linking ion chemistry with enzyme activation, photosynthesis, respiration, and protein synthesis.

Practical Guidance

Fertilization strategies should consider nutrient balance rather than single-nutrient supply. Rates, sources, and combinations must be selected to avoid inducing deficiencies or toxicities of interacting nutrients, especially under conditions of high phosphorus, high potassium, liming, salinity, or redox-sensitive soils. Monitoring nutrient ratios and soil properties can help manage antagonistic effects and support optimal crop growth.

Why This Source Matters

Provides the physiological and chemical principles of multi-nutrient interactions that govern how soil and solution nutrient environments influence root uptake, internal nutrient balance, and plant growth responses. Essential framework for interpreting why visual deficiency symptoms may not correspond to a single nutrient's absence and why soil or tissue analysis is necessary to move beyond symptom-reading alone.

Publication Type

Cultivar Description Article

Full Citation

Martínez-Damián, M. T., López-Santiz, J. A., Hernández-Epigmenio, F., Sosa-Montes, E., & Cruz-Álvarez, O. (2025). Descripción morfológica y nutricional de Yaretzi: una variedad de dalia para flor de corte o maceta [Morphological and nutritional description of Yaretzi: a dahlia variety for cut or potted flower]. Revista Mexicana de Ciencias Agrícolas, 16(4), e3689.

Study System

Dahlia × hortorum variety Yaretzi, grown at Universidad Autónoma Chapingo, Mexico, and characterized for cut flower and potted plant production.

Experimental Context

Variety description of Yaretzi, selected through open-pollinated half-sib family evaluation and reciprocal crossing at Universidad Autónoma Chapingo. Plants measured for mineral content were propagated from tubers in a perlite and peat substrate with manual irrigation and divided fertilization during 2023.

Experimental Design

A population of 500 Dahlia × hortorum genotypes was grown under open pollination. Selected half-sib families were evaluated for ornamental traits and used in reciprocal crosses. Thirty plants propagated from tubers of the selected variety were grown in 2023 and measured for vegetative, floral, tuberous-root, physicochemical, mineral, bioactive-compound, antioxidant-capacity, color, proximate-composition, and inulin traits. Variety description followed distinctness, uniformity, and stability criteria and 57 morphological descriptors.

Key Results

Flower mineral concentrations in Yaretzi ligulate flowers were: nitrogen 23.6 g/kg, phosphorus 2.5 g/kg, potassium 24.5 g/kg, calcium 4.4 g/kg, magnesium 3.5 g/kg, iron 65.75 mg/kg, copper 24.75 mg/kg, zinc 20.25 mg/kg, manganese 5.5 mg/kg, and boron 14.26 mg/kg. Tuberous roots contained 78.73% moisture, 21.27% dry matter, 8.7% crude protein, 1.99% crude fat, 12.62% crude fiber, 4.96% ash, and 23.61% inulin. Mean plant height was 100.81 cm, stem diameter 13.6 mm, capitulum diameter 112.36 mm, days to flowering 90.16, and flowers per plant 14.75.

Mechanistic Insight

The article reports descriptive morphological, physicochemical, mineral, and bioactive-compound values for Yaretzi. Mechanistic analysis of the mineral concentrations is not provided in the source.

Practical Guidance

The Yaretzi variety is described as suitable for commercial cut flower or potted plant production. The mineral concentrations reported in ligulate flowers and tuberous roots represent a documented nutritional reference for this variety under the described production conditions at Universidad Autónoma Chapingo. These values reflect one variety and should not be generalized as universal dahlia tissue norms.

Why This Source Matters

Provides direct dahlia evidence on flower and storage-root mineral concentrations in a characterized Dahlia × hortorum variety, offering a documented tissue-mineral reference point for nutrient-status assessment. The micro- and macronutrient concentrations reported across flowers and roots make this a useful baseline for interpreting foliar correction trials and tissue analysis results in dahlia cut flower and potted plant production.

Publication Type

Experimental Research Article

Full Citation

Mills-Ibibofori, T., Dunn, B., Maness, N., & Payton, M. (2019). Use of diatomaceous earth as a silica supplement on potted ornamentals. Horticulturae, 5(1), 21.

Study System

Potted dahlia (Dahlia Cav. × hybrida 'Dahlinova Montana'), black-eyed Susan (Rudbeckia hirta 'Denver Daisy'), and gerbera daisy (Gerbera jamesonii 'Festival Light Eye White Shades') grown in soilless greenhouse media. Dahlia-including source.

Experimental Context

Plants were grown in 15 cm pots under greenhouse conditions with natural photoperiods. Media treatments used Metro-Mix 360 without silica amendment, with soluble silica, or amended with diatomaceous earth. Irrigation was controlled with tensiometers under well-watered and water-stressed conditions.

Experimental Design

Two-factor factorial greenhouse experiment with irrigation and silicon treatment as factors. Irrigation treatments were 10 and 20 centibars. Silicon treatments included unamended Metro-Mix 360, Metro-Mix 360 with soluble silica, top-dressed diatomaceous earth at 20, 40, 60, or 80 g, and incorporated diatomaceous earth at 50, 100, 150, or 200 g. Each species had six single-pot replicates per silicon treatment per irrigation treatment. Measurements included plant height, width, shoot dry weight, stem diameter, flower number, flower diameter, transpiration, soil silica, leaf silica, and leaf nutrient concentrations.

Key Results

In dahlia, irrigation significantly affected all measured growth and flowering traits, with well-watered plants showing greater height, width, shoot dry weight, stem diameter, flower number, and flower diameter than water-stressed plants. Diatomaceous earth treatment affected dahlia height, shoot dry weight, stem diameter, leaf nutrient content, soil silica, and transpiration. Dahlia shoot dry weight was greatest in the control, all top-dressed treatments, and the 100 g incorporated treatment. Stem diameter was greatest in all top-dressed treatments and in the 50 and 100 g incorporated treatments. Dahlia leaf concentrations of nitrogen, phosphorus, magnesium, calcium, sulfur, silica, copper, iron, and manganese varied by diatomaceous earth treatment. Metro-Mix with soluble silica was similar to unamended Metro-Mix and equivalent to most diatomaceous earth treatments for growth and flowering traits.

Mechanistic Insight

Diatomaceous earth supplementation altered soil silica, leaf silica, mineral concentrations, and transpiration responses under different irrigation conditions. Silicon is described in the study as playing a role in cell membrane integrity associated with osmosis, photosynthesis, and transpiration.

Practical Guidance

Diatomaceous earth can be used as a silica supplement in soilless potted ornamental production. Plant responses depend on species, application rate, application method, and irrigation condition. Results from this study should be applied to dahlia with attention to species-level differences from the other ornamentals tested.

Why This Source Matters

Provides dahlia-inclusive evidence on diatomaceous earth as a silica supplement in soilless potted greenhouse production, documenting treatment effects on dahlia leaf mineral content, soil silica, stem diameter, and transpiration under two irrigation regimes. Useful as a mineral-accumulation and tissue-mineral reference in the context of potted dahlia production, complementing the flower-tissue concentration data in KC-0966.

Publication Type

Journal Article

Full Citation

Kashif, M., Rizwan, K., Khan, M. A., & Younis, A. (2014). Efficacy of macro and micro-nutrients as foliar application on growth and yield of Dahlia hybrida L. (Fresco). International Journal of Chemical and Biochemical Sciences, 5, 6–10.

Study System

Dahlia hybrida 'Fresco' grown as a field ornamental crop under foliar fertilization treatments.

Experimental Context

Field-grown ornamental dahlia evaluated under foliar fertilization to determine the effects of macro- and micronutrient formulations on growth, flowering, and tuber traits.

Experimental Design

Randomized complete block design with four foliar treatments: untreated control, NPK 17:17:17, NPK 15:32:7 combined with micronutrients, and NPK 15:32:7 combined with chelated micronutrients. Treatment effects were measured on vegetative growth, flowering, and tuber traits.

Key Results

Foliar nutrition significantly improved growth and yield across treatments relative to the control. The NPK 17:17:17 formulation maximized flower number and flower size. Treatments combining macro- and micronutrients increased branching, extended the bloom period, and increased tuber number. The chelated micronutrient formulation showed distinct effects from the non-chelated treatment on some measured traits.

Mechanistic Insight

Balanced foliar nutrient supply may enhance photosynthesis, vegetative growth, flowering, and tuber initiation under the study conditions. The comparison between chelated and non-chelated micronutrient formulations suggests that micronutrient availability and uptake efficiency are influenced by chelation form, which is relevant to interpreting foliar correction results where product formulation varies.

Practical Guidance

Foliar macro- and micronutrient formulations affected flower and tuber traits in this field trial. Formulation choice in dahlia production should be tied to soil fertility status, crop production goals, and local micronutrient deficiency risk rather than to generic product selection.

Why This Source Matters

Provides direct dahlia field evidence on how macro- and micronutrient foliar formulations, including chelated micronutrients, affect growth, flowering, and tuber production in Dahlia hybrida. A core card for evaluating foliar micronutrient delivery strategies in dahlia and for comparing chelated versus non-chelated micronutrient availability.

Publication Type

Experimental Research Article

Full Citation

Younis, A., Anjum, S., Riaz, A., Hameed, M., Tariq, U., & Ahsan, M. (2014). Production of quality dahlia (Dahlia variabilis cv. Redskin) flowers by efficient nutrients management. American-Eurasian Journal of Agricultural & Environmental Sciences, 14(2), 137–142.

Study System

Dahlia variabilis cv. Redskin seedlings grown in 12-inch pots under floriculture research conditions.

Experimental Context

Potted dahlia plants were grown in a floriculture research area to test foliar nutrient application as a method for improving vegetative growth, flowering, and tuber production under potted-plant conditions.

Experimental Design

Sixteen foliar nutrient treatments combined different concentrations of a macronutrient product containing nitrogen, phosphorus, and potassium with a micronutrient solution containing zinc, boron, iron, manganese, copper, chloride, and molybdenum. Treatments were applied at seven-day intervals. A completely randomized design with four replications and 192 plants was used. Measured traits included plant height, lateral shoots, lateral shoot length, leaves per plant, leaf area, days to first flower emergence, root length, blooming period, flower size, flowers per plant, and tubers per plant.

Key Results

The combined treatment of 6 mL/L macronutrient product and 7.5 mL/L micronutrient solution produced the highest values for plant height, branch number, branch length, leaf number, leaf area, root length, flower size, flower number, and tuber number among all tested treatments. This treatment produced 49.08 cm plant height, 26.00 branches per plant, 108.33 leaves per plant, 22.08 cm root length, 10.60 cm flower size, 15.70 flowers per plant, and 12.00 tubers per plant. Control plants had the lowest values for most measured traits, including 32.81 cm plant height, 10.00 branches per plant, 54.17 leaves per plant, 5.07 cm flower size, 4.20 flowers per plant, and 3.83 tubers per plant. The longest blooming period was recorded at the lower macronutrient rate of 4.00 mL/L combined with 7.5 mL/L micronutrient solution, not the highest-rate combination.

Mechanistic Insight

The source attributes treatment differences to combined macro- and micronutrient supply. Nitrogen is described as supporting vegetative growth, starch production, and amino acid synthesis. Phosphorus is described as a structural component of nucleic acids and phospholipids and as involved in energy metabolism. Micronutrients are described as having stimulatory and catalytic roles in physiological and metabolic processes, including enzyme activation.

Practical Guidance

Under the potted-plant conditions of this study, combined foliar application of 6 mL/L macronutrient product and 7.5 mL/L micronutrient solution produced the highest growth and flowering responses. The longest blooming period was associated with a lower macronutrient rate combined with the same micronutrient concentration, suggesting that optimizing for bloom duration may require a different formulation balance than optimizing for vegetative growth or tuber number.

Why This Source Matters

Provides direct dahlia evidence on combined macro- and micronutrient foliar management in a potted-plant system, with measured effects on vegetative growth, flowering traits, root length, and tuber number in Dahlia variabilis cv. Redskin. The 16-treatment design covers a wider concentration range than most comparable dahlia foliar trials and distinguishes bloom duration responses from growth and yield responses across formulations.

Publication Type

Thesis or Dissertation

Full Citation

Saxena, P. (2023). Influence of combined sources of nutrients and foliar management of micronutrients on growth, flowering and tuber production of dahlia (Dahlia variabilis L.) in Western Uttar Pradesh conditions [Master's thesis, Sardar Vallabhbhai Patel University of Agriculture and Technology].

Study System

Dahlia variabilis L. cultivar Giani Zail Singh grown under Western Uttar Pradesh field conditions.

Experimental Context

A field experiment conducted during 2022 to 2023 at the Horticulture Research Centre, Sardar Vallabhbhai Patel University of Agriculture and Technology, Modipuram, Meerut, Uttar Pradesh, India. Experimental soil was sandy loam with pH 7.58, EC 0.31 dS/m, organic carbon 0.33%, available nitrogen 136.29 kg/ha, available phosphorus 14.65 kg/ha, and available potassium 129.36 kg/ha.

Experimental Design

Randomized complete block design with 12 nutrient-management treatments, three replications, 36 plots, and 9 plants per plot at 45 cm by 45 cm spacing. Treatments combined no recommended dose of fertilizers, full recommended dose of fertilizers, 75% recommended dose of fertilizers, or 50% recommended dose of fertilizers with farmyard manure, vermicompost, foliar ZnSO4 at 0.2%, foliar FeSO4 at 0.2%, or combined ZnSO4 and FeSO4 foliar sprays. Full farmyard manure, vermicompost, phosphorus, and potassium were incorporated before transplanting. Nitrogen was applied in two split doses at transplanting and at 30 days after transplanting. Foliar ZnSO4 and FeSO4 sprays were applied at 45 and 90 days after transplanting. Observations included vegetative growth traits, flowering traits, tuber yield parameters, soil analysis, and economic returns.

Key Results

Treatment T5, consisting of 75% recommended dose of fertilizers at NPK 75:90:75 kg/ha combined with farmyard manure at 5 t/ha and foliar ZnSO4 at 0.2%, produced the highest values for plant height, plant spread, leaf number per plant, stem girth, leaf area, single tuber weight, tubers per plant, tuber yield per plot, and tuber yield per hectare. T5 produced 6.00 tubers per plant, 5.57 tons tuber yield per hectare, and a benefit-cost ratio of 3.61. Treatment T6, consisting of 75% recommended dose of fertilizers combined with vermicompost at 2 t/ha and foliar FeSO4 at 0.2%, produced the better results for flowering parameters, including days to flower bud initiation, days to 50% flowering, flower number per plant, blooming period, fresh weight of single flower, and flower yield per hectare. The untreated control produced the lowest values for most yield and economic parameters.

Mechanistic Insight

The thesis attributes improved vegetative growth under integrated nutrient treatments to nutrient availability from inorganic fertilizers, soil conditioning from farmyard manure, nutrient and microbial contributions from vermicompost, and catalytic and enzyme-activation roles of foliar micronutrients. Tuber-yield responses are attributed to improved photosynthate transfer to storage tissue and zinc-associated enzyme and chlorophyll-related processes. Flowering responses under foliar FeSO4 and vermicompost treatments are attributed to iron-associated metabolic activity, chlorophyll production, photosynthesis, and carbohydrate accumulation.

Practical Guidance

Under the one-season field conditions of this study, T5, combining 75% recommended dose of fertilizers with farmyard manure and foliar ZnSO4, was the most suitable treatment for vegetative growth, tuber yield, and economic returns. T6, combining 75% recommended dose of fertilizers with vermicompost and foliar FeSO4, was the better treatment for flowering parameters. Results represent a single location and single season and should not be generalized without further validation. The thesis notes that additional research may be needed to confirm the conclusions.

Why This Source Matters

Provides direct dahlia field evidence on integrated nutrient management combined with foliar zinc sulfate and iron sulfate, with separate outcome profiles showing that ZnSO4 and FeSO4 foliar applications produce distinct responses for vegetative growth and tuber yield versus flowering traits. The only card in this collection that directly compares foliar ZnSO4 and FeSO4 as distinct treatments across multiple agronomic measurements in a single dahlia field trial.

Publication Type

Journal Article

Full Citation

Mohammed, S. A., Abd-Allatif, S. A., & Obaidi, A. A. (2016). Effect of foliar application with potassium sulphate and ascorbic acid on growth and flowering of dahlia (Dahlia variabilis L. cv. Arizona). Diyala Journal of Agricultural Sciences, 8(1), 232–243.

Study System

Dahlia variabilis L. cv. Arizona grown under field conditions with foliar potassium-sulphate and ascorbic-acid applications.

Experimental Context

Foliar potassium-sulphate and ascorbic-acid application tested under field conditions to evaluate effects on vegetative growth, leaf chemistry, and flowering in dahlia.

Experimental Design

Randomized complete block design factorial experiment testing potassium sulphate at 0, 3.5, and 5 g/L crossed with ascorbic acid at 0, 50, and 100 mg/L as foliar sprays.

Key Results

Increased plant height, leaf number, leaf area, chlorophyll content, and leaf nitrogen, phosphorus, and potassium concentrations were reported across treatments. The strongest vegetative and flowering responses occurred at 5 g/L potassium sulphate combined with 100 mg/L ascorbic acid.

Mechanistic Insight

Potassium is described as supporting photosynthesis and nutrient translocation. Ascorbic acid is described as influencing antioxidant activity and growth regulation. The combined application at higher rates produced the largest measurable effects on vegetative traits and leaf chemistry.

Practical Guidance

In this field trial, foliar potassium sulphate combined with ascorbic acid improved vegetative and flowering traits in dahlia cv. Arizona. Application should be guided by cultivar response, local soil fertility status, and production goals. Ascorbic acid as a foliar adjuvant represents an experimental approach not yet widely validated across dahlia cultivars or production environments.

Why This Source Matters

Provides direct dahlia field evidence on foliar potassium sulfate combined with ascorbic acid as a secondary-nutrient and antioxidant-supported correction approach for vegetative growth and flowering improvement. Extends the foliar-correction evidence base in this cluster into potassium-sulfate effects and illustrates how a non-nutrient antioxidant compound can interact with nutrient delivery responses in dahlia.

Publication Type

Journal Article

Full Citation

Hamayl, A. F., El-Saka, M. M., El-Boraie, E. A. H., & Gad, A. E. A. (2016). Effect of potassium sulfate and calcium borate on improving quality and production of Dahlia flowers. Journal of Plant Production, 7(12), 1281–1286.

Study System

Dahlia pinnata grown as a field ornamental crop under potassium sulfate and calcium borate fertilization regimes.

Experimental Context

Field-grown ornamental dahlia evaluated under soil-applied potassium sulfate and foliar calcium borate treatments over two seasons.

Experimental Design

Randomized complete block design with potassium sulfate soil applications at 10 or 20 g/plant and calcium borate foliar sprays, applied alone and in combination, over two growing seasons.

Key Results

Combined potassium sulfate at 20 g/plant with the higher calcium borate foliar treatment produced the highest values for vegetative growth, flower number, flower size, stem strength, vase life, tuber number, and tuber diameter across the trial.

Mechanistic Insight

Potassium is described as supporting carbohydrate synthesis and vegetative growth. Calcium and boron are described as supporting cell-wall integrity, lignification, stem strength, and nutrient transport. The synergistic response observed under combined application reflects the interacting structural and metabolic roles of these nutrients, which is directly relevant to the boron-calcium cell wall interactions reviewed in KC-0678.

Practical Guidance

Combined potassium sulfate and calcium borate improved flower quality traits and tuber characteristics in this field experiment. Direct application in production settings should be guided by soil testing, boron toxicity limits, and local fertility context. Boron is phytotoxic at relatively low excess levels and should not be applied without knowing baseline soil and tissue boron status.

Why This Source Matters

Provides direct dahlia field evidence on the effects of calcium borate and potassium sulfate on flower quality, stem structure, and tuber development. In this collection, the card is used specifically for its secondary-nutrient and micronutrient interaction evidence around calcium, boron, and sulfur, not for its yield or cut-flower optimization framing from prior collection appearances.

Publication Type

Review Article

Full Citation

Grzebisz, W., Zielewicz, W., & Przygocka-Cyna, K. (2022). Deficiencies of secondary nutrients in crop plants—A real challenge to improve nitrogen management. Agronomy, 13(1), 66.

Study System

Field crop plants across multiple species, including cereals, oilseed rape, maize, potato, sugar beet, and legumes. Non-dahlia support source.

Experimental Context

Physiological and agronomic analysis of calcium, magnesium, and sulfur roles in crop nitrogen uptake, utilization, and yield formation under field conditions, including soil constraints such as acidity and aluminum toxicity.

Experimental Design

Conceptual synthesis of published physiological, soil chemistry, and crop nutrition research examining interactions among calcium, magnesium, sulfur, and nitrogen fertilizer use efficiency, including nutrient uptake dynamics, plant tissue ratios, and soil amendment effects from lime and gypsum applications.

Key Results

Secondary nutrient deficiencies disrupt nitrogen uptake efficiency and utilization by impairing root development, energy metabolism, and protein synthesis. Calcium deficiency restricts root system growth and exacerbates aluminum toxicity. Magnesium deficiency limits ATP-dependent nutrient transport and photosynthesis. Sulfur deficiency impairs cysteine and protein synthesis, increases non-protein nitrogen, and reduces yield component formation. Correcting calcium, magnesium, and sulfur nutrition narrows plant nitrogen-to-magnesium and nitrogen-to-sulfur ratios and improves nitrogen fertilizer productivity.

Mechanistic Insight

Nitrogen uptake depends on root system architecture and proton pump activity, which require adequate calcium and magnesium. Calcium supports root meristem function, membrane stability, and stress signaling. Magnesium is central to chlorophyll structure, ATP formation, and phloem loading. Sulfur assimilation is required for cysteine formation, linking nitrogen and sulfur metabolism through amino acid and protein synthesis. Secondary nutrient supply regulates enzymatic systems involved in nitrate reduction, nitrogen assimilation, and stress defense.

Practical Guidance

Maintain adequate soil calcium to support root growth and mitigate aluminum toxicity through liming or gypsum where needed. Correct magnesium deficiency via soil or foliar magnesium fertilizers, especially before reproductive stages. Ensure sufficient sulfur supply, particularly in high-production systems, using soil or foliar sulfate sources. Monitor plant nitrogen-to-magnesium and nitrogen-to-sulfur ratios to optimize nitrogen fertilizer efficiency.

Why This Source Matters

Provides mechanistic framework for how calcium, magnesium, and sulfur status governs root function, nutrient uptake efficiency, and nitrogen productivity in crop plants. Directly relevant to understanding why secondary-nutrient deficiencies can present as nitrogen-related growth problems and why correcting only the most visible symptom, without evaluating the secondary-nutrient context, may not resolve the underlying disorder.

Publication Type

Review Article

Full Citation

Ya-Lin, L., Xiu-Wen, W., Lei, Y., Chen-Qing, D., & Cun-Cang, J. (2018). Research progress on the effect of boron and calcium on plants and the interaction mechanism in the cell wall. Plant Science Journal, 36(5), 767–773.

Study System

Plants across multiple species. Literature review focusing on boron and calcium interactions in plant growth, metabolism, and cell wall structure. Non-dahlia support source.

Experimental Context

Synthesis of physiological, cell wall biochemical, and metabolomic findings from studies conducted under varying boron and calcium supply conditions.

Experimental Design

Literature review of experimental evidence from physiological, cell wall biochemical, and metabolomic studies examining boron and calcium effects and their interactions under varying nutrient conditions.

Key Results

Boron and calcium both play essential roles in plant growth and development and exhibit synergistic and antagonistic interactions depending on concentration and ratio. Calcium stabilizes cell walls by cross-linking de-methylesterified homogalacturonan in pectin, forming gel networks that enhance mechanical strength. Boron forms borate diester cross-links with rhamnogalacturonan II, contributing to pectin network structure through a separate mechanism. Imbalances in either nutrient affect plant morphology, biomass accumulation, metabolic profiles, and stress responses. Boron deficiency alters central metabolism, amino acid profiles, and carbohydrate accumulation. Excess calcium can exacerbate boron deficiency symptoms. Balanced co-application of boron and calcium has improved growth and quality in some crop systems.

Mechanistic Insight

Calcium cross-links negatively charged galacturonic acid residues in homogalacturonan via egg-box structures, while boron cross-links rhamnogalacturonan II side chains as borate diesters. These interactions govern pectin network architecture and cell wall stability. Calcium also functions in signaling pathways through calcium-binding proteins and kinase cascades. The structural interdependence of boron and calcium in cell wall assembly means that deficiency or excess of either nutrient affects the functional contribution of both.

Practical Guidance

Maintaining appropriate boron and calcium supply and balance is important for normal plant growth, cell wall integrity, and quality outcomes. Excess calcium can exacerbate boron deficiency symptoms. Balanced co-application should be guided by tissue and soil status, since their structural interdependence at the cell wall level means that correcting one while neglecting the other may not produce the expected result.

Why This Source Matters

Provides mechanistic principles of boron and calcium interaction, pectin cross-linking chemistry, and cell wall structural regulation relevant to understanding how mineral nutrition affects plant structural integrity at the cellular level. Essential context for interpreting why boron and calcium deficiencies can be difficult to distinguish by visual symptom alone and why their correction requires attention to the balance between both nutrients.

Micronutrient and secondary-nutrient problems are rarely solved by symptom-matching alone. Leaf color, scorch, distortion, weak stems, poor flowering, and reduced growth can point toward nutrition, but they can also reflect pH, nutrient antagonism, water stress, heat stress, root injury, cultivar response, or disease.

The safest lesson from this collection is not to apply more trace elements whenever a plant looks wrong. Boron, iron, zinc, calcium, magnesium, sulfur, and potassium all matter, but their effects depend on balance, availability, and plant tissue status. Soil testing, tissue testing where practical, and careful attention to growing conditions are more reliable than treating visual symptoms as a single-nutrient diagnosis.

For dahlia growers, micronutrient nutrition is best understood as part of a diagnostic process: observe the pattern, check the growing conditions, consider nutrient interactions, and correct only when the likely cause is supported by evidence.

The Knowledge Card summaries in this collection were developed from the Dahlia Doctor research archive and checked against available source records during editorial preparation. AI tools assisted with retrieval, formatting, comparison of candidate Knowledge Cards, and assembly of the collection. All curatorial decisions, including source selection, topic organization, citation corrections, interpretation, and final editorial framing, were made by the author.