Zinc (Zn) Deficiency

Scientific Name

Zinc (Zn)

Atomic Number

Atomic Weight u

65.38

Elemental Group

Micro elements (B, Cl, Cu, Fe, Mn, Mo, Ni, Zn) | Micronutrients

Available Forms

Available forms of Zinc (Zn) for Horticultural Production

Zinc sulfate (ZnSO₄·7H₂O, “White vitriol”) – highly soluble; widely used for rapid foliar or substrate correction.
Zinc sulfate monohydrate (ZnSO₄·H₂O) – more concentrated, soluble form of zinc sulfate; effective in foliar and fertigation use.
Zinc nitrate [Zn(NO₃)₂·6H₂O] – highly soluble; supplies both Zn and N; suitable for foliar sprays and fertigation.
Chelated zinc (Zn-EDTA, Zn-DTPA, Zn-EDDHA) – stable across different pH ranges; ideal for fertigation and substrate application.
Zinc oxide (ZnO) – slow-release, less soluble; commonly used in granular or controlled-release fertilizers.
Zinc carbonate (ZnCO₃, “Smithsonite”) – low solubility, slow-release Zn source.
Zinc chloride (ZnCl₂) – soluble, but less commonly used in horticulture.
Zinc frits – glass-fused carriers supplying Zn slowly in controlled-release formulations.

Affects younger leaves first (Zn is only slightly mobile in plants).
Leaf size reduction: “Little leaf” appearance; small, narrow leaves.
Interveinal chlorosis: pale or yellow tissue between veins while veins remain green.
Leaf distortion: puckering, twisting, upward cupping, or rosetting at shoot tips.
Internode shortening: compact, bushy growth due to shortened internodes.
Flowering impact: reduced flower bud initiation, smaller blooms, delayed flowering, uneven bract color in sensitive species (e.g., Poinsettia).
Severe cases may result in terminal dieback and loss of apical dominance.

High substrate pH (>6.2–6.5) reducing Zn solubility and uptake.
Excess phosphorus fertilization causing antagonism (“P-induced Zn deficiency”).
High CaCO₃ or bicarbonates in irrigation water increasing pH and limiting Zn availability.
Low organic matter or cation exchange capacity (CEC) in substrates leading to Zn leaching and poor retention.
Continuous use of Zn-free fertilizers without supplementation.

Foliar sprays: Apply zinc sulfate (ZnSO₄·7H₂O) at 0.1–0.25% for rapid symptom relief.
Substrate applications: Use chelated Zn sources (Zn-EDTA, Zn-DTPA) to ensure reliable uptake across a range of pH conditions.
Controlled-release blends: Incorporate granular or liquid micronutrient mixes with Zn at planting or during production.
pH correction: Adjust and maintain substrate pH between 5.5–6.0 for optimal availability.

Maintain substrate pH in the optimal 5.5–6.0 range.
Use balanced fertilizers that include Zn in micronutrient packages.
Avoid excessive P fertilization, which suppresses Zn uptake.
Regularly monitor substrate and plant tissue to detect early imbalances.
Incorporate Zn-containing fertilizers in standard nutrient programs for bedding and container crops.