1. The role of Zinc in Crops Growth :
It involves in the metabolism of auxin (IAA) and nucleic acid/protein synthesis, determining the vitality of meristematic tissue and internode length.
It is the key for enzyme: Over 300 enzymes depend on Zn (such as alcohol dehydrogenase, carbonic anhydrase, RNA polymerase, etc.), associated with photosynthesis, respiration, and antioxidant processes.
Membrane and Stress Resistance: Maintains biological membrane integrity and enhances stability under drought, salinity, and pathological stress.
Pollination/Fruit Setting: Adequate Zn helps in pollen tube elongation and fertilization, reducing the incidence of 'flowers without fruit'.
2. Why does Zinc difficiency caused ?
Alkaline/calcareous soil (pH>7.5) or irrigation high HCO₃⁻ water→ Zn²⁺ fixed by carbonate/hydroxide and low effectiveness.
Phosphorus excess (P-induced zinc deficiency) → High phosphorus inhibits Zn absorption/formation of insoluble compound salts on the root surface.
Poor cold and wetness/waterlogging/ventilation → The roots are weak in activity and slow in diffusion, and cannot be sucked.
Sandy soil/low organic matter/low CEC → easy to leach, small storage capacity; For a long time, only NPK is chased, and a small amount of "long-term supply is cut off".
3. The differentiate of Zinc difficiency compare with other micro element difficiency ( Fe, Mg)
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Zinc difficiency(Zn) | Iron difficiency(Fe) | Mg diffieiency(Mg) |
|---|---|---|---|
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New leaves / tender shoots | New leaves / tender shoots | Old leaves/leaves close earth |
| Leaf morphology | Small leaf morphology, narrow leaves, short internodes (clustered leaves/tufted leaves/'apical small leaves') | The new leaves show a loss of green between the veins, almost becoming dessicated and thin. | Old leaves lose their green between the veins → Leaf edges are scorched. |
| Leaf color texture | Slight green fading/spotting | Green veins and yellow veins. | net like yellowing |
| Reproduction | Pollen vitality decline, poor fruit set. | Overall yellowing |
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Vegetable/Fruit Tree Old Leaves Net-Like Yellow |
4. Zinc source
| Zinc source |
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|---|---|---|---|---|---|
| Zn-DTPA |
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irrigation / Foliar | pH≤7.5 stable
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| Zn-EDTA |
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irrigation / Foliar |
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pH>6.5 lose it efficiency
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| ZnSO4 |
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irrigation / Foliar |
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| ZnO |
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slow release |
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| Glycine Zn trace elements |
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irrigation / Foliar |
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foliar better,low solt, limited by water/pH/temperature |
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5. Recommendation
Tomatoes/Pepper/Cucumber
2-3 weeks before flowering: Provide Zn at 0.1-0.2 mg/L to the roots, best use Amino Zn; if "new leaf internodes are short", foliar spray EDTA Zn at dilution of 1000-1500 times for 1-2 times.
Fruit set - young fruit stage: Foliar spray Zn and B according to label; maintain low amounts of Zn at the roots, control high phosphorus/high HCO₃⁻ product during the foliar of Zn.
Color change period: Focus on K/Mg/B nutrition, maintain low amounts of Zn at the roots; avoid excessive phosphorus that causes secondary zinc deficiency.
Grapes/Apples/Citrus
After leaf drop/dormancy or before bud burst: Fruit trees can apply high multiples of zinc sulfate in the clean-up system (as per plant protection experience).
Leaf expansion - before flowering: Foliar spray EDTA Zn at dilution of 1000-1500 times for 1-2 times; Gardens with alkaline soil/high HCO₃⁻ water sources, maintain low amounts of Zn at 0.1-0.2 mg/L to the roots.
Young fruit stage: Maintain Zn and togather B to stabilize fruit set and transport.
Corn/Wheat
(summary)Supplementing zinc to the roots during the seedling stage (as base fertilizer/seed dressing/banded application of a small amount of Zn) can significantly reduce "white heart/crowded small leaves." EDTA Zn is strongly recommended