QUICK FACTS
- Zinc is slightly mobile in plants and immobile in soil.
- Excess of Zinc has an antagonistic effect on iron.
- Zinc is required by the plant, about 1/100th amount of Phosphorus. Therefore its place in Indian agriculture in terms of nutrient constraints is next only to Nitrogen and Phosphorus.
- Zinc deficiencies are mainly related to reduced root growth and activity as well as lower microbial activity which further decreases Zinc release from soil organic matter. Zinc uptake by plant decreases with increased soil pH. Uptake of Zinc also is adversely affected by high levels of available Phosphorus and Iron in soils.
- Rhizoctonia Root Rot, Fusarium Wilt and Zinc. Zinc application does not directly inhibit the infection, nor reduce its pathogenicity, but it does strongly increase the growth of the plant. The net result is that Zinc sufficient plants show an increased tolerance to the root pruning effect of the fungus. The plant roots lacking in Zinc would get leaky membranes, thus attracting even more fungal hyphae due to root exudation of phytosiderophores, sugars, phenolics, amino acids and other organic compounds. Zinc deficient plants are more susceptible to Fusarium Wilt. Proper application of Zinc increases plant vigour and decreases severity of the disease.
FUNCTIONS
- Component of dehydrogenase, proteinase, peptidase enzymes.
- Promotes growth hormones and starch formation.
- Promotes seed maturation and production.
- Required by several enzyme systems and auxins and in protein synthesis.
- Zinc is believed to promote RNA synthesis, which in turn is needed for protein synthesis.
- Zinc plays an essential role in DNA transcription. A typical symptom of zinc deficiency is the stunted growth of leaves, commonly known as ‘little leaf’ which is caused by the oxidative degradation of the growth hormone auxin.
GENERAL DEFICIENCY SYMPTOMS
- Leaves exhibit chlorosis, rosetting, randomized rusty brown necrotic spots, little leaf symptoms, etc.
- Dwarfing and shortening of the internodes, reduction in root growth
- Zinc-deficient plants exhibit delayed maturity.
SPECIFIC DEFICIENCY SYMPTOMS
- Leaf spot of Citrus, Tomato, Brinjal, Chilli, Cotton, Grapes (or Manganese deficiency also)
- Premature fruit shedding in Grapes / other fruits (may be Manganese/Copper deficiency)
- Premature boll shedding of cotton
- Little leaf, distorted leaf, crinkled, curled, brittle or mottled leaf of Chilli, Brinjal, Tomato, Cotton, Okra
- Brown streak disease of Paddy
- Stem rot and rust of Soybean
- Chlorotic bands along the midribs in Corn
CAUSES OF ZINC SYMPTOMS
- Sandy or coarse textured, calcareous, cold and wet soils.
- Eroded soils, soils low in organic matter
- Alkaline soils occurring in low rainfall areas
- Heavy or excessive use of Phosphatic fertilizers and liming of sandy soils may accentuate Zinc deficiency.
SENSITIVE CROPS
Cotton, Maize, Grapes, Onion, Citrus, Beans, Lowland Rice, Castor, Flax
