Zinc is an essential element for photosynthesis and its deficiency may play a role in the reduction of activity of rubisco and hence decreased rate of photosynthesis in higher plants. Zinc deficiency sometimes resembles Fe/Mn deficiencies. Under severe zinc deficiency the shoot apices die ('die-back') as is widely distributed. Zinc toxicity leads to chlorosis in young leaves. Induced manganese deficiency might also be of importance as high zinc supply strongly decreases the manganese content of plants. Most preventing measures for zinc deficiency are selection of Zn efficient variety that is tolerant to high level of bicarbonate as well as low zinc in soil. Curative measure for correcting are application of 20-25 kg/ha ZnSo4 in acid soil, 22 kg Zn/ha initially followed by 5-10 kg Zn in the later years or 50% gypsum + 10 t GM + 22 kg Zn once in 2-3 years in sodic soils, 1.0-1.5 kg/ha Zn as foliar spray at tillering stage and 2 times latter is very helpful for correct this deficiency. Zinc is very tightly bound to phytic acid and the formation of protein-zinc-phytic acid complexes increases the resistance to hydrolysis that leads to decrease in bioavailability of Zn to human and animals. Enrichment of cereal grains with Zn through both genetic (e.g., breeding) and agronomic (e.g., application of Zn fertilizers) biofortification is a high priority area of research, and will contribute to minimizing Zn-deficiency-related health problems in human populations.

The present study was carried out to evaluate the effect of different oils (lemongrass, neem, karanj, zinger, eucalyptus and patchouli oils), different plant product extracts (garlic, zinger, false ashoka and datura) and different antagonistic microorganisms (different species of Trichoderma spp., Bacillus sp. and Pseudomonas sp.) on grey blight of tea, Pestalotiopsis theae. Results reveal that eucalyptus oil and neem oil (0.05%) showed 98.1 and 94.3% inhibition of mycelial growth over the control, respectively. Although, both of them at 0.1% showed 100% inhibition for the pathogen. Similarly, plant extract garlic and datura showed 98.2 and 95.4% inhibition of mycelial growth over control. Among the different antagonistic agents, Trichoderma viride showed 74.3% inhibition of mycellial growth over the control. Among chemical fungicide, bavistin showed 100% inhibition over control. The various antifungal extracts showed inhibitory/fungicidal effect against grey blight of tea. These could serve as sources for development of new antifungal agent.

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TIn the process of miniaturization nanotechnology has unleashed enormous prospects for the development of new products and applications for a wide range of industrial and consumer sectors. Currently the most commonly investigated nanomaterials are variants of nanorobots, nanocrystals, Dendrimers, Nanopore sensors, quantum dots, and carbon based materials (e.g., fullerenes, nanotubes). While the source elements are often the same as the ions already used in commercial products, nanomaterials are highly reactive and often differ in many physical and chemical characteristics than their ionic counterparts. These different characteristics make them suitable for improvement or replacement of commercial products and applications. The current and projected applications of engineered nanomaterials span a wide range of sectors. These include cosmetics and personal care products; pesticides and fungicides, lubricants and fuel additives; paints and coatings; agrochemicals, plant protection products, and veterinary medicines, plastics, and weapons and explosives. More than 140 companies worldwide have already engaged in manufacture of nanomaterials. The concerns due to emergence of nanotechnology include health and safety, environmental, analytical, ethical, policy and regulatory issues. While it is often difficult to predict the future, some things seem inevitable. Just as a ball thrown into the air can be expected to fall to the ground, so we can expect our technology to reach the molecular scale.

Plant essential oils have the potential to replace the synthetic fungicides in the management of different fungal diseases. Four different essential oils of eucalyptus (Eucalyptus globulus), citronella (Cymbopogon citrate), karanj (Pongamia pinnata) and neem (Azadirachta indica) were selected because of their high inhibitory activities against ten phytopathogenic fungi. The antifungal screening for all the four Eos clearly indicates the effective lowest concentration to control the fungal growth. The more lower the MIC value, the better antifungal potency of the relative plant volatile E. globulus. Among the plant volatile essential oils, eucalyptus oil showed the lowest minimum inhibitory concentration (MIC), i.e. 0.5 mg/disc. Higher MIC values were registered, in the order, for citronella, karanj and neem oils, singly used to control all the ten fungal pathogens. Highest zone of inhibition (ZI) values followed the same pattern. These results indicated that plant volatile essential oils after suitable formulation could be used to control of different fungal pathogens. This may encourage the farmers to produce organic commodities to generate more revenue.