Vol. 11, Issue 6 (2022)

Author(s):
Sandeep Kumar, Javid Ahmad Wani, Khanday Mehraj, Bilal Ahmad Lone, Aijaz Nazir, Zahoor Ahmad Lone, Rehana Rasool, Shahnaz Mufti, Tauseef Ahmad Bhat and Shalu Devi Thakur

Abstract:
Micronutrients or Trace elements are essential for plant growth & development but it is needed in very small quantities in the plant system. It includes Fe, Cu, Cl, Mn, B, Ni, Zn & Mo. The accumulation of these micronutrients by plants generally follows the order of Mn>Fe>Zn>B>Cu>Mo. This order may change among plant species and growth conditions (e.g.; flooded rice). They is usually found in association with larger molecules such as cytochromes, chlorophyll & protein (usually enzymes). Micronutrients may be minor in terms of the amounts needed by the crop, but they can be major in terms of their impact on crop growth. Whenever the supply of one or more of these elements is inadequate, yields will be reduced and the quality of crop products impaired, but crop species and cultivars vary considerably in their susceptibility to deficiencies. Zinc deficiency is the most ubiquitous micronutrient problem throughout the world affecting many crops including the staples maize, rice and wheat which reduces not only grain yield but also nutritional grain quality (Graham and Welch, 1996). Boron deficiency is the second most widespread micronutrient problem and dicotyledons species tend to be more sensitive to B deficiency than graminaceous crops. Iron deficiency is important in some regions, especially those with a Mediterranean climate and calcareous soils. Copper deficiency is important in some parts of the world, such as Europe and Australia where cereals are most affected. Likewise, Mn and Mo deficiencies vary in importance around the world. Acute micronutrient deficiencies in plants are accompanied by distinct symptoms, but hidden deficiencies without obvious symptoms are generally more widespread. Other mineral nutrients at low concentrations considered essential to growth of some plants are Ni and Co. When soil is in pH range of 6-6.5, most micronutrients are moderately available for plants. Soil pH values over 7 reduce the availability of Zn, B, Fe& Mn resulting in deficiency. Micronutrient constitutes in total less than 1% of dry weight of most plants. Micronutrient availability is greatly influenced by soil pH. As pH increases from 4-7. Zn, Fe, Mn & B decreases in solubility & availability while Mo increases in solubility & availability (Jacobsen, 2009).