When was zinc defined as a vital micronutrient for crop and plant growth?
The essentiality of zinc for plants has only been scientifically established for around 70 years and in some parts of the world the existence of deficiencies has only been recognised during the last 20 or 30 years. The relatively recent discovery of widespread zinc deficiency problems in rice and wheat is linked to the intensification of farming in many developing countries. This has involved a change from traditional agriculture with locally – adapted crop genotypes and low inputs of nutrients to growing modern, high yielding plant varieties and the use of relatively large amounts of fertilisers. Many of the new crop varieties are much more susceptible to zinc deficiency than the traditional crops and the increased use of fertilisers, especially phosphorus, can render a deficiency of zinc more likely. A whole new type of farming, involving the sequential cropping of rice and wheat on the same land in some regions has been made possible by new crop varieties and agronomic expertise.
