Functions of Nutrient Elements in Higher Plants

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Functions of Nutrient Elements in Higher Plants 279 Tab. 2.2 Element contents of some higher plants. (Epitomized from Schilling et al. 2000.)... 

Functions of Nutrient Elements in Higher Plants 285 Tab. 2.3 I nstances of non-protein components of enzymes (from different sources)... 

Calcium is an essential element for all higher plants, but it is often overlooked as a plant nutrient because Ca levels are usually adequate for crops grown on soils above pH 5.0. The specific physiological functions of Ca are not clearly defined, but a deficiency results in the failure of terminal bud development. A paramount role played by Ca appears to be that of maintaining membranes and hence, intracellular organization (Epstein, 1972). 

Besides the 16 elements discussed above that are generally considered to be essential for all higher plants, and for most lower plants, there are several others that are sometimes important. They have been designated as functional or metabolism nutrients , defined as any mineral nutrient that functions in plant metabolism irrespective of whether or not its action is specific (Nicholas, 1961). There are several of these but the chief ones are cobalt, vanadium, sodium and silicon. 

Boron, chlorine, copper, iron, manganese, molybdenum (for N-fixation), and zinc are considered essential plant micronutrients. These elements are needed by plants only at very low levels and frequently are toxic at higher levels. There is some chance that other elements will be added to this list as techniques for growing plants in environments free of specific elements improve. Most of these elements function as components of essential enzymes. Manganese, iron, chlorine, and zinc may be involved in photosynthesis. Though not established for all plants, it is possible that sodium, silicon, and cobalt may also be essential plant nutrients. 

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