Principles of Substance Formation

Principles of Substance Formation and Role of Nutrient Elements 

The higher plant represents a spatially divided system (organs, tissues, cells, cell compartments) that forms distinct groups of organic compounds in each part. The fundamental reaction is the photosynthetic splitting of water in shoots. The derived hydro- 

In this chapter, attention is paid to the role of the nutrient elements listed in Table 2.1 -which are occasionally also referred to as nutrients . However, nutrients are in reality those forms of elements which are taken up and involved in metabolism, for example K , Ca +, Mg +, Mn +, NH/, CO(NH2)2, and H2 P04. Many elements are absorbed in more than one form, but because the element concerned - and not its ligands - is related to the nutritive value, it is referred to only occasionally as a nutrient in the literature. This also holds true for the elemenf s oxides (e.g., P2O5, K2O) which are, in practice, not present in plants. Such a nomenclature is incorrect and so is not used in this chapter. 

The following criteria are commonly accepted as typical characteristics for essential nutrient elements (Arnon and Stout 1939)  

It is of interest that the substrate for the ATPases appears to be a MgATP complex rather than free ATP (Rea and Sanders 1987, Rea 1999). In addition, MgATP can be utilized very well for the transfer of energy-rich phosphoryl groups (Balke and Hodges 1975). K also plays a role in such processes (Mansour etal. 1998). Therefore, the simultaneous involvement of a variety of nutrient elements in such reactions is verified. ATP that underwent decomposition for the phosphorylations is later rebuilt from ADP + Pin- In plants, the energy for this process is obtained in chloroplasts directly from sunlight (the process of photophosphorylation), whilst in cells and compart- 

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