Phosphorus (Р2О5) – i s o ne o f t he m ost i mportant plant nutrients. Its content in them reaches 0.2-1.2%. Most of this element is found in reproductive and young growing organs. In the 18th century, the Swiss naturalist Saussure discovered that phosphorus in the form of calcium phosphate was found in the ashes of all plants. Later it was found out that the overwhelming majority of metabolic
processes take place with its participation.
The indisputable fact is that without this element no cells can exist. In plants, phosphorus is present in the form of inorganic and organic compounds. Inorganic compounds (4-16% of phosphorus) are ammonium, potassium, sodium, magnesium and calcium salts of phosphoric acid. The most common forms are dihydrophosphate ion H2PO4- and monohydrophosphate ion HPO4-2. They perform not only the storage function, but also play the role of buffering agents, maintaining the constancy of pH of cytoplasm. The range of organic compounds is much wider: they contain 85-95% of phosphorus contained in plant. The most important compounds that include phosphorus are DNA and RNA. These two nucleic acids are involved in synthesis of proteins, transfer of hereditary traits, growth and development. They consist of nitrogenous base, carbohydrate (ribose or deoxyribose) and phosphoric acid. Examples of
elementary units – nucleotides of these acids – are ATP (adenosine triphosphoric acid), ADP (adenosine diphosphoric acid) and AMP (adenosine monophosphoric acid). These nucleotides are involved in protein and lipid metabolism, processes of energy transfer and accumulation, biosynthesis of carbohydrates. As it can be seen from the above, without phosphorus, as well as without nitrogen, life
is impossible. Below some groups of substances and individual representatives found in plants containing phosphorus are described. Phytin (27.5% Р2O5) is a magnesium-calcium salt of inositol phosphoric (phytic) acid. It is a reserve substance; phosphorus, which is part of it, is used by embryo during germination. Seeds of some crops (beans, canola) contain up to 2.5% of this substance. Industrially important source of phytin is hemp cake and seeds. Sugar phosphates can be found in all plant parts. They take part in the processes of photosynthesis and respiration. Their content reaches 1.0% of dry matter. The composition of food lecithin includes up to 65% of phospholipids. Phospholipids are esters of glycerol, high molecular weight fatty acids and phosphoric acid. They are part of cells cytoplasm and cell membranes. Most of this element is found in reproductive and young growing organs; it has a positive effect on the development of root system. In the process of reusing it is able to move from the old plant parts to young ones.
Phosphorus deficiency signs:
• Rapid phosphorus deficiency reversal
• Prevention of phosphorus deficiency
• Increased resistance to fungal diseases
• Activation of growth processes
• Activation of protein and carbohydrate biosynthesis
• Increased mineral fertilizers utilization rate
• Improved commercial yield quality (transportability, storability, increased fruit size, colour, smell)
• Promotion of maximum accumulation of carbohydrates, proteins and vitamins in fruits, berries and vegetables
• Reduced safety interval
• Uniform ripening