ROLE OF PHOSPHORUS IN PLANTS
Phosphorus (P) is an essential nutrient. It is part of many plant structural compounds, but also acts as a catalyst in many key biochemical reactions in plants. Phosphorus is particularly notable for its role in capturing and converting solar energy into useful plant compounds.
Phosphorus is a component of various enzymes and proteins. It is a vital component of DNA, the genetic ‘memory unit’ of all living things. It is also a component of RNA, the compound that reads the genetic code of DNA to build proteins and other compounds essential for plant structure, seed production and gene transfer. The structures of both DNA and RNA are held together by phosphorus bonds. Phosphorus is a vital component of ATP, the ‘energy unit’ of plants. ATP is formed during photosynthesis, has phosphorus in its structure and participates in processes from the beginning of seedling growth to seed formation and maturity.
Phosphorus is essential for the general health and vigour of plants. Applying an optimal amount of phosphorus to the crop ensures strong root development, optimal stem growth, flower formation, increased seed number, uniform and early crop ripening. The plants also have an increased nitrogen-fixing capacity in legumes, high quality indices and increased resistance to environmental factors.
Phosphorus is responsible for a number of functions that underline its importance to plants:
- Stimulates root development, which is necessary for the plant to absorb nutrients from the soil. Roots are also necessary for the plant’s support. When the roots are well developed, they are able to penetrate deep into the soil and gather the nutrients needed for plant growth as efficiently as possible.
- Enhance plant growth. Plants require adequate nutrition for their development. Food is processed in the leaves and then stored or transferred to other parts of the plant. Phosphorus is needed for photosynthesis and also for the storage and transport of nutrients throughout the plant.
- Phosphorus is responsible for the maturity of crops. Plants that are deficient in phosphorus take longer to mature; when they do, the fruit or seeds they bear are few and poor in quality.
- Vegetables help fix nitrogen in the soil through their roots. This function cannot be achieved without phosphorus, which stimulates root development.
- Phosphorus is the macro-element responsible for the flowering process and therefore for fruit formation.
- Phosphorus is involved in the pollen maturation process; phosphorus deficiencies are likely to induce flower sterility.
- Plants that have access to sufficient phosphorus are able to resist diseases because all parts of the plant are well developed. They also grow much faster.
Phosphorus is a constituent of the substances responsible for the transport of energy in plants, an indispensable element in the functioning of generative organs. Phosphate is valued in oxidised form, not in reduced form.
Soluble phosphorus is absorbed from the soil by plants in several forms, it is translocated into the plant quickly and easily, which is why deficiency symptoms appear on mature leaves.
It is strongly fixed in the soil, hardly moving under the action of water. The roots are only able to absorb phosphorus from a short distance away, phosphorus has a slower movement in the soil than any other element. In some cases phosphorus applied to the soil does not infiltrate or remains fixed and is thus lost to the plants.
Phosphorus fertilization
In terms of phosphorus demand, it is essential in several phenological phases. First of all during germination, root system growth and shoot growth; then during flower and seed formation (e.g. in rapeseed the maximum phosphorus uptake is once at flowering and once at ripening), in vines during fruit development.
Phosphorus helps growth, strong root system development, generative development, has a favourable effect on yield quality and protein formation.
It plays a role in achene size and filling degree, oil synthesis, fertilisation and dry matter accumulation.