Potato development phases

Potato (Solanum Tuberosum L.) is a herbaceous multi-stemmed plant from the Solanaceae family. In the region of natural origin – South America – the culture can successfully survive for many years, forming wild species. Foliage disappears with the onset of cold weather, and tubers serve as a source of nutrition. In a different climate, the plant does not occur in nature, and in agriculture, its life span is one year.

The following phases of potato development are distinguished:

1. From the beginning of the formation of shoots to the emergence of seedlings to the surface.
2. Formation of stems and foliage up to the appearance of buds.
3. Active flowering.
4. Tuber formation and growth.
5. The withering away of the tops.

The duration of potato development from planting to full ripeness depends on varietal properties and ranges from 45 to 130 days.

Phase 1 – germination and emergence

Seed potatoes stored for storage are dormant for a long time. The duration of the period depends on the concentration of the so-called growth inhibitors – acids and phenols, which naturally inhibit the emergence of sprouts. Gradually, the amount of these substances decreases, and the eyes are activated. The process is facilitated by heat and air access.

Stages of potato development in the first phase:

• germination up to 2 mm;
• the end of the dormant period – the processes exceed the length of 3 mm;
• the beginning of the formation of the root system – primary and stolonic roots;
• growth of shoots and lower leaves;
• the emergence of seedlings on the surface.

The upper eyes are usually activated first. Breaking off the shoots negatively affects the development of the plant and can subsequently cause less intensive formation of underground shoots. In the first phase, the mother tuber acts as a source of nutrients.

Stolonic roots, which are responsible for the yield of potatoes, are formed at this stage. Most of them are in the treated soil layer near the surface. The development of the underground part depends on the variety; in late-ripening varieties, the root system is more powerful and penetrates to a depth of one meter.

Conditions for growth

Favorable soil temperature for the first phase is + 7-8 ° С. Planting too early leads to stunted growth, fragility of the shoots and the risk of contracting fungal diseases. The optimum soil moisture is up to 80%. At this stage, the potatoes do not require feeding, since all the nutrients are present in the tuber. You can increase the number of stolons, stems and ultimately increase yields by applying various pre-planting methods.

Phase 2 – stem formation

The period is characterized by active formation of stems, leaves and root system. The processes run in parallel and include:

• growth of the main and lateral (basal) shoots:
• active foliage formation;
• gradual closing of the stem – as a result, up to 90% of the area of ​​neighboring plants are in contact with each other;
• the beginning of the formation of tubers – the stolons swell and grow to a size that is twice their original diameter.

During this period, the resources of the mother tuber have already been exhausted, and it loses its significance. The potatoes begin to receive the substances necessary for growth from the root system. At this time, the plant needs moderate heat, light and sufficient moisture. Favorable air temperature – from +18 to 25 ° C, at higher rates, the growing season is shortened, and the shoots are abnormally lengthened.

The soil should warm up well, this is directly related to the activity of tuberization. At temperatures below +6 ° C, the processes are completely stopped. For the development of the root system, potatoes need air flow, which is why the first hilling is carried out during this period. Plantings are watered as needed.

Phases 3 and 4 – flowering and tuber formation

The development of potato tubers coincides with flowering, starting from budding. This period is characterized by a sharp increase in leaf mass. The development of tops is progressive, the active formation of tubers begins only after the stems and leaves are fully formed. 20-30 small potatoes appear, about half of them reach maturity.

Tuberization stages:

• growth from 30 to 70% of the maximum mass, depending on the variety;
• 100% varietal weight, the skin is not formed;
• the appearance of a thin skin, easy separation from the stolon;
• the peel is compacted, at the ends of the tuber it is not rubbed off with a finger.

During the flowering period of the potato, the foundation is laid for the future harvest. At this stage, two-thirds of the potato tuber mass is formed, medium-late varieties can give a daily increase of 10 centners per hectare and more. The plant needs a sufficient amount of moisture – up to 80%, therefore, at high air temperatures, planting requires periodic irrigation. By the end of growth, the need for water in plants decreases.

Phase 5 – extinction of tops

Aging of the stem is manifested by the yellowing of the aerial part of the plant and its gradual withering away. With the loss of 70% of the foliage, the growth of tubers stops. Potatoes reach their maximum yield when the tops are completely wilted. Premature removal of the stems is undesirable, as this does not allow the potential yield of the variety to unfold. Early death of the leaf mass from diseases and pests has a negative effect on tuberization.

There are the following stages of the last stage of maturation:

• the beginning of the lightening of the foliage;
• completely yellow aboveground part;
• up to 50% of the leaves become brown;
• tops are dry and discolored;
• tubers are ready for harvesting.

When using a mechanized technique, the stems are removed ten days before harvest. In order to avoid the spread of diseases, all tops are removed from the site, since late blight spores are intensively carried by wind and precipitation. The work is completed before the onset of cold weather – the critical temperature is +5 ° С. The storage period of potatoes is directly affected by the preparation of the crop for laying: careful sorting, rejection of tubers with signs of disease; drying and airing, treatment with biofungicides.