In production conditions, the variety is gradually deteriorating. To maintain all its valuable biological properties at a high level at all stages of seed production, special seed methods and measures are used: selection of typical healthy plants in the primary links of seed production in the production of elite seeds; growing plants in optimal agrotechnical conditions that contribute to the formation of high-yielding tubers; prevention of damage to plantings and tubers by diseases and pests; carrying out varietal and phytopathological cleanings; allocation of the most complete fractions for planting.
The seed material obtained under such conditions provides an increase in yield in commercial plantings by 20-30%. That is why it is so important every year to provide on seed plantations a complex of agrotechnical, phytosanitary and organizational measures aimed at obtaining planting material with high yielding qualities.
The varietal qualities of tubers depend on the genotype of the seed itself, that is, if the seeds belong to a high-yielding variety, then they potentially make it possible to grow a high yield, and if to a low-productive one, then even when planting a high-yielding seed material, a high yield cannot be obtained.
The yielding properties of seeds mean the ability of different seeds of the same variety under the same agrotechnical conditions to give different yields, and plants obtained from planting tubers with different yielding properties may differ in a number of phenotypic and economically valuable 4 traits. Thus, the yielding qualities of tubers are a set of properties and characteristics of seeds that can accordingly influence the formation of plantings as a photosynthetic system, their structure, growth, development, which ultimately determine the biological and economic yield. The yield properties of tubers are associated with the influence on them of climatic and meteorological factors, agricultural technology, seed technology.
The first of these factors is soil. It was found that the difference between the yield properties of tubers grown on different types of soil is quite significant. Tubers grown for several years on peat and loamy soils have the best seed properties compared to tubers grown on sandy or sandy loamy soils.
To a large extent, the formation of the productive properties of tubers is influenced by temperature, especially during the period of tuberization. The most productive tubers are formed at a temperature of 15-18 ° C. Both an increase and a decrease in air temperature, especially with unbalanced soil moisture, during this period worsens the productive properties of tubers.
Insufficient soil moisture (below 50-60%) and relative air humidity (below 30%) have a negative impact on the quality of tubers. Light affects plants in two ways: as an energy factor (it determines the productivity of photosynthesis), and also plays a regulatory role through different systems.
New high-yielding varieties are an important factor in the intensification of agriculture, however, in the process of reproduction and cultivation in production conditions, the quality of varieties is gradually deteriorating. Let’s consider the main reasons for the deterioration of varietal qualities.
- Mechanical blockage. It can occur in planters, potato diggers, during harvesting and sorting, in clumps, etc. Mechanical clogging with other varieties leads to the rejection of varietal plantings during approbation.
The emergence of somatic mutants is a continuous biological process that takes place in the plant world in small volumes.
- A decrease in immunity and an increase in the incidence of plant diseases. Potatoes are very quickly affected by diseases, and especially by new races of pathogens, that is, new, disease-resistant varieties lose their immunity after a few years. Therefore, disease control is a must at all stages of seed production. Especially a lot of work is carried out in the primary links of seed production, where the variety can be completely freed from diseases.
- Ecological variety depression. By their nature, there are varieties with wide ecological plasticity and low plasticity. The former are capable of producing high yields in different zones and in different environmental circumstances, the latter – only in certain local zones, which is explained by their reaction to changes in external conditions.
