Sergey Banadysev, Doctor of Agricultural Sciences, Head of the breeding program of Doka-Gene Technologies LLC
This material is a small excerpt from S. Banadisev "Storage of seed potatoes", which came out in a small edition just two months ago.
The book summarizes and analyzes modern world information about the specifics and theoretical foundations, advanced and promising storage technologies for seed potatoes. The standards and features of the use of various technological means and methods of ensuring the high safety of products have been substantiated. Recommendations for eliminating storage problems are given. The economic efficiency and return on investment in advanced long-term storage technologies have been analyzed.
The book will be useful to everyone who is interested in the topic of organizing the storage of potatoes. As the author notes: "The professional understanding of the heads and specialists of potato-growing enterprises of the nuances of storage and the full use of the capabilities of modern technological means provides a significant increase in the quality of seed potatoes and the level of potato seed production."
The volume of the book is 292 pages.
Contents:
1. Physico-biological characteristics and processes during storage of seed potatoes (pp. 6-69): the value of the quality of seed potatoes, potatoes as an object of storage, theoretical foundations of storage of potatoes, physiological age of seed material.
2. Technological means for storing seed potatoes (pp. 70-171): preparation of seed material for storage, active ventilation systems, technical cold, humidification and heating of air, control of germination and germination, basic technological operations.
3. Efficiency of storage of seed potatoes (pp. 172-281): risks and control of storage problems, disease and damage to tubers during storage, storage hygiene, technological level of storage, storage economics.
Additional humidification should not be used when storing seed potatoes. Potato tubers, using respiration and direct evaporation at rest, create an almost ideal relative air humidity in the intertubular space - 92-93%. Moreover, these indicators are recorded in the thickness of the embankment literally 7-10 minutes after the active ventilation stops, and only slightly change under the influence of the relative humidity of the air in the storage room (at a depth of 0,4-0,5 m at a uniform temperature along the height of the embankment). Thus, we can talk about self-regulation of the humidity regime during storage of potatoes.
Accordingly, when operating active ventilation systems, it is necessary to take this property into account and not interfere with breathing plant products to show their inherent natural properties, while providing protection from external influences and maintaining a technologically sound temperature regime. Continuous ventilation with dry air will, of course, lead to unwanted water loss from tubers and loss of turgor (tab. one). During the entire storage period, with the exception of the drying period, ventilation should be carried out only as necessary, strictly limited.
Table 1. Loss of water by potato tubers with different ventilation rates and different humidity of the air used
Air humidity 90% | Air humidity 75% | |
35 | 0.047 | 0.097 |
70 | 0.093 | 0.192 |
105 | 0.138 | 0.286 |
The duration of the storage period, when excess moisture does not need to be removed from the tubers, is six months (from November to April). This is 4320 hours. For all tasks, the standard ventilation time does not exceed 200 hours. Even if this figure is doubled, it turns out that 90% of the time the storage product is at rest, which means it is in conditions of ideal and comfortable humidity created by the potatoes themselves. Therefore, even when using relatively dry air for ventilation, weight loss increases by a maximum of 1%. The main thing is to conduct ventilation sessions for a short period of time.
It should also be understood that air humidity above 80% is quite favorable and does not lead to dehydration of tubers with short-term ventilation. Air humidity during storage of potatoes in a number of regions of the Russian Federation is not at all critical - 75-88% (tab. 2) and is comparable to the air humidity in storage facilities in Central Germany.
table 2 . Average monthly relative air humidity,%
Region | |||||||||
September | October | November | December | January | February | March | April | May | |
Kaliningrad region. | 82 | 85 | 87 | 87 | 85 | 84 | 80 | 75 | 72 |
Leningrad region. | 81 | 84 | 87 | 88 | 86 | 84 | 78 | 72 | 65 |
Smolensk region. | 83 | 86 | 89 | 89 | 86 | 84 | 82 | 77 | 71 |
Moscow region. | 80 | 85 | 85 | 85 | 84 | 81 | 77 | 69 | 66 |
Bryansk region | 77 | 83 | 88 | 88 | 86 | 84 | 82 | 73 | 66 |
Lipetsk region | 71 | 80 | 86 | 87 | 84 | 83 | 82 | 72 | 60 |
Sverdlovsk region. | 76 | 78 | 80 | 80 | 78 | 75 | 74 | 67 | 58 |
Germany center. | 79 | 82 | 85 | 86 | 85 | 85 | 79 | 76 | 73 |
Why is this comparison? The fact is that German experts in the field of storing potatoes consider it inappropriate to use additional moisture when storing table and, moreover, seed potatoes. And they don't even discuss the topic of hydration. It is on the basis of the available climatic resources that allow the use of outside air with a sufficiently high humidity for ventilation. At night, the relative humidity in spring and autumn rises by 20% compared to daytime hours, in winter, at low temperatures - by 10% (tab. one).
Table 3. Relative air humidity during the day during the storage period of potatoes,% (in the central part of Germany)
Sep | Oct | But I. | Dec | Jan. | Feb | March | Apr | |
1 | 89 | 89 | 87 | 88 | 87 | 88 | 85 | 85 |
3 | 90 | 89 | 88 | 88 | 87 | 88 | 86 | 86 |
5 | 91 | 90 | 88 | 88 | 87 | 88 | 87 | 88 |
7 | 89 | 90 | 88 | 88 | 87 | 88 | 87 | 87 |
9 | 79 | 84 | 86 | 87 | 87 | 87 | 82 | 77 |
11 | 69 | 74 | 81 | 84 | 83 | 82 | 74 | 69 |
13 | 64 | 69 | 77 | 81 | 80 | 77 | 69 | 64 |
15 | 63 | 69 | 79 | 82 | 80 | 77 | 68 | 62 |
17 | 67 | 75 | 84 | 85 | 83 | 81 | 71 | 64 |
19 | 78 | 83 | 85 | 87 | 86 | 85 | 77 | 71 |
21 | 85 | 86 | 86 | 87 | 86 | 86 | 82 | 79 |
23 | 87 | 88 | 87 | 88 | 86 | 87 | 84 | 83 |
The probability of very humid ventilation air in Germany is over 30%, i.e. such a specific gravity of the period of time of day with air humidity 91-100% (tab. 4)
Table 4. Probability of time with relative humidity,% (in central Germany)
Relative humidity,% | Month | |||||||
Sep | Oct | But I. | Dec | Jan. | Feb | Mar | Apr | |
Until 50 | 6 | 4 | 1 | 1 | 1 | 1 | 6 | 12 |
51-60 | 10 | 6 | 2 | 2 | 3 | 3 | 7 | 10 |
61-70 | 13 | 11 | 8 | 5 | 6 | 8 | 13 | 13 |
71-80 | 16 | 16 | 19 | 16 | 17 | 18 | 19 | 15 |
81-90 | 22 | 26 | 33 | 36 | 35 | 32 | 25 | 21 |
91-100 | 33 | 37 | 37 | 40 | 38 | 38 | 30 | 29 |
There is no such accurate information on the regions of the Russian Federation in the public domain, but tables have been published for accounting for days in which the relative humidity exceeds 80%. In the coastal Kaliningrad region during the storage period, these figures are in the range of 10-22, in the sharply continental Sverdlovsk region - 4-18 days per month (more in winter, less in April-May). And these are daily averages, the difference between daytime and nighttime relative humidity is understandable. This means that with precise control of the operation of the CAB, the resources of natural air humidity are quite sufficient for ventilating the potato storage facilities.
If, under the influence of advertising from equipment suppliers and when assessing these indicators, there is still a desire to install humidifiers in the seed storage of potatoes, then we can only recommend that you carefully study the conditions for the development of storage diseases and compare the risks of losing one percent of weight and losing the quality of seed.
The level of humidity in the storage room should not provoke the formation of condensation on the inner surface of the fences and on the surface of the product. Humidified air must have a temperature below the temperature of the embankment before entering it, so that there is no condensation. Equipping storage facilities with humidifiers in Russia leads to ambiguous results, because in winter there are significantly lower air temperatures here than in Western Europe. For example, the average January temperature in Germany is -1,2о C, and in the Sverdlovsk region -16,2оС. At high relative humidity and low temperatures, the storage structure, the air in the storage or the product itself often cools below the dew point, resulting in condensation. Condensation damage is superior to and equal to weight loss. Therefore, control of the upper limit of air saturation with moisture, dew point, constant temperature equalization in the mass of products and around it are among the most significant factors in increasing storage efficiency. The use of humidification is important when storing technical potatoes at high temperatures, but in any case, it is permissible only in well-sealed storages with the ability to control the temperature within an accuracy range of below 0,5 ° C. It is inappropriate to use moisture when storing seed potatoes and lots of table potatoes with the risk of disease.