Conditions that ensure high quality of stored tubers.Potato production technology can be represented as two blocks: a field work block and a storage block. In this regard, obtaining a high yield is only half the battle; it is still important to be able to save it. This is especially true for seed potatoes, which are stored for a longer period compared to food. The most difficult and responsible storage is in the spring, because it is necessary to maintain high planting qualities of tubers, preventing premature germination.
Storage losses consist of natural loss, technical waste (tubers partially rotted, mostly dry), absolute rot (completely rotted tubers - wet rot) and sprouts. In many ways, these indicators depend on the initial quality of tubers, which also determines the planting qualities of potatoes. Seed potatoes must meet the requirements of GOST 33996-2016, according to which in the seed material:
- the presence of tubers with signs of suffocation, frostbite, with burns, ugly, with outgrowths and easily breaking off growths, cut, crushed, with peeled skin (more than 1/4 of the tuber surface) is not allowed;
- the presence of earth and foreign impurities is allowed, not more than 2% by weight in the categories OS, ES, RS1-2;
- the presence of tubers is allowed, in percent:
- not meeting the requirements in terms of size - no more than 3%;
- other botanical varieties - no more than 0,5% (only for category PC);
- affected by ring rot - no more than 0,5% (only for category PC);
- affected by stem nematodes - no more than 0,5% (only for category PC);
- with glandular spotting and darkening of the pulp (with damage to more than 1/4 of the longitudinal section of the tuber) - no more than 5% (in total);
- with mechanical damage more than 5 mm deep and more than 10 mm long (cuts, tears, cracks, dents in tuber tissues) - no more than 5% (in total);
- with damage by agricultural pests without damage to the eyes (wireworm - more than three moves, rodents, beetles and scoops) - no more than 2% in total.
The quality of seed material largely depends on growing technologies, post-harvest processing and storage of tubers. Firstly, during the growing season (in accordance with weather conditions, in a timely manner and in the required quantity), plants should be treated with contact, systemic and translaminar preparations against late blight, alternaria, anthracnose and other fungal and bacterial diseases. To relieve stress from the action of pesticides, it is necessary to include plant growth regulators in the protection system. Secondly, in order to avoid mass soil suffocation of tubers, the system of pre-planting soil preparation and inter-row cultivation should ensure the loose state of the soil in the ridges and between rows until harvesting. In a number of regions, planting with a row spacing of 90 cm has proven itself. Thirdly, pre-harvest haulm removal with a chemical agent (Reglon Super 2,5 l / ha, Dry wind 2,5 l / ha, Basta 2,0 l / ha) must be carried out, by mechanical or combined methods, depending on the conditions and the development of the tops, at least 10-12 days before digging up the tubers. Fourthly, cleaning should be carried out at an air temperature of at least +10 0C, otherwise the percentage of mechanically damaged and affected by Fusarium rot tubers sharply increases.
Choice of cleaning equipment. Currently, potatoes are harvested by combines or diggers with the selection of tubers by hand. The second option is associated with significant manual labor costs and a great need for bags or nets for packing potatoes. However, compared with the use of harvesters, the use of diggers provides a significantly lower level of mechanical damage to tubers. Given the high labor intensity, harvesting with a digger should be used mainly in the primary seed production system (in this case, potatoes are grown, as a rule, in small areas). As an exception, the use of technology is allowed in extreme conditions, when due to unfavorable soil and weather conditions, combines are inoperative.
Mowing the tops with a combine harvester simultaneously with digging up the tubers (the bottler is installed in the receiving part of the combines) is unacceptable for most areas of Russia, since the main point of its destruction is lost: the period of ripening and hardening of the peel is excluded; the reduction in the probability and degree of damage to tubers by late blight is not provided. The use of this method is possible only when harvesting early potatoes, which are immediately sold.
Comparing self-propelled and trailed technical means (harvesters, diggers, loaders) with each other, preference should be given to self-propelled units in large-scale potato production. Despite the higher cost, they generally win in terms of operational and economic indicators.
Technologies for laying potatoes for storage. Harvesting is followed by the technological stage of laying potatoes for storage. There are three bookmarking technologies - in-line, transshipment and direct-flow, each of which determines the corresponding level of mechanical damage to tubers (table 1).
Table 1. Mechanical damage to tubers depending on the storage technology, %
Damage types | Technology | ||
in-line | transshipment | once-through | |
Peeling up to ½ of the surface of the tuber | 16,5 | 6,9 | 5,5 |
Peeling more than ½ of the surface of the tuber | 22,6 | 5,7 | 4,6 |
Cracks, tears and cuts in the pulp of tubers | 9,3 | 6,8 | 2,9 |
Darkening of the pulp with a size and depth of more than 5 mm from blows | 18,0 | 11,9 | 7,2 |
TOTAL damage | 66,4 | 31,3 | 20,2 |
Total losses for 8 months of storage, % | 32,2 | 18,7 | 8,3 |
Waste from cleaning tubers, % | 26,0-28,0 | 20,0-22,0 | 13,0-15,0 |
Streaming - potatoes harvested by a combine or digger are delivered to a sorting station to separate impurities and calibrate into fractions, followed by storage. Compared with other technologies, this method causes the greatest amount of mechanical damage to the tubers. Therefore, it should be used only in the case of the autumn sale of potatoes or when the potatoes harvested by the combine come from the field with an admixture of soil of more than 25-30% and with plant residues. Also, the use of this technology is permissible when it comes to harvesting fully mature tubers, with a stronger skin and not affected by diseases.
Transshipment - tubers are kept in temporary heaps before being stored or sorted at the point. The choice in favor of this technology should be made in case of significant damage to tubers by suffocation, late blight, wet rot, or in a situation where harvesting is carried out in cold and rainy weather, especially with combines on heavy soils.
Direct-flow - potatoes coming from the field are immediately stored for storage without autumn sorting. Depending on the conditions, cleaning can be performed according to two scenarios. If the admixture of soil in a heap does not exceed 10-15%, and the content of small tubers up to 30 mm in size in the total volume of the crop is insignificant, they are harvested according to the simplest “combine-storage” scheme, i.e. Potatoes from the harvester are transported to the storage and unloaded into the bunker of the TZK-30/60 type conveyor-loader, which places the tubers in the embankment. If the soil admixture is more than 20% and the percentage of small tubers is high, then the potatoes coming from the combine are unloaded into a modern receiving hopper (for example, manufactured by GRIMME) installed in front of the storage gate. The bunker is equipped with a heaper, which separates the soil and small tubers, and the main part of the potato is fed by a system of conveyors (conveyors) to the storage, where the piler is located. Non-standard tubers, lumps, stones and other impurities are manually selected on conveyors. Seed potatoes planted using this technology are stored until spring, and the fractions are calibrated during pre-planting preparation, at the same time the tubers are treated with a solution of Maxim, Prestige, Aktara, etc. or when planting in the coulter of the planter.
From the data in Table 1, it follows that in the absence of autumn sales, potatoes on the farm should be stored using direct-flow technology, and in extreme conditions, using transshipment technology. With in-line, in addition to the general high level of mechanical damage to tubers, the percentage of darkening of the pulp from impacts increases significantly, which leads to increased waste during cleaning of tubers - twice as high due to a general decrease in the quality of potatoes compared to direct-flow technology.
type of potato store. For storage of seed potatoes, storage bins with a central passage or with isolated sections are well suited. (picture 1).
For ware potatoes, storage facilities of a simpler design (mainly bulk type) are used, which have a higher utilization rate of the premises. Seed potatoes, especially in primary seed production, are also stored in containers (Figure 2).
Figure 2. Potato container storage technology:
a) air-pressure pedestals supplying air through vertical sockets above the containers; b) stacking containers in five tiers
This is a more expensive method, but it provides a higher mobility of work in the preparation and sorting of various varieties and reproductions.
Long-term storage technology algorithm. The storage technology, which, if strictly implemented, ensures a minimum of losses, includes five main periods: sequential drying tubers in the process of loading potatoes into storage due to continuous ventilation with outside air at the rate of 100-200 m3/t per hour; treatment period - within 20-25 days at a temperature of 18-20 0C with cyclic ventilation with internal air by the recirculation method for 30-40 minutes a day; cooling period with intensity 0,5 0C per day; main period at storage temperature 4-5 0C with periodic ventilation for 40-50 minutes two or three times a week and spring - the most responsible and difficult, since it is necessary to exclude premature germination of tubers, especially when the planting date or the planting itself is delayed due to weather reasons. The task is to exclude the entry of fresh outside warm air into the storage and maintain the temperature in the storage at a given level due to short-term ventilation during the coldest time of the day, for example, in the early hours.
The relative humidity of the air in the storage during the storage of potatoes, with the exception of the drying period, should be at the level of 90-95%.
The use of chemicals and growth stimulants. In recent years, abroad and in Russia, in addition to the use of protective and stimulating drugs (Maxim 0,2 l / t, etc.), the technology for storing seed potatoes is increasingly including such a technique as gassing with phytohormone ethylene. According to the results of studies conducted at the FGBNU VNIIKH in 2015-2017, the storage of seed potatoes in the environment of the phytohormone ethylene from November to May at a temperature of 4 0C contributed to an increase in the number of pecked eyes (mainly due to lateral ones with the exclusion of apical dominance), earlier (by 3-5 days) and friendly emergence of seedlings, the formation of a larger number of stems per bush (by 19,9-36,0% in depending on the variety), an increase in plant height by 2-3 cm, an increase in the number of tubers per bush (by 6,3-19,0%) with an earlier onset of tuberization, an increase in yield (total - by 9,9-19,0% , marketable - by 7,0-23,9%, especially when using irrigation), the formation of a more uniform crop in structure (table 2).
Table 2. Biometric indicators and potato yields on the example of the mid-early variety Gala with the use of ethylene, depending on subsequent growing conditions (average for 2015-2017)
Growing area | Option to store seed tubers and apply irrigation | Number of stems, pieces/bush | Number of tubers pcs/bush | Productivity, t / ha | |
overall | marketable (fraction tubers >50 mm) | ||||
Lyubertsy (sandy loamy soil) | control | 5,4 | 17,4 | 23,9 | 19,1 |
with ethylene | 7,2 | 21,2 | 27,3 | 22,2 | |
Ozersky (loamy soil) | control | 5,8 | 18,3 | 29,4 | 25,3 |
with ethylene | 7,7 | 22,9 | 34,5 | 30,5 | |
control (irrigation) | 6,3 | 19,2 | 33,9 | 30,4 | |
with ethylene (irrigation) | 8,6 | 24,0 | 40,3 | 37,0 |
For a number of years, the drug Vist 10 g/t (a.i. thiabendazole) has received a positive assessment of the effect on the keeping quality of seed potatoes. The viability of Rhizoctonia sclerotia after fumigation with this preparation during active ventilation decreased 14 times. In production experiments (Moscow region), the loss of tubers decreased on the variety Amadeus by 8,7%, Asterix - by 9,4%, Luck - by 17,3%, Nevsky - by 25,8%. The output of healthy potatoes increased by 9,4-11,8%. The cost of production decreased by 1,2 times, and the level of profitability was in the range of 49,6-75,5%.
Stanislav Maltsev, Doctor of Agricultural Sciences; Vladimir Zeiruk, Doctor of Agricultural Sciences;
Sergey Andrianov, postgraduate student; Sofia Shishkova, junior researcher,
Federal State Budgetary Scientific Institution “FRC of Potato named after A.G. Lorch"