C. STORAGE OF CARROTS - SOME BIOLOGICAL PECULIARITIES AND STORAGE METHODS OF CARROTS
In order to keep carrot for 4–7 months without significant losses it is kept at a temperature of about 0°. The temperature is allowed to go down to 0.5° below the freezing point for short periods of time (two or three weeks) and rise to 1° above the freezing point. It is also very important for the carrot that a favourable relative humidity of the air is maintained, from 90 to 95%. In these conditions there are no practically significant differences in keeping quality between varieties.
When the rules concerning air temperature and humidity in the storage are observed, the storage result depends on the quality of the carrots put in storage. In the middle zone of the country carrot for storage is preferentially grown on soddy-meadow and peat soils (of light texture). Carrots grown on these soils have high market quality and increased resistance against diseases. On soddy-podzolic and meadow soils (of a heavy texture) carrots have reduced resistance during storage. When carrot is grown on fen soils, high in nitrogen, increased doses of phosphorus-potassium fertilizers are applied. It is particularly important that carrots for storage are grown in the crop-rotationfields where the soil is not infected with the causal organism of white rot (Sclerotinia).
Immediately after harvesting, the top is cut, leaving 1 cm of the petioles. If the tops are not cut, they will transpire water contained in the roots. Experiments have shown that the leaves transpire water coming to a considerable degree from the outer layers of the root which become non-resistant to disease causing organisms, and therefore lose the ability of prolonged storage.
In the last years mainly large vegetable storehouses with natural cooling and active ventilation are built. Active ventilation makes it possible to lower the temperature of carrots put in storage to the optimum level about one month earlier than in storehouses with natural cooling, and thereby maintain the keeping quality of the produce and reduce losses. Active ventilation allows the carrot to be loaded 2–2.5 m high, and this makes it possible to increase the amount of carrots 2–3 times in the same storage volume and reduce the storage costs accordingly. Unlike other vegetables, the storage of carrots in active ventilation encounters