Potato and Tuber Crops

Post-harvest Handling and Storage

• Great care should be taken in handling of potatoes especially for seed purpose.
• Nearly 1/5 of potato production in the country is utilised for planting in next season.
• Harvested potatoes are heaped under shade for a couple of days, so that their skin becomes hard and soil adhering with them is also separated out.
• After harvesting, tubers are kept in heaps in a cool place for 10-15 days for drying and curing of skin.
• Heaps of 3-4 m long and wide at base and 1 m central height is the best. In hills tubers are spread in well ventilated rooms.
• The sorting operation is the most important, in that all cut tubers, bruised, injured by insects-pest and disease are removed.
• Sorted healthy tubers are graded in to different grades based on diameter of the tubers other wise attract reduced prices in the market.
• Therefore, such tubers should be sorted and marked separately.
• Over sized tubers are great in demand for chips making.
• Very small sized tubers are also not remain unsold. These tubers are purchased by poor people for making vegetable by partially Crushing them before cooking. However, both the over sized and under sized are quite unsuitable for seed purposes.
• Four sizes used for grading potatoes are small (below 25 g), medium (25-50 g), large (50-75 g) and extra large (above 75 g).
• Potatoes for seed purpose are treated with 3% boric acid solution for 30 minutes for protection against soil borne diseases like black scurf, common scab etc before storing in bags.
• In plains, cured tubers after grading are stored in cold storage at 2-4°C and 75-80% RH. Potatoes stored at less than 0°C suffer from internal break down known as “Black heart”. Low temperature prevents sprouting and rotting. High relative humidity reduces weight loss in tubers.
• Big cold stores for potato are established in main producing states by APEDA and other agencies and 361 cold storages with a total capacity of 360,305 tonnes were established in 1961 itself. At present, total cold storage capacity is adequate to store 35-40% of total potato production in the country.
• In indigenous method, seed tubers are stored in a single layer on sand. Frequent examination is necessary to discard tubers showing symptoms of rotting.
• Tubers are also stored in pit method. Here, pits of 60-75 cm depth 240 cm length and 90 cm width are made in cool shady places. Water is sprinkled inside the pit to cool it. After two days, pits are lined from inside with neem leaves, dry grass or sugarcane trash.
• Bamboo chimneys of 1.2 to 1.5 m length placed inside the pit at 1.2 to 1.5 m apart for escaping moisture due to evaporation of tubers. Pits are then filled with tubers up to 15 cm from top followed by a 30 cm layer of trash. A thatch is also provided over the pit as a protection from rain and sun. Sprouting is a serious problem in storage.
• A pre-harvest spray of maleic hydrazide (500-2500 ppm) checks sprouting of tubers in the storage.