The effect of temperature on potato tuber respiration
Respiration rate is a key indicator of the physiological activity of tubers and many factors affect the rate including variety, field growth conditions, maturity level, harvest, damage, disease, sprouting and storage temperature.
Temperature is the most important store management tool and there are delicate balances to be struck when selecting a store temperature. Higher temperatures accelerate biological deterioration due to disease and sprouting but minimise cold-induced sweetening. Lower temperatures minimise biological deterioration but at increased energy costs of refrigeration and cold-induced sweetening.
Tubers of five different varieties were stored at temperatures between 1.0oC and 20oC for up to seven months with respiration rate measured at monthly intervals. There were differences in respiration rate between the varieties with Russet Burbank having the lowest mean respiration rate. King Edward, Maris Piper and Melody had very similar respiration rates and Lady Claire the highest rate. Differences in respiration rate were found between seasons.
Respiration rate varied greatly from intake to end of storage for all varieties. In particular there were large changes from intake to approx. 2 - 3 months’ storage at low temperatures (1 and 2.5oC) and at higher temperatures (15 and 20oC). Following this period of adaptation, for each variety there was little difference in the respiration rate at storage temperatures between 1.0 and 9.0oC from two/three months to the end of the storage period.
Overall less variation in respiration rate in relation to storage temperature was observed in a range of varieties evaluated than had been previously measured. Respiration rates during early storage showed similarity to the observations reported by Burton (1989). The high rates of respiration at low temperatures, the “respiratory burst”, are part of the response to, and protection of tubers from, low temperature stress.