Relative contributions of respiration and transpiration to the weight loss of russet-type potatoes

Potatoes are typically stored at low temperatures (5.5–8.9 °C) and high relative humidity (95–97%) to reduce water loss, the primary factor contributing to tuber weight loss. Water loss occurs mainly through transpiration from the tuber skin (97.6%), with only 2.4% through the lenticels. However, ignoring respiration as a water-loss mechanism can lead to inaccurate weight-loss determinations. This study aimed to evaluate respiration's contribution to mass loss (water loss) in russet-type potatoes. Four russet-type cultivars (Russet Burbank, Ivory Russet, Dakota Russet, and Rainier Russet) were cured at 12.8 °C and 95% relative humidity for 14 days. After curing, the temperature was gradually reduced to 5.5 °C, 7.2 °C, or 8.9 °C with 95% RH and stored for up to 9 months. Dakota Russet had the highest and Ivory Russet the lowest weight loss during storage, irrespective of temperature. The transpiration rate per unit of initial mass varied by storage temperature, from 14 ± 50.014±0.005 g kg⁻¹ h⁻¹ at 5.5 °C, 16 ± 60.016±0.006 g kg⁻¹ h⁻¹ at 7.2 °C, and 17 ± 70.017±0.007 g kg⁻¹ h⁻¹ at 8.9 °C. The transpiration rate per unit area decreased until the 4th -5th month of storage. The water vapor pressure deficit was the main factor contributing to total weight loss, with respiration rates contributing less than 10%. Further studies are needed to understand why Dakota Russet experiences significantly greater weight loss than other russet cultivars, despite the observed data on respiration rates.