Potato storage stress physiology and disease

Abstract

Russet Burbank and WC230-14 tubers were stored at 32 and 41°F in atmospheres of air, 4 or 8% CO2 over a 175 day storage period. At approximately 6 week intervals, physiological and pathological measurements were made on tubers direct from storage and again following a 14 day reconditioning period (62°F and 95 -100% relative humidity). Physiological measurements included free glucose, free fructose, and sucrose content, and cell membrane permeability. The rate of decay by Erwinia car otovora var. atroseptica (van Hall) Dye (soft rot bacterium) or Fusarium roseum var. sambucinum (LK.) Sn. & H. (dry rot fungus) represented the pathological components. Compared to 41°F, storage at 32°F increased the sugar content, cell membrane permeability rate, and predisposed the tubers to disease. Increasing CO2 during storage at 32 or 41°F increased each of the above parameters. Carbon dioxide effects became more pronounced as storage time increased. With increasing storage time, reducing sugar content usually leveled off in both varieties while sucrose, permeability, and disease susceptibility increased. WC230-14 tubers developed more reducing sugars during storage than Russet Burbank tubers and failed to eliminate the reducing sugars during reconditioning. A linear regression analysis gave significant positive correlations between Erwinia decay and either cell membrane permeability or sucrose content. A multiple linear regression analysis combining cell membrane permeability and sucrose content accounted for 80% (R2) of the difference between storage treatments in rate of decay by Erwinia. No significant correlations were obtained between the physiological parameters measured and Fusarium decay. Therefore, other factors not measured in this study must contribute to decay by this fungus.