INFLUENCE OF CROP MANAGEMENT FACTORS ON CHIPPING POTATO MATURITY AND STORAGE PROCESSING PERFORMANCE

Russet Burbank, Norchip, and Gemchip potatoes were grown under three nitrogen fertilizer levels to study the relationship between physical/physiological maturity components and long-term storage processing performance. Potatoes from all treatment combinations were physiologically mature for processing (ie sucrose less than 1.5 mg g(-1) tuber fresh weight basis) at harvest while physical maturity differences (periderm shear strength, vine appearance and tuber size) were evident during the growing season and harvest. A quadratic regression model, using date and (date)(2) as regressors, provided the best description for potato chip color variation over a 13-month storage period compared to linear, logarithmic, and higher order polynomial models. The optimal processing date (date in which the lightest chip color was predicted to occur during storage) for each nitrogen fertilizer by cultivar treatment combination was correlated with field maturity components. Russet Burbank and Gemchip potatoes that were less physically mature, indicated by vine appearance and periderm shear strength, resulted in optimal processing dates later in the storage season. Tuber size was negatively correlated with optimal processing date for Norchip tubers. These results suggest that physical and physiological maturity measures taken at or shortly before harvest may augment chemical maturity data for the purpose of selecting potato lots for long-term storage.