Date of Graduation
Davis College of Agriculture, Natural Resources and Design
The relationship between lipoxygenase activity (LOX) and superficial scald was studied in the four apple cultivars (Malus domesticus Borkh.), Granny Smith (GS), Red Delicious (RD), Golden Delicious (GD) and York (YK) to determine if LOX is the genetic source of superficial scald or a means of predicting % scalded fruit. For 1993, three harvests (five trees each) for GS and four harvests (five trees each) for RD, GD and YK of one bushel box each were picked at one week intervals. For 1994, there were three harvests (five trees each) for GS, RD and GD and four harvests (three trees each) for YK. LOX activity was determined on apple peel homogenates. Superficial scald evaluations were made visually after fruit was stored for 150 days in refrigerated storage (4 C) plus seven days at room temperature (20 C). There were significant cultivar differences in LOX and in scald for both years. Correlations between % scalded fruit and LOX were significant for the combined cultivars for both years but not significant for each cultivar each year. All correlations were low. More than 50% of the variances in % scalded fruit and LOX for both years were due to cultivar. LOX is an enzyme in the biosynthetic pathway leading to scald but is not the primary cause of scald. An economically useful LOX activity scale might be developed to predict % scalded fruit in cultivars or in market lots of fruit.
Reynolds, Judith Lynne Hercules, "Differences in lipoxygenase activity as related to cultivar differences in superficial scald of apples" (1999). Graduate Theses, Dissertations, and Problem Reports. 1039.