Assessment of pre-harvest physiological infiltration methods for predicting commercial bitter pit in 'Braeburn' and 'Golden Delicious'
Although management practices are followed to reduce the incidence of bitter pit in commercial orchards, this defect still surfaces and causes serious problems with fruit quality that lead to losses in especially export produce. Current methods e.g. fruit mineral analysis, magnesium (Mg) infiltration and ethylene forcing that were developed to predict bitter pit incidence, vary in reliability. However, there is still a need to predict bitter pit incidence, before it becomes visible. The effectiveness of ethylene forcing and Mg infiltration-were assessed under local conditions for 'Braeburn' and 'Golden Delicious' apples. The correlation coefficients for the two methods were compared, as well as the correlations between the bitter pit-like incidence induced by the individual methods and actual bitter pit after storage. During the first season, the coefficient determination for Mg infiltration and actual bitter pit (R2 = 0.45) was higher compared to the coefficient for ethylene forcing and actual bitter pit (R2= 0.13). The R2 for the linear relationship between bitter pit incidence with Mg-infiltration and ethylene forcing was 0.43. The actual bitter pit incidence per season influenced the accuracy of the methods.