Mineral composition, harvest maturity and storage quality of 'Red Pippin','Gala' and 'Jonagold' apples

An experiment was carried out in 1996 to assess the importance of pre-harve st factors on the storage quality of 'Red Pippin', 'Gala' and 'Jonagold' ap ples grown in the UK and the requirement for further work to develop fruit mineral analysis standards for these cultivars. Quality from store was dete rmined primarily by the choice of controlled atmosphere (CA) regime. 'Red P ippin', 'Gala' and 'Jonagold' apples were stored in high CO2, low O-2 regim es of 3/2, 5/1 and 4/1.2 (kPa CO2/O-2) respectively, and in low CO2, low O- 2 regimes of <1/1.2, <1/1 and <1/1.2 respectively. Scald development in hig h CO2, low O-2 regimes was nil ('Jonagold') or slight ('Red Pippin' and 'Ga la') but extensive in low CO2, low O-2 regimes where there was marked orcha rd variability. 'Gala' apples stored in either CA regime developed slight b reakdown after six months of storage. Fruit firmness was maintained better in high CO2, low O-2 regimes but the concentrations of sugars and acids in the fruit were generally unaffected by CA conditions. For each cultivar the mineral composition of fruit from different orchards at the time of commer cial harvest varied greatly. On average, 'Gala' apples were lower in N and higher in Ca and Mn than 'Red Pippin' or 'Jonagold'. 'Red Pippin' apples we re highest in B and 'Jonagold' lowest in K and Mg. There were also cultivar differences in the mineral composition of leaves and fruits sampled in Aug ust and July respectively. For each cultivar samples for storage had been t aken on the same date during the commercial harvesting period. Coefficients of variation (CV) were used to indicate the degree of variation in various indicators of maturity. In 'Gala' apples variability in firmness (CV - 6.3 %) and soluble solids (CV - 4.9%) was approximately three-fold less than fo r starch coverage (CV - 15.5%). Some significant correlations were found be tween fruit quality and mineral/maturity variables. For all cultivars acidi ty was correlated positively with fruit K and sugar concentration with dry weight and soluble solids concentration in the fruit at harvest. Firmness o f the three cultivars in the study was not correlated consistently with par ticular mineral constituents in the fruit at harvest or with harvest maturi ty parameters. Firmness of 'Gala' apples ex-store was highly correlated wit h harvest firmness and was positively correlated with Ca and B concentratio n in the fruit at harvest and negatively with K. There was a strong negativ e correlation between the incidence of scald in 'Jonagold' apples and the C a concentration in the fruit at harvest. Increased flesh breakdown in 'Gala ' apples was associated with high K, Mg, Na and Cu in harvest fruits, high Cu in fruitlets and high K, Mg and Zn in leaves.