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  • Author or Editor: Mack Drake x
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Abstract

In a 4-year study of the relationships between Ca, K, P, Mg, and N concentrations in ‘McIntosh’ apples at harvest and the quality of fruit after storage, Ca was the most variable element among samples within seasons and was the element most consistently related to disorders, being negatively correlated with senescent breakdown, rot, and scald. No element was correlated significantly with fruit firmness at harvest or after storage. Susceptibility of orchard lots of fruit to breakdown could be predicted from mineral analyses of fruit 2 weeks before harvest. An arbitrary scoring system incorporating all 5 elements was correct 69% of the time in identifying lots with high or low potentials for breakdown, but the middle range of scores was not closely related to breakdown potential. A regression equation was developed relating only Ca concentration in fruit at harvest with occurrence of breakdown after storage. This equation represented samples either stored in 0°C air for 5 months or in 3° CA storage for 8 to 9 months, and also represented samples taken in 2 different years. This equation was a better predictor of breakdown during storage than was the mineral scoring system, and we propose that such an equation could be used to predict storage potential for ‘McIntosh’ apples.

Open Access

Abstract

A 4-year study compared 4 methods of subsampling ‘McIntosh’ apples for mineral analyses intended for use in predicting postharvest senescent breakdown. Concentrations of Ca, Mg, K, P, and N were determined in outer cortex, whole fruit, and juice in 1979 and 1980, and in outer cortex and cortical plugs in 1981 and 1982. Multiple linear regression equations were developed for each sampling in 1979 and 1981 relating the natural logarithms (In) of Ca and P concentrations and Mg:Ca, K:Ca, and N:Ca ratios to In (breakdown percentage +1). Effectiveness of each equation as a predictor of breakdown during and following storage was tested using data collected the following year. Paired t tests comparing predicted breakdown, using 1979 equations and 1980 mineral analyses, to breakdown observed after storage in 1980-1981 showed that outer cortex- and whole fruit-based predictions were not significantly different from observed breakdown, but juice equations predicted significantly more breakdown than was observed. Correlation coefficients relating actual to predicted breakdown were positive and significant for all 3 methods. In 1981, separate equations were developed to predict fruit breakdown after air and after controlled atmosphere (CA) storage. Paired t tests showed the predicted incidence of breakdown following CA storage was not significantly different from actual breakdown incidences for either outer cortex or cortical plug equations. Breakdown incidence following air storage was less than predicted. In all instances, correlation between actual and predicted breakdown incidence was positive and significant. Outer cortex, whole fruit, and cortical plug analyses showed promise as breakdown predictors, but juice analyses were ineffective.

Open Access

Abstract

A 4-year study compared CaCl2, Ca(H2PO4)2, and a polyphenolic acid chelate of Ca, applied as foliar sprays, for improving apple (Malus domestica Borkh.) fruit quality. Technical grade 77% to 80% flake CaCl2 consistently increased fruit Ca concentrations and reduced senescent breakdown after storage and occasionally reduced superficial scald after air storage. When materials other than Ca(H2P04)2 were applied at concentrations providing soluble Ca concentrations equal to that of technical grade CaCl2, equal benefits were achieved. Treatments that increased Ca also usually reduced Mg concentrations in outer cortex tissue. Ca(H2PO4)2 increased fruit P but not fruit Ca concentration, and a reduction in superficial scald was the only accompanying benefit to the fruit.

Open Access

Abstract

Calcium (Ca) level of leaves sampled in mid- or late summer was closely related to peel Ca levels of mature apples (Malus pumila Mill. cv. Baldwin). Ca content of fruit was directly related to fruit yield of the tree, cycling with biennial bearing. In 1971 bitter pit incidence could be predicted from either leaf or peel Ca; internal breakdown and decay were less predictable. In 1972 leaf Ca and peel Ca averaged, respectively, 27 and 17% higher than in 1971, accompanying increased yield. Little bitter pit, internal breakdown, or decay occurred, even at Ca levels correlated with high incidence rates the previous year. We concluded that Ca must be only 1 among several factors regulating these occurrences.

Open Access