Mechanisms regulating apple cultivar susceptibility to bitter pit

Control efficacy of Ca‐containing foliar fertilizers on bitter pit in bagged ‘Fuji’ apple and effects on the Ca and N contents of apple fruits and leaves

“…In short, the Ca content, N content and N/Ca ratio of pitted tissue was between that of healthy fruit and healthy tissue surrounding the pitted regions with no significant difference. Our results were consistent with those of previous reports and confirmed that BP is related to low Ca contents and high N contents of fruits . The results also indicated that the fruit sampling for the Ca and N analysis in our experiment was feasible; thus the results of Ca and N analysis would be reliable for the evaluation of the efficacy of Ca sprays on the Ca content, N content, and the N/Ca ratio of bagged apple fruits and leaves in our study, completely excluding the influence of the BP exhibition in fruits.…”

“…At the physiological level, Ca 2+ is transported from the root cortex through the xylem and is distributed to vegetative and reproductive tissues . The Ca content is generally much higher in leaves, which have greater transpiration rates than do fruits, because Ca is imported into fleshy fruits only in small amounts . The rate of water supply and nutrients to fruits is lower than to the rest of the plant, and Ca 2+ delivery to organs depends on the concentration of Ca 2+ in the xylem sap, transpiration and growth rate …”

“…Bitter pit (BP) is a Ca 2+ deficiency physiological disorder that affects apple fruit production worldwide, especially for bagged apples, and often causes significant economic losses . In addition to Ca 2+ , other nutrients, including magnesium (Mg 2+ ), potassium (K + ), boron (B) and nitrogen (N), may play an important role in the development of BP in apple fruits, and commercial apple growers frequently rely on the (K + + Mg 2+ )/Ca 2+ and N/Ca 2+ ratios as guides both for predicting fruit's susceptibility to BP and for deciding the application time of Ca fertilizers . In general, high Ca and B content is related to a low incidence of BP, especially for moderate and severe BP, whereas high incidence of BP is positively associated with N, K and Mg content .…”

Assessment of calcium and zinc accumulation in cultivated and wild apples

“…In addition, it is worth noting that ‘Fuji’ had a relatively low concentration of calcium in mature fruit (0.5 mg g −1 DW), which is consistent with previous studies . However, ‘Fuji’ has a long storage and shelf life, since most of the calcium in cell walls shifts from the water‐insoluble pectin into the water‐soluble pectin fraction via the catalyzation of pectin methylesterases (PMEs) during storage . These results suggest that CAX and PME genes are good candidates for calcium accumulation in apple fruit.…”

Bitter pit in apples: pre- and postharvest factors: A review

“…Translocation depends on the capacity of binding Ca 2+ ions in the cell wall, adoption of Ca 2+ at the peduncle end tissue of the fruit, the number of functional xylem tubes through which Ca 2+ travels to the calyx, and the hydrostatic gradient of concentration that is required for the translocation process (Freitas & Mitcham, 2012). Freitas et al (2015) suggested that Ca 2+ , together with organic acids in vacuole, can form strong precipitates, thus making Ca 2+ unavailable to other cell processes and also enhance susceptibility to form bitter pit.…”