Effects of Low Temperature, Shading, Defoliation, and Crop Load on the Flesh Coloration of the Type 2 Red-fleshed Apple ‘Kurenainoyume’

Abstract

Kurenainoyume' is a newly released type 2 red-fleshed apple with pinkish flesh color. In our previous study, we revealed the effects of light condition on red coloration of the skin, flesh, and core of 'Kurenainoyume' apple fruit. In this study, we investigated the effects of temperature, shading, defoliation, and crop load on red coloration of the flesh. Low temperature improved flesh coloration; apples subjected to cooling treatment at 5°C or 10°C showed higher a* values of the Lab color space than the control (without cooling treatment), in a temperature-dependent manner. Low temperature reduced the soluble solid content to a lesser extent in some years, whereas fresh weight, malic acid content, and flesh firmness were not affected. Thus, the importance of temperature for flesh coloration was confirmed, similar to its effect on skin coloration. When the trees were covered with cheesecloth with a 50% shading rate from August 1 (82 days after full bloom: DAFB) to October 28 (170 DAFB), flesh coloration was negatively affected, and fresh weight, soluble solid, and malic acid contents were reduced relative to the control treatment (without shading). We also investigated the effects of defoliation (one-seventh of the control) and crop load (two-or threefold the crop load of the normal case control) on flesh coloration. Both defoliation and over crop load also decreased a* values, but their effects on the parameters related to fruit quality were not clear. Because all the treatments of shading, defoliation, and crop load relate to the efficiency of photosynthesis and the distribution of photosynthetic assimilates, our results also demonstrated that photosynthetic assimilates (carbohydrates) were one of the crucial factors affecting flesh coloration.

Sunlight Differentially Affects the Fruit Skin, Flesh, and Core Coloration of the Type 2 Red-fleshed Apple ‘Kurenainoyume’: Optimization of Fruit Bagging Treatment

“…In general, skin color as well as flesh color tends to deteriorate in apple trees with active vegetative growth, which indicates that too much soil nitrogen has a negative impact on anthocyanin accumulation. In addition, cooler climate conditions are advantageous for flesh coloration in 'Kurenainoyume' (Matsumoto et al, 2018b). Honda et al (2014Honda et al ( , 2017 also showed the effect of cooler temperature on the flesh red coloration in 'Pink Pearl'.…”

“…The one-layer white bag had 0.9-2.3% light permeability from 280-750 nm wavelength, while the 1-layer red bag had lower light permeability of 280-575 nm compared to the 1-layer white bag, but its light permeability of 576-750 nm was higher than the 1-layer white bag (Matsumoto et al, 2018b). Half of each paper bags were removed at 100 DAFB (August 20) (bag-removal treatment) and the remaining half were covered continuously until the final harvest at 139 DAFB (September 28) (continuous-bagging treatment).…”

Effect of Orchard Management Factors on Flesh Color of Two Red-Fleshed Apple Clones

“…They reported decreased anthocyanin concentration as crop load increased, or for bagged vs. un-bagged fruit or for fruit grown in the shade vs. that exposed to the sun. Similarly, [15] found decreased red color in the outer flesh as indexed by the a-value of the flesh when the fruit was shaded (by bagging), when crop load was high or when trees were defoliated. When bags were removed, color intensity increased again in the outer flesh.…”

Effects of 1-MCP and Pre-harvest Fruit Bagging Treatments on Cold Storability of the Red-fleshed Apple ‘Kurenainoyume’

“…Thus, cool water treatment of the fruit during developmental stage was effective for flesh coloration (Matsumoto et al, 2018a); however, such effects were not recorded in the harvested fruit during cold storage. The skin color of the harvested apples such as 'Tsugaru' and 'Fuji' may be generally promoted by cold treatment (Bai et al, 2014;Ban et al, 2007;Ubi et al, 2006).…”

“…Therefore, it is desirable to provide information about the storability of 'Kurenainoyume' and changes in the parameters related to fruit quality such as skin/flesh coloration, flesh firmness, soluble solid content, and acidity during cold storage to all growers. In our previous reports, we showed an improvement in the flesh red coloration by low temperature treatment during the growing stage (Matsumoto et al, 2018a), which suggests the possibility of improvement in the flesh red coloration by cold storage after harvest. However, there are few available reports on the changes in the parameters related to fruit quality, including changes in the skin and flesh coloration in red-fleshed type 2 apples .…”