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Proposed descriptors for the evaluation of skin color, flesh firmness and juiciness, and sugar composition in Japanese persimmon breeding

Asakuma, Hideaki, Shiraishi, Mikio
Euphytica 2017 v.213 no.3 pp. 69
Diospyros kaki, analysis of variance, carbohydrate composition, color, cultivars, firmness, genotype, juiciness, palatability, persimmons, plant breeding, pollination, sucrose, sweetness, trees
Descriptors to evaluate fruit skin color, flesh firmness, flesh juiciness, and sugar composition using pollination constant non-astringent (PCNA)-type cultivars and selections of Japanese persimmon were proposed. A highly positive correlation was observed between the hue angle and color chart, and the skin color was classified as yellowish, hue angle ≥60°; orangish, hue angle between 51° and 59°; and reddish, hue angle ≤50°. Flesh firmness varied from 1.2 to 2.4 kg, and was classified as firm, ≥2.0 kg; medium, 1.4–1.9 kg; and soft, ≤1.3 kg. Flesh juiciness ranged from 0.18 to 0.39 mL g⁻¹ FW, and was classified into very juicy, ≥0.30 mL g⁻¹ FW; juicy, 0.21–0.29 mL g⁻¹ FW; and slightly juicy, ≤0.20 mL g⁻¹ FW. The analysis of variance for the flesh firmness, flesh juiciness, and sugar composition showed that the effect of genotype was large, while the effects of year, genotype × year interaction, among trees within genotype, and tree × year interaction were small or negligible. High varietal differences in sugar composition were found, ranging from 11.6 to 61.5% of the sucrose percentage. Furthermore, the sucrose to hexose (SH) ratio would be a useful descriptor for improving the palatability, especially sweetness, of PCNA-type persimmon fruits. The SH ratio ranged from 0.14 to 1.57, and was classified as very sweet, ≥1.00; sweet, 0.31–0.99; and less sweet, ≤0.30.