FRUIT CHARACTERISTICS OF "SHIMA SARUNASHI" (ACTINIDIA RUFA (SIEB. ET ZUCC.) PLANCH. EX MIQ.), A UNIQUE RESOURCE OF ACTINIDIA NATIVE TO JAPAN

“Shima sarunashi” (A. Rufa (Sieb. et Zucc.) Planch. ex Miq.), an indigenous Actinidia species grown in warm coastal regions in Japan, has several unique characteristics including very low chilling requirement, hairless fruit skin, late fruit maturity and cross compatibility with A. chinensis. Fruit characteristics of A. rufa accessions were examined and compared with other introduced Actinidia species. Accessions of A. rufa conserved at Kagawa University and Kagawa Prefectural Experiment Station were used. Mature fruit had hairless brown skin and fruit weight ranged from 8.9 to 13.5 g. Total soluble solids content and titratable acid were 11.7–13.9% and 1.0–1.2% respectively. Major sugars were glucose, fructose and sucrose. Major acids were quinic, citric and malic, with quinic acid predominant. Ascorbic acid content was 17.5–20.7 mg per 100 g FW. Total and soluble oxalate content was 18.3–52.3 and 4.5–8.4 mg per 100 g FW respectively. Protease activity in the flesh was as low as 0.4–1.2 nmol pNA released per min. Harvested mature fruit did not produce ethylene for two weeks at room temperature, but did respond to exogenous ethylene and ripened quickly.