The fruit of mume, Japanese apricot (Prunus mume Sieb. et Zucc.), was evaluated for its phenolics content, high performance liquid chromatography (HPLC) profile and antioxidative activities. The phenolics content of mume fruit was relatively high, the flesh of fully matured fruit containing up to 1% of phenolics on a dry weight basis. Reflecting such a high content of phenolics, the ORAC (oxygen radical absorbance capacity) value for mume fruit flesh showed high values, ranging from 150 to 320 µmol/g Trolox equivalent, depending upon the stage of maturation. 5-O-Caffeoylqunic acid (chlorogenic acid), 3-O-caffeoylquinic acid and tetra-O-acylated sucrose-related compounds were isolated from the flesh of mume fruit, although many unknown peaks were also apparent in the HPLC chromatogram. An alkali hydrolysate comprised four main phenolic acids, caffeic acid, cis/trans-p-coumaric acid and ferulic acid. No flavonoids were observed in the analysis. These results suggest that the majority of phenolics in mume fruit were hydroxycinnamic acid derivatives.

The effects of initiation timing of drought stress on the carbohydrate content and growth of Japanese apricot (Prunus mume Sieb. et Zucc.) 'Nanko' tree were investigated. Three-year-old trees were subjected to drought stress for three months in May ('Spring') and August ('Summer'), respectively. Irrigation was started immediately after drought stress treatment had finished. The starch concentration in the roots of stressed trees increased in both 'Spring' and 'Summer' two months after starting drought stress treatment and rapidly decreased just after starting irrigation in 'Spring'; however, it still temporarily increased in 'Summer'. These different results were attributed to seasonal changes in the carbohydrate demand. The dry matter weight of each tree organ in February of the following year was suppressed by drought stress, particularly in 'Spring'. This result indicates that, if a tree suffers drought stress in spring, vegetative growth is suppressed more seriously than in summer and tree growth, declined by suffering from severe and long-term drought stress, will hardly recover even the tree is reirrigated. The total starch in all organs of the drought-stressed trees in February of the following year was significantly less than that in well-irrigated trees. These results indicate that severe drought stress for three months inhibits not only current tree growth but also the accumulation of carbohydrates that is necessary for the following year's growth. Hence, irrigation to avoid a fatal growth decline due to severe drought stress is needed during the current growth stage, especially in the early growth stage in spring.

SummaryEffects of the time of flowering and harvest as well as the size of the fruit on the compositions of the fruit and the processed Japanese apricot liqueur (ume liqueur) were determined in the Japanese apricot (Prunus mume Sieb.et Zucc.) 'Nanko'. Concentrations of citric acid and sorbitol in the flesh with skin increased until just before the day of full ripening and dropping stage. Growth of fruit that bloomed early was later than that of fruit that bloomed late. The fruit that bloomed early had lower concentrations of citric acid and sorbitol in the flesh with skin than fruit that bloomed late. Concentrations of citric acid and phenolics, antioxidant activity, and browning strength of the ume liqueur increased when the harvest time was delayed to just before the full ripening stage. When fruit was harvested on the same day, the larger fruit showed greater concentrations of citric acid, malic acid, sorbitol and β-carotene in the flesh with skin. Concentrations of citric acid and sorbitol and the browning strength of ume liqueur were higher when fruit above 2L size were processed. These results show that harvest time and fruit size influence the concentrations of components and the quality of both the fruit and the ume liqueur, suggesting that wellgrown and enlarged fruit are most suitable for making ume liqueur.

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