POSSIBLE CAUSE OF ASTRINGENT PEACH FRUIT AND BIOSYNTHESIS OF PEHNOLIC COMPOUNDS

白东桃果实总酚含量在不同果园间差异较大，同一果园内各树种间差异不显著。酚类物质含量与总可溶性固形物含量、果实重量和树龄无关。总酚含量越大，土壤EC值越高，但总酚含量与土壤pH值的关系不明显。无论哪个果园，果实中酚类物质含量在果实生长的第1阶段结束时呈下降趋势，之后迅速增加，并在第2阶段中期达到最大值。酚含量在第3阶段迅速下降到较低水平。在整个果实生长过程中，成熟果实总酚含量高的果园果实总酚含量高于成熟果实总酚含量低的果园果实，特别是在第二阶段。酚类物质含量与地上部生长和土壤水分的关系不明显。l -苯丙氨酸氨解酶（PAL）活性在第1阶段较高，在第2阶段中期达到最大值，之后没有活性。在整个生育期1和生育期2的前半期，果实中酚类物质含量越大，PAL活性越高。PAL活性与与酚代谢有关的N、Mn、Cu和B的含量没有关系。成熟果实中总酚含量以三岛白桃和金桃最高，大久保和白桃次之，川中岛白桃和蜜桃较低。在大多数品种中，酚类物质的分子量在第1阶段较大，在第2阶段较低，然后在第3阶段再次增加。HPLC分析表明，桃果中含有6种酚类化合物，与品种无关。第1、2阶段儿茶素含量大于绿原酸含量，第3阶段儿茶素含量大于绿原酸含量。少

The total phenolic contents in the mature 'Hakuto' peach fruits varied widely among the orchards while significant difference among trees in the same orchard was not observed. Phenolic content ded not correlate with the contents of tatal solublee solids, fruit weight, and tree age. The larger the total phenolic contents, the higher was the EC of soil, but the relationship between total phenolic contents and soil pH was not observed.Regardless of orchard, phenolic contents in fruit decreased towards the end of Stage 1 of fruit growth, after which it increased rapidly and reached a maximum in the middle of Stage 2. Phenolic contents rapidly decreased to a lower level during Stage 3. Throughout fruit growth, total phenolic contents were larger in the fruits from orchard which phenolic content in the mature fruits was high than in the fruits from orchard which it was low, especially during Stage 2. The relationships between phenolic contents and the shoot growth and soil moisture were not … More observed. PAL (L-phenylalanine ammonialyase) activity was high during Stage 1 and reached a maximum in the middle of Stage 2, after which no activity detected. Throughout Stage 1 and the first half of Stage 2, the larger the phenolic contents, the higher was the PAL activitiy in fruit. However, no relationship was observed between the PAL activity and the contents of N, Mn, Cu and B which have been related to phenolic metabolism.Total phenolic contents in the mature fruits were the highest in Mishima-hakuto and Golden Peach, followed in Okubo and Hakuto, while it was very low in Kawanakashima-hakuto and nectalin. In almost cultivars, molecular weight of phenolics was large in Stage 1 and was low in Stage 2, after which it increased again during Stage 3. The HPLC analysis showed that six phenolic compounds were present in peach fruit irrespective of cultivar. Content of catechin was larger than in that of chlorogenic acid during Stage 1 and 2, while in stage 3 latter was larger than in the former. Less