Changes of acids (total, titratable and combined form) and sugars (total, reducing and non-reducing) in the edible part and the rind of 17 varieties the in growing and ripening period were investigated. The results were summarized as follows.
1) The percentage of rind was notably decreased in growing period and slightly in the ripening period- It may suggest that the rates of translocation of metabolite from leaves to each part of fruit are different with growth phase.
2) The heavier the weight of fruit, the higher the percentage of rind was and the varieties having over 200 g per fruit showed the value over 30 in the rind percentage and over 15 in the number seeds per fruit.
3) Total acid contents in the rind were highest at the maximum grow th of fruit except in Citrus grandis having tie lowest value (below 20 me/100 g F.W). of total acid at maximum point in which total acid content is steadily increase.
4) Total acid and titratable acid in the edible part and total acid and combined acid in whole fruit life showed 0.933 and 0.970 of correlation coefficient significant at 1% level respectively, and most acid in the edible part was titratable acid(73%) whereas acid in the rind consists mostly of combined acid.
5) The content of combined acid in the ripening period increased in the edible part and decreased in the rind. It may be contributed to translocation of some cations from the rind to the edible part.
6) The grouping criteria on citrus fruit were applicable on melon, watermelon and tomatoes.
7) The contents of total sugar and non-reducing sugar in the edible part were continuously increased whereas the content of reducing sugar were decreased in certain varieties, notablly in citrus natsudaidai. The correlation coefficient between total sugar and reducing sugar in the edible part with ripening decreased as 0.849^(**), 0.732^(**). 0.583^*. (^(**): significant at 1% level and ^*: at 5%)
8) 61% of total sugar in the edible part was non-reducing sugar whereas 88% of total sugar in the rind was reducing form at the end of ripening and the correlation coefficient between total and non-reducing sugar in the edible part was 0.861 end total and reducing sugar in the rind was 0.972, both significant at 1% level.
9) Varieties having the percentage of the rind below 36 showed higher value than I in the ratio of total sugar in the edible part to one in the rind.
It may suggest that there exists any intimate relation between relative sugar content and growth rate of fruit parts.
10) Citrus unshiu in Guje island showed lower values in the content of acid and sugar, and the rind percentage but higher sweetness index (the ratio of total sugar to titratable acid) comparing with the same variety in Jeiu.
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