Fruit flesh color due to the quantity of brown specks as affected by the number of seeds in fruits of ‘Fuyu’ persimmon

Abstract

The terms pollination constant (PC) and pollination variant (PV), respectively, define persimmon cultivars as those exhibiting no change in flesh color due to seed formation in the fruit and as those exhibiting a change due to brown specks by seed formation in flesh color. 'Fuyu' is the most produced persimmon cultivar in the world, and it has been regarded as a PC and non-astringent cultivar (PCNA). A total of 557 and 101 'Fuyu' persimmon fruits were collected in 1981 and 1982, respectively, from trees grown at Akitsu at the National Institute of Japan and were evaluated for the number of seeds contained in each fruit (SN) and scored according to the quantity of brown specks (BS) in the flesh. The regression of the BS scores on seed numbers was positive and highly significant (P<0.001) in both years. These results showed that fruit flesh color was slightly changed by seed formation in the 'Fuyu' fruits. This change was lower than that observed in most PV cultivars. 'Fuyu' seeds exude ethanol and acetaldehyde, which are responsible for the coagulation and oxidation of tannin substances in the flesh in PV cultivars. The slight change of flesh color in 'Fuyu' is possibly caused by these volatile compounds. The results lead to classifying 'Fuyu' into PV in a strict sense of Hume's classification. To eliminate the confusion, we propose that the term “PCNA” should be redefined with a synonym for Kajiura's term of “perfect non-astringent”, i.e., non-astringent at maturity with no influence of seeds, apart from Hume's classification.