การเปลี่ยนแปลงทางเคมีกายภาพระหว่างการเจริญเติบโตของพลับ

Abstract

The study of physico-chemical relationship in the branch, leaf, and fruit was determined during a bud dormancy breaking phase until a prior to dormant period according to the phenological growth in the BBCH-scale system on astringent persimmon ‘Xichu’, sweet persimmon ‘Fuyu’, and Kluai ruesee grown on the highland approximately 1,400 meters above mean sea level, Fang District, Chiang Mai Province. The results showed that the persimmon in each species had clearly different characteristics and the period of plant growth. ‘Xichu’ persimmon emerged from dormancy faster than ‘Fuyu’ and Kluai ruesee approximately 2 to 4 weeks. The branch growth of Kluai ruesee was smaller and shorter in size than the other two cultivars. The leaf characteristics of persimmon ‘Xichu’ were similar to those of ‘Fuyu’ but differed from Kluai ruesee with a small leaf and pubescent on the leaf blade. Fruit growth of ‘Xichu’ and ‘Fuyu’ cultivars continued to exponential growth until the maturation stage through the skin color changed into orange color and bigger size when compared to Kluai ruesee which had yellow skin color and a pubescent on fruit. In the early stage of branch growth, the accumulation of non-structural carbohydrate, nitrogen, and carbohydrate/nitrogen ratio within the branches was high, reducing during flower and fruit developmental stages, and increasing again before dormancy. Accumulation of secondary metabolite in leaves according to phenological growth of the persimmon ‘Xichu’ and ‘Fuyu’ was found to change over growth stages, unlike Kluai ruesee which tended to increase throughout the growth of trees. The analysis of phenolic, flavonoid, and antioxidant activity in leaves of ‘Xichu’ and Kluai ruesee were 39.75 – 142.13 mg GAE/g DW, 195.05 – 356.19 mg QE/g DW, and 23.64 – 91.82 μg/mL, respectively, which showed the higher values than the sweet persimmon ‘Fuyu’ in leaves. Thus, the utilization of leaves for tea and other products should be chosen based on the species and appropriate harvesting time of leaves. Changes of secondary metabolite during fruit growth on a tree showed that the flesh of young fruit had values of tannin, phenolic, flavonoid, and antioxidant activity more than the mature fruit and found their concentrations in the astringent more than sweet persimmons. The correlation analysis between two factors was shown from the correlation coefficient (R) at P < 0.01 in each characteristic. It was found that the color intensity of persimmon leaves ‘Xichu’ and ‘Fuyu’ was negatively related to the phenolic and flavonoid contents, resulting in less antioxidant activity in leaves too. In contrast to Kluai ruesee leaves, there was a positive correlation between leaf color intensity and the amount of secondary metabolite in their leaves. The changes in persimmon fruit of three cultivars were found a positive relationship between the fruit color and the sugar content. While changes in the amount of analyzed tannin in fruit crops on the tree were also positively related to the phenolic and flavonoid in fruits. The study of tannin content causing astringent taste during the removal astringency by carbon dioxide of ‘Xichu’ persimmon fruit was found that the tannin reduction in the 48th hour affected the firmness, soluble solids, phenolic, flavonoid, and antioxidant activity to decrease accordingly. While the results from fruits that were not eliminated the astringency changed in the same trend, but the value of analyzed secondary metabolites was higher than the astringent effect with the statistical differences. Numerical calculation expressed a positive correlation between tannin content, phenolic, and flavonoid. However, it was negatively correlated with the half-maximal inhibitory concentration (IC50). Therefore, the tannin decreasing by the astringency removal process impacted the physical changes and accumulation of the other metabolites in persimmon fruit.