Abstract:

Using‘Guifei’kiwifruit as the research subject，this study systematically observed the dynamic changes in the fruit shape parameters，single fruit weight，dry matter，vitamin C，total sugar，total acid，sugar-acid ratio and volatile compounds during its development. The aim was to explore the dynamic changes in fruit quality during the development of‘Guifei’kiwifruit and provide a basis for scientific cultivation management and determination of the optimal harvest period. The results showed that during the fruit development of‘Guifei’kiwifruit，the transverse，longitudinal，and lateral diameters exhibited a single“S”curve change，while the single fruit weight displayed a double“S”curve change. The first rapid growth period occurred within 56 days after flowering，during which the fruit expanded rapidly. The second rapid growth period occurred from 84 to 112 days after anthesis（DAA），during which fruit weight and dry matter content increased significantly. The dry matter content of mature fruit reached 18.69%. Vitamin C content displayed a rise-fall-rise trend，peaking at 2.45 g · kg^-1 at 140 DAA. Similarly，total sugar content exhibited a rise-fall-rise trend，rising to 7.52% at maturity. Total acid content initially increased and then declined，decreased to 0.99% at 140 DAA. The sugar-acid ratio showed a fall-rise-fall-rise trend，and dropped to a minimum of 3.98 at 112 DAA，and increased to 7.66 at maturity. A total of 59 aroma compounds were detected in‘Guifei’kiwifruit. During post-harvest ripening，the total aroma content increased significantly and then decreased，peaking at 1 162.53 μg · kg^-1 after 4 days after harvest（DAH）with a shift from aldehydes to esters（aldehydes accounted for 83.08% after 2 days of ripening，while esters accounted for 76.15% after 4 days of ripening）. Twenty-one key aroma components were identified as direct contributors，with ethyl 2-methylbutyrate，1-octen-3-one and ethyl butyrate being the main components. During fruit development and the first 0-2 days of post-harvest ripening，fatty and grassy aromas predominated，while fruity aromas increased significantly after 4 DAH. In summary，140 DAA is considered the optimal harvest period. During the first rapid growth stage，combined application of nitrogen，phosphorus，and potassium fertilizers is recommended，while during the second rapid growth period，attention should be given to phosphorus and potassium fertilizer application. The increase in esters can serve as an indicator of‘Guifei’fruit maturity. The fruit exhibits the strongest fruity aroma after 4 days of post-harvest ripening，making it the optimal consumption period.

Key words: kiwifruit, fruit, growth and development, fruit quality, aroma