Changes of pigment contents and flesh color generation analysis during fruit development of‘Ganmi 6' (Actinidia eriantha)

Abstract:【Objective】The flesh colors of Actinidia Lindl. have shown priorities for green, yellow and red,the present-color materials primarily associated with chlorophyll, carotenoids, anthocyanins and other pig-ments, which are the relative contents for determining the fruit's color. As a unique berry resource in ourcountry, Actinidia erientha Benth. is mainly distributed in Jiangxi, Zhejiang, Yunnan, Guizhou, Fujian and Hunan provinces, mostly in their wild state, which has rich antioxidants, and a high content of ascorbic ac-id and other nutrients. Its flowers and fruits have strong ornamental value, and in addition, the fruit iseasy-peeling and tree resistance is strong. With all these advantages, A. eriantha has a broad prospect fordevelopment and utilization. At present, the flesh color of the kiwifruit has gotten more and more atten-tion, but the color analysis research of the green-flesh kiwifruit during the whole development process hasnot yet been reported. In this study, we want to explore the changes of pigment contents during the fruit de-velopment of A. eriantha.【Methods】A. eriantha‘Ganmi 6'fruits were collected from the kiwifruit orchardof the Fengxin County Agricultural Bureau of Jiangxi Province. 15 kiwi fruits were randomly selected every 15 days beginning 20 days after full bloom to 170 days after full bloom until reaching their maturestage, which totaled 11 times. Five similar situations were selected as sampling trees, and 3 disabled fruitswere also chosen. The collected samples were wrapped with a polyethylene closure pocket and stored inan ice box. Subsequently, the fruits were transported to the laboratory. The fruit flesh was cut up, then fro-zen using liquid nitrogen and stored at -80 ℃. Colorimeter(MINOLTA CR-400) was used to determine the h* values of the‘Ganmi 6'fruit's flesh for each period. H* represents the hue angle. When h*=0°-90°,the colors changed from a purplish red(0°), red, orange-red, orange yellow to yellow(90°) along withthe increase of the hue angle. When h*=90°-180°,the colors changed from yellowish green, green to blu-ish green(180°) along with the increase of the hue angle. The method of chlorophyll and carotenoids extrac-tion and determination were referenced from Li Hesheng. Each experiment was repeated 3 times【.Results】The hue angle of the flesh in the ongoing process of the 'Ganmi 6' fruit's development rose stably. The ris-ing range of each stage was small, the rates for every 30 d were 2.94%, 0.55%, 1.29%, 0.34% and 0.47%,which only obviously changed at 20-50 days after full bloom and 80-90 days after full bloom with 118.55°rising to 120.45° and 121.66° rising to 122.38° respectively. The chlorophyll a content reached a peak of46.6 mg·kg^-1 at 95 days after full bloom, then fell to a low point of 31.9 mg·kg^-1 at 110 days after full bloom,which was the minimum result for all the periods. Later we saw an increase to the top, 62.9 mg·kg^-1 at 140 days after full bloom, at then it decreased to 47.6 mg·kg^-1 at 170 days after full bloom. The chlorophyll bcontent reached a peak of 25.8 mg·kg^-1 at 80 days after full bloom, then fell sharply to 15.8 mg·kg^-1 at 110 days after full bloom. After that, it rose to a max value of 29.1 mg·kg^-1. At finally, it was 25.4 mg·kg- 1atpicking time. The chlorophyll content was 47.7 mg·kg^-1 at 110 days after full bloom which was the mini-mum content during the entire development time. Following this, the chlorophyll content then rose to itsmaximum content of 92.0 mg·kg^-1 at 140 days after full bloom, and then down to 73.0 mg·kg-1at harvesttime. And the consequences obtained from chlorophyll a had a greater impact than chlorophyll b. The ca-rotenoids content remained stable until 110 days after full bloom, and then it showed an up-down trend,rising to the maximum(26.3 mg·kg^-1) at 140 days after full bloom, then reducing to 21.2 mg·kg^-1 at har-vest time. The chlorophyll/carotenoid(ratio) in the process of the‘Ganmi 6'fruit development appeared toshow a trend of down-up-down-up, with a generally downward trend. It had a maximum value(4.02) at20 days after full bloom, then declined to a low point of 3.34 at 65 days after full bloom, and then after-wards increased to 4.02 at 80 days after full bloom, followed by a minimum value(3.09) at 110 days afterfull bloom, and then up to a value of 3.51 at 140 days after full bloom; in the last stage it remained un-changed with a value of 3.44 in the harvest period(170 days after full bloom). Chlorophyll and carotenoidwere significantly correlated with chlorophyll a, chlorophyll b and the hue angle, the two also had signifi-cant correlation with each other.【Conclusion】With the observation of the‘Ganmi 6'pigment contentsduring fruit development, we found that the chlorophyll content was basically maintained at 60.0 mg·kg-1up to 95 days after full bloom, then it rose to a maximum content(92.0 mg·kg^-1) at 140 days after fullbloom, and it always occupied a larger proportion in the total high level contents of the pigments. Al-though there was some degradation in the chlorophyll and carotenoid contents after 140 days following fullbloom, the remaining pigments contents were still higher than the young fruit stage. This result was different from the other varieties of the kiwifruit. Correlation analysis showed that chlorophyll and carotenoidhad a highly significant correlation with chlorophyll a, chlorophyll b and the hue angle, and also there wasobserved a highly significant correlation between the chlorophyll and carotenoid. It was the high expres-sion level of chlorophyll which kept the flesh color green throughout the development of A. eriantha.