Studies on the fruit development and its relationship with sugar accumulation in bayberry fruit

Studies were carried out with 3 bayberry cultivars (Myrica rubra Sieb. et Zucc.) : Dongkui,Biqizhong and Shuimei. Results showed that the fruit development could be divided into 3 stages in a S curve. At stage 1, in the period about 32 days after full bloom (DAF),the increase of fruit vertical and horizontal diameter were the fastest. At stage 2,from 32 to 63 days after DAF, fruit stone hardened and fruit weight increased distinctly. At stage 3,fruit growth and development arrived at the peak,fruit weight increased immediately, and photosynthetic products accumulated quickly into fruits. The sugars in fruit were mostly accumulated with sucrose. Fructose and glucose were only one fourth of total sugar contents. Sucrose was lower during early and middle fruit development stage and rapidly accumulated after 52 DAF. This sugar content of Dongkui maturity fruit was higher than that of Shuimei and Biqizhong. Fructose and glucose contents were consistently higher at stage 1 and lower at stage 2, then were accumulated rapidly till ripe. Their content in Dongkui and Shuimei maturity fruit were higher than Biqizhong. The change trend of activity of acid invertase(Ivr) and neutral invertase(Nvr) were consistently kept higher at young fruit, lower at middle stage then maintained lower activity. The pH trend in different cultivars was similar the highest at stage 1 and the lowest at stage 2 then was increased after turned red. The correlation results showed that there was extremely significant correlation between the characters of fruit development and the accumulation of sucrose, glucose and fructose. The increasing of fruit horizontal diameter had the closest correlation with the change of sucrose (r=0.932 55**).