The Quality Analysis Of Guanxi Pummelo From Different Production Regions And The Identification Of Hybrid From Clementina’s Sexual Hybridization

1.Guanxi pummelo(C. grandis Osbeck) is originally cultivated in Pinghe Country, Zhangzhou City, Fujian Province. It is the second largest pomelo variety for cultivation. Guanxi pummelo’s sarcocarp is limpid. It has moderate sour and sweet taste. It also has non-bitter smell. Most Guanxi pummeloes are seedless. It is favored by consumers. The content of Vc in pomelo is 2-4 times more than that in sweet orange and tangerine. It is known as "natural canned fruit". Affected by eco-climate and orchard’s management conditions, the quality of Guanxi pummeloes from different regions vary a lot. Therefore, it is necessary to analyse the difference in quality of Guanxi pummeloes from different regions, and confirm its dominant areas.This study investigated the distribution of the main producing regions of Guanxi pummelo and defined its maturity for timely harvesting. Through the quality analysis of Guanxi pummeloes from different regions, we study the correlation between latitude, altitude and Guanxi pummelo’s quality, in order to determine the suitable area of Guanxi pummelo.The results are as follows:(1) In general, ranging from lower latitudes to higher latitudes, Guanxi pummelo’s acid content is increasing, while the sugar content and sugar-acid ratio are decreasing with the increasing latitude. The impact of latitude on the acid content is larger than sugar content. Besides, the effect of altitude on the quality of Guanxi pummel mainly reflects in the change of the acid content. Within the altitude ranging from 100 m to 300 m, the acid content of Guanxi pummelo showes significant positive correlation with the altitude, but the soluble solid content and solid-acid ratio are on the contrary.The Guanxi pummelo from 300 m show the lowest soluble solids, soluble sugar and the highest acid content. Within the altitude ranging from 300 m to 400 m, the acid content of Guanxi pummelo shows significant negative correlation.,while the soluble solids, solid-acid ratio and the sugar/acid content shows significant positive correlation.(2) According to the evaluation of the quality of Guanxi pummeloes from different regions, we can get the following information: Guanxi pummelo from Taiwanese and southeastern Guangxi regions show a best external and internal quality, which have the highest sugar-acid ratio. The southern Hunan 、 southern Jiangxi and northeastern Guangdong regions rank the second. The southern Guizhou、northern Guangxi and middle Hainan regions have the medium quality. In addition, western Hunan、midwestern Fujian、southwestern and southeastern Zhejiang regions have a level below average. While midwestern Hubei、southeastern Guizhou and the upper reaches of the Yangtze River has a lowest sugar-acid ratio and worst quality.2. Cross breeding is one of the most important breeding methods in citrus. Hybridization can regroup the parental genetic materials, and the hybrid offsprings have a lot of excellent traits. This study has set up two cross combinations: Clementina(C. clementina hort ex Tanaka) ×Sunburst(C. reticulata Blanco) and Clementina ×Chandler pummelo(C. grandis Osbeck), using SSR(Simple Sequence Repeat) molecular marker technology to identify hybrids from the sexual hybrid offspring. The results are as follows:3 pairs of polymorphic primers were screened from 56 pairs of SSR primers for the hybrid identification of Clementina and Chandler pummelo, the result of identification is 100% hybrid rate.2 pairs of polymorphic primers were screened from 125 pairs of SSR primers for the hybrid identification of Clementina and Sunburst, synthesizing the identification of the two primers,the rate of hybrid is 71.23 %.