Appraisal And Studies On Genetic Relationships Of Sweet Sorghum Germplasm Resources

Sweet sorghum is native to Africa , it has been planted for thousands years since be introduced into China in A.D.400.The importance of sweet sorghum was detected gradually with the development of science and economy,it was widely used in feedstuff,fuel ethanol,refine sugar and so on. The exploitation and utilize of sweet sorghum is very important to food safety and energy safety. Sweet sorghum germplasm resources is rich in China, but there are few systemic study in sweet sorghum germplasm resources. In this study, it is not only study the genetic relationship by morphological and SSR marker but also study appraisal of sweet sorghum germplasm resources by grey relation grade analysis. The main results were as follows:By relevancy analysis, in the 64 sweet sorghum, Wray,LVNENG NO。5,saerte,White Africa were relatively perfect energy sources sweet sorghum resources, characterized by higher inheritance of stalk biomass,stalk yield,Brix degree,contents of total sugar and rate of squeeze were; Wray,HL1,LVNENG NO。5 were relatively perfect cane sugar sweet sorghum resources, characterized by higher inheritance of stalk biomass,stalk yield,Brix degree,contents of total sugar,contents of cane sugar and lower contents of deoxidization sugar,starch and aconitic acid.Abundant genetic variance is found in sweet sorghum germplasm through research on the morphologic traits. Variation coefficients of the 20 morphological characters distributed widely ranged from 0 to 92%,the diversity index among the accessions was ranged from 0 to 2.18 based on the data of 20 morphological characters. The 64 accessions were clustered into eight groups based on morphological data when genetic distance was 6.5, 358 and White Africa was far from other accessions. It was apparent that there was some association between morphological similarity and geographical distribution, from this we found that it is hard to get to the bottom of genetic essence depend on morphological characters.Simple sequence repeats were used detect genetic diversity among 64 cultivars. 11 SSR primers selected from 30 primers gave stable profiles amplified in sample of 64 cultivars. 11 primers produced 127 amplified fragments of which 104 were polymorphic. The average number of allele per SSR locus was 11.5 with range from 7 to 20. Genetic similarity among the 64 cultivars ranged from 0.5512 to 0.9921 with an average of 0.7280, it indicated that the genetic relationships between the cultivars were close. The UPGMA cluster analysis showed that the 64 cultivars could be classified into three distinct groups when genetic similarity coefficient was 0.73, The result indicate that NKY-04 was separated from most of cultivars and formed into an independent group. Compare the results of different clustering method, though there were some similarity between the clustering analysis of morphological characters and SSR, a majority of results were different. We can see that it is difficult to make sure the genetic relationships between the cultivars with the clustering analysis of morphological characters.