Abstract:

【Objective】 To in vestigate the trends in genetic diversity among widely used inbreds from 1991 to 2001 in China and to compare genetic variation among three major germplasm groups. 【Method】 In this paper, 88 inbreds of 66 maize hybrids which widely used commercially in 1991 through 2001 were used to analyze the changing trends of the genetic base with 111 SSR markers. 【Result】 Firstly, 659 SSR alleles were detected in 66 hybrids with the average of 5.95 per locus. Nei’s genetic diversity index of the widely extended hybrids during the past decade was increased from 0.67 to 0.69 and the allele number increased from 603 to 653. Only 0.9% absent alleles but 8.5% new alleles were detected by comparing the hybrids in 2001 with those released in 1991. Secondly, there were 583 alleles detected with 111 SSR markers in 39 inbreds including 16 from SPT group, 15 from Reid and 8 from Lancaster. Of which the alleles detected in SPT group were the most and took the percentage of 77.4%, Reid and Lancaster groups were 61.5% and 60%, respectively. The alleles frequency difference between Reid and SPT, Lancaster and SPT was both at about 32%, but the frequency difference between Reid and Lancaster was only 25%. Most of the special alleles existed in SPT group (24%), and Reid and Lancaster groups provided fewer (7.9% and 7.3%, respectively). 【Conclusion】 With the introduction of new germplasm and improvement of the old germplasm, the genetic diversity of maize hybrids was not decreased but increased to some extent. There are many unique alleles in local germplasms which maybe become the genetic base to produce elite hybrids when crosses with those abroad. So it is necessary to pay attention to the improvement and utilization of domestic germplasm.

Key words: maize, genetic diversity, germplasm group