engleski

Genetic diversity of maize inbred lines and grain yield of their test-crosses in stress and non-stress conditions

The main goal of modern maize breeding is to find hybrid combinations with superior agronomic performances under broad range of growing conditions including drought and low soil fertility. Implementations of molecular markers in maize breeding programs can help in attaining this goal by providing better insight into germplasm diversity. We evaluated 16 elite maize inbred lines crossed to four testers under stress and non-stress conditions to (i) estimate the combining ability for grain yield (GY), (ii) assess the genetic diversity among inbred lines using 53 SSR markers, and (iii) estimate the correlation between F1 hybrid performance and genetic distance (GD). The F1 hybrids were evaluated under moderate drought stress, low N stress, and non stress conditions from 2007 to 2009. Mean grain yield for hybrids ranged from 3.72 Mg ha-1 under moderate drought stress in 2007 to 7.73 Mg ha-1 under non-stress conditions in the same year. General combining ability (GCA) effects were significant under all conditions whereas specific combining ability (SCA) effects were significant under all conditions except under moderate drought in 2007. The 53 SSR markers revealed in total 197 alleles among 20 inbred lines with 3.7 alleles per locus and a mean polymorphism information content (PIC) value of 0.55. Cluster analysis based on genetic similarity (GS) calculated using SSR marker data grouped lines mostly according to their pedigrees. Correlation coefficients between F1 GY and SSR based GD varied from 0.51 for low N stress in 2007 to 0.77 for the same stress in 2009.

maize; genetic diversity; SSR markers; drought; low N stress

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