Growing numbers of candidate varieties, decrease of their variability for morphological traits, and internationalization of the national list all contribute to excessive increase of the trial costs, thus creating the need for the improvement of current variety evaluation procedures, especially regards their distinctness, Uniformity, and Stability (DUS) component. Due to rapid advancement in molecular techniques, the use of molecular markers in DUS testing as a complement to, or replacement of, morphological observations became the subject of great interest in scientific studies, and consequently topic for discussion within International Union for the Protection of New Varieties of Plants (UPOV). In order to explore the potential of simple sequence repeat (SSR) markers for distinctness tests, present study involved set of 41 maize inbred lines that were scored for 32 DUS characters prescribed by UPOV and genotyped at 28 SSR loci. Results were largely in favor of the use of molecular markers, revealing or confirming their already known advantages over morphological markers like better consistency with the pedigree, and relatively higher discriminative power. However, their integration into DUS testing protocols still depends upon resolving of several important issues.

Combining experimental studies on grain yield variability with crop model simulations in maize could assist in choosing the optimum maturity group for a certain location, counteracting the effect of climate change. However, studies considering specificities in Southeast Europe are lacking. The objectives were to put various environmental covariates including stress degree days (SDD) into FAO maturity settings to determine the impact of climate change on maize growing in Southeast Europe and to compare trends for grain yields over twenty years of maize experimental and simulation data grouped in five FAO maturity groups (FAO 200–FAO 600). Pre-registration yield trials of maize planted in one location in Croatia grown from 1996 to 2015 were used to determine “potential yield”. Correlation coefficients between 12 climate covariates and grain yield (GY) across the maturity groups revealed the tightest negative associations between SDD and GY that were weakened by later-maturity groups. Similar trends in GY were obtained by both experimental and simulation data, highlighting FAO 600 as a nearly no yield-reducing FAO group over the two decades. Our results indicate that choosing early maize hybrids in Southeast Europe does not seem to be an optimum option in the future, since these hybrids are more sensitive to omnipresent heat stress than late hybrids.

In this paper, changes of genetic diversity of the most important maize inbred lines used for hybrid production within the Bc Institute in the 1970s, 1980s, 1990s and 2000s were examined using the SSR markers. The average number of alleles per SSR locus was 3.14, 3.43, 3.07 and 3.25 for lines from 1970s, 1980s, 1990s and 2000s, whereas the number of private alleles for the same four decades was 8, 4, 0 and 6, respectively. Mean genetic distance among inbreds within decades steadily decreased over time from 0.64 in 1970s to 0.57 in 2000s, but the observed differences were not statistically significant. The clustering of the studied inbred lines indicates the exploitation of a known BSSS x LSC heterotic pattern within the Bc Institute maize breeding program. The overall results show that recycled inbred lines within these pools do not decline in genetic variation over the past 40 years.

No abstract