COMBINING ABILITY OF SOME NEW Bc MAIZE INBREDS

U dvogodišnjim poljskim pokusima na dvije lokacije ispitana je kombinacijska sposobnost sedam srodnih samooplodnih Bc linija kukuruza križanih s četiri testera (Bc252, F2, Bc16881, Rx370-811). Efekti opće kombinacijske sposobnosti (OKS) linija za svojstvo sadržaj vode u zrnu su bili opravdani u sva četiri pokusa, za prirod zrna u dva, a za broj poleglih i polomljenih biljaka u tri pokusa. Linija Bc21491 je imala najviše pozitivne efekte OKS za svojstvo priroda zrna, međutim najkasnija je s najvećim pozitivnim efektom OKS za sadržaj vode u zrnu kod berbe. Linije Bc01/84, Bc706-43 i Bc24331 su se pokazale kao rane s negativnim efektom OKS za sadžaj vode u zrnu kod berbe. Linije Bc24331, Bc01/84 i Bc706-9 su se na osnovi efekata OKS pokazale kao najotpornije prema lomu, dok su najbolji opći kombinatori za broj poleglih biljaka bile inbred linije Bc706-43, Bc706-9 i Bc24331. Specifična kombinacijska s posobnost je najznačajnija za svojstvo priroda zrna gdje su u tri pokusa dobiveni opravdani efekti SKS. Križanci Bc24331xBc16881, Bc24331xRx370-881, Bc406-87xF2 i Bc21491xBc252 su se istakli pozitivnim efektima SKS za prirod zrna. To su uz rani hibrid Bc706- 9xBc252 i gospodarski najvrednije kombinacije. Primijenjena shema linija x tester pokazala se djelotvornom u praktičnom oplemenjivanju kukuruza.Combining ability of seven related Bc maize inbreds, crossed with four testers (Bc252, F2, Bc16881, Rx370-811) was tested in two year field trials, at two locations. GCA effects of the lines were significant for grain moisture in all four trials, for grain yield in two trials, and for lodged and broken plants in three trials. The line Bc21491 had the highest positive GCA effects for grain yield. However, it was latest, with the highest positive GCA effect for harvest grain moisture. The lines Bc01/84, Bc706-43, and Bc24331 proved to be late with negative GCA effect for harvest grain moisture. Based on GCA effects, the lines Bc24331, Bc01/84 and Bc706-9 proved as most resistant to breakage. The best general combiners for number of lodged plants were the lines Bc706-43, and Bc706 and Bc24331. Specific combining ability was omst significant for grain yield. In three trials, SCA effects were significant. The crosses Bc24331 x Bc16881 ,Bc24331 x Rx370-811 , Bc406-87 x F2, and Bc21491 x Bc252 were distinguished by their positive SCA effects for grain yield. Along with the early hybrid Bc706-9 x Bc252, they are economically the most valuable combinations. The applied line x tester scheme proved to be effective in practical maize breeding

Okolinska varijabilnost mase tisuću zrna kod hibrida kukuruza različitih skupina zriobe

Thousand kernel weight (TKW) is an important yield component trait affected by the environmental conditions. This study’s objectives were to determine an environmental variability for the TKW in 32 maize hybrids, sorted in four FAO maturity groups (FAO300, 400, 500 and 600), and to compare 12 environments in Croatia (six locations in two years) according to the joint linear regression and stability analyses across the maturity groups. In general, the effects of the environment, genotype, and their interaction (GEI) were significant. A three-factor ANOVA revealed the greatest and highly significant year effect, while the location effect was non-significant across all four FAO groups. A stability analysis did not detect any preferences with regard to the locations and trends across the FAO groups. It indicates that all locations in the Pannonian region included in this study were suitable for an evaluation of the TKW in maize genotypes belonging to all maturity groups. The TKW seems to be an appropriate yield-component trait for maize breeding due to a high heritability and linear GEI nature.Masa tisuću zrna (TKW) važno je svojstvo – komponenta prinosa koja je pod utjecajem okolinskih čimbenika. Ciljevi su ovoga rada odrediti okolinsku varijabilnost TKW‐a 32 hibrida kukuruza kategorizirana u četiri FAO‐ve skupine zriobe (FAO 300, 400, 500 i 600) i usporediti 12 okolina u Hrvatskoj (šest lokacija u dvjema godinama) prema združenoj linearno-regresijskoj analizi i analizi stabilnosti po grupama zriobe. Općenito, učinci okoline, genotipa i njihove interakcije (GEI) bili su statistički značajni. Tročimbenična ANOVA pokazala je najveći i visoko signifikantan učinak godine, dok učinak lokacije nije bio statistički značajan u sve četiri FAO‐ve skupine. Analiza stabilnosti nije detektirala preferencije među okolinama niti trend pod FAO‐vim skupinama. Naši rezultati ukazuju da su sve okoline u Panonskoj regiji uključene u istraživanje pogodne za procjenu TKW‐a kod hibrida kukuruza svih FAO‐vih skupina. TKW se pokazao prikladnom komponentom prinosa za oplemenjivanje kukuruza zbog visoke heritabilnosti i linearne naravi interakcije GEI‐ja

Genetic Variability of Tocol Content in a Genebank Collection of Temperate Maize Inbred Lines from Southeastern Europe

Maize is considered a promising candidate for biofortification through breeding, given its widespread cultivation and significance as a food crop. This cost-effective and sustainable approach could be used to increase the content of different tocol compounds, i.e., vitamin E, in maize grain due to the well-documented genetic variability. In the present study, an evaluation of the content of nine different tocol traits was performed in a genebank collection of 88 inbred lines of temperate maize grown at two locations in Croatia in 2019. A large genotypic variability within the studied material was observed for α-tocopherol, γ-tocopherol, δ-tocopherol, total tocopherols, α-/γ-tocopherol ratio, α-tocotrienol, γ-tocotrienol, total tocotrienols and total tocols with corresponding coefficients of variation of 52, 61, 51, 45, 106, 24, 54, 33 and 38%, respectively. Heritability estimates ranged from 0.66 for α-tocotrienol to 0.95 for γ-tocopherol. The content of α-tocopherol, which has the highest vitamin E activity and is therefore most interesting for selection, was not significantly correlated with either grain color or grain type. Comparison of the effects of simulated selection with an intensity of 20% on increased α-tocopherol content using the two selection criteria, absolute α-tocopherol content and α-/γ-tocopherol ratio, showed that the highest absolute α-tocopherol content was a better selection criterion. Indeed, simulated selection based on the absolute α-tocopherol content resulted in a 64% increase in this compound without significantly affecting the total tocopherols, the total tocotrienols, and the α-/γ-tocopherol ratio

Changes of genetic diversity of maize inbred lines over four decades of hybrid breeding in the Bc institute revealed by SSR markers

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