Stability parameters of commercial maize (Zea mays L.) hybrids

Many authors showed the possibility of developing highly yielding and stable hybrids. The assumption was that commercial maize hybrids were characterized not only by the level of average yield bat also by their stability. Fifteen commercial maize hybrids of medium late and late FAO maturity groups (400-700) were used in the present study. The two-year four-replicate trials were set up in six locations according to the randomized complete-block design. Stability parameters were determined after the method of EBERHART and RUSSEL (1966), in which the genotype was considered stable if it had a high average yield, a coefficient of regression of approximately 1.0 and deviation from regression as small as possible. The obtained results show that early maturity hybrids responded better to more modest growing condition and had a greater deviation from regression, while late maturity hybrids had a coefficient of regression closer to unity and they generally better responded to improved growing conditions.Mnogi autori su pokazali mogućnost stvaranja prinosnih, a istovremeno stabilnih hibrida. Pretpostavljeno je da se komercijalni hibridi kukuruza razlikuju ne samo po prosečnom prinosu već i po stabilnosti. Petnaest komercijalnih ZP hibrida kukuruza, srednje ranih, srednje kasnih i kasnih FAO grupa zrenja (400-700) je bilo uključeno u ovo ispitivanje. Ogled je bio postavljen u šest lokacija, dve godine i četiri ponavljanja po kompletno randomiziranom blok dizajnu. Parametri stabilnosti su određeni po metodu EBERHART I RUSSEL (1966), po kojem se genotip smatra stabilnim ako ima visok prosečan prinos, koeficijent regresije oko jedinice i devijaciju od regresije što je moguće manju. Dobijeni rezultati pokazuju da srednje rani I srednje kasni hibridi imaju veću devijaciju od regresije i daju bolji odgovor u lošijim sredinama, dok kasni hibridi imaju koeficijent regresije blizu jedinice i generalno daju bolji odgovor na poboljšanje uslova gajenja

A simple ssr analysis for genetic diversity estimation of maize landraces

collection of 2217 landraces from western Balkan (former Yugoslavia) is maintained at Maize Research Institute Zemun Polje gene bank. Nine flint and nine dent accessions from six agro-ecological groups (races), chosen on the basis of diverse pedigrees, were analyzed for genetic relatedness using phenotypic and simple sequence repeat (SSR) markers. One of the aims was to establish a reliable set of SSR markers for a rapid diversity analysis using polyacrilamide gels and ethidium bromide staining. In the principal component analysis (PCA) the first three principal components accounted for 80.86% of total variation and separated most of the flint from dent landraces. Ten SSR primers revealed a total of 56 and 63 alleles in flint and dent landraces, respectively, with low stuttering and good allele resolution on the gels. High average PIC value (0.822) also supports informativeness and utility of the markers used in this study. Higher genetic variation was observed among flint genotypes, as genetic distances between flint landraces covered a larger range of values (0.11- 0.38) than between dent (0.22 - 0.33) genotypes. Both phenotypic and SSR analyses distinguished flint and dent landraces, but neither of them could abstract agro-ecological groups. The SSR method used gave clear, easy to read band patterns that could be used for reliable allele frequency determination. Genetic diversity revealed for both markers indicated that the landraces were highly adapted to specific environmental conditions and purposes and could be valuable sources of genetic variability. [Projekat Ministarstva nauke Republike Srbije, br. TR31028: Exploitation of maize diversity to improve grain quality and drought tolerance

Efficiency of Biological Typing Methods in Maize Hybrid Genetic Purity Estimation

A high level of genetic purity in crop varieties must be achieved and maintained for agronomic performance, encouraging investment and innovation in plant breeding and ensuring that the improvements in productivity and quality imparted by breeders are delivered to the consumer. Since the success of hybrid seed production is dependent upon the genetic purity of the parental lines, in this study, the experimental F1exp maize hybrid and its parental inbreeds were used as a model system to examine the discriminative power of morphological, biochemical and SSR markers for seed purity assay. The highest number of off-type plants was estimated by morphological markers. According to the comparison of prolamins and albumins banding patterns of parental and derived F1exp seeds, genetic impurities could not be detected. Molecular analysis detected two types of genetic profile irregularity. Beside its use for verifying varieties of maize, report on umc1545 primer pair ability to detect non-specific bands (i.e., off-types), in both the maternal component and F1exp, which is the first report on this issue yet, strongly supports the recommendation of this SSR marker use for more accurate and time-efficient maize hybrids and parental lines genetic pyrity testing