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.

Information regarding the adaptation of maize (Zea mays L .) inbred lines to various field conditions and seed longevity is essential for seed companies. The objective of this work was to evaluate different vigour tests for detecting differences among naturally aged seeds and to assess the relationship between seed quality parameters and pedigree data of maize inbred lines. A seed of 15 maize inbred lines, selected at Maize Research Institute Zemun Polje, belonging to different heterotic groups was produced during 2011. Seed quality was assessed in 2015 by standard germination , radical emergence, accelerated ageing, and cold test. Root length of 4-day old seedlings was measured in all applied tests. Analysis of variance showed that genotype and storage conditions had a significant effect on all seed quality parameters. Large variation among inbred lines was detected in seed vigour determined by three tests, in particular by the accelerated ageing test. Cold test results showed very good chilling tolerance of tested genotypes, except two inbred lines with Lancaster background. The correlation between the cold test and the accelerated ageing test was significant, while the radical emergence test had a poor correlation with them. Obtained results indicate that the application of either cold test or accelerated ageing test is reliable for screening seed vigour of maize inbred lines.

Accuracy and random selection of seeds when testing the 1000 seeds weight in the laboratory is of great importance in order to ensure the representativeness of the sample and precise information for further packaging process. The aim of this research was to check whether the laboratory seed counter selects seeds by shape and size and whether there is a trend during operation at maximum and reduced speed. Ten species of different seed sizes were used. Ten replicates of 100 seeds were counted by counter, the number of seeds was manually checked and the weight measured. The analysis of the obtained results showed that the counter is precise, but weight results showed selection of smaller seeds (Capsicum annuum and Glycine max) at maximum counting speed. Trend of larger seed selection was observed in Medicago sativa and pelleted Beta vulgaris. Slower counting (50% of the maximum speed), is ensured precise counting without trends.

Standard laboratory germination seed test provides information on seed performance under defined environmental conditions aiming to estimate field planting value. Purpose of this study was to compare results from the standard germination test with seedling emergence in different outside temperature conditions. Sowing was done in three periods during spring, in trays exposed to outside conditions. Data obtained showed that differences in the germination, detected in the standard laboratory test, were also confirmed in field conditions. Expression of these differences, however, was dependent on temperature conditions during different sowing periods. Low temperatures during the early sowing were more discriminative than later temperature increase which completely reduced differences detected in the standard germination test.

High and stabile yield in different production environments is priority in maize breeding. New statistical methods are constantly being sought to accompany analysis of variance, in order to achieve more reliable hybrid assessment. In this study nonparametric stability analysis is applied in order to assess GxE interaction for yield of 36 commercial maize hybrids. The experiment was set up at five locations in Serbia for three years according to the Randomised complete block design in three replications. Yield stability of investigated genotypes was analysed by stability parameters Si (1), Si (2), Si (3), Si (6) TOP and RS. Analysis of variance identified highly significant F values for all experimental factors. Bredenkamp method confirmed the existence of non-crossover GxE interaction, for maize yield. Hybrid ZPH15 achieved the most stable yield based on parameters Si (1) and Si (2). According to parameter Si (3) it was ZPH5, while based on parameter Si (6) it was ZPH34. The highest overall yield achieved ZPH36 (11.18 t ha-1), which was quite unstable (rank 24 in parameters Si (1) and Si (2)), and very unstable (rank 34 in parameters Si (3) and Si (6)). The most stable hybrids had average yields. In total, the hybrid ZPH23 had the best average rank (15.93). Based on TOP parameter, ZPH36 had the best rank (yield), followed by ZPH11, ZPH20, ZPH21 and ZPH9. However, RS parameter revealed that ZPH21 was the most stable hybrid, so taking into account both TOP and RS parameters this is the most productive and the most stable hybrid. Based on this research, TOP and RS are the best parameters for selecting new maize hybrids for production in particular environment. In case of identical TOP value, the genotype with the lowest RS value should be selected. The parameters Si (1), Si (2), Si (3) and Si (6) can be used as alternative methods for the selection of genotypes with moderate yield and high stability.

Five direct and reciprocal early hybrids, five direct and reciprocal late hybrids and a total of their 12 parental inbred lines were used in order to test reciprocal effects among hybrids in early germination phase and seed quality of their parental inbred lines. Five hybrids were of early maturity FAO 300-400 group, and five of late maturity FAO 500-600 group. In the early group one line of Lancaster origin (L1) was in common, and in direct crosses used as male parent, while in reciprocal crosses as female parent. The same case was with late hybrids where another Lancaster line (L2) was in common. In 2015 and 2016 all the material was multiplied in hand pollination and after six months of storage three tests according to ISTA standards were performed: standard germination test (SGT), cold-test (CT) and vigor radicle test (RE). According to the Analysis of variance, a strong reciprocal effect was found among early hybrids for four out of five parameters in RE and SGT, while it was found only for RE in late hybrids. However, in CT none of the parameters had significant reciprocal effect. Two tested Lancaster inbreds were superior in the hybrids over non-Lancaster lines when used as maternal components, while as lines per se they did not display such superiority. Mid-parent heterosis (MPH) ranged from -62.32% to 211.11% in RE test, with an average of 44.26%; from -10.15% to 17.93% in SGT test, with an average of 6.27%, and from -5.31% to 4.49% in CT, with an average of 0.64%. Significant differences of MPH were found for nine pairs of reciprocal hybrids for RE, three pairs for SGT and seven pairs for CT. This shows that reciprocal differences in MPH were higher as the applied level of stress during early seed growth raised. All the results showed very complicated mode of inheritance of tested traits in the early developmental stages of young plants, including the phenomenon of heterosis which is expressed already at the germination stage.