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Monitoring genetic uniformity and identity is very important in maize breeding and seed production. Due to practical reasons, molecular and biochemical methods for the determination of genetic purity and uniformity should reliably reflect genetic differences associated with traditional morphological traits, even when they are not agriculturally important. A comparison of genetic purity and uniformity of one maize hybrid lot, based on morphological UPOV markers and the UTLIEF (Ultrathin-layer isoelectric focusing) method is performed in this research. Tested hybrid samples expressed uniform protein markers profiles, but on the other hand, unsatisfactory uniformity of morphological markers in the field, indicating some laches in seed production. Although the UTLIEF method, standardized by ISTA rules, provides enough accurate distinction between F1 seed and self-pollinated maternal seed, a "clean" isozyme or protein profile will not necessarily correlate with morphological homogeneity. It is most likely that the non-uniformity of the tested hybrid lot originates from the non-uniformity of one of the parental lines. Therefore, to establish where the laches occurred, it is necessary to perform post-control tests with reference samples of maize hybrid and parental lines, as well as, the insight into their official descriptions according to the UPOV descriptor. Thus, it is very important to require the deposition of referent samples of hybrids and varieties whose seed production is allowed in Serbia, as well as to have harmonised protocols for conduction of laboratory and field post-control tests.

This study's primary objective was to assess the quality parameters of fifteen different genotypes of Serbian maize hybrids in order to establish whether they were suitable for making high-quality silage for ruminant feed. The study was carried out as a two-year field experiment at the Maize Research Institute in Zemun Polje, Serbia. Laboratory analyses included the yield structure of the examined maize hybrids, the evaluation of the composition of lignocellulosic fiber and the percentage of their ratios, as well as the in vitro dry matter digestibility and NDF digestibility of the whole plant samples. The Fisher's LSD test was used to statistically analyse the data, which were then reported as the mean and standard deviation of at least three independent replicates. The graphical representation of correlations among the observed parameters used the principal component analysis (PCA) method. All maize hybrids have displayed high-quality characteristics, which are required for the production of high-quality silage.

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.

Identification of high yielding and stable genotypes is one of the main goals in all breeding programmes. Estimation of hybrids is often aggravated due to the presence of genotype x environment (GE) interaction. One of the ways to eliminate negative effect of this interaction is the application of reliable statistical models such as AMMI model, which singles out high yielding and stable genotypes that have positive reaction to the improvement of production environments. This research aimed to establish specific maize hybrids interactions in different environments in two years by AMMI analysis. Twelve KWS maize hybrids belonging to FAO 400-500, were examined in two years over eight locations in Vojvodina. The highest yield in both years had the hybrid KWS2 (12.764 kg ha-1). Based on the AMMI1 model, hybrid KWS9 showed the highest stability and adaptability at all locations. According to AMMI2, hybrids KWS1, KWS3 and KWS12, had the highest stability and adaptability, while hybrids KWS2, KWS6, KWS8, KWS9 and KWS10 showed a satisfactory level of stability and it is necessary to pay attention to which locations they have positive interactions in order to be recommended in such regions. Nevertheless, based on the AMMI2, locations Temerin, Kikinda and Zrenjanin, showed similar interaction response, which points out that the number of trial locations could be reduced. Obtained results would contribute to the more precise decision in hybrids recommendation for the certain region, but also in defining further aims in maize breeding.

Taste and nutritional value make sweet corn a valued plant and an important component of the human diet worldwide. Kernel nutritive composition of sweet corn has been reported in various papers, but a description of carotenoid and tocopherols profile, especially after cooking is scarce. Therefore, the present study was carried out to compare the carotenoid and tocopherol content in sweet corn before and after cooking. Contents of b-carotene, lutein+zeaxanthin and tocopherols (d-T, b+g-T, a-T) in the kernels of twelve sweet corn hybrids were determined by High-Performance Liquid Chromatography (HPLC) and were expressed as the mean value of three independent measurements. Both genotype and cooking affected the content of the carotenoids and tocopherols in the kernel. The highest content of total carotenoids before and after cooking was found in hybrid ZP486/1su (27.77/45.28 µg/g) whereas the lowest content was in hybrid ZP 355su (10.27 µg/g) before cooking i.e. in hybrid ZP 347su (24.55 µg/g) after cooking. The cooking resulted in a significant increase in the content of total carotenoids and tocopherols, lutein+zeaxanthin, and b-carotene in all hybrids, except the ZP504su in which the b-carotene content decreased. An increase in a-tocopherol after cooking was observed in hybrids ZP485/1su and ZP484/1su, while a decrease was in hybrids ZP481/1su, ZP486/1su and ZP477/2su. The results showed that increasing micronutrient content is genotype-dependent. This study confirmed that cooking increases the nutritional value of sweet corn and gives it additional value in terms of functional food.

The protein content is an important parameter of the technological quality of soybean grain. Therefore, the selection work is aimed at creating a genetic basis for obtaining varieties not only of high yield but also varieties of improved grain quality. In order to provide sustained progress in breeding, it is necessary to find a stable source for breeding for desired traits. The aim of this study was to examine the value of the genotype × environment (G× E) interaction for protein content in 14 Maize Research Institute "Zemun Polje" short-season soybean accessions and to identify stable sources that can be used in breeding for protein content improvement. G×E interaction for grain protein content was analyzed using a linear-bilinear AMMI-1 model. The influence of genotype and environment on the total variation of protein content was approximately equal, while the smallest variation is attributed to genotype x environment interaction. A large number of genotypes with different protein content (Korana, PI 180 507, Kabott, Krajina, Canatto) showed a small contribution to the interaction in studied environments, the most important of which were genotypes with above-average protein content, as potential sources for future breeding programs.

Physical quality traits (1000-kernel weight, density, milling response and soft endosperm portion), basic chemical (starch, protein, oil, cellulose and ash) and amino acids composition of ten ZP maize genotypes differing in kernel hardness and colour were studied. The objectives of this study were to characterize differences in ZP maize genotypes regarding to various physical traits and nutritional quality parameters such as basic chemical and amino acid composition and the data was correlated to find the interrelationship between these parameters. Kernel physical traits and chemical composition significantly varied among tested genotypes. A significant negative correlation was found between protein content and portion of soft endosperm as well as a significant positive correlation between protein content and two physical traits, milling response and density. Protein content showed a non-significant negative correlation with starch content. The results showed that the protein content exhibited negative correlation with lysine as well as positive correlation with methionine. It has not been observed a significant improvement in the amino acid composition regarding the specialty genotypes such as the selected white and red kernels and popping maize genotypes. The information presented in this study could be useful for the utilization improvement of maize kernel and the development of maize-based ingredients to prepare nutritious feed and food products.

Sweet corn is considered as tasty and quality food. Its kernels contain sugars that are in good balance with amino acids, minerals and vitamin B. It is used as fresh product right after the harvest, but also for further industrial processing, freezing and canning. In breeding of sweet corn, equal attention is paid to the production of high and stable yielding hybrids, and to the enhancement of technological and sensory properties of the ear and kernel. The aim of this research was to establish agronomic and sensory properties of 12 sweet corn hybrids, 3 commercial and 9 experimental. The trial was set up according to the RCBD on two locations and in three replicates. The evaluation of agronomic parameters encompassed: fresh ear yield without husk, ear length, number of kernel rows and shelling percentage. Also, sensory characteristics were analyzed: appearance, color, smell, sweetness, juiciness, crispiness, pericarp hardness. Sensory characteristics were evaluated by voluntary panelists and scaled with 1 - 9 point hedonic scale. Fresh ear yield significantly varied over locations and hybrids. The highest fresh ear yield had experimental hybrid ZP 481/1su - 13.33 t ha-1, while the lowest was 7.14 t ha-1 (ZP504su). The difference between sensory characteristics among hybrids was also noticed, although all hybrids had satisfactory sensory characteristics with the average sensory marks above 7.30/9.00. The best sweet corn hybrid according to sensory characteristics was ZP 483/1su (8.29), while the highest yielding one ZP 481/1su had an average sensory mark 7.70.

Western corn rootworm (WCR) (Diabrotica virgifera virgifera LeConte) is one of the most important and potentially most dangerous pests of maize. Since its occurrence in Serbia in 1992, it has been present in almost all areas under maize cultivation. Alongside with all preventive measures, first of all, the crop rotation, which is considered the most economic one, a great attention has been paid to the forecast of the pest occurrence based on the flight dynamics and the population level. The flight dynamics, sex dominance, variations in the population level depending on the trap types and climate factors were observed on two locations: Crepaja in three-year continuous cropping (2005-2007) and in the experimental field of the Maize Research Institute, Zemun Polje in the duration of five years (2005-2009). According to the flight dynamics of WCR adults, the highest population level of this pest was observed in 2005, while the comparison of the number of adults over locations showed greater abundance of the pest in Crepaja than in Zemun Polje, which was attributed to extreme favourability of agro-ecological conditions on this location for the WCR development. The 2008-2009 period was characterised by the reduced number of WCR, which coincided with the extremely arid conditions that do not favour the development of this pest.

Maize hybrids (Zea mays L.) with specific traits, such as those with red pericarp, high-protein flints or white kernel hybrids, have increased utility value as they contain some vitamins and minerals beneficial to human and animal nutrition. Furthermore, their cultivation with the application of specific fertilisers could further increase the grain quality through increased participation of macro- and micro-elements that are lacking in the diet. Agronomic biofortification encompasses the application of different production technology that enables better absorption and effective accumulation of essential elements such as iron, zinc, manganese, copper in the edible parts of cultivated plants. On the other hand, fertilisation influences the weed infestation levels and especially the presence of nitrophilic weed species in maize crop. The fertiliser application changes the balance in competition between crops and weeds, not only for nutrients but also for other resources. The effects of different fertilisers were compared within developmental research in the field of ecological agriculture to point up the advantages of microbiological and organic fertilisers, since these fertilisers can contribute to higher yields, but unlike mineral fertilisers, they positively affect the soil and agro-ecosystem. The studies were carried out to determine to what extent agronomic biofortification contributed to the increase of yielding potential and grain quality of maize genotypes with specific traits, as well as how it affected the occurrence and distribution of weeds. The red kernel maize hybrid ZP5048C, high-protein flint maize hybrid ZP737 and white kernel maize hybrid ZP552b, were grown in variants with mineral fertiliser urea, microbiological fertiliser Team Micorriza Plus and organic fertiliser Fertor, that contained essential elements necessary for the nutrition of cultivated plants. No fertiliser was applied to the control treatment. The fertilisation mainly contributed to the increase of weed mass in comparison with the non-fertilised control variant in extremely dry 2017. The highest weed mass was recorded in the hybrid ZP737 in the variant with organic fertiliser, while the lowest weed mass was recorded in all hybrids when microbiological fertiliser had been applied. The highest, i.e. lowest grain yield was recorded in the hybrid ZP5048C (5.83 t ha-1), i.e. ZP737 (3.36 t ha-1), respectively. The protein content was increased at the highest extent in the kernel of ZP737 hybrid after the application of urea, while oil and starch contents were the highest in the grain of white kernel hybrid ZP552b treated with microbiological fertiliser. Due to the specificities and importance of meteorological conditions, the studies will be continued during the next few seasons. .

In plant breeding programs, it is often necessary to cross genotypes incompatible in time of flowering. In maize, when the incompatibility in flowering period could not be overcome by different sowing dates, or by the ability of silk to preserve its fertility in 10-15 days, conservation of pollen could be of great importance. For many plant species, the appropriate methods for pollen management have been set up, including methods of collecting, desiccation, testing of viability and longevity, as well as for pollen storage. The longevity of pollen during its storage depends upon plant species, conditions at the time of pollen collecting, pollen moisture content, as well as upon storage temperature and duration. Even within the same plant species, different genotypes exhibit different level of viability preservation during the conservation. Although maize pollen belongs to a tricellular pollen group and rapidly loses viability under field conditions, its preservation is possible. According to the literature, pollen viability could be preserved for 30 days in the conditions of refrigerator (+4°C), while in liquid nitrogen (-196°C) up to 120 days. In the majority of studies, pollen viability was evaluated in the laboratory conditions, and the results obtained could largely be differed from those obtained under field conditions, due to impossibility to control a number of environmental factors. This experiment was conducted under field conditions in order to evaluate the ability of pollen from commercial maize inbred line L217, stored under the conditions of +4°C and -20°C, to pollinate maize inbred L73B013 and produce grain. Inbred L73B013 is sown in five sowing dates in order to ensure the longer presence of fresh silk. Pollen samples from line L217 were taken twice, and along with silica gel, stored in refrigerator and freezer. Each of successive pollination included five silks. Except for the expected good ear seed set when silks were pollinated with fresh pollen, the next successive pollination resulted in extremely poor ear seed set. Pollen stored in the freezer for one day completely lost vitality, while the pollination with pollen stored for three days resulted in one kernel per ear (for two ears). Pollination with pollen stored for four days resulted in one kernel per ear for only one ear. Pollen stored at + 4°C gave slightly better, but still very poor results. Compared to control, the percentage of seed set for pollen stored only for one day was 4.4%, being decreased to 0.2% and 0.4% for pollen stored for four and five days, respectively. Plants pollinated with pollen stored for 20 days did not give any grain. Such poor results may be a consequence of species specific properties of inbred L217, but also a consequence of failure in the manipulation of pollen. A highly sensitive point during the storage of pollen, especially in species with pollen sensitive to dehydration, such as the maize pollen, is the process of drying before its storing. Therefore, we concluded that the procedure of pollen desiccation probably was not adequate. With the aim of correcting the deficiencies observed, the experiment will be repeated in 2017.

Sweet corn is used as food in the milky stage of endosperm, when its kernel is tender, succulent and sweet. It is consumed in form of fresh ears, or it is industrially processed. Breeding of sweet corn has several equally important aims that are directed by the market demands and different modes of consumption. The ear yield, in sweet corn is the most important but not the only main goal of breeding. In the two year study (2013, 2014) we observed the effect of the genotype, year and their interactions on the yields of 8 sweet corn hybrids. Two of the hybrids were commercial and six were experimental hybrids. The field experiment was arranged according to the RCBD with four replications. Hybrids were harvested 23 days after pollination, i.e. silking. Average yield in 2013 was significantly higher (12.19 t ha-1) than in 2014 (11.49 t ha- 1). In 2013 it ranged from 10.21 t ha-1 for the experimental hybrid ZP 489/1su, up to 13.52 t ha-1 for the commercial hybrid ZP 355su. In 2014 the lowest yielding hybrid was ZP 485/1su (10.14 t ha-1) while the highest yielding was ZP 486/1su (13.41 t ha-1). On average those two were also the highest (13.19 t ha-1) and the lowest yielding (10.66 t ha-1) hybrids. Statistical analysis showed that the effect of genotype and the year, as well as their interactions had significant impact on the yield performances of sweet corn hybrids.

During 2008 and 2009, efficacy of insecticidal products, based on thiamethoxam and imidacloprid, were tested. Furthermore, effects of entomophatogenic fungus Beauveria bassiana on the infestation intensity of European corn borer (Ostrinia nubilalis), were established over effects of both, 10 different treatments of maize seed (8 treatments and 2 controls) and the application of the fungal inoculum. Trials were carried out on maize crop under field conditions in accordance with the EPPO method. Results obtained in the studies with the product Cruiser 350 FS (350g l-1 thiamethoxam) applied in the amount of 0.9 l per 100 kg of seed and the products Imidor 600 FS and Gaucho 600FS (600g l-1 imidacloprid) applied in the amount of 0.7 l per 100 kg of seed, point out to satisfactory efficacy in controlling ECB and satisfactory effects on maize yields. The intensity of ECB infestation, expressed in percentages, ranged from 50.1% to 74.1%. The interrelation between average percentages of infested plants and obtained yields in both investigation years (2008-2009) in Zemun Polje was established. Results over treatments indicate that the highest percentages (62.2%) of infested plants were observed in the control variant (K1- Captan). Moreover, as expected, the lowest yield was also recorded in this variant. The treatment with the fungicide Maxim combined with the insecticide Criuser proved to be the most efficient. At the same time, the percentage of infested plants was the lowest in this treatment (53.32%) and the yield was the highest (8.610 t ha-1). The infestation level of maize plants in this treatment was significantly reduced over years of investigation in comparison with remaining treatments. Meteorological factors during the years of investigation, especially unfavourable agroecological conditions in 2009, affected the average yield of maize per hectare. The yield (8.314 t ha-1) recorded in the treatment with the inoculum of B. basssiana was almost equal to the one recorded in the treatment with the product Cruiser (8.610 t ha-1), while it was higher than the yield obtained in the treatment with the products Gaucho (7.506 t ha-1) and Imidor (8.259 t ha-1) combined with the fungicide Maxim. These differences were not statistically significant. Seed treatments with the fungal inoculum were not significantly different in any of observed parameters, except in the seed treatment with Captan. The comparison of data obtained in the two-year studies (2008-2009) under conditions of natural ECB infestation, shows prevalence of plants with damages of leaves (type H2) and tassels (type M3-4), which is indicated with the average score of 2.43. According to the average scores, it can be concluded that ECB infestation did not result in damages that would have significantly affected maize yield. In order to establish significance of certain observed parameters, they were compared and their correlations were determined. The greatest negative correlation with the 0.05 probability level (r= -0.96533) was established between the plant damage score and the recorded yield. Since recorded value of coefficients of correlation was approximately 1, it can be stated that the complete functional linear dependence existed among variables. Achieved results show efficiency of insecticides based on thiamethoxam and imidacloprid in the regulation of the infestation level in maize and also point to negative effects of the fungus B. bassiana on entomofauna of maize and its mycoinsecticide activity that could find an application in biocontrol of insect pests of maize.

Mineral elements deficiency in food can cause serious health problems. Being one of the three most importatnt macroelements for plant nutrition, phosphorus is involved in several key processes: photosynthesis, respiration, synthesis of starch, transport of carbohydrates and products of photosynthesis, cell division and increased water utilization. The objective of this study was to estimate the dynamics of inorganic phosphorus (Pi), as a precursor in the synthesis of phytic acid, and phytic phosphorus (Pphy) accumulation during the grain filling of two maize inbred lines differing in FAO maturity groups - L217 and L773. In addition, possible linkage between phosphorus content in grain and agro-morphological performances was observed. For the analysis of the dynamics in Pi and Pphy contents, seed samples were taken at 15th, 30th, 45th and 60th day after the polination. The obtained results showed a continuous decline of Pi content in both genotypes, with the most intensive decline observed at the first interval (e.i. 15-30 days) after the polination. The trend observed was much more pronounced in L217. Moreover, this inbred acheaved higher grain yield for 61.8 % at first sowing and for 63.1 % at 10-day delayed sowing, respectively, compared to inbred L773. In all three intervals observed, the decrease of Pi content was highly correlated with Pphy content increase for both genotypes. Based on lower accumulation rate, followed by lower Pphy content (2.635 mg g-1) during the stage of physiological maturuty, it could be concluded that inbred L217 could be considered as potentialy suitable genotype for low-phytic hybride selection.

According to regional reports on climate, more frequent and severe droughts and floods are already apparent. Modern maize breeding for different purposes (e.g. drought tolerance) emphasizes the importance for improved maize ability to withstand adverse environmental conditions. Genotypes with drought tolerance obtain high grain yield under optimal conditions and lower, but stable yield under dry environmental conditions. Field testing was conducted in 2014, on twenty-three maize inbred lines differing in drought tolerance. The inbreds were evaluated in respect to morphological traits (plant and ear height, total number of leaves, number of leaves above uppermost ear, ear leaf length and width), yield components and grain yield per plant. The experiment was set up according to RCB design with two replications. To simulate water stress, two plant densities were applied. According to Principal Component Analysis and cluster analysis, five inbred lines (T1, T2, T4, T8 i T15) performed the highest stability in both experimental conditions. Those inbreds could be used as a source for drought tolerance in breeding programs.

Popping maize is a specific type of maize differing from other types of maize by its capability to form a large puff or flake after explosive 'pop' that is a response to heating. Besides grain yield, an economically important trait, it is necessary that popping maize hybrids are characterized by a great popping volume and quality and testy flakes as well as other essential production traits. The grain yield of 12 selected popping maize hybrids was observed and the interrelationship among the grain yield, popping volume and the number of kernels per 10 g was established. Obtained results point out to a negative statistically significant correlation (-0,684*) between the grain yield and the popping volume. Furthermore, insignificant negative correlations (-0,135 and -0,399) were established between the grain yield and the number of kernels per 10 g and the popping volume and the number of kernels per 10 g, respectively. The traits observed in the present study are the quantitative ones, that is, their expression is determined by the greater number of genes and by environmental conditions. .

The protection of breeders rights provides the chance to establish the exclusive right which will enhance the chances for protection of intellectual property and therefore provide the greater accumulation of the necessary founds for the further investments in the area of plant breeding. Concerning this UPOV has established detail guidelines for conduction of DUS tests for more then 170 plant species. Considering that the living systems are in the constant interaction with the environment, and most of the traits are polygenic, mistakes are always possible, regardless of the very precisely established procedures for description of traits in the Guidelines. On the other hand the subjectivity of the human factor is always present. Errors could be the result of the mistakes in writing during the estimation in the field or while transferring the data into the computer. Also errors could occur as the replacement of the estimates between two neighboring plots. Specificity of genotype and missing estimate could also enter confusion in the evaluation of traits. Application of some cultural practices, especially herbicides applied after seedling emergences, could lead to the false estimate. Assuring the timely detection of the false estimate and its verifying and correction, during the experiment, is of a great importance, so that errors could be avoided in characterization of genotype and in the estimate of its distinctness, uniformity and stability.

Beside the yield, as an economically important trait, the popping volume that breeders have been improving is equally important. At the same time, it is the main trait distinguishing popping maize from other types of maize. In order to provide a successful breeding and selection of popping maize, specific procedures are necessary for the evaluation of the traits selection is performed for (e.g. determination of the degree of popping and flake quality). Breeding of popping maize for improved yield is not a primary aim of breeding. If popping maize hybrids do not have a high popping volume and high quality of flakes, they will not be used in the production no matter how high yielding they are. The yield, the popping volume and the relation of these two equally important traits, were estimated in the trial with popping maize hybrids sown in two locations. According to means for both trial locations, the observed hybrid combinations were ranked for the traits of grain yield and popping volume. Obtained ranks were used to calculate the Spearman shrank correlation coefficients. A gained value is not statistically significant, but it points to a weak dependence between these traits. Achieved results, once again, confirmed the difficulties of the task set before popping maize breeders - to select a hybrid combination with a high yield and at the same with a good popping volume.