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Quality protein maize (QPM) has high contents of essential amino acids lysine and tryptophan. The substitution of standard maize (SM) with QPM in feeds can be profitable due to improved livestock performance and decreased costly dietary lysine supplementation and protein ingredients. Herein, effects of QPM adapted to temperate climate on broiler performance were tested. Feeding experiment was performed on control (fed with SM) and treatment (fed with QPM) broilers. Each feeding trial of 42 days duration was carried out in three phases - starter (1-14), grower (15-35) and finisher (36-42). Diets for each growth phase was formulated based on the biochemical analysis of maize kernels. At the end of each growth phase, feed intake (FI), body weight gain (BWG), average daily gain (ADG) and feed conversion ratio (FCR) were calculated. In the first experiment, SM was completely replaced with QPM in treatment group diets. The results indicated better FCR in the treatment group for grower (1.51:1.56) and finisher (1.56:1.61) phases. In the second experiment QPM was increased and soybean component decreased by 3%. This time, FCR improvement was even better but in all three phases – 1.16:1.33 for starters, 1.28:1.36 for growers and 1.30:1.46 for finishers. These results indicate significant financial reduction in feed as the price of soybean is usually two to four times higher than the price of maize. Overall, it can be concluded that using adapted QPM in broiler diets can be profitable for both feed industry and broiler producers.

With global climate change, including unpredictable geographic and temporal weather patterns causing significant Genotype × Environment interaction (GEI), modelling by climate variables can reveal their influence on phenophases of maize (Zea mays L.) development. The objectives of this study were dissection of the phenotypic variation of grain yield of late maturity maize hybrids grown in multi-environment trial, and quantification of the influence of climatic factors on the GEI for each vegetative and reproductive phenophase. Eight FAO 700 maize hybrids were evaluated across five locations in Serbia during 2020 and 2021 years. The hierarchy of sources of variation according to three-way ANOVA were: Year (Y) > Location (L) > Location×Genotype (G) > L×Y×G > G > L×Y > Y×G. The average maximum temperature (mxt, 22.1%), average minimum temperature (mnt, 19.2%), average mean temperature (mt, 18.2%) and relative humidity (rh, 15.1%) in April significantly influenced emergence stage. The mxt (21.1%) and mt (15.7%) in May influenced significantly vegetative phases V1-V9. June contributed the largest percentage of the sum of squares of the GEI with mxt (25.2%), mnt (20.9%), mt (16.1%) influencing vegetative phases V10-V18 and tassel emergence. In July mxt (17%), mt (15.6%), precipitation sum (15.2%), and sunshine hours sum (15.1%), influenced R1, R2, R3, and R4 reproductive phases. In August mxt (23.2%), mnt (20.8%), mt (15.7%), rh (17.1%) influenced R5 reproductive phase. The extreme heat as a stressor had a more critical role for late maturity maize hybrids production than drought in crucial phenophases of maize development.

The study was carried out at the Maize Research Institute “Zemun Polje”, Belgrade, Serbia during 2021 growing season in three location. Six inbred lines were crossed according to complete diallel method. In this way 15 hybrids and 15 reciprocal combinations were obtained. Hybrid and reciprocal combinations derived from these parental components were used in this paper. The present study was carried out to study the variability, broad-sense heritability (H2 bs), genetic advance (GA), correlation among traits, genotypic and phenotypic path analysis among grain yield and its components. The results indicated that the genotypes were significantly different for all traits. For all traits, the phenotypic coefficient of variation was higher than the genotypic coefficient of variation. The highest heritability was found in 1000 kernel weight, followed by grain yield, ear diameter and anthesis-silking interval (ASI). In our study Genetic Advance over Mean (GAM) for the traits ranged from lowest value (9.739%) for cob diameter to the highest value (90.579%) for anthesis-silking interval. According to results of path analysis, the trait 1000 kernel weight with the value of 0.365 has the strongest direct positive effect on grain yield. Positive direct effects on grain yield were also observed for ear length (0.202), ear diameter (0.248) and number of rows per ear (0.076), while negative direct effects were observed for cob diameter (-0.057). The trait 1000 kernel weight had the highest indirect positive effects on grain yield via ear diameter (0.232). The cob diameter had highest negative indirect effect on grain yield via ear diameter (-0.048). Coefficient of multiple determinations (R2 ) had a value of 0.428. This indicated the important role of additive gene effect in the inheritance of these traits and could be improved through simple selection.

Micro RNAs (miRNAs) are known regulators of various processes in plants, including growth, development and stress responses. They achieve this through mRNA cleavage or translational inhibition, in a process called RNA interference. Herein, their role in chilling stress response in young maize seedlings (Zea mays L.) is examined, using high-throughput sequencing methods. Bringing light to all aspects of chilling stress response in maize is necessary since earlier sowing, during colder periods, is one of the most promising strategies of avoiding maize yield loss due to effects of climate change in these areas. Sterilized seeds of two maize genotypes (tolerant - T and sensitive - S to low temperatures) were germinated in the dark for five days (optimal conditions), after which the 5-d old seedlings were exposed to chilling conditions for 6h (10° C). Samples for RNA isolation and cDNA library preparation were taken after the treatment ended, and single-end 50 bp sequencing was performed (Illumina® Novaseq 6000). The miRNAs were then filtered, mapped, identified and quantified using adequate bioinformatics tools; and the differential expression analysis was carried out using the DEGseq R package. The analysis was performed on 859 miRNAs, after previously executed TPM normalization using the MA-plot-based method with random sampling model (MARS). The threshold for significantly differential expression was set as the Bayesian adjusted p-value, or q-value < 0.01 and log2 fold change > 1. A total of 612 were expressed differentially, but only 55 miRNAs were common for both genotypes and at the same time differentially expressed between control and treatment conditions – 40 novel and 15 known. Half of the common miRNAs showed the same expression patterns in both genotypes, while the other half did not. Among them, seven known miRNAs showed opposing expression patterns between the genotypes (zma-miR167b-3p zma-miR167e-3p, zma-miR159c-5p, zma-miR164g-3p, zma-miR166a-5p, zma-miR

Maize (Zea mays L.) is an important cereal crop of the world and plays a key role in worldwide agriculture with highest production and productivity. Maize is also an important grain crop grown in Serbia, used as a component of feed. Many studies have been conducted on correlations, heritability and path analysis on grain yield. The results have been widely used in maize breeding programs. The present research was carried out at the Maize Research Institute “Zemun Polje” in Serbia during the 2021 growing season effects of grain yield and quantitative traits of maize. Six inbred lines were crossed according to complete diallel method. In this way fifteen hybrids and fifteen reciprocal combinations were obtained. The hybrids and reciprocal combinations derived from these parental components were used in this paper. The objective of study was to estimate direct and indirect effects of five morphological traits on grain yield by the application of the simple coefficient correlation, heritability and path coefficient analysis. 1000-kernel weight with the value of 0.365 had the strongest direct positive effect on grain yield. Positive direct effects on grain yield were also observed for ear length (0.202), ear diameter (0.248) and number of rows per ear (0.076), while negative direct effects were observed for cob diameter (-0.057). Thousand-kernel weight had the highest indirect positive effect on grain yield via ear diameter (0.232). Cob diameter had highest negative indirect effect on grain yield via ear diameter (-0.048). The coefficient of multiple determination (R2y12345) had a value of 0.428.

Maize breeding program at the Maize Research Institute "Zemun Polje" begun during the fifties of the last century and it was based on the principles of inbreeding hybridization. During the sixties, first maize hybrids were registered and each subsequent decade a new generation of hybrids was created. So far, more than 800 maize hybrids have been registered in Serbia and more than 170 hybrids abroad. Testing program includes field evaluations of experimental hybrids in a large number of locations in Serbia, paying attention to the correct choice of environments. Each season 5000-7000 new hybrid combinations have been tested in Serbia. Additionally, the most promising hybrids of different maturity groups are being tested at more than 20 locations abroad, with the aim of selecting the best hybrids for each foreign market. In order to accelerate breeding procedure, service of winter generation in Chile is used, with the aim of obtaining two generations during one calendar year. Since 2014, the application of double haploid technology in maize breeding has started. So far, 13000 double haploid lines have been created from 350 original populations. Optimization of each step in the methodology towards the higher efficiency is the main task for breeders: higher induction rate, higher duplication rate, better agronomic traits of inducers. This year the first hybrid containing a double haploid line has been registered. In addition, several hybrids developed using this method are in registration procedure. Application of molecular markers represents an essential part of modern breeding programs. Use of SNP markers became a routine tool in breeding program of Maize Research Institute. In the last few years, 400 most elite ZP maize inbred lines were characterized using this type of markers. In addition to the creation of hybrids with standard grain quality, breeding program of specific maize hybrids exists and it includes breeding for hybrids with white endosperm, sweet maize an

Hibridi srednje grupe zrenja FAO 500 imaju sve veći značaj u proizvodnji kukuruza u Srbiji. Imajući u vidu da je u poslednjih nekoliko godina prisutan trend gajenja hibrida koji imaju niži sadržaj vlage u momentu žetve, hibridi grupe zrenja FAO 500 predstavljaju odličnu kombinaciju visokog prinosa i nižeg sadržaja vlage u zrnu. Mogu se ubirati i u klipu i u zrnu, što ih čini veoma dobrom alternativom za hibride kasnih grupa zrenja koji se odlikuju visokim potencijalom za prinos ali i visokim sadržajem vlage u žetvi. Hibrid ZP 5557 registrovan je 2023. godine. U ogledima Sortne komisije je ispitivan u periodu 2021-2022. godine. Karakteristično je da su obe godine bile nepovoljne za gajenje kukuruza, što se naročito odnosi na 2022. godinu. Hibrid ZP 5557 je u obe godine ispitivanja ostvario viši prosečan prinos u odnosu na prosek standardnih hibrida, uz niži sadržaj vlage i manji procenat poleglih i slomljenih biljaka. U dvogodišnjem proseku ostvario je prinos od 104,4% u odnosu na prosek standardnih hibrida. Na osnovu rezultata postignutih u ogledima sortne komisije, hibrid ZP 5557 biće uključen u postkomisijske oglede Instituta za kukuruz i u slučaju da ponovi dobar rezultat biće započeta komercijalizacija ovog hibrida., Hybrids of medium maturity group FAO 500 become more important in maize production in Serbia. Taking into account that in the last few years there has been a trend of growing hybrids with lower harvest moisture, the hybrids of the FAO 500 maturity group represent an excellent combination of high yield and lower grain moisture content in harvest. They can be harvested both in ear and grain, which makes them a very good alternative for hybrids of late maturity groups that are characterized by high yield potential but also high moisture content at harvest. Hybrid ZP 5557 was registered in 2023. It was tested in the trials of the State Variety Commission in the period 2021-2022 years. It is characteristic that both years were unfavorable for growing maize, which especially applies to the year 2022. Hybrid ZP 5557 achieved a higher average yield in both years of testing compared to the average of check hybrids, with lower moisture content and a lower percentage of broken and lodged plants. In the two-year average, it achieved a yield of 104.4% compared to the average of check hybrids. Based on the results achieved in the tests of the variety commission, hybrid ZP 5557 will be included in the post-official trials of the Maize Research Institute and in case it obtain good result, the commercialization of this hybrid will be started.

Institut za kukuruz "Zemun Polje" (MRIZP) razvija program oplemenjivanja kukuruza vise od 75 godina. Stvaranje novih hibrida, koji po svojim najvažnijim agronomskim osobinama prevazilaze hibride prethodne generacije predstavlja primarni zadatak svakog oplemenjivača kukuruza. Prisustvo ZP hibrida kukuruza na tržištima Republike Srbije, ali i u inostranstvu, zahteva stvaranje hibrida za različite agroklimatske uslove, kao i za razlicite namene. Spajanje različitih naučno istraživačkih disciplina dovelo je do ubrzanja i povećanja tačnosti procesa oplemenjivanja kukuruza, a samim tim i do smanjenja trajanja ciklusa oplemenjivanja kukuruza u svetu do pet, a u MRIZP-u na 6-7 godina. Od 2014. godine MRIZP uspešno primenjuje program dvostrukih haploida (DH) u oplemenjivanju. Primenom takvog pristupa storeno je više od 13.000 novih DH inbred linija. Kao rezultat primene DH tehnologije, registrovan je prvi hibrid ZP 4019. MRIZP intenzivno radi na karakterizaciji najelitnijeg materijala uz pomoc SNP (Single Nucleotide Markers) markera koristeći 25k SNP Ilumina Infinium Array. Na ovaj način je ostvaren najprecizniji uvid u germplazmu oplemenjivača, odnosno odredjivanjem genetičke udaljenosti (GD). Uz pomoć GD vrednosti povećana je verovatnoća dobijanja superiornih inbred linija i hibrida kukuruza. Već dve sezone MRIZP je započeo visokoinformativnu fenotipizaciju u polju (HTFP), koristeći RGB i multispektralne kamere zasnovane na dronovima za ekstrakciju i vizuelizaciju podataka po parceli. U ovoi fazi istražujemo mogućnost zamene ručnih merenja (kao što je broj i poleganje biljaka), dok je naš konačni cilj da upotrebimo HTFP za donošenje presudnih odluka za hibrid u našim programima oplemenjivanja.

Quality protein maize (QPM) can be beneficial for use in feeds as it was shown that substitution of standard maize (SM) with QPM can improve livestock performance and decrease costly dietary lysine supplementation and protein ingredients. Herein, nutritional and financial effects of QPM adapted to temperate climate in broiler diets were tested. Feeding experiment was performed on two groups of broilers – control (fed with SM) and treatment (fed with QPM). Duration of each feeding trial was 42 days, comprising three phases - starter (1-14), grower (15-35) and finisher (36-42). Diets for all growth phases were formulated based on the biochemical analysis of SM and QPM kernels. Body weight of the chickens was measured on days 1, 7, 14, 35 and 42. Feed intake (FI), body weight gain (BWG), average daily gain (ADG) and feed conversion ratio (FCR) were calculated at the end of each phase. Two trials were performed. In the first, SM was completely replaced with QPM in treatment group diets. As the results indicated better FCR in the treatment group for grower (1.49:1.54) and finisher (1.55:1.60) phases, in the second trial QPM was increased and soybean component decreased by 3%. That led to better results as FCR was even lower but in all three phases, confirming the results of the first trial and further confirming the effects of QPM on feed conversion. Moreover, significant financial reduction in feed was observed, as the price of soybean is usually two to four times higher than the price of maize.

ZPQPM13 is a maize hybrid with improved protein quality, adapted to temperate climate growth conditions, developed by crossing a QPM version of ZPL5 commercial line (developed by marker assisted selection) and GS-6 (a QPM line with 50% tropical and 50% temperate germplasm). This hybrid has grain yield as commercial hybrids, over 90% of hard endosperm, contents of tryptophan and protein over 0.075% and 10%, respectively, and stability of tryptophan content over different locations and years. ZPQPM13 was tested for use in broiler feeds, with the aim to reduce utilization of costly synthetic lysine or soybean components. The feeding experiment on Ross 308 broilers was divided into two groups – control (fed with standard maize) and treatment (fed with QPM). In treatment group diets, ZPQPM13 was increased and soybean component decreased for 3%. Chemical analyses revealed higher contents of limiting essential amino acids in mercantile ZPQPM13 compared to standard maize – 0.44 vs. 0.25 % lysine, 0.077 vs. 0.070 % tryptophan and 0.39 vs. 0.27 % threonine. Duration of each feeding trial was 42 days, comprising three phases - starter (1-14 days), grower (15-35 days) and finisher (36-42 days). Feed intake (FI), body mass gain (BMG), average daily gain (ADG) and feed conversion ratio (FCR) were calculated at the end of each phase. In treatment group, FI was reduced, while BMG and ADG were higher in starter phase but lower in grower and finisher phases. FCR was lower in all three phases in treatment group – 1.13 vs. 1.30, 1.25 vs. 1.33 and 1.28 vs. 1.45. Although a small drawback is that final weight was 3.4 % higher in control broilers, comparison of feed and meat prices show that financial benefits of using QPM are still significant compared to using standard maize in feeds, as soybean is four times more expensive than maize.

Maize hybrids are created by crossing inbreds of opposite heterotic groups, where the discovery of genetic distances (GD) is of great significance. With the presence of modern breeding tools for discovering heterotic pairs and GDs in used material an efficiency in breeding can be increased for more precisely planned field work. For this study 11 crosses were made in order to compare the prediction of data obtained by GDs between crossed inbreds with the results of same hybrids from field testing. Crosses were done in 2020 according to the GD suggestions which ranged from 0.386 to 0.465 to check out is it possible to predict specific superior hybrid performance before the field results itself. 25k SNP Ilumina Infinium Array for maize was used to determine GD values. As a check ZP 457-market accepted hybrid (registered in 2018 in Republic of Serbia) was used together with 10 other hybrids. All 11 hybrids shared the same female component (Lancaster Sure Crop heterotic group), while male components from opposite heterotic groups (BSSS and Iowa dent) were used. GD values of used males ranged from 0.190 to 0.412 clearly stating one broad heterotic group. The most famous heterotic pair B-73 x Mo-17 as well as two Institute’s top selling hybrids (ZP 434 and ZP 606) were also included for GD comparison with test hybrids with the GD values of 0.488, 0.466 and 0.462 respectively. Review of B-73 x Mo-17 through ZP 434 and ZP 606 to the newly created hybrids suggests GD values are decreasing with every new cycle of selection between crossed material. Results from field testing compared to GD values show somewhat positive correlation as for ZP 3 exp which ranked 2nd highest GD value and 3rd rank in grain yield outyielding ZP 457 significantly, but ZP 457 GD value of 0.458 (ranking third in GD) suggests higher yielder should be though to find. Grain yield results proved same hybrid ZP 457 to be one of the lowest yielders being superior only to ZP 4123 despite high GD value. In top

Maize breeding in Maize research institute “Zemun Polje” was conducted for more than 75 years resulting in the creations of numerous maize hybrids with superior traits and performance. The source breeding material used in the breeding programs was very diverse and varied from the domestic landraces to the introduced inbred lines. This resulted in a very diverse and complex structure of the breeding pools used in commercial maize breeding in “Zemun Polje” Institute. As genetic material in this study, 24 maize inbred lines of different origin, heterotic and maturity goups were selected were selected from the 3rd and 4th cycle of breeding in Maize research institute “Zemun Polje”. These are inbreds that were commonly used in breeding programs during the 1980s and were parental components of most important commercial maize hybrids. The genotyping was performed using a Maize 25k Infinium array. The neighbor-joining cladogram, PcoA and Structure were used to analyze the genetic structure and diversity of the panel. Population structure analysis of the panel initially showed a clear divide between Lancaster and Non-Lancaster inbred lines, revealing the dominant heterotic pattern in the breeding program. Further analysis with an increased number of population (k) showed a more complex structure of the non-Lancaster group of inbred lines with best number of ancestral population being k=5. The average genetic distance in the panel was 0,385, ranging from 0,039 to 0,544, with paternal inbreds in most of commercial hybrids being the most distant ones. The genotyping results of the Zemun Polje maize panel were further merged with DROPS European panel of 247 dent maize inbred lines in order to view the results of the diversity analysis of the Zemun Polje panel from a broader perspective.

Small non-coding RNAs (sRNAs) have an important role in regulating plant gene expression, both in developmental processes and stress responses, through RNA interference or silencing. sRNAs respond to environmental stressors in manners dependant on the type of stress, tissue and genetic background. Herein, their role in chilling stress response is examined in young maize seedlings (Zea mays L.) of two inbred lines of contrasting chilling tolerance, using high-throughput sequencing methods. Understanding this response is critical since one of the most promising strategies of avoiding maize yield loss due to climate change is earlier sowing, during periods of suboptimal temperatures. Sterilized seeds of the two lines, marked as LT (tolerant), and LS (sensitive), were germinated in the dark for five days (optimal conditions), after which the 5-d old seedlings were exposed to chilling conditions for 24h (temperature: 10/8 °C; photoperiod: 12/12h). Samples for RNA isolation were taken after 6h and 24h of treatment. After the cDNA library preparations were finished, single-end 50 bp sequencing was performed (Illumina® Novaseq 6000). sRNAseq analysis was performed using a custom pipeline that included quality control, mapping, known miRNA alignment and novel miRNA prediction and quantification. This is an ongoing research and a selection of results will be presented. On average 81% of sRNA reads were succesfully mapped and belong to the class of microRNAs (miRNAs). Some of the sRNAs appear to be differentialy regulated depending on the genotype and the chilling conditions, but more research is needed to verify their potential role in this process.

Maize (Zea mays L.) is the third most grown cereal crop in the world, after wheat and rice. Immature dehusked maize ears harvested before fertilization, within 2-4 days after white silk emergence are classified as baby corn. The objective of this study was to investigate the suitability of baby corn cobs obtained from different maize hybrids for their enrichment with anthocyanins extracted from the black soybean seed coats. Three different maize hybrids, namely, a popcorn hybrid ZP 6119k, a sweet hybrid ZP 553su, a semi-flint with a short vegetation period (105 days) ZP 161, as well as black soybean genotype “Black Tokyo”, were used in this study. Plant material was grown in the experimental field of the Maize Research Institute at the location of Zemun Polje, Serbia in 2021. Maize was harvested after the emergence of silk from the ears (silking stage), while soybean plants were harvested in the stage of full maturity (R8). The baby maize cobs differed in length (9.5-20.0 cm) and girth (12-21 mm), the number of kernel rows (12-20), color, and length of the silk outside the husk (3-7 cm). Soybean seeds were manually dehulled and seed coat was ground in a laboratory mill prior to the extraction of anthocyanins. After dehusking and measuring, the baby corn cobs were washed and blanched for two minutes in boiling water, and then cooled. Subsequently, the baby corn cobs were immersed in a marinating brine enriched with anthocyanins extracted from the seed coat of black soybean, pasteurized, and kept in closed glass jars in a cool dry place for 30 days. After chemical and sensory analyzes, the product obtained from popcorn hybrid ZP 6119k was chosen as the most suitable for the preparation of the marinated baby corn product enriched with anthocyanins from black soybean

Circular RNAs (circRNAs) are endogenous, single-stranded, covalently closed RNA molecules, generated by back-splicing events. Their role as regulators of different processes in animal cells has been widely studied and proven, however functional studies on circRNAs in plants are still few and far between. Here we attempt to bring light to their role in abiotic stress response – particularly chilling stress, in young maize seedlings (Zea mays L.) using high-throughput sequencing methods. One of the strategies of avoiding yield loss is earlier maize sowing as to escape exposure to extremely high temperatures and drought in the summer. This means submitting maize plants to suboptimal temperatures during earlier developmental stages. Two maize inbred lines of contrasting tolerance to chilling were selected and marked as LT (tolerant), and LS (sensitive). Sterilized seeds of the two lines were germinated for five days, in the dark, in optimal conditions and after the germination period was finished, the 5-d old seedlings were exposed to chilling conditions for 24h (temperature: 10/8° C; photoperiod: 12/12h). Sampling was done after 6h and 24h of treatment. After total RNA isolation and purification, quality check, and cDNA library preparations were finished, paired-end 150 sequencing was performed (Illumina® Novaseq 6000). Custom pipeline was used for circRNAseq data analysis and included their identification and quantification (CIRCexplorer2, v2.0.5), differential expression analysis (edgeR Bioconductor v4.1) and functional enrichment (GO, KEGG, psRobot). Processing of this data is still underway, and by now several thousand circRNA molecules and over a thousand 5' and 3' alternative back-splicing sites have been identified. Significant number of those circRNA have shown expression dependent on chilling, as well as genotype, but further studies are necessary to confirm their role in this process, find their target molecules and unravel regulatory networks they create wit

One of the strategies for overcoming global climate change threatening to decrease maize yield is early sowing. To contribute to the development of cold-tolerant hybrids this research focused on the genetic background's comparative analysis in maize inbreds with good combining ability. Leaf whole-transcriptome sequencing of 46 maize genotypes revealed 77 differentially expressed genes (DEGs) between Lancaster and other heterotic groups (i.e. BSSS, Iowa dent, Ohio), referred to as non-Lancaster group, under optimal growing conditions. Cold test of the subset of four Lancaster and four non-Lancaster lines showed that the former were cold sensitive and the latter cold tolerant. Cold-induced expression analysis of seven DEGs in eight lines revealed different expression regulation dependent on the duration of cold exposure and genetic background for six out of seven analysed genes-chloroplast ATP-sulphurylase, photosystem II cytochrome b559 alpha subunit, CIPK serine-threonine protein kinase 15, glutamyl-tRNA reductase, photosystem II reaction centre protein I and Calvin cycle CP12-chloroplastic-like encoding genes. The results imply that differently regulated basic processes between Lancaster and non-Lancaster maize group involve, at least, photosynthesis and sulphate assimilation, contributing to their different cold response and different adaptation to low temperatures.