Drought is a major abiotic factor, which significantly decreases final grain yield and its quality in maize. Predictions of global climate changes for 21st century, towards higher air temperatures, greater evapotranspiration and more frequent occurrence of drought, emphasize the importance for improved maize ability to withstand adverse environmental conditions, and the necessity of employing the multidisciplinary approach for studying the characteristics that contribute to its increased drought tolerance. The material maintained within The MRI “Zemun Polje” gene bank, considering its size (5806 genotypes) and huge genetic variability of the accessions, offers the great opportunity for modern maize breeding for different purposes (e.g. drought tolerance). Field testing for drought tolerance was performed on the entire MRI gene bank collection, subjected to controlled drought in Egypt, as well as to conditions of moderate water deficit in Zemun Polje and Skopje. In order to expose them to drought stress at aproximately the same vegetative stage, grouping the accessions into different maturity groups (acording to the duration of their vegetative period), was necessary. Identification and selection of the most drought tolerant genotypes was performed by visual scoring of drought related secondary traits (ASI - anthesis silking interval, barrenness, seed set, grain filling and stay-green) at each location, and by measuring yield / plant under moderate water deficit conditions. Besides good performances per se in field, the information on combining ability of selected material, in order to classify it into heterotic groups, was necessary to form the core. Therefore, the most drought tolerant genotypes were crossed to three inbred testers from heterotic groups that mutually combined well (BSSS, Lancaster and independent source). It is very important that 6 genotypes had a good combining ability with all three observed heterotic sources, making them a new, completely different source of favourable germplasm. Obtained results revealed the formation of core collection for drought tolerance, comprising 13 local populations, 13 introduced populations and 15 introduced maize inbred lines. Increased tolerance to drought of all genotypes at flowering, was followed by a small ASI (up to 2,69 days), lower barrenness rate (up to 13,16%), higher seed set rate (up to 93,08%), as well as higher grain filling rate (up to 95,38% ), while the trait of stay green was the most pronounced under extreme water deficit conditions. Grain yield / plant of all genotypes was higher in Zemun Polje in relation to Skopje. SSR molecular characterization has revealed a high level of genetic diversity within each group of maize genotypes (genetic similarity of local populations was 0,31, of introduced populations was 0,54 and of introduced inbreds was 0,37) and confirmed genotypes assignment to heterotic groups, based upon their combining ability with used inbred testers. Investigation of morpho-physiological and biochemical basis of drought tolerance at early maize seedling stage under applied osmotic stress, confirmed the existence of variability among the genotypes, as exhibited in the field. In all genotypes, osmotic stress caused the reduction in growth parameters (length and fresh weight of both roots and shoots), as well as increased root to shoot ratio of the observed parameters. The effect of osmotic stress on proline content was much more pronounced in the roots, leading to average increase in its accumulation up to 59,2%. Statistically highly significant correlations between changes in proline content and changes in all observed growth parameters of roots and shoots were detected. Increased POD activities under osmotic stress, as well as increased anionic POD isoforms in treatment, indicated the existance of increased tolerance to osmotic stress. Significant correlations were found between specific POD activity and proline content changes (r = -0,610 *), ie. changes in root fresh weight (r = 0,572*). Significant positive correlation was found between grain yield / plant in the field and change of proline content in seedlings roots (r = 0,519*), as well as a highly significant negative correlation between grain yield / plant and the change of seedling root length (r = -0,658 **). Suša je glavni abioticki faktor, koji znacajno utice na smanjenje i kvalitet konacnog prinosa zrna kod kukuruza. S obzirom na predvidanja globalnih klimatskih promena za 21. vek, u pravcu povecanja temperature vazduha, vece evapotranspiracije i ucestalije pojave suše, poboljšana sposobnost kukuruza da izdrži nepovoljne uslove spoljašnje sredine je esencijalna i zahteva multidisciplinarni pristup u proucavanju osobina koje doprinose njegovoj povecanoj tolerantnosti prema stresu suše. Za potrebe savremene selekcije kukuruza za razlicite osobine (npr. tolerantnost prema suši), materijal koji se cuva u banci gena Instituta za kukuruz “Zemun Polje”, po svom obimu (5806 genotipova) i ogromnoj genetickoj varijabilnosti, pruža velike mogucnosti. Testiranje celokupnog genofonda na tolerantnost prema suši je izvršeno u uslovima kontrolisane suše u Egiptu, kao i u uslovima umerenog vodnog deficita u Zemun Polju i Skoplju, grupisanjem genotipova po dužini vegetacije (po grupama zrenja), kako bi svi bili izloženi stresu suše u približno istoj fazi vegetacionog perioda. Identifikacija i odabir genotipova su vršeni pracenjem sekundarnih osobina relevantnih za stres suše (ASI-a - anthesis silking interval, jalovosti biljke, ozrnjenosti klipa, nalivenosti zrna i osobine stay green-a), na sva tri lokaliteta, i merenjem prinosa zrna / biljci u uslovima umerenog vodnog deficita. Pored dobrih per se performansi u poljskim uslovima, za odabir genotipova najtolerantnijih prema stresu suše, kao buducih komponenti hibrida, bila je neophodna informacija o pripadnosti genotipova odgovarajucim heteroticnim grupama na osnovu ukrštanja sa korišcenim inbred testerima, poreklom iz tri heteroticne grupe - BSSS, Lancaster i nezavisne, kao i informacija o opštoj kombinacionoj sposobnosti ukrštanja genotipova sa odabranim inbred testerima. Od izuzetnog znacaja je bilo izdvajanje 6 genotipova kukuruza, koji su se dobro kombinovali sa sva tri korišcena heteroticna izvora, cineci potencijalno nov, sasvim razlicit izvor poželjne germplazme. Na osnovu dobijenih rezultata, formirana je core kolekcija za tolerantnost prema suši, koju cine 13 domacih populacija, 13 introdukovanih populacija i 15 introdukovanih inbred linija kukuruza. Kod svih genotipova, povecana tolerantnost na stres suše u fazi cvetanja, pracena je malim ASI-jem (do 2,69 dana), niskom jalovošcu biljke (do 13,16%), visokom ozrnjenošcu klipa (do 93,08%) i dobrom nalivenošcu zrna (do 95,38%), dok se stay green najviše ispoljio u uslovima izrazitog vodnog deficita. Prinos zrna / biljci za sve genotipove je bio viši u Zemun Polju u odnosu na Skoplje. SSR molekularna karakterizacija je utvrdila visok stepen genetickog diverziteta unutar svake ispitivane grupe genotipova kukuruza (geneticka slicnost domacih populacija je iznosila 0,31, introdukovanih populacija 0,54 i introdukovanih inbred linija 0,37) i potvrdila grupisanje genotipova u odgovarajuce heteroticne grupe, na osnovu njihove kombinacione sposobnosti sa korišcenim inbred testerima. Ispitivana morfo-fiziološka i biohemijska osnova tolerantnosti na sušu u ranoj fazi razvica kukuruza u uslovima simuliranog osmotskog stresa, potvrdila je postojanje varijabilnosti izmedu genotipova, ispoljene u uslovima stresa suše u polju. Kod svih genotipova je došlo do smanjenja parametara rasta (dužine i sveže mase korena i nadzemnog dela), kao i povecanja odnosa koren - nadzemni deo za posmatrane parametre. Efekat osmotskog stresa na sadržaj prolina je bio mnogo izraženiji u korenu, dovodeci do prosecnog povecanja njegove akumulacije i do 59,2%. Utvrdene su statisticki visoko znacajne korelacije izmedu promene sadržaja prolina i promene dužine, sveže i suve mase korena i lista. Povecane POD aktivnosti u uslovima osmotskog stresa, kao i povecanje intenziteta anjonskih POD izoformi u tretmanu, su ukazale na povecanu tolerantnost genotipova na uticaj osmotskog stresa. Utvrdene su statisticki znacajne korelacije izmedu specificne POD aktivnosti i promene sadržaja prolina (r = -0,610*), odnosno promene sveže mase korena (r = 0,572*). Utvrdena je znacajna pozitivna korelacija prinosa zrna / biljci u polju sa promenom sadržaja prolina u korenu klijanaca (r = 0,519*), kao i visoko znacajna negativna korelacija sa promenom dužine korena klijanaca (r = -0,658**).