Analiza genetičke varijabilnosti kukuruza na tolerantnost prema suši

Abstract

Suša je glavni abioticki faktor, koji znacajno utice na smanjenje i kvalitetkonacnog prinosa zrna kod kukuruza. S obzirom na predvidanja globalnih klimatskihpromena za 21. vek, u pravcu povecanja temperature vazduha, vece evapotranspiracije iucestalije pojave suše, poboljšana sposobnost kukuruza da izdrži nepovoljne uslovespoljašnje sredine je esencijalna i zahteva multidisciplinarni pristup u proucavanjuosobina koje doprinose njegovoj povecanoj tolerantnosti prema stresu suše.Za potrebe savremene selekcije kukuruza za razlicite osobine (npr. tolerantnostprema suši), materijal koji se cuva u banci gena Instituta za kukuruz “Zemun Polje”, posvom obimu (5806 genotipova) i ogromnoj genetickoj varijabilnosti, pruža velikemogucnosti. Testiranje celokupnog genofonda na tolerantnost prema suši je izvršeno uuslovima kontrolisane suše u Egiptu, kao i u uslovima umerenog vodnog deficita uZemun Polju i Skoplju, grupisanjem genotipova po dužini vegetacije (po grupamazrenja), kako bi svi bili izloženi stresu suše u približno istoj fazi vegetacionog perioda.Identifikacija i odabir genotipova su vršeni pracenjem sekundarnih osobina relevantnihza 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 genotipovanajtolerantnijih prema stresu suše, kao buducih komponenti hibrida, bila je neophodnainformacija o pripadnosti genotipova odgovarajucim heteroticnim grupama na osnovuukrštanja sa korišcenim inbred testerima, poreklom iz tri heteroticne grupe - BSSS,Lancaster i nezavisne, kao i informacija o opštoj kombinacionoj sposobnosti ukrštanjagenotipova sa odabranim inbred testerima. Od izuzetnog znacaja je bilo izdvajanje 6genotipova kukuruza, koji su se dobro kombinovali sa sva tri korišcena heteroticnaizvora, cineci potencijalno nov, sasvim razlicit izvor poželjne germplazme. Na osnovudobijenih rezultata, formirana je core kolekcija za tolerantnost prema suši, koju cine 13domacih populacija, 13 introdukovanih populacija i 15 introdukovanih inbred linijakukuruza...

Drought is a major abiotic factor, which significantly decreases final grain yieldand its quality in maize. Predictions of global climate changes for 21st century, towardshigher air temperatures, greater evapotranspiration and more frequent occurrence ofdrought, emphasize the importance for improved maize ability to withstand adverseenvironmental conditions, and the necessity of employing the multidisciplinaryapproach for studying the characteristics that contribute to its increased droughttolerance.The material maintained within The MRI “Zemun Polje” gene bank, consideringits size (5806 genotypes) and huge genetic variability of the accessions, offers the greatopportunity for modern maize breeding for different purposes (e.g. drought tolerance).Field testing for drought tolerance was performed on the entire MRI gene bankcollection, subjected to controlled drought in Egypt, as well as to conditions ofmoderate water deficit in Zemun Polje and Skopje. In order to expose them to droughtstress at aproximately the same vegetative stage, grouping the accessions into differentmaturity groups (acording to the duration of their vegetative period), was necessary.Identification and selection of the most drought tolerant genotypes was performed byvisual scoring of drought related secondary traits (ASI - anthesis silking interval,barrenness, seed set, grain filling and stay-green) at each location, and by measuringyield / plant under moderate water deficit conditions.Besides good performances per se in field, the information on combining abilityof selected material, in order to classify it into heterotic groups, was necessary to formthe core. Therefore, the most drought tolerant genotypes were crossed to three inbredtesters from heterotic groups that mutually combined well (BSSS, Lancaster andindependent source). It is very important that 6 genotypes had a good combining abilitywith all three observed heterotic sources, making them a new, completely differentsource of favourable germplasm. Obtained results revealed the formation of corecollection for drought tolerance, comprising 13 local populations, 13 introducedpopulations and 15 introduced maize inbred lines...