Variability of maize lines in ability to use nitrogen

Abstract

Nitrogen is an important macro-nutrient that influences various physiological processes in plants. Nevertheless, nitrogen could be loosed from the soil by leaching and evaporation. Thus, low nitrogen inputs are required together with a strategy to improve its utilization by crops. Maize genotypes exhibit various susceptibility to low soil nitrogen. From that reason, variability in the reaction of 32 maize lines to growing in conditions with optimal (fertilization with urea), and with low nitrogen (without fertilization) was examined during 2017 and 2018. All other growing measures and fertilization with other elements was applied in the same manner on the whole experimental plot. 2017 was a drier season, with higher average temperatures, particularly during anthesis and grain filling period. High variability among genotypes and seasons was present. The values of maize grain yield and 1000 grain weight were slightly higher in treatment with nitrogen application. Some lines under the low nitrogen conditions reached even higher grain yields (efficacy of yielding was 139.7% and 156.7%, for 2017 and 2018) than in conditions with optimal nitrogen in the soil, such as L1, L2, L5, L10, L11, L13, L15, L23 and L31, declaring them as genotypes with high nitrogen using efficiency. However, these lines achieved moderate yields (in both treatments and years) in regard to other lines. Among tested lines, L1 and L23 had higher grain yields in both fertilization treatments indicating them as prominent for further research, i.e. breeding of maize hybrids with better nitrogen usage from the soil, even in the conditions with low nitrogen.

Azot je važan makro-element koji je uključen u brojne fiziološke procese kod biljaka. Međutim, gubici azota iz zemljišta putem ispiranja i evaporacijom mogu biti veliki, tako da su preporučljivi niži unosi u kombinaciji sa strategijama koje poboljšavaju njegovo usvajanje. Genotipovi kukuruza različito reaguju na nizak nivo azota u zemljištu. Stoga je ispitana varijabilnost u reakciji 32 linije kukuruza na gajenje u uslovima optimalne obezbeđenosti (đubrenje ureom) i niskog nivoa azota (bez đubrenja), tokom 2017. i 2018. godine. Sve ostale mere gajenja i đubrenja sa drugim elementima su primenjene na isti način na celoj eksperimentalnoj površini. 2017. godina je bila sa manje padavina, sa većim prosečnim dnevnim temperaturama, posebno tokom perioda cvetanja i nalivanja zrna kukuruza. Bila je prisutna visoka varijabilnost između ispitivanih genotipova i sezona. Vrednosti prinosa i mase 1000 zrna su bile nešto niže na delu ogleda bez đubrenja azotom. Na istom delu ogleda su neke linije (L1, L2, L5, L10, L11, L13, L15, L23 i L31) imale čak veći prinos, u odnosu na deo ogleda sa optimalnim nivoom azota u zemljištu (efikasnost prinosa je bila 139.7% i 156.7%, za 2017. i 2018.), karakterišući ih stoga kao vrlo efikasne u smislu iskorišćenja azota. Međutim, navedene linije su ostvarile nešto niže vrednosti prinosa zrna (u oba tretmana i u obe godine) u odnosu na ostale linije. Od svih ispitivanih, L1 i L23 su imale relativno veće prinose u oba tretmana, što ukazuje da bi mogle biti pogodne za dalja istraživanja, tj. u oplemenjivanju hibrida sa boljom efikasnošću iskorišćenja azota čak i u uslovima njegovog niskog sadržaja u zemljištu