Variability of maize inbred lines in nitrogen use effciency

Abstract

Nitrogen (N) is an important element for many physiological processes in crops, and grain yield realisation. Nitrogen loss could be significant through leaching and evaporation, and from this reason lower quantities for fertilization are required. A genotype could be an important source for improved N management in crops. Breeding for high yield and nutrient-efficient genotypes is the most important strategy to enable food security, resolve resource scarcity and environmental pollution. Variability of 36 maize lines grown in optimal and low-N (without fertilization) conditions was assessed through grain yield, 1000 kernel weight, N utilization efficiency (NUtE) and N apparent recovery fraction (nitrogen use efficiency – NUE), during seasons 2017 and 2018. The genotype and year are important sources for variation of grain yield, 1000 kernel weight and NUtE, as a factor which defines N utilization efficiency. The lines, such as L1, L6, L13, L16, L26, L27, L32 and L34 are able to achieve higher grain yield when grown on low-N. Furthermore, L16, L22, L24 and L26 have high NUtE values in both experimental years (even in 2017, season with low and unequal precipitation level), especially in low-N treatment. From that point of view, they could be characterized as efficient N users, even in low-N conditions, as well as tolerant to stressful conditions. Nevertheless, L1, L6 and L27 are the lines with negative NUE, what gives them attribute as the best N users in low-N conditions. Based on the similarity of NUtE values, the genotypes such as L2, L3, L4, L8, L11, L12, L14, L15, L16, L18, L19, L24, L26, L32, L33, L34 could be considered as the primary focus for further breeding programs, due to the fact that they don’t have only improved NUE, but also high grain yield (even in unfavourable years), which indicates improved tolerance to various abiotic stressful factors.

Azot je element koji je važan za brojne fiziološke procese, kao i ostvarenje prinosa useva. Veliki gubici azota se ostvaruju putem ispiranja i evaporacije i stoga se preporučuju niže doze ovog elementa za đubrenje. Genotip može predstavljati važnu bazu za efikasniji menadžment azotom kod useva. Selekcija genotipova sa visokim prinosom i efikasnošću iskorišćenja nutritiva predstavlja važnu strategiju za istovremeno obezbeđivanje sigurnosti hrane, rešavanje nedostatka resursa i zagađenja životne sredine. Varijabilnost u reakciji 36 linija kukuruza gajenih u uslovima optimalne N obezbeđenosti i niskog N (bez đubrenja) praćena je tokom 2017. i 2018. godine, preko prinosa zrna, mase 1000 zrna, efikasnosti iskorišćenja N (NUtE) i nadoknade N (NUE). Genotip i godina su predstavljali važne izvore variranja prinosa zrna, mase 1000 zrna i NutE, kao faktora koji definišu efikasnost iskorišćenja N. Linije L1, L6, L13, L16, L26, L27, L32 i L34 su imale veće vrednosti prinosa u uslovima niskog N. Osim toga, L16, L22, L24 i L26 su imale veće vrednosti NutE tokom obe eksperimentalne sezone (čak i u 2017, sezoni sa nižim nivoom i lošijim rasporedom padavina), posebno pri niskom N. Sa te tačke gledašta, navedene linije bi mogle biti okarakerisane kao efikasni N potrošači, kao i genotipovi sa većom toleratnošću na stresne uslove. Takođe, L1, L6 i L27, sa negativnim NUE vrednostima bi mogle predstavljati najekonomičnije N potrošače u uslovima niske N obezbeđenosti. Na osnovu sličnosti NutE vrednosti, genotipovi L2, L3, L4, L8, L11, L12, L14, L15, L16, L18, L19, L24, L26, L32, L33, L34 bi mogli da predstavljaju fokus, odnosno, mogli bi načelno da se uzmu u razmatranje u selekcionim programima, s obzirom da nemaju samo poboljšan NUE, već i visok prinos (čak i tokom nepovoljne sezone), u odnosu na ostale genotipove, što bi ih moglo okarakterisati kao genotipove sa poboljšanom tolerantnošću na abiotički stres.