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The variations in temperature and rainfall patterns under climate change are threatening crop production systems, and optimizing fertilization practices is a prerequisite for sustainable cereal production. This two-year field study investigated the effects of eight treatments (T1: P60K60; T2: P60K60 + Nmin spring; T3: P60K60 + N40autumn + Nmin spring; T4: P60K60 + N60spring; T5: P60K60 + N100spring; T6: P60K60 + N40autumn + N60spring + Zn; T7: P60K60 + N60autumn + N80spring + Zn; and T8: P60K60 + N160spring + Zn) on the grain yield and quality of four divergent maize cultivars (NS-4023, NS-640, NS-6010 and NS-6030). The observations on climatic data showed substantial variations in monthly and cumulative rainfall only, which was 174 and 226 mm for 2011 and 2012, respectively, and much less than the historical cumulative rainfall of 339 mm. However, temperature during growth years showed little deviation from the historical data. The data showed that treatment and maize cultivar significantly influenced grain yield; however, grain yield remained lower in 2012 than in 2011 for each treatment and cultivar. Applying N as split doses in combination with Zn, resulted in higher grain yields than adding at once. However, the treatments and cultivars affected grain quality variables differently, including oil, thiol SH, phytate, inorganic P, soluble protein, starch, total phenol, protein, total sugars and tryptophan contents. Despite the pronounced difference in grain yields between 2011 and 2012 for each treatment and cultivar, grain quality did not always vary significantly between cultivars. Principal component analysis (PCA) revealed that the relationships between grain yield and grain quality varied significantly during 2011 and 2012. The changes in rainfall patterns at critical growth maize stages seemed to be a more important factor than temperature in regulating the response of maize cultivars in terms of grain yield and quality to various fertilization regimes in this study. [ABSTRACT FROM AUTHOR]

The topic of N wheat nutrition was prevalent during the last decades of the 20th century for many reasons such as energy crises, profitability of small grain production, and ecosystem protection and preservation. The objective of this study was to determine the interrelationships between wheat (Triticum aestivum L.) grain N content and other indicators of N nutrition efficiency to better understand the N nutrition process in wheat plants. The experiment included 30 wheat cultivars and experimental lines from Serbia. Plant samples of each genotype were taken at anthesis and maturity. The following parameters related to N accumulation and translocation within the wheat plant were calculated: N content (at anthesis, grain, straw, and total at maturity), N harvest index (NHI), N reutilization (N reU), and N lost (-) or gained (N post-anthesis). Our results showed that N content in the aboveground part of the plant expressed very strong direct positive effects on N yield (phenotypic coefficient 3.78** to 9.34** and genotypic coefficient 1.43** to 2.32**), while its indirect effects varied. The influence of independent variables on grain N content has been changing from year to year in a negative way. Total N accumulation (N total) had the highest negative direct effect in the first year of the study (phenotypic coefficient -2.11**), N total in the second (phenotypic coefficient -2.78**), and N reutilization in the third (phenotypic coefficient -8.49**). Genotypic coefficients indicate that the most frequent strong direct negative effect was N reutilization (-0.47** and -0.99** in the first 2 yr of research, respectively). Nitrogen reutilization and its current assimilation are very important and related to grain N supply processes. Their interaction leads to the conclusion that forming N yield is a very complex mechanism and, as a result, grain yield and quality. The abovementioned parameters could be considered as important criteria in wheat breeding to improve production efficiency and reduce adverse impacts of N fertilizers on the ecosystem. [ABSTRACT FROM AUTHOR]