Analysis of yield components to address inconsistent maize (Zea mays L.) grain yields across plant populations is limited in Europe and the United States. The research objectives were to compare maize yield components at low and high plant populations in eastern Nebraska and central Croatia using path analysis to better understand maize grain yield determination with changing plant population and determine relative importance among maize primary and secondary yield components. Research was conducted by planting three maize hybrids at 65,000 plants ha−1 to 105,000 plants ha−1 in 2012 and 2013 at Zagreb, Croatia, and Mead, NE. Grain yield, ears per square meter, rows per ear, ear circumference, kernels per ear, kernels per row, ear length, and kernel weight were determined. Average grain yield was 10.7 Mg ha−1 and plant population influence on yield was inconsistent and <2 Mg ha−1. Among yield components, the number of rows per ear (direct effect of 0.54 [P ≤ 0.01] with kernels per ear and 0.39 [P ≤ 0.01] with kernels per row) and the number of kernels per ear (direct effect of 0.54 [P ≤ 0.01] with grain yield) were of most importance for maize at high plant populations, while the number of kernels per row (direct effect of 0.93 [P ≤ 0.01] with kernels per ear and 0.61 [P ≤ 0.01] with kernel weight) and kernel weight (direct effect of 0.47 [P ≤ 0.01] with grain yield) were most important at low plant populations. Future maize management research for low plant population environments should focus on production of the number of kernels per ear and kernel weight, while for high plant populations, the focus should be on the number of rows per ear.

Maize (Zea mays L.) yield component analysis is limited. Research was conducted in 2012 and 2013 at Zagreb, Croatia and Mead, Nebraska, United States with the objective to determine the influence of environment, hybrid maturity, and plant population (PP) on maize yield and yield components. Three maturity classes of maize hybrids were produced at five PP ranging from 65,000 to 105,000 plants ha -1 under rainfed conditions. Yield, ears m -2 , rows ear -1 , ear circumference, kernels ear -1 , kernels row -1 , ear length, and kernel weight were determined. Average yield was 10.7 t ha -1 , but was variable for hybrids across PP. The early maturity-hybrids had lesser ear circumference, more kernels ear -1 , greater ear length, and fewer rows ear -1 than mid-and late-maturity hybrids. Kernels ear -1 had the highest correlation with yield (r = 0.47; P < 0.01 for early-maturity hybrids; r = 0.55; P < 0.01 for the mid-and late-maturity hybrids). Path analysis indicated that ears m -2 , kernels ear -1 and kernel weight had similar direct effects on yield for early-maturity hybrids (R = 0.41 to 0.48) while kernels ear -1 had the largest direct effect (R = 0.58 versus 0.32 to 0.36) for the midand late-maturity hybrids. Rows ear -1 had an indirect effects on yield (R = 0.30 to 0.33) for all hybrids, while kernels row -1 had indirect effect (R = 0.46) on yield for mid-and latematurity hybrids. Yield component compensation was different for early-maturity hybrid than the mid-and late-maturity hybrids, likely due to the proportion of southern dent and northern flint germplasm present in these hybrids.

The aim of this paper is to determine the difference in quality of the digested residue a�er the process of anaerobic digestion by using different input raw materials. The research was conducted in the Republic of Austria on four facilities for biogas production. The raw materials used for biogas production were chicken manure, pig manure, Sudan grass and organic household waste. The research included chemical analysis and bacteriological tests of the samples taken. It was found that the digested residue in all of the samples, all of which are mildly alkaline, contains a low level of dry ma�er, 70% of which is organic ma�er. Biogenic elements were present in moderate concentration; the values of heavy metals were within approved limits. This analysis leads to the conclusion that the digested residues of all input materials can be used in agricultural production, especially so in plant production and grassland cultivation. Mesophilic and thermophilic microorganisms were found in the digested residue samples, but there were no cryophilic microorganisms and no pathogenic bacteria.

Analysis of yield components in maize (Zea mays L.) hybrids across planting dates is limited. Research was conducted in 2013 and 2014 at Mead, Nebraska, United States with the objective to determine the influence of year, hybrid, drought tolerance type, and maturity classification across planting dates on maize yield and yield components. Early-and late-maturity DroughtGard (with CspB transgene) maize hybrids, and a late-maturity non-DroughtGard maize hybrid were planted at three dates in each year. Average maize yields were 10.8 ± 1.3 t/ha in 2013 and 13.6 ± 1.6 t/ha in 2014 with little difference across planting dates. Yield for 109 to 114 CRM (610 to 650 FAO maturity) hybrids was 13 ± 1.9 t/ha compared to 11 ± 1.6 t/ha for 97 to 100 CRM (450 to 480 FAO maturity) hybrids, and similar yields for late DroughtGard and non-DroughtGard hybrids were found. The yield of the earlymaturity DroughtGard hybrids was associated most with direct effects of the number of ears per square meter (R = 0.53**) and kernels per ear (R = 0.44**) while the latematurity DroughtGard hybrids were affected most by the direct effects of ears per square meter (R = 0.54**) and kernel weight (R = 0.57**). Yield components accounted for most yield differences between hybrids with different maturity classifications. Yield component compensation which occurred between DroughtGard and non-DroughtGard hybrids led to similar grain yields across planting dates.

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