This study aimed to analyze the seasonal dynamics of sugar beet leaf and root yield and quality in different plant populations and the nitrogen fertilization rate. The field trials were set as four different planting densities (60,000 to 140,000 plants ha−1) and three different spring nitrogen fertilization rates: no fertilization, pre-sowing (45 kg ha−1 N), and pre-sowing with top dressing (99 kg ha−1 N in 2014 and 85.5 kg ha−1 N in 2015. The changes of leaf growth were done measuring leaf area (LA), leaf area index (LAI), specific leaf area (SLA), and leaf area ratio (LAR). The highest LAI in 2014 was determined on 30 July at 140,000 plants ha−1 (9.35 m2 m−1) and in 2015 on 20 June at 100,000 plants ha−1 (4.83 m2 m−2). In both years, the SLA and LAR was highest at the end of May. In relation to plant density, higher plant densities had on average the highest root yield, sucrose content, and white sugar yield. In both years, pre-sowing with top dressing spring nitrogen fertilization resulted in the highest root (95.0 t ha−1) and white sugar yield (11.4 t ha−1), whereas the highest sucrose content was after pre-sowing fertilization (14.9%).

Sixty honey samples from different parts of the northeastern Croatia were examined for pollen content and pollen share. In total, 84 different pollen grains were identified belonging to 40 families. The most represented families in the honey are: Asteraceae, Fabaceae and Rosaceae. Forty samples are unifloral and twenty are multifloral. Twenty six samples of unifloral honey are from Black locust, twelve from Rapeseed, and two from Lime tree. Honey samples contain 9-25 different types of pollen. Dominant pollen types are Brassicaceae and Robinia pseudacacia.

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The aim of this study was to investigate the possibility to reduce the application of mineral nitrogen fertilizers through the application of beneficial microorganisms (genus Bradyrhizobium, Azotobacter, bacteria Pseudomonas fluorescens, Bacillus spp., etc.). Research was conducted during 2013 and 2014 on Eutric brown soil. The experiment was set up in a split-block scheme with 12 different variants in 4 repetitions: two soybean cultivars were used; two different treatments of nitrogen fertilizers and three different treatments of microbiological preparation were applied. Analysed parameters were soybean grain yield (kg/ha) based on 13% moisture, protein content (%), oil content (%) and hectolitre mass (kg). Given that the climatic conditions in the second year of research were more favourable than in the first year of research, all the elements of research, including control variants, achieved better results in the second year of research. All variants treated with microbiological preparations, either by application in soil or by application in soil combined with foliar treatments, also achieved statistically significant differences compared to the control variants.