Variation for Nitrogen Use Efficiency Traits in Wheat Under Contrasting Nitrogen Treatments in South-Eastern Europe.

Wheat cultivars differ in their response to nitrogen (N) fertilizer, both in terms of its uptake and utilization. Characterizing this variation is an important step in improving the N use efficiency (NUE) of future cultivars while maximizing production (yield) potential. In this study, we compared the agronomic performance of 48 diverse wheat cultivars released between 1936 and 2016 at low and high N input levels in field conditions to assess the relationship between NUE and its components. Agronomic trait values were significantly lower in the low N treatment, and the cultivars tested showed a significant variation for all traits (apart from the N remobilization efficiency), indicating that response is genotype-dependent, although significant genotype × environment effects were also observed. Overall, we show a varietal improvement in NUE over time of 0.33 and 0.30% year-1 at low and high N, respectively, and propose that this is driven predominantly by varietal selection for increased yield. More complete understanding of the components of these improvements will inform future targeted breeding and selection strategies to support a reduction in fertilizer use while maintaining productivity.

Thermal Pretreatment of Harvest Residues and Their Use in Anaerobic Co-digestion with Dairy Cow Manure.

Several batch experiments were conducted on the anaerobic co-digestion of dairy cow manure (DCM) with three harvest residues (HR) (soybean straw, sunflower stalks, and corn stover). The influence of thermal pretreatment of HR on biogas production was investigated, where the HR were thermally pretreated at two different temperatures: T = 121 °C and T = 175 °C, during t = 30 and t = 90 min, respectively. All anaerobic co-digestion batch experiments were performed simultaneously under thermophilic regime, at T = 55 °C. Biogas and methane yields were significantly improved in experiments performed with corn stover thermally pretreated at 175 °C for 30 min (491.37 cm3/g VS and 306.96 cm3/g VS, respectively), if compared to experiments performed with untreated corn stover. The highest VS and COD removal rates were also observed in the same group of experiments and were 34.5 and 50.1%, respectively. The highest biogas and methane yields with soybean straw (418.93 cm3/g VS and 261.44 cm3/g VS, respectively) were obtained when soybean straw pretreated at 121 °C during 90 min. The highest biogas and methane yields with sunflower stalk (393.28 cm3/g VS and 245.02 cm3/g VS, respectively) were obtained when sunflower stalk was pretreated at 121 °C during 90 min.

Reduced Dietary Selenium Impairs Vascular Function by Increasing Oxidative Stress in Sprague-Dawley Rat Aortas.

This study aimed to determine whether low dietary Se content affects the function and mechanisms mediating the vascular relaxation of rat aortas, and to test the role of oxidative stress in observed differences. Male Sprague Dawley (SD) rats were maintained for 10 weeks on low Se (low-Se group; N = 20) or normal Se content (norm-Se group; N = 20) rat chow. Dose responses to acetylcholine (ACh; 10-9-10-5M) and the response to reduced pO2 were tested in noradrenaline-precontracted aortic rings in the absence/presence of the nitric oxide synthase (NOS) inhibitor nitro-l-arginine methyl ester (l-NAME), the cyclooxygenase 1 and 2 (COX-1, 2) inhibitor Indomethacin, and the antioxidative agent Tempol in tissue bath. mRNA expression of glutathione peroxidase 1 (GPx1), catalase (CAT), and Cu/Zn superoxide dismutase (SOD) was measured in rat aortas. Oxidative stress (Thiobarbituric Acid Reactive Substances; TBARS), antioxidative plasma capacity (ferric reducing ability of plasma assay; FRAP), and protein levels of GPx1 were measured in plasma and serum samples, respectively. Reduced ACh-induced relaxation (AChIR) (dominantly mediated by NO) in the low-Se group compared to the norm-Se group was restored by Tempol administration. Hypoxia-induced relaxation (HIR) (dominantly mediated by COX-1, 2), TBARS, and FRAP as well as GPx1 serum concentrations were similar between the groups. mRNA GPx1 expression in rat aortas was significantly decreased in the low-Se compared to the norm-Se group. These data suggest that low dietary Se content increases the local oxidative stress level, which subsequently affects the NO-mediated vascular response.

Soil chemicals properties and wheat genotype impact on micronutrient and toxic elements content in wheat integral flour.

AIM: To determine impact of soil chemical properties and different wheat genotypes in Croatia on micronutrient and toxic elements content in wheat integral flour. METHODS: Research was conducted and soil samples were collected from two different production areas in the Republic of Croatia: Ovcara and Dalj. Besides soil samples, grain samples of four different Croatian wheat genotypes were also collected and analyzed. In total, 40 samples of soil and 40 samples of wheat grain were analysed for total (aqua regia) and plant available (EDTA extraction) heavy metal content of Fe, Mn, Zn, Cu, Pb, Cd RESULTS: Determined soil pHKCl ranged from 5.63 to 6.25 at Ovcara and from 6.95 to 7.37 at Dalj sampling sites. The highest total concentration of heavy metals in soil were determined for Fe, followed by Mn, Zn, Cu, Pb and the lowest total concentration was recorded for Cd. The highest EDTA concentrations in soil were determined for Mn, than followed by Fe, Cu, Pb, and the lowest EDTA concentration was recorded for Cd. The highest concentration in integral wheat flour was found for Fe, than lower for Mn, Zn, Cu, Pb and the lowest concentration was found for Cd. If consumers in Croatia used daily 203 g of bread made of integral flour, they would take 2.31 to 8.44 µg Cd daily, depending on soil and wheat genotype. CONCLUSIONS: The analysed soil and winter wheat genotypes have significant impact on potential daily intake of toxic and essential heavy metals by integral flour or bread.