Rational application of different forms of nitrogen (N) fertilizer for peanut (Arachis hypogaea L.) requires tracking the N supplied sources which are commonly not available in the differences among the three sources: root nodule, soil and fertilizer. In this study, two kinds of peanut plants (nodulated variety (Huayu 22) and non-nodulated variety (NN-1)) were choosed and four kinds of N fertilizers: urea-N (CONH2-N), ammonium-N (NH4 +-N), nitrate-N (NO3 –-N) and NH4 ++NO3 –-N labeled by 15N isotope were applied in the field barrel experiment in Chengyang Experimental Station, Shandong Province, China, to determine the N supplied sources and N use efficiency over peanut growing stages. The results showed that intensities and amounts of N supply from the three sources were all higher at middle growing stages (pegging phase and podding phase). The accumulated amounts of N supply from root nodule, soil and fertilizer over the growing stages were 8.3, 5.3 and 3.8 g m–2 in CONH2-N treatment, which are all significantly higher than in the other three treatments. At seedling phase, soil supplied the most N for peanut growth, then root nodule controlled the N supply at pegging phase and podding phase, but soil mainly provided N again at the last stage (pod filling phase). For the whole growing stages, root nodule supplied the most N (47.8 and 43.0%) in CONH2-N and NH4 +-N treatments, whereas soil supplied the most N (41.7 and 40.9%) in NH4 ++ NO3 –-N and NO3 –-N treatments. The N use efficiency was higher at pegging phase and podding phase, while accumulated N use efficiency over the growing stages was higher in CONH2-N treatment (42.2%) than in other three treatments (30.4% in NH4 +-N treatment, 29.4% in NO3 –-N treatment, 29.4% in NH4 ++NO3 –-N treatment). In peanut growing field, application of CONH2-N is a better way to increase the supply of N from root nodule and improve the N use efficiency.

    A 45 d pot experiment was conducted to examine the effects of silicon fertilizer or iron fertilizer on the growth of two typical Ipomoea aquatica cultivars (Daye and Liuye) and arsenic (As) accumuation of Daye and Liuye grown in As-contaminated soils at different As dosage levels. The results showed that the application of these two fertilizers generally enhanced the growth of the plants, which may be partly attributable to the reduction in As toxicity. The addition of these two fertilizers also significantly reduced the uptake of As by the plants though the iron fertilizer was more effective, as compared to the silicon fertilizer. The accumulation of As in shoot portion was weaker for Daye than for Liuye. The research findings obtained from this study have implications for developing cost-effective management strategies to minimize human health impacts from consumption of As-containing I. aquatica.

Supercritical carbon dioxide (SC-CO2) extraction was employed to extract oil from Nigella glandulifera Freyn seed in this study. Response surface methodology (RSM) was applied to evaluate the effects of the process parameters (pressure, temperature, and CO2 flow rate) on oil yield of N. glandulifera seed. A Box-Behnken design was used to optimize the extraction parameters. The analysis of variance indicated that the linear coefficients of pressure and CO2 flow rate, the quadratic term coefficients of pressure and temperature and the interactions between pressure and temperature, as well as temperature and CO2 flow rate, had significant effects on the oil yield (P<0.05). The optimal conditions to obtain the maximum oil yield from N. glandulifera seed were pressure 30.84 MPa, temperature 40.57°C, and CO2 flow rate 22.00 L h-1. Under these optimal conditions, the yield of oil was predicted to be 38.19%. The validation experiment results agreed with the predicted values. The fatty acid composition of N. glandulifera seed oil extracted using SC-CO2 was compared with that of oil obtained by Soxhlet method. The results showed that the fatty acid compositions of oil extracted by the two methods were similar. Identification of oil compounds with gas chromatography-mass spectrometry (GC-MS) showed that the contents of unsaturated fatty acids linoleic acid (48.30%), oleic acid (22.28%) and saturated fatty acids palmitic acid (16.65%), stearic acid (4.17%) were the most abundant fatty acids in seed oil from N. glandulifera.