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by
Fei Li |
Total Records (
3 ) for
Fei Li |
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Zhenling Cui
,
Xinping Chen
,
Yuxin Miao
,
Fei Li
,
Fusuo Zhang
,
Junliang Li
,
Youliang Ye
,
Zhiping Yang
,
Qiang Zhang
and
Chunsheng Liu
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High soil nitrate-N accumulation has been observed in North China Plain (NCP), but it was seldom considered as a N source in N management due to the lack of data on crop response to soil nitrate-N accumulation. A total of 124 on-farm N-response experiments were conducted from 2003 to 2006 in seven key winter wheat (Triticum aestivum L.) production regions of NCP to evaluate wheat yield response to residual soil nitrate-N. High soil nitrate-N accumulation ( ≥172 kg N ha–1 in 90 cm soil depth) was observed during wheat growing season. Compared with 165 nitrate-N ha–1 in 0 to 90 soil layer before sowing, added fertilizer N did not increase wheat yield under 262 kg nitrate-N ha–1 condition, but increased residual nitrate-N and N losses and reduced recovery N efficiency (P < 0.05). Wheat yield response to residual soil nitrate-N could be fitted by a linear plus plateau model, and calculated minimum soil nitrate-N content for maximum grain yield was 211 kg N ha–1 (R2 = 0.31) before sowing across all 223 zero-N plots in 124 sites. When two growth periods (before and after shooting stage) were analyzed separately, the coefficient of determination between yield and soil nitrate-N increased significantly. We conclude that winter wheat yield response to added N fertilizer was unlikely if soil nitrate-N content exceeded 72 (0–30 cm soil depth) and 175 kg N ha–1 (0–90 cm soil depth) before sowing and shooting stage, respectively. According to these thresholds, 55% and 37% of farmer`s fields did not need to apply N fertilizer before sowing and at shooting stage, respectively. |
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Fei Li
,
Chaojie Zhang
,
Yan Qu
,
Jing Chen
,
Xiang Hu
and
Qi Zhou
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In order to help to elucidate the transport and fate of perfluorinated acids (PFAs) in the environment, a reliable and sensitive analytical method has been developed in present study for determination of short- and long-chain PFAs in various solid matrices. The method consisted of solvent extraction of PFAs from solid matrices using sonication, solid phase extraction (SPE) using weak anion exchange (WAX) cartridges, clean-up of SPE eluent with dispersive carbon sorbent and quantitation by high performance liquid chromatography-negative electrospray-tandem mass spectrometry (HPLC-negative ESI-MS/MS). The method detection limits (MDL) and quantitation limits (MQL), which were analyte- and sample-dependent, ranged from 0.02 to 0.06 ng g−1 and 0.10 to 0.90 ng g−1, respectively. The recoveries of all PFAs were generally good enough for quantitative analysis of these chemicals (57−115%), especially for short-chain (<C8, 80−115%) PFAs excluded in previous studies because methods were not available. The precisions of this method, represented by the percent relative standard deviation (RSD) of spiked measurements, were in a range of 1−19%. In addition, matrix effect did not affect analyte quantification in solid matrices in most cases, and the validated method was successfully applied to analyses of short- and long-chain PFAs in various solid matrices. |
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Xiao-Hong Wu
,
Ye Liu
,
Lin Zhang
,
Fei Li
,
Fei Wang
,
Li Cao
,
Xiao-Jun Yang
and
Jun-Hu Yao
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This experiment was conducted to investigate the effects of natural Vitamin E (Nat E Ac) level and duration of supplementation on growth performance, carcass traits, meat quality and α-tocopherol content as well as oxidation stability of plasma and breast meat (refrigerated at 4°C) of broilers. Cobb broilers (n = 315, 21 days old, female) were randomly assigned to 7 treatments (1 control and 6 experiment groups) with 5 replicates and 9 broilers per replicate. Control group was fed with basal diet (Nat E Ac:30 IU kg-1). For the experimental groups, a 2x3 factorial design was used with 2 Nat E Ac levels (Nat E Ac:60 and 120 mg kg-1) and 3 durations (7, 14 and 21 days prior to slaughter at 42 day). The broilers were in the finisher phase (22-42 days) during the treatment. Results showed that broilers fed with higher Nat E Ac levels or fed for a longer duration had significantly (p<0.05) increased percentage of breast and thigh meat, pH24h in breast, glutathione peroxidase in liver and α-tocopherol in plasma, liver and breast meat. Moreover, the broilers also exhibited notably (p<0.05) decreased drip loss and pH in breast meat as well as decreasing content of Malondialdehyde (MDA) in the plasma and breast meat refrigerated at 4°C for 0, 2, 4, 6 and 8 days. There was a significant (p<0.05) interaction between Nat E Ac level and feeding duration that affected the level of MDA in breast meat refrigerated at 4°C for 0, 2, 6 and 8 days. Nat E Ac level, feeding duration and the interaction of these two factors did not markedly (p>0.05) influence growth performance, breast meat color, percentage of eviscerated carcass and abdominal fat, total superoxide dismutase and glutathione peroxidase activities and antioxidation capacity in plasma. Higher Nat E Ac level or prolonged duration of feeding increased the percentages of breast and thigh meat, enhanced the water-holding capacity, the pH24h as well as α-tocopherol retention of breast meat and oxidative stability during refrigerated storage of breast meat thus enhancing the oxidative stability during refrigerated storage and improving breast meat quality. |
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