Effects of crop rotation on soybean (Glycine max (L) Merr.) seed composition have not been well investigated. Therefore, the objective of this study was to investigate the effects of soybean-corn (Zea mays L.) rotatio...Effects of crop rotation on soybean (Glycine max (L) Merr.) seed composition have not been well investigated. Therefore, the objective of this study was to investigate the effects of soybean-corn (Zea mays L.) rotations on seed protein, oil, and fatty acids composition on soybean. Soybeans were grown at Stoneville, MS, from 2005 to 2008 in five different scheduled cropping sequences. In 2007, following three years of rotation with corn, seed oleic acid percentage was significantly higher in any crop rotation than continuous soybean. The increase of oleic fatty acid ranged from 61 to 68% in 2007, and from 27 to 51% in 2008, depending on the rotation. The increase of oleic acid was accompanied by significant increases in seed concentrations of phosphorus (P), iron (Fe), and boron (B). In 2007, the increase of P ranged from 60 to 75%, Fe from 70 to 72%, and B from 34 to 69%. In 2008, the increase of P ranged from 82 to 106%, Fe from 32 to 84%, and B from 62 to 77%. Continuous soybean had higher linoleic:oleic ratio and linoleic: palmitic + stearic + oleic ratio, indicating that relative quantity of linoleic acid decreased in rotated crops. The total production of protein, oil, stearic and oleic fatty acids was the lowest in continuous soybean. The total production of palmitic acid was inconsistent across years. The results show that soybean- corn rotation affects seed composition by consistently increasing seed oleic fatty acid, P, Fe, and B concentrations. Higher oleic acid, unsaturated fatty acid, is desirable for oil stability and long-shelf storage. The mechanisms of how these nutrients are involved are not yet understood.展开更多
This study investigated that epoxidized soybean oil （ESO） was blended as plasticizer with poly （lactic acid） （PLA） and its effects on the melt rheological properties, such as melt flow index, apparent shear visc...This study investigated that epoxidized soybean oil （ESO） was blended as plasticizer with poly （lactic acid） （PLA） and its effects on the melt rheological properties, such as melt flow index, apparent shear viscosity, and melt strength of the blends. PLA was blended by the twin-screw plastic extruder at five mass fractions： 3%, 6%, 9%, 12%, and 15% （based on PLA mass）. Melt flow index （MFI） was examined with a melt flow indexer. The results indicate that the blends of PLA/ESO had higher MFI than pure PLA, except for MFI at 9% reaching to the lowest point, even lower than that of pure PLA. Melt rheological properties were studied by a capillary rheometer in a temperature range of 160-180℃. The blends exhibited shear-thinning behavior and the apparent shear viscosity was well described by the power law in this shear rate region. The melt strength of PLA plasticized with 6% ESO reached the maximums. ESO was more effective in increasing the melt strength at the mass fractions less than 6%, which could toughen the blends to some extent. Therefore, the authors suggested the optimum addition level of 6%-9% ESO will get good melt rheological performance balance.展开更多
文摘Effects of crop rotation on soybean (Glycine max (L) Merr.) seed composition have not been well investigated. Therefore, the objective of this study was to investigate the effects of soybean-corn (Zea mays L.) rotations on seed protein, oil, and fatty acids composition on soybean. Soybeans were grown at Stoneville, MS, from 2005 to 2008 in five different scheduled cropping sequences. In 2007, following three years of rotation with corn, seed oleic acid percentage was significantly higher in any crop rotation than continuous soybean. The increase of oleic fatty acid ranged from 61 to 68% in 2007, and from 27 to 51% in 2008, depending on the rotation. The increase of oleic acid was accompanied by significant increases in seed concentrations of phosphorus (P), iron (Fe), and boron (B). In 2007, the increase of P ranged from 60 to 75%, Fe from 70 to 72%, and B from 34 to 69%. In 2008, the increase of P ranged from 82 to 106%, Fe from 32 to 84%, and B from 62 to 77%. Continuous soybean had higher linoleic:oleic ratio and linoleic: palmitic + stearic + oleic ratio, indicating that relative quantity of linoleic acid decreased in rotated crops. The total production of protein, oil, stearic and oleic fatty acids was the lowest in continuous soybean. The total production of palmitic acid was inconsistent across years. The results show that soybean- corn rotation affects seed composition by consistently increasing seed oleic fatty acid, P, Fe, and B concentrations. Higher oleic acid, unsaturated fatty acid, is desirable for oil stability and long-shelf storage. The mechanisms of how these nutrients are involved are not yet understood.
基金Supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China (20030561014)
文摘This study investigated that epoxidized soybean oil （ESO） was blended as plasticizer with poly （lactic acid） （PLA） and its effects on the melt rheological properties, such as melt flow index, apparent shear viscosity, and melt strength of the blends. PLA was blended by the twin-screw plastic extruder at five mass fractions： 3%, 6%, 9%, 12%, and 15% （based on PLA mass）. Melt flow index （MFI） was examined with a melt flow indexer. The results indicate that the blends of PLA/ESO had higher MFI than pure PLA, except for MFI at 9% reaching to the lowest point, even lower than that of pure PLA. Melt rheological properties were studied by a capillary rheometer in a temperature range of 160-180℃. The blends exhibited shear-thinning behavior and the apparent shear viscosity was well described by the power law in this shear rate region. The melt strength of PLA plasticized with 6% ESO reached the maximums. ESO was more effective in increasing the melt strength at the mass fractions less than 6%, which could toughen the blends to some extent. Therefore, the authors suggested the optimum addition level of 6%-9% ESO will get good melt rheological performance balance.
