稻田入土生物质炭自然陈化过程理化特性变化规律

为探究生物质炭入土后其长期理化特性变化,以水稻秸秆生物质炭为试验材料,通过分析长期定位试验田中的入土生物质炭样品,探究了稻田土壤中生物质炭的理化特性变化规律。结果表明,入土生物质炭颗粒随时间推移经历持续性物理破碎,平均孔径显著降低,入土11年后,生物质炭比表面积从初始的55.0 m²·g^-1增大到259.0 m²·g^-1,氢与碳的摩尔比从最初的0.423提升至0.568,不饱和度显著提升。入土生物质炭C=O（1 600~1 630 cm^-1）和C—O—C（1 080 cm^-1）的骨架振动强度和芳香族C—H（790 cm^-1）的平面振动均增强,其含氧官能团的类型和含量呈现明显增加的趋势。与此同时,入土生物质炭的可热降解组分占比不断提高,热稳定性逐渐降低。研究表明,与实验室老化模拟试验结果明显不同,受诸多外力作用和环境因素的影响,稻田中入土生物质炭的理化特性发生了更显著的变化,稳定性随着时间的推移逐年降低。因此,为精准科学评估稻田生态系统生物质炭化还田的固碳减排效应,开展入土生物质炭长期稳定性分析测试与相关评价模型研究十分必要。     

基于电磁感应数据的电导率反演模型研究

【目的】土壤盐渍化是限制新疆南部棉花高产的主要因子,准确获取区域尺度土壤剖面盐分信息。【方法】以南疆阿拉尔垦区为研究区,以田间尺度采集的30个不同盐渍化程度棉田的540个样点的0~0.375、0~0.750、0~1.000 m的土壤剖面电导率数据和对应的电磁感应数据为数据源,采用线性模型和非线性模型分别构建了田间尺度和区域尺度的土壤剖面电导率的电磁感应反演模型,并采用缩减建模样本量方法进一步检验了区域尺度模型的可靠性和稳定性。【结果】多元线性回归(MLR)、偏最小二乘回归(PLSR)和主成分回归(PCR)建模方法的田间尺度模型R²在0.88~0.95,而对应的区域尺度模型R²在0.34~0.53。基于随机森林(RF)、神经网络(NN)和支持向量机(SVM)非线性建模方法构建的土壤剖面电导率的区域尺度电磁感应反演模型R²在0.60~0.85,其中RF模型的精度最高。0~0.375、0~0.750、0~1.000 m土壤剖面电导率的RF反演模型R²分别为0.80、0.85和0.84,相较于线性建模方法的区域尺度模型精度有明显的提高。RF区域尺度模型的样本数量由540个缩减到240个,模型精度没有明显变化,表明采用区域尺度模型,可大幅度降低土壤剖面样本采集数量,从而可显著提高采样效率和降低采样成本。【结论】区域尺度下构建土壤剖面电导率反演模型时,随机森林建模方法效果较优,模型预测能力具有较高的可靠性。     

外源甘氨酸态氮、硝态氮和铵态氮的浓度配比对小白菜生长和品质的影响

为优化不同形态氮浓度配比,提高设施栽培蔬菜营养品质,在局部无菌水培条件下,研究了不同外源甘氨酸态氮、硝态氮和铵态氮的浓度配比对小白菜生物量、根系形态及营养品质的影响.结果表明,小白菜生物量及其营养品质受外源氮浓度组成影响差异显著(P <0.05).在高甘氨酸态氮(2500 μmol·L^-1)和铵态氮(2500 μmol·L^-1)、低硝态氮(250 μmol·L^-1)浓度处理中,小白菜生物量最高,达94.5 mg·株^-1,且小白菜总根长、根表面积、根体积、根系活力等指标的变化趋势与生物量一致;在高甘氨酸态氮、低无机氮浓度处理中,小白菜可溶性蛋白、游离氨基酸和可溶性糖含量最高,分别为26.2、126、24.0 mg·kg^-1,且硝酸盐含量较高无机氮处理显著降低(P <0.05).适当提高甘氨酸态氮浓度、降低无机氮(尤其是硝态氮)浓度能够一定程度改善其营养品质.     

Rice root growth and nutrient uptake as influenced by organic manure in continuously and alternately flooded paddy soils

Rice (Oryza sativa L.) root systems play an important role in uptake of water and nutrients from soil. A 4-year field experiment was conducted to determine the effects of different nutrient and water regimes on root growth by measuring the root diameter, root density, and root activity. Three nutrient regimes were used: (i) combined application of chemical fertilizers with farmyard manure (CM), (ii) integrated use of chemical fertilizers and wheat straw (CS), (iii) chemical fertilizers only (CK). Two soil moisture regimes included continuous waterlogging (CWL) and alternate wetting and drying (AWD). Incorporation of organic sources into paddy soil markedly improved root morphological characteristics of rice plant. In the alternate wetting and drying (AWD), root length density (RLD), and root weight density (RWD) for organic fertilization treatments (CS and CM) increased by 30 and 40%, respectively, as compared with the sole chemical fertilization (CF). Relative to root activity, CWL had adverse effects on root active absorption area (AAA), root oxidation ability of alpha-naphthylamine (α-NA) (ROA), and root surface phosphatase (RSP) of rice plants treated by integrated application of organic and inorganic fertilizers. In particular for the CM treatment, the AAA, ROA, and RSP of rice plants by the continuous flooding decreased by 22, 28, and 35%, respectively, compared to the alternately flooded regime. In the water regime of AWD, incorporation of organic manure significantly increased N, P, and K uptake by rice plants and facilitated the allocation and transfer of nutrient elements, especially P to rice ears and grains. This resulted in significant increases in the filled grains panicle⁻¹, 1000-grain weight and grain yield. The beneficial effects of integrated use of organic and mineral fertilizers on grain yield were significantly (P < 0.05) decreased by the water regime of CWL.     

Measurement of Gliadin and Glutenin Content of Flour by NIR Spectroscopy

Traditional NIR calibration methods rely on assembling a calibration set of samples and using procedures such as multiple linear regression or partial least squares to develop the calibration. The problem with this methodology is to assemble a calibration set which maximises the diversity of samples represented whilst minimising the intercorrelations between constituents, particularly total protein content and moisture content. The application of NIR measurements of grain has moved beyond simply measuring protein and moisture content. There is now considerable interest in using NIR to measure a range of quality parameters such as Extensograph extensibility and maximum resistance. These parameters are not themselves represented in the NIR spectrum, but are a direct result of the protein composition of the sample. Consequently, a method for predicting the protein composition would be useful. In this paper, we present the results of a comparison of a curve fitting methodology and the more usual partial least squares curve fitting of the component protein spectra, using samples obtained from a wheat breeders» trial. Gliadin and glutenin contents were measured by SE-HPLC and used to develop a partial least squares calibration and the results compared with a curve-fitting methodology. For the situation examined here, the curve fitting methodology did not perform as well as partial least squares calibration. For glutenin, SEP=0·65 for the curve fitting compared to SECV=0·38 for a traditional PLS calibration. However, the results from the curve-fitting are independent of the total protein content and show sufficient discrimination for potential use in sample protein ranking.     

Effects of Pseudomonas fluorescens and fertilizers on the reproduction of Meloidogyne incognita and growth of tomato

A 60-day glasshouse experiment was conducted to assess the influence of two strains of Pseudomonas fluorescens (GRP3 and PRS9), organic manure, and inorganic fertilizers (urea, diammonium phosphate (DAP), muriate of potash and monocalcium phosphate) alone and in combination on the multiplication of Meloidogyne incognita and growth of tomato. Pseudomonas fluorescens GRP3 was better at improving tomato growth and reducing galling and nematode multiplication than PRS9. Organic manuring resulted in less galling and nematode multiplication than occurred with DAP. However, DAP was found better in reducing nematode multiplication and improving plant growth than urea. Muriate of potash was the inorganic fertilizer least effective in reducing galling and nematode multiplication. Pseudomonas fluorescens GRP3 with organic manure was the best combination for the management of M. incognita on tomato but improved management of M. incognita can also be obtained if DAP is used with the GRP3 strain of P. fluorescens.     

蚕蛹在现代医药和食品方面的应用

本文简要介绍了近几年来蚕蛹在医药和食品方面的研究成果,内容包括蚕蛹多糖及提取物、蚕蛹蛋白、蚕蛹油、蚕蛹吸附材料、蚕蛹生物反应器和蚕蛹培养基,以及蚕蛹粉在食品方面的直接利用和作为添加原料利用等方面的概况。蚕蛹在医药和食品等方面的利用不仅可以创造巨大的经济价值,还可以为蚕桑资源的高效利用提供新途径。     

基于可见/近红外光谱技术的毛脚茧的光谱快速鉴别方法研究

基于可见/近红外光谱技术,研究了鲜茧毛脚茧快速鉴别的方法。采用主成分分析法对毛脚茧和成熟茧进行定性分析,再对光谱数据采用最小二乘支持向量机方法建模鉴别,通过连续投影算法从400-1000 nm波段的鲜茧光谱数据中选取了12个特征波长。采用最小二乘支持向量机法基于400 nm,430 nm,487 nm,512 nm,604 nm,616 nm,732 nm,759 nm,784 nm,852 nm,985 nm,999 nm这12个特征波长建模,结果对毛脚茧的判别准确率达到100%。表明可见/近红外光谱可以用于毛脚茧的鉴别检测。     

丝素作为固定化酶载体材料的研究进展

酶的固定化在化学、生物医学以及生物感应器等领域应用较广。固定化酶的效果在很大程度上取决于载体结构。丝素作为固定化酶载体材料有其独特的优势。本文综述了国内外以不同的丝素形态作为固定化酶载体材料的研究进展,重点介绍了非纳米丝素固定化酶和纳米丝素固定化酶（丝素纳米颗粒和丝素纳米纤维）的研究进展。