Determination of ultratrace cadmium in food and environmental samples by ETAAS after vapor generation and in situ preconcentration

A method is described for the determination of ultratrace cadmium by coupling a continuous flow vapor generation system with in situ preconcentration technique and electrothermal atomic absorption spectrometry (ETAAS). A graphite tube coated with Ir as permanent chemical modifier was used for trapping cadmium vapor species. The effects of the flow rates of carrier gas and sample injection in vapor generation systems on the trapping measurement for cadmium were respectively investigated. Graphite tubes with different characteristic surfaces were comparatively studied for trapping cadmium vapor. The experimental results showed that the permanent chemical modifier of Ir is an alternative to the thermolabile modifier of Pd for simplifying the trapping measurement. The trapping efficiency of cadmium on the graphite tube coated with Ir was estimated. The trapping temperature and time were also investigated. A detection limit (3σ) of 0.005 μg·L⁻¹ was obtained for this proposed method. The relative standard deviation (RSD) was 1.4% for 0.5 μ·L⁻¹ of Cd (n = 11). This method can be applied to the determination of ultratrace cadmium in food and environmental samples with good agreement between the certified and found values.     

豫麦34低分子量谷蛋白亚基一个新基因的克隆

为了解强筋优质小麦品种豫麦34的低分子量谷蛋白亚基(LMW-GS)的基因构成,利用普通小麦LMW-GS基因特异引物,采用PCR扩增技术从中克隆得到一个LMW-GS新基因LMWY34(GenBank No.GU183486)。该基因具有LMW-GS基因的典型结构特征,编码区全长906 bp,编码302个氨基酸。推导氨基酸序列显示,LMWY34的编码产物N-端具有LMW-m型低分子量谷蛋白亚基的典型特征,与已报道的GluD3-4位点编码的LMW-GS基因序列有很高的一致性(98.68%)。     

我国主要杂交水稻组合及其亲本SSR标记和纯度鉴定

选用分布于水稻12条染色体上的26对SSR引物对我国9个主要的杂交水稻组合及其亲本进行了SSR标记分析,21对多态性引物共扩增出62条条带,平均2.95条,能够有效地区分所有恢复系和大部分不育系。杂交种条带均为父母本的互补型,很适合做杂交种纯度鉴定。用引物RM17对杂交稻组合汕优63和两优培九进行了100粒单种子SSR鉴定,所测纯度分别为96.0%和98.0%,与田间纯度96.2%和97.7%非常接近,显示出SSR技术在品种认证和纯度鉴定中有广阔的前景。     

施用新型土壤调理剂改善烟草产量品质及土壤理化性质

为了考察新型土壤调理剂施用对植烟酸性障碍土壤的调理效果,在田间条件下以不施用调理剂以及传统调理剂为对照,研究了不同用量的新型土壤调理剂对烟草产量品质以及土壤理化性质的影响。结果表明：施用调理剂可以显著提高烤烟根层土壤pH（P<0.05）,比不施调理剂的处理提高0.7~1.3,土壤pH和烤烟的产量以及上等烟比例呈极显著正相关关系。和传统调理剂（白云石粉）相比,新型土壤调理剂在1100（三分之二用量）和1500（等量）kg/hm ²用量下,上等烟叶比例比传统调理措施分别提高了6.5和6.9个百分点,烟叶产量分别增加4.8%和5.1%,烟叶产值分别提高4830.0、3989.3元/hm ²。同时,1100、1500 kg/hm ²这2个用量下烟草无论在农艺性状、烟叶产量、上等烟比例和烟叶产值上均无差异,因此从节约成本的角度出发,1100 kg/hm ²为最佳的调理剂施用量。     

旱地油用亚麻优化施肥的研究

通过５年多点氮磷肥料田间试验,对内蒙古自治区干旱、半干旱区旱地油用亚麻合理施肥进行了研究。提出了根据基础产量进行土壤肥力分级的氮磷肥料效应回归模式及最佳施肥量。在此基础上进一步探讨了不同年度降水量与肥料效应的关系,结果表明,年度降水量是影响产量和施肥肥效的主要因素,是确定旱地施肥配方的重要依据。为此,提出了以基础产量划分土壤肥力等级,同时考虑年度降水量的旱地油用亚麻氮磷肥料推荐施肥量,为无灌溉旱作地区油用亚麻合理施肥提供了科学依据。     

60Co-γ辐射对糜子种子萌发及幼苗生长的影响

为了研究不同剂量⁶⁰Co-γ射线对糜子种子萌发、幼苗生长以及生理效应的影响,以齐黍2号种子为材料,采用0、150、200、250、300和350Gy的⁶⁰Co-γ射线辐射糜子种子,并分析辐射对其幼苗的生长和叶片生理生化的影响。结果表明,⁶⁰Co-γ辐射对糜子种子出苗率、株高、叶长以及苗鲜重有明显抑制作用,尤其是高剂量（300和350Gy）辐射对糜子种子损伤较大,严重影响其出苗及幼苗生长。辐射剂量150Gy时,辐射处理能促进糜子种子萌发;叶片中可溶性糖、脯氨酸、可溶性蛋白和丙二醛含量等均有不同程度的提高。根据半致死剂量计算公式得出糜子的辐射半致死剂量为287Gy。     

新疆孜然黄酮超声提取及抗氧化作用研究

探讨新疆孜然黄酮的最佳提取工艺,并考察新疆孜然黄酮的抗氧化活性。采用超声波提取法,分别考察了溶剂浓度、料液比、超声时间、超声功率对结果的影响。选用L9(34)正交试验对黄酮的提取工艺进行研究。并采用总还原力法和DPPH法,测定了新疆孜然的抗氧化活性。孜然中黄酮的最佳提取工艺参数为：70%乙醇浓度,料液比1:35,超声提取时间80 min,超声提取功率125W。正交试验中影响黄酮得率的因素依次为：超声功率,料液比,溶剂浓度,提取时间。抗氧化活性试验结果显示,孜然总黄酮具有较好的总还原力,并对DPPH自由基的清除作用明显,IC50值为0.109 mg/mL。超声提取是一种理想的提取方法,新疆孜然黄酮作为抗氧化剂具有很大的开发应用价值。     

间套作条件下作物根系数量与活性的空间分布及变化规律研究 Ⅱ.间作早春玉米根系数量与活性的空间分布及变化规律

本文在冬小麦‖早春玉米 /夏玉米条件下 ,研究了麦田间作地膜覆盖早春播种玉米 (简称早春玉米 )根系数量与活性的空间分布及变化规律 ,主要结果 :(1)间作地膜覆盖早春玉米拔节期根深 10 0cm左右 ,大口期 140 cm左右 ,乳熟期达到最大根深 160 cm左右。 (2 )随生育进程推进 ,根量与根重密度基本呈小→大→小变化 ;根系数量及重量密度在垂直土体中呈“T”型分布 ,0～ 2 0 cm为高密度层 ,2 0～ 4 0、 4 0～ 80 cm为中密度层 ,80～ 12 0 cm为低密度层 ,12 0～ 160 cm为稀密度层。根系相对稳定后 ,约有 75 %的根干重分布在 0～ 2 0 cm土层 ,85 %左右在 4 0 cm以上 ,95 %左右在 80 cm以上。 (3)根系含水率在垂直空间呈上低下高趋势 ,随生育期推进 ,含水率呈下降趋势。 (4 )根系活性与根量相反呈倒“T”型分布 ,根系活性随生育进程推进 ,呈减低趋势 ,且活力高位点又呈下移变化 ,拔节期 2 0～ 4 0cm根系活性较高 ,大口期 4 0 cm以下较高 ,乳熟期和成熟期以 80 cm以下较高。 (5 )根系 TTC还原总量及总量密度随生育进程推进呈低→高→低变化 ,以大口期为高。上下又呈“T”型分布 ,0～ 2 0 cm为高量高密度区 ,2 0～ 80 cm为中量中密度区 ,80～ 12 0 cm为低量低密度区 ,12 0～ 160 cm为稀量稀密度区。 (6)成熟期 2 0     

大豆秸秆基保水剂对南阳烟田土壤物理性状及烟叶生长的影响

为了促进大豆秸秆基保水剂在农业生产中的应用和推广,作者在河南南阳旱区利用田间试验考察了保水剂用量对烟田土壤物理性状和烟叶生长的影响。结果表明,烟田施用大豆秸秆基保水剂可以显著抑制土壤水分的流失,并且抑制作用随保水剂用量的增加而增强;同时保水剂改善了土壤物理性状,降低土壤体积质量,使土壤孔隙数量增加,提高了土壤总孔隙度,尤其增加了非毛管孔隙度,增强了土壤通气性能。但施用过量容易降低土壤非毛管孔隙度,造成土壤板结;保水剂还可以降低烟叶的蒸腾速率,改善其光合特性,提高水分利用效率,增强烟叶抗旱性,从而提高烟叶株高、茎围和最大叶面积等农艺性状,改善烟叶化学成分。保水剂用量为240 kg/hm2时,土壤平均含水率较对照提高3.1%,总孔隙度提高6.8%,烟叶增产18.4%,上等烟比例提高6.8%。     

Effects of microbial inoculants on phosphorus and potassium availability,bacterial community composition,and chili pepper growth in a calcareous soil: a greenhouse study

Purpose

Phosphorus (P) and potassium (K) are two important essential nutrient elements for plant growth and development but their availability is often limited in calcareous soils. The objective of this study was to determine the effects of applying microbial inoculants (MI, containing effective strains of Bacillus megaterium and Bacillus mucilaginous) on the availability of P and K, plant growth, and the bacterial community in calcareous soil.

Materials and methods

A greenhouse experiment was conducted to explore the effects of the addition of MI (control: without MI addition; treatment: with MI addition at the rate of 60 L ha^?1) on the concentrations of P and K in soil and plant, soil bacterial community diversity and composition, and chili pepper (Capsicum annuum L.) growth.

Results and discussion

The results showed that MI inoculation significantly increased the fruit yields by 28.5% (p?<?0.01), available P and K in the rhizosphere soil by 32.1% and 28.1% (p?<?0.05), and P and K accumulation in the whole plants by 40.9% and 40.2%, respectively (p?<?0.05). Moreover, high-throughput sequencing revealed that Proteobacteria, Acidobacteria, Bacteroidetes, Chloroflexi, and Gemmatimonadetes were the dominant phyla of soil bacteria. MI application did not significantly impact the diversity and composition of soil bacterial communities, but increased relative abundances of bacterial genera Flavobacterium responsible for promoting root development across growing stages (p?<?0.05), and changed the soil bacterial community structure associated closely with soil properties of available P, K, and pH in soil.

Conclusions

The application of MI improved the bioavailability of P and K and plant growth due to its impact on the soil bacterial community structure.