Long-term greenhouse vegetable cultivation alters the community structures of soil ammonia oxidizers

Journal of Soils and Sediments - Continuous cropping obstacles derived from long-term intensive cultivation has severely affected the healthy development of greenhouse vegetable industry in China....     

The failure of using equilibrium adsorption of fosthiazate onto montmorillonite clay particles to predict their cotransport in porous media as revealed by batch and column studies

Journal of Soils and Sediments - Adsorption of fosthiazate onto montmorillonite clay particles (MPs) and cotransport of fosthiazate and MPs in sand and soil porous media were investigated for the...     

Starch physicochemical properties and their associations with microsatellite alleles of starch-synthesizing genes in a rice RIL population

The physicochemical properties of starch, such as apparent amylose content, gelatinization temperature, and pasting viscosities, determine the eating, cooking, and processing qualities of various products of rice. A recombinant inbred line (RIL) population derived from the reciprocal cross of Lemont (a premium high-quality tropical japonica rice) and Jiayu 293 (a high-yield but low-quality indica rice) was used to test the association of microsatellite markers of starch-synthesizing genes with starch quality parameters. The results confirmed the association of Wx and starch synthase I (SSI) alleles with various starch properties measured in rice flour. However, the starch properties were not associated with the starch branching enzyme 1 (SBE 1) gene alleles.     

Nondestructive prediction of total phenolics, flavonoid contents, and antioxidant capacity of rice grain using near-infrared spectroscopy

Phytochemicals such as phenolics and flavonoids, which are present in rice grains, are associated with reduced risk of developing chronic diseases such as cardiovascular disease, type 2 diabetes, and some cancers. The phenolic and flavonoid compounds in rice grain also contribute to the antioxidant activity. Biofortification of rice grain by conventional breeding is a way to improve nutritional quality so as to combat nutritional deficiency. Since wet chemistry measurement of phenolic and flavonoid contents and antioxidant activity are time-consuming and expensive, a rapid and nondestructive predictive method based on near-infrared spectroscopy (NIRS) would be valuable to measure these nutritional quality parameters. In the present study, calibration models for measurement of phenolic and flavonoid contents and antioxidant capacity were developed using principal component analysis (PCA), partial least-squares regression (PLS), and modified partial least-squares regression (mPLS) methods with the spectra of the dehulled grain (brown rice). The results showed that NIRS could effectively predict the total phenolic contents and antioxidant capacity by PLS and mPLS methods. The standard errors of prediction (SEP) were 47.1 and 45.9 mg gallic acid equivalent (GAE) for phenolic content, and the coefficients of determination ( r (2)) were 0.849 and 0.864 by PLS and mPLS methods, respectively. Both PLS and mPLS methods gave similarly accurate performance for prediction of antioxidant capacity with SEP of 0.28 mM Trolox equivalent antioxidant capacity (TEAC) and r (2) of 0.82. However, the NIRS models were not successful for flavonoid content with the three methods ( r (2) < 0.4). The models reported here are usable for routine screening of a large number of samples in early generation screening in breeding programs.     

日粮中添加藜麦秸秆对湖羊生长性能和屠宰性能的影响

文章研究了日粮中添加不同比例黎麦秸秆对湖羊生长性能和屠宰性能的影响,为藜麦秸秆作为肉羊饲料原料提供数据基础.试验选用80只体重30 kg左右的健康断奶湖羊公羔,随机分为4组,按照日粮粗饲料分为0％、33.3％、66.7％、100％藜麦秸秆组(玉米秸秆分别为100％、66.7％、33.3％和0％),饲喂60 d后测定湖羊...     

不同地表状况耕地的田面糙率研究

田面糙率是影响田面水流运动的重要参数之一.该文针对裸地、翻耕地和作物地3种不同地表状况耕地的田面糙率进行研究.分析确定了裸地和翻耕地田面糙率的主要影响因素为田面凹凸程度,作物地田面糙率的主要影响因素还包括根茎宽度和根茎高度;进行了3种地表状况的田面凹凸程度、根茎宽度和根茎高度的田间实测及田面水流运动试验;将零惯量模型与优化方法相结合,建立了田面糙率求解的优化模型;根据田面实测资料,利用优化模型求得3种耕地的田面糙率值,据此,建立了裸地、翻耕地和作物地3种耕地田面糙率与其主要影响因素之间的关系式,验证试验结果表明,所建立的关系式正确.这对合理设计田面灌溉系统,提高灌水质量具有重要参考价值.     

基于图像的昆虫远程自动识别系统的研究

只有对害虫进行鉴定才能在农业生产中对害虫进行有目的的防治,而对昆虫进行鉴定只有少数分类专家才能完成,鉴定需求的日益增加与专家相对较少形成了一对尖锐的矛盾.该文的研究尝试为该矛盾的解决提供一条新的思路:在标准方法下获取昆虫图像,并经由Internet网络上传给自动种类识别系统服务器,从而实现远程识别.系统首先对昆虫图像进行基于形状和颜色特征值的提取.昆虫图像的形态特征值由矩形度、延长度、球状型、叶状型、似圆度和7个Hu不变矩等12个特征值组成,颜色特征值由红、绿、蓝、灰度真方图及基于红、绿的二维色度直方图特征值分别组成,然后建立径向基神经网络分类器,每一特征向量由独立的径向基神经网络做为分类器,最终识别由每个分类器识别结果的线性组合而成.采用该系统对16种昆虫进行了测试,每种昆虫取40个样本,20个用做训练、20个用做测试,准确率达到96%以上.     

田块尺度上土壤重金属污染地统计分析及评价(简报)

该文以北京市某生态农场的大田为例,应用地统计学分析方法进行了变异函数的计算和模型拟合,建立了计算土壤重金属含量的最适空间插值理论模型,随后运用克立金估值方法绘制了田块尺度上土壤重金属的空间分布图,并与土壤重金属污染标准进行比较,土壤重金属污染评价结果表明：研究范围内的土壤重金属含量较低,未发现污染。该研究结果表明地统计学分析方法可为田块尺度上的农业优化管理提供决策支持。     

耐冷菌的适冷分子机制及在污水处理中的应用

指出了低温是影响冬季寒冷地区生活污水处理效果的一个主要原因,在低温环境下,活性污泥中大多数中温菌的生长活性受到抑制,只有少数的耐冷菌可以存活下来并保持一定的活性。简要介绍了低温微生物的概念及分类,从细胞膜结构、低温酶、蛋白质合成以及冷休克蛋白等方面对耐冷菌的适冷机制进行分析,最后对耐冷菌在污水处理中的应用现状与发展方向进行了展望。     

家蚕Ras3基因全长cDNA克隆及在感染BmNPV家蚕组织中的表达谱分析

Ras(rat sarcoma viral oncogene homolog)蛋白是GTPase超家族成员之一,该蛋白质可以将细胞外信号传导到不同的细胞,从而调控细胞的吞噬作用、凋亡、抗微生物侵染的酶防御系统等生理过程.运用RACE技术,从家蚕中肠中克隆出一个新的BmRas3基因,该基因cDNA全长987 bp,包含5'UTR(153 bp)、3'UTR(279 bp)和一个编码184个氨基酸残基的ORF(555 bp).BmRas3具有小G蛋白的典型特征,其氨基酸序列中含有3个GTP/GDP结合结构域,1个效应子结合结构域以及1个烯丙基化的CAAX基序.多重比对发现BmRas3与海波斯莫科马属蛾(Hyposmocoma kahamanoa)Rap1、斜纹夜蛾(Spodoptera litura)Rap-1b、烟草天蛾(Manduca sexta)Rap1的序列相似性较高,系统进化分析也显示BmRas3与这些蛋白质的亲缘关系最近.BmRas3在食桑期的表达量高于眠期;在感染BmNPV的家蚕中肠和脂肪体中,BmRas3的表达量有不同程度提高,且与正常对照相比差异显著,暗示BmRas3可能作为免疫活化因子,在家蚕抵抗BmNPV的入侵过程中发挥着重要作用.研究结果为下一步探讨BmRas3对BmNPV感染的应答提供了理论基础.