氧化锌压敏电阻在不同电流环境下老化规律研究

通过试验室模拟氧化锌压敏电阻在不同电流环境下的老化过程,依据氧化锌压敏电阻的非线性特性与双肖特基势垒理论分析试验现象,得到其老化规律:在直流老化中正反向压敏电压与漏电流参数呈不对称变化,温度线性上升;交流老化中正反方向压敏电压与漏电流呈对称变化,温度呈上升-稳定-上升的趋势;冲击老化中压敏电压呈上升-稳定-急速下降的趋势,漏电流以稳定-急速上升的趋势变化,非线性系数始终下降的变化规律.该结论在氧化锌压敏电阻避雷器的使用和检测中具有一定参考意义.     

马铃薯原生质体游离与培养体系的研究

普通马铃薯四倍体栽培种“甘农薯2号”、“Favorita敗ⅰ癛usset Burbank”试管苗叶片为材料来源,游离培养马铃薯原生质体。结果表明,游离前材料的低温预处理,酶解前对组织和酶液进行真空渗透处理,均能显著提高原生质体产量。用Ficoll密度梯度离心法收集原生质体进行培养,结果表明第三、四层界面的原生质体有较好的培养效果。培养液中加入10 %～15 % 的马铃薯提取液并进行愈伤组织看护培养,有良好的培养效果。     

野猪、家猪及野家杂种猪CAPN1基因3′UTR区的SNPs检测及PCR-RFLP分析

μ-钙蛋白酶(μ-calpain,CAPN1)是动物体内肌原纤维蛋白降解的主要酶,为了揭示其基因变异与瘦肉率和嫩度的关系,文章以野猪、家猪及野家杂种猪为研究对象,通过测序和PCR-RFLP方法对CAPN1基因3′UTR进行了SNPs检测和多态性分析。结果表明,共发现7个SNPs,分别是C114T,G220C,C344T,T380C,G501A,T543C,T610C;对G220C/T380C两处突变建立了基于限制性内切酶HinfⅠ/AlwNⅠ的PCR-RFLP检测技术;群体遗传学分析表明,在这两个位点不同基因型在不同品种(品系)猪中的分布都存在着极显著的差异(P<0.01),野猪和民猪之间的差异都不显著(P>0.05),并且HinfⅠ位点的B等位基因频率具有随着品种瘦肉率的增加而增多的趋势。该结果为寻找高瘦肉率的分子标记提供了基础。     

香蕉套种黑皮冬瓜对香蕉枯萎病的防控效果及土壤微生物群落的影响

【目的】探索香蕉套种黑皮冬瓜后对香蕉枯萎病的防控效果及蕉园土壤微生物群落的影响,为香蕉枯萎病的综合防控提供理论参考。【方法】以抗（耐）枯萎病香蕉品种桂蕉9号、易感枯萎病香蕉品种桂蕉1号为试验材料,在上一造香蕉枯萎病发病率大于50%的蕉园进行随机区组试验,设桂蕉9号套种黑皮冬瓜、桂蕉9号单作、桂蕉1号套种黑皮冬瓜和桂蕉1号单作4个处理,调查香蕉枯萎病发病率、香蕉和冬瓜采收后产量,检测冬瓜采收后蕉园土壤的理化性质和微生物数量,并通过高通量测序技术研究不同处理间土壤细菌群落结构和组成的差异。【结果】桂蕉9号套种黑皮冬瓜、桂蕉9号单作、桂蕉1号套种黑皮冬瓜和桂蕉1号单作香蕉枯萎病发病率分别为1.48%、14.44%、52.96%和70.00%。香蕉套种黑皮冬瓜后虽平均单株产量与单作香蕉相比差异不显著（P>0.05）,但折合每公顷香蕉产量因枯萎病发病率的降低而有所增加。桂蕉9号和桂蕉1号套种黑皮冬瓜后土壤pH分别较单作该香蕉品种显著提高24.00%和19.45%（P<0.05,下同）、土壤电导率（EC）显著下降78.48%和72.55%、土壤碱解氮含量显著升高72.92%和72.73%、土壤细菌及放线菌数量显著增加,Chaol指数和Shannon指数显著提高,Simpson指数显著降低。套种黑皮冬瓜提高了土壤细菌变形菌门（Proteobacteria）、厚壁菌门（Firmicutes）、酸杆菌门（Acidobacteria）、芽单胞菌门（Gemmatimonadetes）和拟杆菌门（Bacteroidetes）的相对丰度,降低了绿弯菌门（Chloroflexi）和放线菌门（Actinobacteria）的相对丰度。套种黑皮冬瓜改变了土壤细菌群落结构,增加了土壤细菌的多样性及丰富度。抗（耐）枯萎病香蕉品种套种黑皮冬瓜的防病效果比感病品种更明显。【结论】抗（耐）枯萎病香蕉品种套种黑皮冬瓜可通过提高土壤pH、降低土壤电导率、提高土壤碱解氮含量、改变土壤细菌群落结构达到降低香蕉枯萎病发病率的目的。抗（耐）枯萎病香蕉品种套种黑皮冬瓜种植模式可在广西香蕉枯萎病病区推广应用。     

11种四省市售淡水鱼肌肉中重金属含量特征与污染状况评价

为明确我国湖北、广东、河南和黑龙江四省市售淡水鱼肌肉中重金属含量现状,本研究于2021年9月至10月在四省11个市县(区)采集11种淡水鱼,共计133份样本,采用微波消解-电感耦合等离子体质谱(ICP-MS)法检测淡水鱼肌肉中铬(Cr)、铜(Cu)、砷(As)、镉(Cd)、汞(Hg)和铅(Pb)6种元素含量,依据《GB 2762-2017食品安全国家标准食品中污染物限量》对重金属污染状况进行评价。结果表明,所测样品中Cr、Cu、Cd、Hg和Pb 5种重金属元素均未超标;淡水鲈鱼和乌鳢中As含量均大于0.1 mg·kg^-1,其含量分别为0.182～0.738 mg·kg^-1和0.180～0.628 mg·kg^-1,且较其他淡水鱼类具有蓄积显著性差异(P<0.05)。对总砷含量高于0.1 mg·kg^-1的样品,进一步采用液相色谱-原子荧光光谱(LC-AFS)法对其无机砷含量进行检测,结果均为未检出,表明其无机砷含量在总砷含量中占比非常低。采用单因子污染指数法和内梅罗综合污染指数法评价所检淡水鱼中6...     

PREVIOUS CROPS AND ORGANIC FERTILIZERS IN LETTUCE: EFFECTS ON YIELDS AND SOIL PROPERTIES

The use of organic amendments in agriculture could sustain crop production and preserve the agroecosystem, due to their importance in the conservation of organic matter in soil. The objective of this research was to evaluate the effects of differing organic fertilizers and of previous crops on lettuce growth, nutritional status and yields. The effects on soil characteristics were further investigated. The research was carried out during two years (2006 and 2007) at Metaponto (MT) in southern Italy, on lettuce crops cultivated after eggplant and melon to avoid their continuous cropping. The effects of application of a mineral fertilizer (MF), and of three treatments with organic fertilizers (commercial stable manure - OM; anaerobic digestate based on wine distillery wastewater - AD; composted municipal solid organic wastes coming from the separate collection - MSW) were studied. Head average weight, leaf area index, nitrate content and SPAD readings during the cropping cycles did not show significant differences among fertilizer treatments. On the contrary, marketable yield and head average weight at the harvest presented significantly different among the three organic fertilizers. The average marketable yield and head average weight of organic fertilizers experimental (AD and MSW treatments) decreased of 16 and 17%, respectively, compared to OM treatment. The previous melon crop influenced positively all analyzed parameters of the lettuce compared with previous eggplant crop. The previous melon crop reached the highest marketable yield with an increase of 59% compared with previous eggplant crop. Compared to the mineral fertilizer, the organic ones significantly increased the extracted fraction of soil organic carbon (6.9, 10.7 and 14.9% for OM, AD and MSW, respectively), without significant changes for the humic and fulvic content.     

Assessing solid waste compost application as a practical approach for salt-affected soil reclamation

Abstract

A short-term pot experiment was made to evaluate the effectiveness of municipal solid waste compost amendment on salt-affected soil. Hordeum maritimum plants were cultivated in pots filled with a clay-loam soil containing 0 or 40 t ha^?1 of compost and irrigated with tap water at 0 or 4 g l^?1 NaCl. Soil properties and heavy metal (Zn^{2 +}, Pb^{2 +}, Cd^{2 +}) accumulation were investigated. Municipal solid waste compost application significantly increased the soil contents of carbon, nitrogen and potassium under both non-saline and saline conditions. Soil heavy metal concentrations increased substantially too, but the recorded values were below the toxicity limits. Interestingly, plants subjected to the salt–compost interaction were more vigorous, compared with those grown on non-amended soil. Altogether, our data indicate that short-term utilization of municipal solid waste compost at 40 t ha^?1 may be of potential interest in the perspective of the rehabilitation of salt-affected soils. Yet, it must be stressed that the present findings are preliminary and need to be further evaluated under field conditions before practical recommendations can be inferred.     

Bioassays and application of olive pomace compost on emmer: effects on yield and soil properties in organic farming

Abstract

Composting olive oil pomace could solve the problem of disposal, by recycling this organic waste for agricultural purposes. Furthermore, application of composted organic waste could be a way to sustain both soil fertility and production, especially in organic farming. Therefore, the aim of this research was to evaluate the phytotoxicity and the effects of application of olive pomace composts on emmer performance and soil properties. Two types of olive pomace composts, with a different initial C/N ratio, were stopped at the active phase and processed until maturation. The obtained four olive pomace composts were compared with a commercial fertilizer in a two-year field experiment. Before the field trial, a bioassay was performed to assess phytotoxicity both for the raw pomace and the not-stabilized composts. Growing and yielding data for emmer were determined during the two-year period and soil characteristics were measured at the start and at the end of the experiment.

The composts were not phytotoxic (germination index was higher than 90%) and their total organic carbon content was always higher than the minimum values established by the Italian fertilizers legislation. The emmer protein content was significantly higher in the matured compost treatment with low C/N, than in the other compost treatments. Its value was comparable with that of the commercial fertilizer, suggesting a good performance on crop yield quality. Although not significant, this compost showed an increase of 9.8% in grain yield compared with commercial fertilizer treatment. On the whole, it can be suggested that repeated compost application might preserve the soil organic carbon content and supply macronutrients to a crop.     

Genetic diversity and population structure of a common bean (Phaseolus vulgaris L.) collection from Calabria (Italy)

Eighty-seven Phaseolus vulgaris landraces, still cultivated in Calabria (Italy), were investigated in order to study the patterns of common bean genetic diversity in this region, to better understand the evolutionary development of beans in Europe and to properly manage these genetic resources. Four American accessions and five Italian varieties were also included. Different markers, such as 12 microsatellites, seed traits, phaseolins and 100-seed weight were combined with different statistical approaches. For each microsatellite, expected (H _e ) and observed (H _o ) heterozygosities, polymorphism information content (PIC), probability of identity (PI) and homozygosity were calculated. Furthermore, in Calabrian group of bean landraces, total (N _a ) and private (N _pa ) number of alleles, observed (H _o ), expected heterozygosities (H _e ) and allelic richness (AR) were calculated. Genetic distances among landraces were estimated using Nei’s coefficient and a cluster analysis using the UPGMA algorithm was performed. The results clearly indicated that: (1) Calabrian germplasm showed a high level of diversity (H _e  = 0.595); (2) Mesoamerican and Andean gene pools were clearly distinguished in Calabrian germplasm, with the Andean gene pool predominating (83 %); (3) Calabrian landraces were largely hybridized within and between the gene pools. A model-based approach, using the STRUCTURE software, was adopted. Six groups, including 4 of Andean origin and one of Mesoamerican origin were identified. Even more interesting, a small group (8 %) showed a distinct genetic structure, in which interspecific hybridizations with runner bean (Phaseolus coccineus L.) could have occurred. Nevertheless, a relatively high proportion of Calabrian bean landraces (12.6 %) was derived from intra and interspecific hybridizations.     

X射线辐照对梨小食心虫成虫寿命和生殖相关参数的影响

为建立基于X射线辐照的害虫不育技术,以梨小食心虫2、5、8日龄的雄蛹为研究对象,利用X射线对其进行0（CK）、67、133和200 Gy剂量的辐照处理,明确其最适辐照蛹龄;并对最适辐照蛹龄的梨小食心虫进行X射线辐照,明确辐照处理对其羽化成虫的繁殖能力、寿命、飞行能力和交配竞争力的影响。结果表明,梨小食心虫最适辐照蛹龄为8日龄;雄蛹经67 Gy与133 Gy辐照剂量处理后,与其羽化后成虫交配后的雌成虫单雌产卵量分别为25.14粒和24.56粒,卵孵化率分别为18.21%和14.61%,寿命分别为16.80 d和15.60 d,均显著低于对照;梨小食心虫雄蛹辐照处理对其羽化成虫与雌成虫的交配次数无显著影响,但辐照处理雄蛹羽化后的雄成虫与雌成虫交配后,雌成虫的日产卵量比对照明显减少,且辐照剂量越高,日产卵量变化幅度越小,产卵期也越短;辐照处理对雄蛹羽化后雄成虫的飞行能力无明显影响,但其与雌成虫的交配竞争指数下降为0.15。