Do cover crops change the lability of phosphorus in a clayey subtropical soil under different phosphate fertilizers?

Plants have developed different mechanisms to absorb and solubilize phosphorus (P) in the soil, especially in environments with low P availability. This study evaluated the effects of different winter cover crops on soil P availability in a clayey subtropical (Hapludox) soil receiving soluble P fertilizer and a rock phosphate applied to the summer crop, under no‐tillage. The experiment was carried out over 3 yrs (2009–2011) with five different cover crop species: common vetch, fodder radish, ryegrass, black oat, white clover and fallow as control. The soil was sampled after the third year of cover crop cultivation and analysed for inorganic and organic P forms according to the well‐established Hedley fractionation procedure. Phosphate fertilizers promoted accumulation of both labile and nonlabile P pools in soil in the near surface layer, especially under rock phosphate. Fertilizer applications were not able to change P fractions in deeper layers, emphasizing that the Brazilian clayey soils are a sink of P from fertilizer and its mobility is almost nil. Although the cover crops recycled a great amount of P in tissue, in a short‐term evaluation (3 yrs) they only changed the content of moderately labile P in soil, indicating that long‐term studies are needed for more conclusive results.     

品种间大豆脂肪氧化酶活性差异及β-胡萝卜素漂白性研究

为了解东北地区大豆品种间大豆脂肪氧化酶(LOX)活性差异规律,整理适于东北地区种植的大豆种质资源307份(6份半野生品种,17份地方品种及4份国外品种,其余为栽培品种),统一种植,秋季收获后,测定各品种成熟籽粒脂肪氧化酶总活性。分析品种间脂肪氧化酶总活性分布规律、大豆脂肪氧化酶总活性与β-胡萝卜素漂白性之间关系。结果表明,307份大豆品种间脂肪氧化酶总活性差异极显著,平均值为21.68 U·mL~(-1),最小值为2.51 U·mL~(-1),最大值为42.38 U·mL~(-1)。根据脂肪氧化酶总活性差异,通过聚类分析将307份大豆品种分为3类。低活性品种占总量43.65%,脂肪氧化酶总活性平均值为15.25 U·mL~(-1);中等活性品种占总量43.97%,脂肪氧化酶活性平均值为24.64 U·mL~(-1);高活性品种占总量12.38%,脂肪氧化酶总活性平均值为33.87 U·mL~(-1)。脂肪氧化酶总活性与油分含量呈正相关,与蛋白含量呈负相关,与漂白性呈正相关。     

Comparison of the microbial communities of alpacas and sheep fed diets with three different ratios of corn stalk to concentrate

The objective of this study was to investigate the characteristics of ruminal microbial communities of alpacas (Lama pacos) and sheep (Ovis aries) fed three diets with varying ratios of roughage (corn stalk) to concentrate, 3:7 (LS), 5:5 (MS) and 7:3 (HS). Six alpacas (one-year-old and weighing 29.5 ± 7.1 kg) and six sheep (one-year-old and weighing 27.9 ± 2.7 kg) were used in this study, in a replicated 3 × 3 Latin square experiment. Total protozoa concentration was determined under the microscope; total fungi and methanogens were assessed using quantitative polymerase chain reaction and expressed as a percentage of total bacterial 16S rRNA gene copies; bacterial communities were investigated by targeted 16S rRNA gene (V3–V4 region) sequencing. The percentage of fungi was significantly higher in alpacas than in sheep under the LS diet, while the concentration of protozoa was significantly lower in alpacas under HS, MS and LS diets. The alpha diversity including Shannon, Chao l and ACE indices of bacterial communities was higher in alpacas than in sheep, under the LS diet. A total of 299 genera belonging to 22 phyla were observed in the forestomach of alpaca and sheep, with Bacteroidetes and Firmicutes dominating both animal species. Phyla Armatimonadetes and Fusobacteria, as well as 64 genera, were detected only in alpacas, whereas phyla Acidobacteria and Nitrospira, as well as 44 genera, were found only in sheep. The abundance of cellulolytic bacteria, including Butyrivibrio and Pseudobutyrivibrio, was higher in alpacas than in sheep under all three diets. These differences in the forestomach microbial communities partly explained why alpacas displayed a higher poor-quality roughage digestibility, and a lower methane production. Results also revealed that the adverse effects of high-concentrate diets (70%) were lesser in alpacas than in sheep.     

Soil quality assessments in integrated crop–livestock–forest systems: A review

Integrated crop–livestock–forest is a promising strategy to improve soil quality. It comprises four different integrated farming systems: crop–livestock, crop–forest, forest–livestock and crop–livestock–forest. This work systematically reviewed studies about integrated crop–livestock–forest systems and soil quality. A total of 92 papers were retrieved from the Web of Science—Clarivate Analytics platform, and the following information was analysed: publication year, institution, region of the studied site, type of integrated system, soil type, tillage system, maximum soil depth and the soil quality indicators assessed. Most studies were published in the second half of the 2010s. Brazil is a prominent focus of research about soil quality and integrated crop–livestock–forest systems, with significant contribution from its central and southern regions. The Embrapa was the main publishing institution, present in over one‐third of the studies. Crop–livestock was the most common integrated system, Ferralsols was the most common soil group, and most of the studied soils were clayey. No tillage was the main tillage system. Most studies focused on the topsoil, assessing physical and/or chemical soil quality indicators. More emphasis on biological indicators of soil quality is required, as well as assessments integrating biological, physical and chemical indicators of soil quality. Future works should compare different integrated systems, including assessments deeper in the soil profile, especially in systems with the forest component, and also in sandy and silty soils. Soil quality indicators that have been rarely used should be further tested. Novel indicators should be added to better understand the promotion of soil quality by integrated crop–livestock–forest systems.     

马疱疹病毒1型主要毒力基因分析及TK基因缺失载体的构建

为了解新疆马疱疹病毒1型（EHV-1）主要毒力基因遗传进化情况并构建TK基因缺失株，本研究以EHV-1 XJ2015株DNA为模板，对其主要毒力基因TK、gI和gE全长进行克隆、测序及生物信息学分析，并扩增TK基因左右重组臂TKL和TKR，构建质粒pUC-TKLR，将扩增后的增强绿色荧光蛋白（EGFP，含有CMV+polyA）插入pUC-TKLR质粒，构建TK基因缺失打靶质粒。TK、gI和gE基因同源性分析结果显示，XJ2015株与国外EHV-1分离株TK、gI和gE基因同源性均较高，分别为99.8%~100.0%、99.6%~100.0%和99.9%~100.0%；与EHV-3分离株同源性均最低，分别为72.9%、59.4%和62.1%；遗传进化分析显示，3个基因均与国外EHV-1同属于一个遗传进化分支，与EHV-9和EHV-4进化关系较近，但与EHV-3进化关系较远，表明XJ2015毒株与国外EHV-1毒株TK、gI、gE基因核苷酸上差异不明显，没有明显的地域性特征，功能基因保守且进化缓慢，同源基因功能相同或相近；经PCR扩增、酶切、测序及转染鉴定，本试验成功构建了用于TK基因缺失的打靶质粒pUC-TKLR-EGFP。通过对EHV-1主要毒力基因的分析及TK基因缺失打靶载体的构建，为新疆地区马鼻肺炎流行病学调查分析、TK基因缺失株的构建提供理论依据。     

A comparison of the effects of carbon dioxide and medical air for abdominal insufflation on respiratory parameters in xylazine-sedated sheep undergoing laparoscopic artificial insemination

AIMS: To determine if abdominal insufflation with medical air will improve oxygenation and ventilation parameters when compared to insufflation with CO₂ in xylazine-sedated sheep undergoing laparoscopic artificial insemination (AI).

METHODS: Forty-seven sheep underwent oestrus synchronisation and were fasted for 24 hours prior to laparoscopic AI. Each animal was randomised to receive either CO₂ or medical air for abdominal insufflation. An auricular arterial catheter was placed and utilised for serial blood sampling. Respiratory rates (RR) and arterial blood samples were collected at baseline, after xylazine (0.1?mg/kg I/V) sedation, 2 minutes after Trendelenburg positioning, 5 minutes after abdominal insufflation, and 10 minutes after being returned to a standing position. Blood samples were collected in heparinised syringes, stored on ice, and analysed for arterial pH, partial pressure of arterial O₂ (PaO₂), and CO₂ (PaCO₂). The number of ewes conceiving to AI was also determined.

RESULTS: Repeated measures ANOVA demonstrated temporal effects on RR, PaO₂, PaCO₂ and arterial pH during the laparoscopic AI procedure (p<0.001), but no difference between insufflation groups (p>0.01). No sheep experienced hypercapnia (PaCO₂>50?mmHg) or acidaemia (pH<7.35). Hypoxaemia (PaO₂<70?mmHg) was diagnosed during the procedure in 14/22 (64%) ewes in the CO₂ group compared with 8/23 (35%) ewes in the medical air group (p=0.053). Overall, 15/20 (75%) ewes in the CO₂ group conceived to AI compared with 16/22 (72.7%) in the medical air group (p=0.867).

CONCLUSIONS AND CLINICAL RELEVANCE: There were no statistical or clinical differences in RR, PaO₂, PaCO₂, pH, or conception to AI when comparing the effects of CO₂ and medical air as abdominal insufflation gases. None of the sheep experienced hypercapnia or acidaemic, yet 42% (19/45) of sheep developed clinical hypoxaemia, with a higher percentage of ewes in the CO₂ group developing hypoxaemia than in the medical air group. Based on the overall analysis, medical air could be utilised as a comparable alternative for abdominal insufflation during laparoscopic AI procedures.     

Identification,characterization and full-length sequence analysis of a novel endornavirus in common sunflower (Helianthus annuus L.)

To identify the possible quarantine viruses in seven common sunflower varieties imported from the United States of America and the Netherlands, we tested total RNAs extracted from the leaf tissues using next-generation sequencing of small RNAs. After analysis of small RNA sequencing data, no any quarantine virus was found, but a double-stranded RNA(dsRNA) molecule showing typical genomic features of endornavirus was detected in two varieties, X3939 and SH1108. Full-length sequence and phylogenetic analysis showed that it is a novel endornavirus, temporarily named as Helianthus annuus alphaendornavirus(HaEV). Its full genome corresponds to a 14 662-bp dsRNA segment, including a 21-nt 5′ untranslated region(UTR), 3' UTR ending with the unique sequence CCCCCCCC and lacking a poly(A) tail. An open reading frame(ORF) that encodes a deduced 4 867 amino acids(aa) polyprotein with three domains: RdRP, Hel and UGT(UDP-glycosyltransferase). HaEV mainly distributed in the cytoplasm but less in the nucleus of leaf cells by fluorescence in situ hybridization(FISH) experiment. This virus has a high seed infection rate in the five varieties, X3907, X3939, A231, SH1108 and SR1320. To our knowledge, this is the first report about the virus of the family Endornaviridae in the common sunflower.     

橡胶园酸性、中性土壤交换性钙、镁测定方法研究

为了获得简单、易操作、准确度高的橡胶园酸性、中性土壤交换性钙、镁测定方法,本试验通过响应面优化试验,建立称样量、提取液体积、提取方式与交换性钙测定结果之间的数学模型。结果表明：在25℃条件下,以1 mol/L的乙酸铵为土壤浸提液,称样量为2 g、提取液体积175 mL、振荡36 min,为橡胶园酸性、中性土壤的最佳提取条件。将上述条件下得到的结果与标准方法条件下得到的结果相对比,两结果的相对误差在1.25~3.04之间,均属合理范围。利用标准样品对优化方法进行试验验证,结果与推荐值相符。改进后的方法分析成本低、操作简便、测定结果准确、稳定性好,可用于橡胶园酸性、中性土壤交换性钙、镁的测定。