绵羊BMP15基因B2突变可视化检测技术的建立

骨形态发生蛋白15（bone morphogenetic protein 15,BMP15）基因突变对绵羊排卵率、产仔数以及繁殖力有很大影响,本研究旨在建立快速可视化检测BMP15基因B2突变的技术。将改良的扩增阻滞突变系统（amplification refractory mutation system,ARMS）与核酸染料SYBR Green Ⅰ结合,针对BMP15基因B2突变设计ARMS特异性引物,使引物下游3'端的最后一个碱基为A,并在下游引物3'端的第3位碱基处设计额外的错配,以提高引物的特异性;经ARMS PCR扩增后,向产物中加入SYBR Green Ⅰ,通过肉眼观察PCR管内的颜色变化来检测BMP15基因的B2突变。经测序发现所采集的样本均为野生型,因此,利用重叠延伸PCR构建BMP15基因B2突变型模板,测序结果显示BMP15基因B2突变型模板构建成功。ARMS PCR结果显示,ARMS特异性引物能够只扩增突变型模板,而不会扩增野生型模板,且扩增效果良好。ARMS PCR扩增后加入SYBR Green Ⅰ发现已知野生型模板与阴性对照一致,呈SYBR Green Ⅰ原始颜色橙黄色,而已知突变型模板呈亮绿色,且色差明显,肉眼可辨。用建立的可视化检测BMP15基因B2突变的技术检测50个小尾寒羊基因组DNA （随机向其中20个样本中加入构建的BMP15基因B2突变型模板）,将可视化检测的突变型样本编号与混合样本时记录的编号对比,结果表明该技术能够准确检测绵羊BMP15基因的B2突变,且准确率高达100%。将构建的BMP15基因B2突变型的模板进行梯度稀释,对本试验可视化检测体系的灵敏度进行检测,发现ARMS可视化检测技术的灵敏度达到0.006 ng/μL。因此,本研究建立的技术能够可视化地检测绵羊BMP15基因B2突变,且准确率高,有望为高繁殖力绵羊的选育提供技术支持。     

Green tea polyphenols supplementation alters immunometabolism and oxidative stress in dairy cows with hyperketonemia

Peripartal cows often experience negative energy balance, and are therefore prone to suffering from metabolic diseases such as hyperketonemia, which causes financial losses in dairy farms. This study aimed to investigate the effect of green tea polyphenol (GTP) supplementation during the periparturient period on production performance, oxidative stress and immunometabolism in dairy cows with hyperketonemia. One hundred Holstein cows were assigned to GTP (0.2 g/kg DM; n = 50) or control (without GTP; n = 50) group based on body weight, previous milk yield, and parity on d 15 before expected parturition. Subsequently, 10 cows with hyperketonemia were selected from each group, according to blood β-hydroxybutyric acid (BHBA) concentration between 1.2 and 2.9 mmol/L from 2 to 3 d postpartum. All cows were fed a close-up diet and a lactation diet with or without GTP supply from 15 d prepartum until 30 d postpartum. Milk and blood samples were obtained from 20 cows selected with hyperketonemia on 10, 20, and 30 d postpartum. Compared with control cows, greater milk yield and lower somatic cell count were observed in GTP cows. The GTP group had lower concentrations of BHBA, free fatty acids, cholesterol, triglyceride, reactive oxygen species, malondialdehyde, and hydrogen peroxide, greater concentrations of glucose, lower activities of aspartate aminotransferase, alanine aminotransferase, and glutamyl transpeptidase, alongside greater activities of superoxide dismutase, glutathione peroxidase, and total antioxidant capacity. Additionally, GTP supplementation up-regulated concentrations of interleukin-6 and interleukin-10, but down-regulated concentrations of tumor necrosis factor-α, interleukin-1β, interleukin-2, interleukin-8, and interferon-γ in plasma. Greater concentrations of plasma immunoglobulin G were also detected in the GTP group. Overall, the data suggested that GTP supplementation from 15 d prepartum to 30 d postpartum improved the milk yield and health status in cows with hyperketonemia during early lactation.     

平原丘陵地区水土资源联合优化配置

通过对区域水资源和土地资源概况进行研究,利用大系统递阶优化思想,以供水对象相对缺水率最小和农业经济效益最大为目标,建立了区域水土资源联合优化配置模型,并以句容市为例,对平原丘陵地区的水资源在时间和区域上进行了合理安排、设计、组合和布局,对农业种植结构进行了调整。研究结果表明:水资源是土地资源发挥最大优势的基本条件,水资源利用合理与否,直接影响到土地资源的生产效率;而土地资源的利用程度也影响着水资源的变化,土地资源利用效率高,则为水资源的合理开发利用创造条件。     

基于HHT变换的PSO-LSSVM耦合模型估算气象资料短缺地区ET_0

为准确估算气象资料短缺地区参考作物腾发量,构建了一种基于HHT变换的PSO-LSSVM耦合模型,并利用新疆和田气象站2000—2009年单日数据做训练、双日数据做验证。结果表明,该模型估算ET0方法明显优于常规的PSO-LSSVM和GRNN,预测精度较二者分别提高了15.7%~85.6%和15.8%~93.7%;该方法预测ET0的气象要素重要性为RsTmaxTminRHWn,利用该方法对气象要素组合为Tmax/Tmin/RH/Wn、Tmax/RH/Wn、Tmin/Wn、Wn条件下的ET0预测,MSE分别为0.407、0.185、0.149、0.135,说明该方法可以很好地估算资料缺失地区ET0。     

基于Z比分数的参考作物腾发量计算方法优选

参考作物腾发量(ET0)是计算作物需水量的关键,是进行农田水分管理和灌溉预报的主要参数。但不同ET0计算方法的结果存在明显差异。用能力统计量Z比分数,对FAO56Penman-Monteith、Hargreaves-Samani、Irmark-Allen拟合和Priestley-Taylor四种常用ET0计算方法在不同天气条件下的计算结果精度进行了对比分析。结果表明,Priestley-Taylor与FAO56Penman-Monteith方法的计算结果在精度上具有较高的一致性,与有关文献结果相吻合,其中前者精度略佳。且Z比分数参数受极端值的影响较小,计算简便、适用性强,克服了常规方法公式繁杂、编程实现困难的缺点,说明Z比分数法能够更好地适用于ET0计算方法的优选。研究结果可为农业水土工程领域有关参数计算与测定方法的优选提供借鉴。     

四种替代药剂对梨火疫病菌的抑制活性及其田间防效

为筛选农用链霉素替代药剂,以其为对照药剂,测定春雷霉素、中生菌素、噻霉酮和噻菌铜这4种常用细菌病害防治药剂对梨火疫病菌Erwinia amylovora的抑制活性、对梨火疫病的田间防效及不同药剂处理后梨中的农药残留,并对这4种药剂的作物安全性进行评价。结果表明,中生菌素、噻霉酮和春雷霉素对梨火疫病菌有抑制作用,抑制中浓度EC50分别为1.60、6.64和60.57 mg/L,中生菌素的抑制效果高于链霉素。在连续2年田间试验中,中生菌素1 000倍液和春雷霉素400倍液对梨火疫病的保护效果和治疗效果均达90.33%以上,噻霉酮500倍液和噻菌铜200倍液对梨火疫病的保护效果均达100.00%,治疗效果均超过86.97%,与对照药剂农用链霉素2 000倍液的效果相当。所有药剂处理后均未检出中生菌素、春雷霉素、高效氯氰菊酯和农用链霉素的农药残留,而噻虫嗪、阿维菌素和矮壮素虽有检出,但其残留量均低于国家限量标准。花期前后、幼果期和果实膨大期施药,中生菌素、春雷霉素、噻霉酮和噻菌铜对梨花、叶片、枝梢及果实生长均无不良影响。综合来看,中生菌素、春雷霉素、噻霉酮和噻菌铜均可作为农用链霉素的替代药剂,...     

Evaluation of the pattern of spray released from a moving multicopter

BACKGROUND

Multicopters are used for releasing particulates seeds, fertilizer and spray. Their low cost and high manoeuvrability make them attractive for spraying in steep terrain and areas where overspray is undesirable. This article describes a model of multicopter wake and its influence on particulate dispersion, which is computationally economical compared to many computational fluid dynamics (CFD) approaches, yet retains reasonable accuracy.

RESULTS

A model was successfully implemented in OpenFOAM . It features source terms for the rotor wash, Lagrangian particle tracking, an evaporation model, and a porous medium approach to model the effect of the ground vegetation. Predictions were validated against the field tests of Richardson et al. which used a DJI Agras MG-1 multicopter in three different flights with airspeeds of 3.2–4.9 m s⁻¹, ground speeds of 2.1–2.9 m s⁻¹ and cross-wind speeds of 0.04–2.2 m s⁻¹. The effective swath width (30% line separation) was predicted to within one standard deviation. Sensitivity to a rotor rotational speed, flight height, flight velocity, multicopter roll and yaw angles, surface roughness length, plant height and leaf density was checked.

CONCLUSION

In all flight trials, the modelled swath was closest to the experimentally obtained swath when the surface roughness of the fetch was equal to 0.5 m (bushes) and the rotational speed of all rotors was equal to 2475 rpm with 0.75R (0.2 m) tall plant canopy (grass) introduced to the model. The model showed acceptable validity for flight velocities of ≤2.8–5 m s⁻¹ when flight parameters can be approximately estimated. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Application and mechanisms of metal-based nanoparticles in the control of bacterial and fungal crop diseases

Nanotechnology is a young branch of the discipline generated by nanomaterials. Its development has greatly contributed to technological progress and product innovation in the field of agriculture. The antimicrobial properties of nanoparticles (NPs) can be used to develop nanopesticides for plant protection. Plant diseases caused by bacterial and fungal infestations are the main types of crop diseases. Once infected, they will seriously threaten crop growth, reduce yield and quality, and affect food safety, posing a health risk to humans. We reviewed the application of metal-based nanoparticles in inhibiting plant pathogenic bacteria and fungi, and discuss the antibacterial mechanisms of metal-based nanoparticles from two aspects: the direct interaction between nanoparticles and pathogens, and the indirect effects of inducing plant resilience to disease. © 2022 Society of Chemical Industry.     

Challenges and opportunities of unmanned aerial vehicles as a new tool for crop pest control

The application of pesticides is not simply delivering chemicals to the target area. It also involves considering the negative aspects and developing strategies to deal with them during the application process, to ensure the maximization of pesticides use efficiency and the maintenance of the ecosystem. Unmanned aerial vehicle (UAV) sprayers demonstrate unique advantages compared to traditional ground sprayers, particularly in terms of maneuverability and labor intensity reduction, showed great potential for chemical application in pest control. It is undeniable that there exist challenges in the practice of UAV spraying, such as higher potential risks of pesticide drift or pathogen transmission, uncertainty canopy deposition for different crops, and unexpected leaf breakage induced by downwash flow. Maximizing the utilization of downwash flow while avoiding lateral air movement outside the intended target crop area is a major issue for chemical application with UAV sprayers, particularly in light of the increasingly apparent consensus on the need for enhanced environmental protection during the chemical application process. It must be considered that the operation strategy in different scenarios and for different crop targets is not the same, unique requirements should be given on nozzle atomization, flight parameters, adjuvants and aircraft types in specific working situations. In future, the implementation of spray drift prediction, technical procedures development, and other solutions aimed at reducing pesticide drift and improving deposition quality, is expected to promote the adoption of UAV sprayers by more farmers. © 2023 Society of Chemical Industry.