Using expected allele number as objective function to design between and within breed conservation of farm animal biodiversity

Conservation of genetic diversity in farm animal species can be achieved by preventing extinction of breeds and by reducing genetic drift within breeds. It is suggested to use the expected number of alleles segregating in the species after a given time period as objective function in the design of conservation strategies. A formal approach is presented to predict this quantity based on marker information, accounting for extinction probability of breeds and effective population size within breeds as the major component of genetic drift. Based on this model, relative efficiency of different strategies of diversity conservation can be quantified. Formulas are given to derive the marginal expected number of alleles with respect to genetic drift within population and extinction probability, respectively. The suggested approach is illustrated with an example of 13 European cattle breeds. With the assumed parameters, drift is shown to be the major force leading to loss of alleles, and different breeds are prioritized for activities to reduce risk of extinction and for measures to reduce genetic drift, respectively. Although different aspects of the model need to be further refined, the suggested methodology provides a general and flexible tool to derive the optimum conservation strategy in various scenarios.     

Development and assessment of a novel servo-controlled spraying system for real time adjustment of the orientation angle of the nozzles of a boom sprayer

Background

Pesticide spray drift, which is the movement of pesticide by wind to any location other than the intended area, is hazardous to human, animal, food safety and environmental health. It is not possible to completely eliminate spray drift during spraying with field crop sprayers, but spray drift can be reduced by developing new technologies. The most common methods to reduce spray drift are carrying the droplets to the target with air-assisted spraying, electrostatic spraying, preferring air induction nozzles and boom shields. With these methods, it is not possible to make a change on the sprayer depending on the wind intensity during spraying. In this study, a novel servo-controlled spraying system was designed and developed to change the nozzle orientation angle in the reverse direction of the wind current to reduce the ground spray drift in real time and automatically in a wind tunnel. The displacement in the spray pattern (D_c) was used as a ground drift indicator for each nozzle to evaluate the spray drift.

Results

The developed system, operated by LabVIEW software, calculated different nozzle orientation angles depending on nozzle types, wind velocities and spraying pressures. Orientation angles calculated for different test conditions achieved in reduction were up to 49.01% for XR11002 nozzle, 32.82% for AIXR11002 nozzle and 32.31% for TTJ6011002 nozzle at 400 kPa spray pressure and 2.5 m s⁻¹ wind velocity.

Conclusion

The developed system, which has a self-decision mechanism, calculated the nozzle orientation angle instantaneously according to the wind velocity. It has been observed that the adjustable spraying nozzle system, sprayed with high precision towards the wind in the wind tunnel, and the developed system have advantages compared to conventional spraying systems. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Low glyphosate rates do not affect Citrus limonia (L.) Osbeck seedlings

BACKGROUND: Glyphosate is used to control weeds in citrus orchards, and accidental spraying or wind drift onto the seedlings may cause growth arrest owing to metabolism disturbance. Two experiments were carried out to investigate the effect of non‐lethal rates (0, 180, 360 and 720 g AI ha^?1) of glyphosate on four‐month‐old ‘Cravo’ lime, Citrus limonia (L.) Osbeck, seedlings. Photosynthesis and the concentrations of shikimic acid, total free amino acids and phenolic acids were evaluated. RESULTS: Only transitory effects were observed in the contents of shikimate and total free amino acids. No visual effects were observed. CONCLUSION: The present study showed that glyphosate at non‐lethal rates, which is very usual when accidental spraying or wind drift occurs in citrus orchard, did not cause severe metabolic damage in ‘Cravo’ lime seedlings. Copyright © 2009 Society of Chemical Industry     

侧向风对航空植保无人机平面扇形喷头雾滴飘移的影响

目的 侧向风是影响植保无人机航空喷施雾滴飘移和作业效果的主要因素。探究航空植保喷施过程中侧向风对雾滴沉积和飘移的影响,为植保无人机航空喷施作业参数的选择和作业关键部件的改进提供数据支持和理论指导。方法 以常用平面扇形喷头Lechler系列的LU 120-015和LU 120-03标准压力喷头为研究对象,基于计算流体力学离散相模型的粒子跟踪技术,在适宜的边界条件下对喷施作业过程中风洞内雾滴流场和农药喷洒离散相进行模拟试验;通过仿真模拟对平面扇形喷头喷施的雾滴沉积和飘移分布情况进行可视化分析,探究雾滴粒子在不同侧风风速条件下的飘移特性;在农业航空专用风洞中,采用近似条件对雾滴的沉积飘移特性进行试验验证和分析。结果 仿真模拟结果表明,随着侧向风速的增加,离散相雾滴粒子飘移程度越严重,雾滴水平飘移越明显。随着侧向风速的增加,模拟离散相雾滴粒子的准确沉积率(R_a)呈指数下降,由14.11%下降到0.66%;水平飘移率(R_h)呈线性增加,由14.25%增加到60.58%。风洞试验结果表明,在侧风风速分别为1、3和6 m/s的条件下,雾滴的R_h分别为0.4%、48.1%和75.1%,且雾滴在风洞内部会随着侧风风速的增加发生一定程度的卷扬现象。仿真模拟与风洞测试试验的R_h具有显著相关性(R²=0.963,P<0.05)。结论 仿真模拟对航空喷施条件下的雾滴飘移具有较好的预测效果;采用仿真模拟辅助风洞试验测试的方法,可以比较准确地得出航空植保无人机作业中常用平面扇形喷头的雾滴沉积与飘移情况。     

田间农药雾滴精准采样技术与发展趋势

采用植保机械喷施化学农药仍是病虫害防治最为有效的手段。喷施过程中,农药雾滴精准的采集并测定沉积、流失飘移量,对于优化植保机械的作业参数、提高农药利用率具有重要意义。该研究综述分析了室内与田间采样过程中不同类型采样器的优缺点,并分析采样效率、采样器的布置及采样条件等因素对雾滴沉积、流失飘移采样结果的影响。针对当前的采样方法,该研究提出了未来在农药雾滴采样方面的5点要求与展望,包括提高采样的准确性、提高采样方法和采样设备的标准化、增加对农药有效成分雾滴运动规律的研究、研发新型的采样传感器以提高采样效率、建立植保无人飞机喷施雾滴沉积、飘移模型。综上,通过更为标准化和精准的采样,获取可比较、准确度高的农药雾滴沉积与流失飘移数据,可为中国农药使用量"零增长"提供科学技术指导。     

不同侧风和静电电压对静电喷雾飘移的影响

为研究不同侧风和静电电压对静电喷雾雾滴飘移的影响规律,设计不同侧风(恒速风1、2、4 m/s及0~4 m/s变化的模拟自然风)及静电电压(0,2,4,6,8 k V),进行喷杆式静电喷雾机的雾滴飘移试验,测定不同静电电压下的雾滴粒径与荷质比,并对比分析雾滴飘移质量中心距和飘失率。结果表明:随着静电电压的增大,雾滴粒径减小,雾滴荷质比增大,0~8 k V电压下电极干燥和电极打湿对雾滴荷质比没有显著影响。在侧风风速为1 m/s时,0~8 k V静电喷雾的雾滴飘移中心距小于0.55 m,雾滴飘失率低于15%。在侧风风速2 m/s时,非静电喷雾的雾滴飘失率为11.9%,6~8 k V静电喷雾的雾滴飘失率超过20%,其中静电电压8 k V的雾滴飘失率(23.9%)比非静电喷雾增加100.8%。在侧风风速4 m/s时,4~8 k V静电喷雾的雾滴飘移中心距在0.9 m以上,雾滴飘失率在30%以上,其中静电电压8 k V下的雾滴飘移中心距为967.2 mm比非静电喷雾下增加了13.7%,雾滴飘失率为35.4%比非静电喷雾下增加了59.5%。相同静电电压下,2 m/s的恒速风和0~4 m/s变化的模拟自然风之间对雾滴飘失率无显著差异。该研究为优化喷雾技术参数和提高雾滴抗飘移的能力提供参考。     

Wind regime for long-ridge yardangs in the Qaidam Basin,Northwest China

Yardangs are typical aeolian erosion landforms, which are attracting more and more attention of geomorphologists and geologists for their various morphology and enigmatic formation mechanisms. In order to clarify the aeolian environments that influence the development of long-ridge yardangs in the northwestern Qaidam Basin of China, the present research investigated the winds by installing wind observation tower in the field. We found that the sand-driving winds mainly blow from the north-northwest, northwest and north, and occur the most frequent in summer, because the high temperature increases atmospheric instability and leads to downward momentum transfer and active local convection during these months. The annual drift potential and the ratio of resultant drift potential indicate that the study area pertains to a high-energy wind environment and a narrow unimodal wind regime. The wind energy decreases from northwest to southeast in the Qaidam Basin, with the northerly winds in the northwestern basin changing to more westerly in the southeastern basin. The strong and unidirectional wind regime for the long-ridge yardangs in the northwestern Qaidam Basin results from the combined effects of topographic obstacles such as the Altun Mountains and of the interaction between the air stream and the yardang bodies. Present study suggests that yardang evolution needs such strong and unidirectional winds in high- or intermediate-energy wind environments. This differs from sandy deserts or sandy lands, which usually develop at low- or intermediate-energy wind environments. Present study clarifies the wind regime corresponding to the long-ridge yardangs' development, and lays firm foundation to put forward the formation mechanisms for yardangs in the Qaidam Basin.     

锥形风场式防飘喷雾装置内流道优化与防飘特性

锥形风场式防飘喷雾装置是利用辅助气流进行防飘作业的一种创新结构形式。为分析其防飘机理,改善防飘喷雾作业效果,对现有装置进行优化设计与防飘特性研究。基于质子动力学基本定律,构建了单个雾滴在运动空气介质中的受力模型,明晰了锥形风场的防飘机理。运用流体力学理论分析内流道气流损失,并利用CFD数值仿真技术结合风场测试对防飘喷雾装置进行优化设计。结果表明：当内流道弯管的曲率半径设计为4 cm时,优化后装置出口处仿真试验风速较优化前提高23.5%,测试试验风速较优化前提高28%,风机有效利用率提高21.2个百分点,优化方案合理。风洞条件下装置防飘特性试验结果表明：侧风风速、喷头高度、锥风风速与总雾滴飘移量占比具有相关性,通过多因素正交试验建立的竖直和水平方向的数学模型显著性较高（P<0.05,R2分别为0.934、0.945）,表明锥形风场可以抵御绕流涡旋的产生,具有减少雾滴在纵向高度上随风飘失的特性。该研究可为综合分析雾滴飘移沉积规律提供一定参考。     

单旋翼无人机作业高度对槟榔雾滴沉积分布与飘移影响

为了阐明3WQF120-12型单旋翼无人植保机喷施槟榔树的雾滴沉积效果、地面流失雾滴沉积分布、飘移及可应用性,研究了无人机不同作业高度对槟榔树冠层及地面喷施效果的影响。试验选用诱惑红染色剂,并配制成质量分数为0. 5%的水溶液,代替农药;用铜版纸进行雾滴采集,并利用图像处理软件Deposit Scan分析得出雾滴沉积结果。结果表明:作业高度对槟榔树各层采样点的雾滴沉积量没有显著性影响,同一高度作业时,树冠上层与树冠下层、树冠上层与树果层之间的雾滴沉积量有显著差异,树冠上层雾滴沉积水平最高可达53. 27%,树冠下层和树果层可达树冠上层的59. 19%和27. 91%;地面流失采样点雾滴沉积结果显示,不同作业高度对地面3列采样点的雾滴沉积量有显著性影响,最低平均沉积水平约19. 9%;飘移区数据显示,3个作业高度对飘移带采样点的雾滴沉积量没有显著性影响,当作业高度为12. 09 m时,飘移带测得的飘移量最大,作业高度10. 40 m时飘移量最小。同时测试发现,飘移距离最远可达36. 35 m,因此实际作业时必须留出足够的安全距离。     

防风式枸杞植保机的研制与试验

针对目前枸杞植保作业中存在飘移严重、喷雾质量差、作业效率低等问题,设计了一款枸杞专用植保机,采用防风翼、智能喷雾控制系统、风送辅助系统、调节机构及大容量药箱等解决枸杞植保中存在的问题。试验结果表明:机器防风性能、喷雾质量、作业效率都符合设计要求,具有一定的推广价值。