常用除草剂对家蚕的毒性试验

８种常用除草剂对家蚕的毒性试验,结果表明：家蚕对其中４种除草剂有一定的毒性反应,表现轻微的中毒症状。除草剂对家蚕的角杀毒力和残毒期因除草剂品种不同而有明显的差异。家蚕对除草剂的抗性因龄期大小不同而异。     

甲拌磷在甘蔗及土壤中的残留动态分析

为了对甲拌磷在甘蔗田施用后的环境安全性进行量化评估及制定安全使用标准,采用田间试验方法,研究了5%甲拌磷颗粒剂在土壤中的消解动态,并对其在甘蔗上使用的安全性作出了评价。采用直接测定甲拌磷及其代谢物和用高锰酸钾作为氧化剂两种方法,用气相色谱火焰光度检测器测定了甲拌磷在甘蔗中的最终残留量和土壤中的消解动态及最终残留量。结果表明甲拌磷在土壤中的半衰期为11~12.3d,在正常使用条件下,不会造成甘蔗残毒污染和土壤的残留积累。     

1t/h棉籽泡沫酸脱绒设备加工中残酸值与氨中和的分析

通过对泡沫酸脱绒后的棉种残酸值与氨中和的研究和探讨,用回归分析法对残酸值和氨中和效果进行了预测,并经优化计算,得出最佳方案。     

Nutrient surpluses on integrated arable farms

From 1990 to 1993 nutrient fluxes were monitored on 38 private arable farms that had adopted farming strategies aiming at reduced nutrient inputs and substitution of mineral fertilizers by organic fertilizers. The nutrient surplus was defined as the difference between inputs (including inputs through deposition, seeds and biological fixation) and outputs in crop products, and amounted to 117 kg nitrogen (N), 14 kg phosphorus (P) and 21 kg potash (K) ha⁻¹ year⁻¹ on average. Potato and sugar beet had relatively high nutrient surpluses resulting both from crop characteristics and the use of organic manure. The surplus varied markedly among farms due to differences in cropping frequency, fertilizer inputs and crop outputs. Averaged over the years, ca. 70% of the participants achieved surpluses below 150 kg N, 20 kg P and 50 kg K ha⁻¹ year⁻¹.

The amounts of residual soil mineral N (RSMN) exceeded those normally found in field experiments except for data collected after the wet summer of 1993. Distinct differences between crops were observed. Only in the case of potato a significant relationship was observed between the effective N input and RSMN. On a whole-farm level, RSMN amounted to more than 70 kg ha⁻¹ N on 77, 74, 87 and 18% of the farms in the consecutive years.     

毛豆中丙溴磷残留量的测定及降解动态分析

在反复试验的基础上,建立了毛豆中丙溴磷残留量定量检测的气相色谱法。对分析方法的适合性测定结果表明,方法的回收率为86.5%～95.1%,其RSD为2.68%～6.79%,最小检测量0.00425ng,最小检出浓度为0.002mg/kg,该分析方法简便、准确、能满足实际样品分析。2004年、2005年对丙溴磷在毛豆的残留动态分析结果表明,丙溴磷在毛豆上有较高的原始沉积量,在毛豆上降解规律符合一级动力学方程,根据该方程测算,丙溴磷在毛豆中的半衰期(DT50)为3.2～3.5d,降解99%所需要的时间(T0.99)为21.3～23.5d。     

酶联免疫法测定水产品中氯霉素的残留量

[目的]探索水产品中氯霉素残留量的快速检测方法。[方法]采用酶联免疫法(ELISA)测定鱼、虾类水产品中氯霉素的残留量。[结果]检测的20个水产品中有1个阳性样品,其他样品均为阴性。ELISA方法的检出限为0.01μg/kg,平均回收率为76.1%~90.7%,相对标准偏差(RSD)≤3.21%,在0.025~1.600 ng/ml范围内有良好的线性关系,相关系数为0.997 5。[结论]该检测方法灵敏度、准确度和精密度均符合残留分析质量控制的要求,适用于大批量水产品中氯霉素残留的快速检测。     

Postharvest residual soil nutrients and yield of spring wheat under water deficit in arid northwest China

In areas where two crops are grown per year or three crops every 2 years, the status of residual soil nutrients after the harvest of the first crop is critical to the crop to be grown immediately after, while the postharvest soil nutrient status can be influenced by irrigation applied to the test crop. This study determined the effect of various soil water treatments applied to the test crop on the status of postharvest residual soil nutrient pools in an arid environment. Spring wheat (Triticum aestivum L.) was grown as test crop under conditions of full- (as control), high-, moderate-, and low-water conditions during jointing, booting-heading, and grain filling stages, in 2003 and 2004. Compared to the control, grain yield and water use efficiency (WUE) were significantly increased by subjecting the wheat crop to moderate-water conditions during various growth stages, and low-water conditions at jointing stage in both years. Soil C at harvest decreased linearly with increased grain yield of the test crop. Moderate- to high-water conditions during jointing stage resulted in 12-24% greater soil C in the top 40 cm depth in 2003, with a marginal difference in 2004. Water treatments impacted the status of residual soil nutrients in 2003; soil total N and available soil P in the top 40 cm depth were significantly higher in low- to moderate-water treatments compared to the control, while in 2004 significantly higher total N and P, available N, P and K were found only in the top 20 cm depth. Increased yield of wheat test crop with moderate-water resulted in increased postharvest residual soil nutrients, whereas the ratios of C/N, C/P, and C/K were largely influenced by years and were less related to water treatments. We conclude that the determination of postharvest soil C and nutrient elements may provide useful information in monitoring potential changes of soil nutrient status over time in the intensified cropping systems, and that the recommendation of fertilization for the crop to be grown immediately following the first crop can be established by simply analyzing the productivity of the first crop without intensive measurements of soil nutrients.     

Double mulching improves soil properties and productivity of maize-based cropping system in eastern Indian Himalayas

A field experiment was conducted for two consecutive years at North Eastern Indian Himalayan region to assess the effect of soil moisture conservation measures on soil and water productivity of different rainfed maize (Zea mays L.) - based cropping sequences. Results revealed that double mulching with in-situ maize stover mulch (MSM) + fresh biomass of white hoary pea (WHP-Tephrosia candida) and MSM + fresh biomass of ragweed (RW- Ambrosia artemisiifolia) improved soil moisture content (SMC) and leaf relative water content of crops during dry season. The soil organic carbon (SOC) content and stocks under MSM + WHP and MSM + RW mulches were significantly higher than that under no mulch at 0–15 cm depth. The soil microbial biomass carbon and dehydrogenase activity were maximum under MSM + WHP/RW. The highest system productivity was obtained from maize-French bean (Pole type-PT) sequence under MSM + RW followed by MSM + WHP. The water productivity was the highest under MSM + WHP. While SOC content was the highest under maize-French bean (PT), the maximum plant available nitrogen and phosphorus were obtained under maize-black gram sequence.Thus, double mulching technology involving MSM and RW (available in plenty) is a viable option for improving soil, crop and water productivity under rainfed hill ecosystems of eastern Indian Himalayas.     

基于改进型YOLOv4的果园障碍物实时检测方法

针对农业机器人在复杂的果园环境中作业时需要精确快速识别障碍物的问题,该研究提出了一种改进型的YOLOv4目标检测模型对果园障碍物进行分类和识别。为了减少改进后模型的参数数量并提升检测速度,该研究使用了深度可分离卷积代替模型中原有的标准卷积,并将主干网络CSP-Darknet中的残差组件（Residual Unit）改进为逆残差组件（Inverted Residual Unit）。此外,为了进一步增强模型对目标密集区域的检测能力,使用了软性非极大值抑制（Soft DIoU-Non-Maximum Suppression,Soft-DIoU-NMS）算法。为了验证该研究所提方法的有效性,选取果园中常见的3种障碍物作为检测对象制作图像数据集,在Tensorflow深度学习框架上训练模型。然后将测试图片输入训练好的模型中检测不同距离下的目标障碍物,并在同一评价指标下,将该模型的测试结果与改进前YOLOv4模型的测试结果进行评价对比。试验结果表明,改进后的YOLOv4果园障碍物检测模型的平均准确率和召回率分别为96.92%和91.43%,视频流检测速度为58.5帧/s,相比于原模型,改进后的模型在不损失精度的情况下,将模型大小压缩了75%,检测速度提高了29.4%。且改进后的模型具有鲁棒性强、实时性更好、轻量化的优点,能够更好地实现果园环境下障碍物的检测,为果园智能机器人的避障提供了有力的保障。     

动物营养与遗传育种学一体化研究的新方向（RFI）

以进食净效应（Residual〈net〉feef intake,RFI）为核心概念指标,进行动物营养学和遗传育种学一体化研究,正在国外少数发达国家的畜牧科学界深入推行,取得了多畜种研究应用的独特成果,将不同学科交叉研究推向了畜牧科学的前沿领域。2007年联合国粮农组织（FAO）动物遗传资源委员会专家团建议各国要研究采用RFI,以此为基础的选择方案可以提高畜群的内在效率,对所有物种和所有生产系统都是一个重要标准。可以获得采食较少的动物,但又不牺牲生长强度和生产性能。本文对近年这方面的研究作了评述,提出了开展这一领域研究的难点,展望这方面研究对动物营养学和遗传育种学基本理论的某些方面可能形成的挑战。