Uronic acid in humus

Introduction

Uronic acids are aldehydic sugar acids. In nature, they are composed mainly of d-glucuronic acid and d-galacturonic acid and scarcely of dmannuronic acid.     

Windborne migration routes of newly-emerged fall armyworm from Qinling Mountains–Huaihe River region,China

The fall armyworm(FAW, Lepidoptera: Noctuidae), Spodoptera frugiperda(J. E. Smith), invaded China in mid-December 2018; since then, it has become a great threat to Chinese agricultural production. Qinling Mountains–Huaihe River region(QM–HRR) is the transitional zone between northern and southern China, an important region for both corn and wheat production. Based on the actual occurrence of QM–HRR invaded by FAW in 2019, daily mean surface air temperature and nocturnal wind conditions at 925 hPa were examined, and migratory routes of FAW moths originated in QM–HRR were modeled by a forward-trajectory-analysis approach. The results indicated that migratory activities of FAW adults emerged in QM–HRR were initiated from late June. The moths from western QM–HRR, where has complex topographic terrain, mainly flied to Ningxia and Inner Mongolia before mid September. However, FAW moths from the eastern QM–HRR primarily engaged in high-altitude northward transport assisted by the prevailing southerly winds before mid August, and the North China Plain was identified as the main destination of FAW. Meanwhile, the migration trajectories of FAW moths had a possibility to reach the Northeast China Plain. From mid August, FAW moths in eastern QM–HRR largely migrated southward and returned to the Yangtze River Valley. This study provides detailed information on the occurrence and migration routes of FAW moths from QM–HRR and will be helpful for early warning and development of integrated pest management strategies for the control of this exotic insect pest.     

青南牧区雪灾危害的防御

为防灾减灾,利用调查研究,分析了降雪量、低温、牲畜膘情、草地产草量、饲草储备、保温、草地载畜量、雪灾预报、抗灾组织等因子,对青南牧区雪灾危害的影响,提出通过人为干预防御雪灾的综合措施,并制定了入冬前进行的抗灾能力评定标准。     

Interactions between phosphorus availability and microbes in a wheat–maize double cropping system: A reduced fertilization scheme

Mechanisms controlling phosphorus(P) availability and the roles of microorganisms in the efficient utilization of soil P in the wheat–maize double cropping system are poorly understood. In the present study, we conducted a pot experiment for four consecutive wheat–maize seasons(2016–2018) using calcareous soils with high(30.36 mg kg^–1) and low(9.78 mg kg^–1) initial Olsen-P content to evaluate the effects of conventional P fertilizer application to both wheat and maize(Pwm) ...     

甘肃天祝牧区白牦牛乳脂肪中脂肪酸的分析

以甘肃天祝地区3个牧场所产的白牦牛乳为研究对象,采用气相色谱-质谱联用检测方法,测定3个牧场所产白牦牛乳中脂肪酸含量,比较在枯草期、枯草末期、返青期、青草期4个时期及不同胎次的白牦牛所产牦牛乳中脂肪酸的构成及含量.结果表明:3个牧场白牦牛乳中乳脂肪酸含量差异不显著(P＞0.05);1～5胎次母白牦牛乳中脂肪酸含量差异不显著(P＞0.05).枯草期、枯草末期、返青期、青草期4个时期白牦牛乳中饱和脂肪酸(SFA)、不饱和脂肪酸(USFA)含量比值分别为1.86、1.75、1.62、1.32.随着气温的升高及牧草的成熟,白牦牛乳中饱和脂肪酸含量逐渐降低,而不饱和脂肪酸的含量逐渐升高.     

白马雪山自然保护区德钦分局辖区鸟类多样性及保护管理对策

白马雪山自然保护区德钦分局辖区内鸟类资源十分丰富,至2005年底共记录到鸟类328种。其中留鸟204种,占总数的62.2%;夏候鸟和繁殖鸟76种,占23.2%;旅鸟和冬候鸟48种,占14.6%。以区系成分分,东洋界106种,古北界48种,广布种68种。针对分布鸟类多样性资源受威胁及限制因子,提出相应的对策。     

基于UHPLC–QTOF–MS技术的五倍子单宁成分分析

目的 基于超高效液相色谱–四极杆飞行时间–质谱（UHPLC–QTOF–MS）技术分析五倍子中单宁成分,建立一种有效的五倍子单宁成分测定方法,并解析单宁的裂解规律。 方法 使用高温和超声波辅助方法提取五倍子中的酚类化合物,基于二级质谱推定化合物的裂解途径。 结果 共鉴定到20种化合物,包含14种没食子单宁、3种酚酸、2种没食子酸酯和1种黄烷醇。以高温121℃为提取条件,均未鉴定到分子质量高于1 500 Da的没食子单宁,而在超声波辅助提取的五倍子水提取液中,成功地检测到1–O–没食子酰基葡萄糖至14–O–没食子酰基葡萄糖,其中,超声功率1 500 W,提取温度65℃条件下,鉴定到更多的没食子单宁异构体。MS/MS图谱显示,五倍子单宁主要通过没食子酸、没食子酰基、糖苷、水、羧基的损失进行裂解。 结论 本研究证明,超声波辅助提取条件下,应用UHPLC–QTOF–MS技术能够全面高效地分析五倍子中的单宁成分,本研究为富含单宁的植物的化学成分研究提供参考依据。     

Mesoscale spatial variability of ichthyoplankton in the Southwest Atlantic during the autumn–winter period

To gain a better understanding of the mechanisms underlying spatial heterogeneity in ichthyoplankton communities in the SW Atlantic, we examined for the first time the latitudinal and continental shelf–slope gradients in ichthyoplankton structure and oceanographic features in the Campos Basin during the relaxation phase of coastal upwellings (late autumn to early winter). This region, located on SE Brazil's continental margin, is the most productive offshore oil basin in the country and has ecological relevance owing to the existence of areas that experiences mesoscale (tens to hundreds of kilometers) processes (eddies, filaments, and upwelling) caused by the interaction of continental shelf and slope circulation with deep water masses. The present study collected a total of 3892 fish eggs and 10,030 larvae from 36 sampling stations, averaging 22 eggs per 100 m³ and 56 larvae per 100 m³. A total of 250 taxa (5 for fish eggs and 248 for larvae) were identified, encompassing 80 families and 145 genera. Species distribution exhibited a considerable degree of spatial variability, which was related mostly to hydrological characteristics. In general, greater densities were associated with higher nutrient concentrations areas. Through distance-based Redundancy Analysis, some discriminating species were found to associate with certain areas of the continental shelf characterized by colder temperatures. The ichthyoplankton distribution patterns suggested a potential influence from mesoscale oceanographic fronts, specifically those that induce upwelling of the cold and nutrient-rich South Atlantic Central Water. Nonetheless, the methodologies used in this study faced challenges in distinctly identifying these processes.     

Arbuscular mycorrhizal fungal hyphae enhance transport of the allelochemical juglone in the field

Allelopathy is a biological phenomenon where plants have harmful effects on growth of surrounding plants through the production of chemical substances. Here we focus on allelochemical processes which operate belowground, can influence plant interactions and therefore potentially affect plant community structure. Soil hyphae of arbuscular mycorrhizal fungi (AMF) may enhance transport processes in the soil matrix by providing direct connections between plants facilitating infochemical exchange.In a two-component field study we showed that soil hyphae likely play a crucial role in movement of allelochemicals in natural soils and greatly expand bioactive zones by providing effective transport pathways for chemical compounds. First, we tested the effects of Juglans regia leaf litter extract addition in intact or disrupted hyphal networks and simultaneously determined growth reducing effects on sensitive Lycopersicon lycopersicum plants. Second, we analyzed the effect of juglone on tomato by directly adding leaf litter. In both approaches we found an increase of juglone transport if a hyphal network was present, resulting in reduced growth of target plants.Our results, together with previous work, add to the body of evidence for hyphae of soil fungi playing an important role in the transfer of allelochemicals and effectively acting as transport highways in the field. We suggest that hyphal connections, mostly formed by AMF, increase the effectiveness of allelochemicals in natural systems and can play a crucial role in chemical interaction processes in the soil.     

Agroecological principles for the redesign of integrated crop–livestock systems

Combining crops and livestock within integrated crop–livestock systems (ICLS) represents an opportunity to improve the sustainability of farming systems. The objective of this paper is to analyse how agroecological principles can help farmers to redesign and improve the resilience, self-sufficiency, productivity, and efficiency of ICLS. Relying on case studies from Brazil and France, we examine how the transformation of two conventional, specialised systems into more integrated-production systems illustrates the different dynamics towards agroecological ICLS. The French case study, based on self-sufficient farming systems belonging to a sustainable agriculture network, highlights that cost-cutting management led to a win–win strategy comprising good economic and environmental performances. The farms decreased their dependence on external inputs and had only a limited loss of production. The past trajectories of the farms illustrate how increasing the interactions between subsystems improved the self-sufficiency and efficiency of the farms. The Brazilian case study compares slash-and-burn agriculture in the Amazonian region with the recovery of degraded grazing area by ICLS. A small increase in chemical inputs linked to a diversification of productions led to a large increase in production and a large decrease in environmental impacts (deforestation). The Brazilian case study also illustrates how the diversification of production increased the resilience of the system to market shocks. Reconstructing the links among soil, crops, and animals following agroecological principles could improve the different performances of ICLS. New agroecological ICLS, benefiting from diversified productions and increased interactions between subsystems, are likely to offset the trade-off between agricultural production and environmental impacts observed in current ICLS.