Utilisation de souches non pathogènes de Fusarium pour lutter contre les fusarioses: situation actuelle dans la pratique1

Des travaux antérieurs ayant permis de démontrer que des souches non pathogènes de Fusarium sont impliquèes dans les mécanismes de résistance des sols aux fusarioses, nous avons tenté d'utiliser des souches de Fusarium sélectionnées pour lutter contre ces maladies. Les bons résultats obtenus en conditions expérimentales nous ont conduits à mettre en place un réseau d'expérimentation en conditions normales de culture dans des serres de production de tomates et de melons. Le premier problème à résoudre est celui de la production massive d'inoculum, de sa conservation et de son introduction dans les sols et substrats de cultures. La production de l'inoculum est réalisée en fermenteur, les propagules produites soni récupérées par filtration et mélangées avec du talc, support inerte qui après avoir été séché assure la conservation et la distribution de cet inoculum dans des conditions satisfaisantes. Les quantités d'inoculum produites en 1985–86 ont permis de réaliser plusieurs essais de lutte dans des conditions normales de production. L'inoculum protecteur est apporté, soit dans les substrats de culture hors sol au moment de leur ensachage, soit dans les sols en place, immédiatement après leur désinfection au bromure de méthyle. L'installation de la souche protectrice est suivie régulièrement grace à des analyses microbiologiques et la gravité de la maladie est notée régulièrement en cours de culture. Les résultats enregistrés en 1986, variables d'une situation à l'autre, ne permettent pas de porter un jugement définif sur l'intéret de ce procédé de lutte. Ils sont cependant intéressants et permettent d'organiser sur des bases plus solides notre campagne d'expérimentation 1986–87.     

工业污染地区盐渍土造林中幼林不同抚育方式水热特征研究

本研究对包头市全巴图工业污染区盐渍土造林中,幼林抚育时生草制和清耕制两种土壤管理方式下,林地的微气象因子进行同时观测,分析了两种抚育方式对林地水热状况的影响。     

三江源地区一年生禾豆混播人工草地最佳混播比例的综合评价研究

【目的】探究青海省三江源地区建立人工草地混播体系最佳综合评价模式。【方法】采用3种不同综合评价方法筛选适宜在三江源地区建植的禾豆混播组合及比例。【结果】3种评价方法,AHP层次分析法评价方法中最优混播组合及比例为燕麦+箭筈豌豆（70∶30）,隶属函数评价方法中最优混播组合及比例为燕麦+箭筈豌豆（60∶40）,灰色关联度评价方法中最优混播组合及比例为燕麦+箭筈豌豆（70∶30）。【结论】结合试验地区海拔条件等因素,在高寒地区优先推荐灰色关联度综合评价方法,燕麦+箭筈豌豆（70∶30）混播模式为一年生禾豆混播最佳混播组合及比例。     

Environmental control of Northeast Atlantic mackerel (Scomber scombrus) recruitment in the southern Bay of Biscay: case study of failure in the year 2000

We investigate the effect of strong meteorological perturbations in early spring on the success of mackerel (Scomber scombrus) recruitment in the N/NW Iberian area (southern Bay of Biscay) for the period 1999–2008. In 2000, the year of the most pronounced recruitment failure on record, two consecutive multidisciplinary surveys sampled hydrographic conditions and mackerel eggs, larvae and post‐larvae over the main mackerel spawning grounds of the north and northwest coast of the Iberian Peninsula. Analysis of egg and larval abundance and birthdates based on the otoliths of mackerel juveniles caught between July and October 2000 showed that there were no survivors from the early spring spawns, indicating a massive loss of early spawning effort. Moreover, the abundance of 1‐year‐old mackerel estimated from an acoustic survey carried out in 2001 was the lowest observed within the 1999–2008 time series. This low or null survival from the early spawns in 2000 could be due to the meteorological and oceanographic conditions of that spring, in particular two storm events in April after a relatively calm March. The first storm event from the north caused strong local wind in the southern Bay of Biscay but a weak oceanographic response. The second storm event from the southwest was mainly felt west of Galicia and caused a notable increase in shelf currents and a shift of the hydrographical structure along the shelf. Detailed analysis of strong wind pulses in early spring within the historical recruitment record suggests that strong local turbulence generated by high wind speeds and advection of larvae caused by the enhancement of shelf currents can contribute to reduced recruitment. Our observations indicate that, in 2000, both mechanisms were present.     

温度、光照和贮藏时间对珍珠梅种子萌发的影响

从温度、光照和贮藏时间等方面对华北珍珠梅和珍珠梅种子萌发特性进行了探讨。结果表明:不同光照条件对两种珍珠梅种子萌发影响较小,温度是影响珍珠梅种子萌发的主要因素;华北珍珠梅的最适发芽温度是25℃,珍珠梅的最适发芽温度是25℃～30℃,在此温度下发芽率和发芽势最高;一年之内,随着贮藏时间的延长两种珍珠梅种子的发芽率与发芽势均有小幅下降,发芽的高峰期推迟。     

REINTEGRATION OF CROP-LIVESTOCK SYSTEMS IN EUROPE: AN OVERVIEW

• ICLS combines the benefits of specialization with increased resilience of the system.• Clear opportunities but also barriers for ICLS were observed.• ICLS need to be embedded within future environmental legislation.• ICLS systems with a range of intensities are needed to support a biodiverse landscape.Ongoing specialization of crop and livestock systems provides socioeconomic benefits to the farmer but has led to greater externalization of environmental costs when compared to mixed farming systems. Better integration of crop and livestock systems offers great potential to rebalance the economic and environmental trade-offs in both systems. The aims of this study were to analyze changes in farm structure and review and evaluate the potential for reintegrating specialized intensive crop and livestock systems, with specific emphasis on identifying the co-benefits and barriers to reintegration. Historically, animals were essential to recycle nutrients in the farming system but this became less important with the availability of synthetic fertilisers. Although mixed farm systems can be economically attractive, benefits of scale combined with socio-economic factors have resulted in on-farm and regional specialization with negative environmental impacts. Reintegration is therefore needed to reduce nutrient surpluses at farm, regional and national levels, and to improve soil quality in intensive cropping systems. Reintegration offers practical and cost-effective options to widen crop rotations and promotes the use of organic inputs and associated benefits, reducing dependency on synthetic fertilisers, biocides and manure processing costs. Circular agriculture goes beyond manure management and requires adaptation of both food production and consumption patterns, matching local capacity to produce with food demand. Consequently, feed transport, greenhouse gas emissions, nutrient surpluses and nutrient losses to the environment can be reduced. It is concluded that reintegration of specialized farms within a region can provide benefits to farmers but may also lead to further intensification of land use. New approaches within a food system context offer alternatives for reintegration, but require strong policy incentives which show clear, tangible and lasting benefits for farmers, the environment and the wider community.     

Regulation of bronchomotor tone in conscious calves

The purpose of this study was to investigate the effects of some a and β sympathomimetic and sympatholytic drugs on respiratory impedance in healthy conscious calves. Ten Friesian calves were investigated in this study. The forced oscillation technique was used to measure the resistance ( R _rs) and the reactance ( X _rs) of the respiratory system at frequencies ranging from 4 to 26 Hz. Isoprenaline (1 μg/kg i.v.), propranolol (3 μg/kg i.v.), noradrenaline (2 μg/kg i.v.), xylazine (20 μg/kg i.v.) and yohimbine (0.25 mg/kg i.v.) were administered. Isoprenaline induced a significant decrease of R _rs. An increase of R _rs after administration of propranolol was observed but without any change of the frequency dependence of R _rs. A small increase in the resonant frequency was also recorded. A decrease of R _rs was recorded after yohimbine injection. Noradrenaline and xylazine administration increased the resistances and the resonant frequency and induced a negative frequency dependence of R _rs. These results suggest that (1) the major effects of β adrenergic drugs are on the central airways, (2) the a adrenergic system may play a role on the regulation of bronchomotor tone in calves, (3) the effects of a adrenergic drugs are on both central and peripheral airways and (4) the forced oscillation technique allows the differentiation of calibre changes occurring in small and large airways.     

High temperature effects on gas exchange for the invasive buffel grass (Pennisetum ciliare [L.] Link)

Buffel grass was introduced to the Sonoran Desert in the mid-twentieth century, where it has aggressively invaded new areas. Given its ecological success at a place where the air temperature can approach 50°C, the effects of high air temperatures on gas exchange were studied for this species. The carbon dioxide uptake and water use efficiency were maximal at day/night air temperatures of 30/20°C for potted plants, substantially decreasing at higher temperatures until the plants died at 45/35°C.