An improved polyurethane support system for monitoring growth in plant cell cultures

An improved culture system for plant cells that employs filter paper resting on polyurethane saturated with liquid medium is described. It combines a simplified version of the system outlined by Weber and Lark [1979, Theor Appl Genet 55: 81–86] with the method of growth estimation described by Horsch et al. [1980, Can J Bot 58: 2402–2406]. The growth of plated cells or callus can be conveniently monitored through repeated non-destructive fresh weight measurements of the filter paper and adhering cells, thereby allowing the construction of a complete growth curve over the course of an experiment. Experiments with 3 Nicotiana genotypes (N. plumbaginifolia Viv., N. tabacum L. ‘SC 58’ and N. tabacum ‘WI 38’) and 3 Vitis vinifera L. genotypes (‘Chenin Blanc’, ‘Dogridge’ and ‘White Riesling’) clearly demonstrate higher growth rates of plated cells on polyurethane supports compared with agar. Further experiments with N. plumbaginifolia illustrate the use of polyurethane supports for culturing cells at low pH (4.0) and the recovery of spent medium for monitoring changes in pH. These features will greatly facilitate quantitative studies of mineral nutrition and metal toxicity in cultured cells. Polyurethane supports also allow the incorporation of conditioned medium or feeder cells to support the growth of cells at low densities and facilitate the rapid recovery of variant cells.     

A Quality Control System Involving Peer Review of Abnormal Cervical Smears

An internal quality control system which is used in the centralized cytology laboratory of a population-based cervical cancer screening programme in Florence is described. It includes a peer review procedure. Abnormal cervical smears are circulated among all the cytologists and a consensus on the final diagnosis is reached. This daily procedure is designed to evaluate the performance of each cytologist and of the laboratory as a whole but can also be considered a valuable training opportunity. During an 18-month period 1197 smears were reviewed by 15 readers using a reporting form with six main categories of reporting (from ‘regative’ to ‘invasive carcinoma’), plus an ‘unsatisfactory’ category. Overall the concordance between the 15 cytologists, assessed using the kappa statistic (range 0.46–0.71; median 0.60), was good. the level of agreement increased when a weighted kappa statistic (range 0.55–0.78; median 0.68) was used. Kappa values were also calculated for specific categories and suggested an increasing concordance with increasing severity of the lesions, the categories of ‘severe dysplasia’ and ‘invasive carcinoma’ showing the highest agreement. the poor results for the ‘moderate dysplasia’ confirmed the need for combining this group with the ‘severe dysplasia’, as proposed in the Bethesda system.     

High efficiency versus maximal performance — The cause of oxidative stress in eukaryotes: A hypothesis

Degenerative diseases are in part based on elevated production of ROS (reactive oxygen species) in mitochondria, mainly during stress and excessive work under stress (strenuous exercise). The production of ROS increases with increasing mitochondrial membrane potential (ΔΨ_m). A mechanism is described which is suggested to keep ΔΨ_m at low values under normal conditions thus preventing ROS formation, but is switched off under stress and excessive work to maximize the rate of ATP synthesis, accompanied by decreased efficiency. Low ΔΨ_m and low ROS production are suggested to occur by inhibition of respiration at high [ATP]/[ADP] ratios. The nucleotides interact with phosphorylated cytochrome c oxidase (COX), representing the step with the highest flux-control coefficient of mitochondrial respiration. At stress and excessive work neural signals are suggested to dephosphorylate the enzyme and abolish the control of COX activity (respiration) by the [ATP]/[ADP] ratio with consequent increase of ΔΨ_m and ROS production. The control of COX by the [ATP]/[ADP] ratio, in addition, is proposed to increase the efficiency of ATP production via a third proton pumping pathway, identified in eukaryotic but not in prokaryotic COX. We conclude that ‘oxidative stress’ occurs when the control of COX activity by the [ATP]/[ADP] ratio is switched off via neural signals.     

A single‐stranded conformational polymorphism (SSCP)‐derived quantitative variable to monitor the virulence of a Barley yellow dwarf virus‐PAV (BYDV‐PAV) isolate during adaptation to the TC14 resistant wheat line

A standardized single‐stranded conformational polymorphism (SSCP) procedure is proposed as an alternative to the time‐consuming biological characterization of Barley yellow dwarf virus‐PAV (BYDV‐PAV) isolates. Using this procedure, six of 21 overlapping regions used to scan the viral genome gave patterns specific to ‘4E’ (avirulent) or ‘4T’ (‘4E’‐derived virulent) isolates. The calibration of samples and integration of SSCP patterns corresponding to the nucleotide region 1482–2023 allowed the estimation of P_T values that reflect the proportions of a ‘4T’‐specific band. Analysis of the biological (area under the pathogen progress curve) and molecular (P_T) data suggested a positive linear relation between these variables. Moreover, sequence analysis of the nucleotide region 1482–2023 highlighted the presence of a nucleotide polymorphism (C/A₁₈₃₅) which can be considered as a candidate for virus–host interactions linked to the monitored virulence. According to these parameters, P_T values associated with ‘4E’‐ and ‘4T’‐derived populations show that: (i) long‐term infection of a BYDV‐PAV isolate on the ‘TC14’ resistant host leads to the fixation of virulent individuals in viral populations; and (ii) the introduction of susceptible hosts in successive ‘TC14’ infections results in the maintenance of low virulence of the populations. Thus, the presented study demonstrates that SSCP is a useful tool for monitoring viral populations during the host adaptation process. The described impact of host alternation provides new opportunities for the use of the ‘TC14’ resistance source in BYDV‐resistant breeding programmes. This study is part of the global effort made by the scientific community to propose sustainable alternatives to the chemical control of this viral disease.     

Application of the Welfare Quality® assessment system on European beef bull farms

Welfare concerns for intensive beef production have often been raised, but on-farm welfare assessment studies are rare. The aim of this study was to apply the Welfare Quality® (WQ) welfare assessment system for fattening cattle on beef bull farms to evaluate the state of welfare at the level of WQ measures and of aggregated scores, as well as overall classification. In addition, the purpose was to evaluate two ways of providing feedback information to the farmers with regard to possible welfare improvements on the farms. The study was conducted in Austria, Germany and Italy on a total of 63 beef bull farms with deep litter or cubicle-housing systems. Assessments were carried out 3 times (1 month and 7 months apart from the initial visit). In every country, farmers were assigned to two treatment groups (feedback from initial visit as written report, F, written feedback plus oral advice, FA) and a control group (C), which did not receive any feedback. At the criterion level, the highest average welfare scores were obtained from ‘Absence of prolonged hunger’ (94/100 points) followed by ‘Absence of pain induced by management procedures’ (88/100) and ‘Comfort around resting’ (77/100). Most welfare concerns related to the criteria ‘Absence of disease’ (40/100), ‘Expression of social behaviour’ (44/100) and ‘Positive emotional state’ (48/100), thus indicating room for improvements. Two-thirds of the farms achieved the ‘Enhanced’ level, about one-third was judged ‘Acceptable’ and only one farm ‘Excellent’. After 6 months of monitoring period, there was no significant welfare improvement in both the treatment groups as compared with the control group. Reasons for the lack of effect may mainly be seen in the short monitoring period and a lack of external incentives. In conclusion, the WQ assessment system revealed areas for improvement, but longer term studies and investigations on alternative ways of transferring outcomes from on-farm welfare assessments to farmers should be carried out in future.     

不同光敏色素分子的特异感光性

简要综述两种光敏色素（ＰｈｙＡ、ＰｈｙＢ） 的分子特性、感光性及作用模式等方面的研究进展。光敏色素是一种调节植物中许多光反应的色素蛋白复合体。不同光敏色素分子具有特异的感光性。ＰｈｙＡ负责‘甚低辐照反应’和远红光‘高辐照反应’; 而ＰｈｙＢ则调节‘低辐照反应’及红光‘高辐照反应’。另外, 讨论了ＰｈｙＡ和ＰｈｙＢ在光周期感受中的作用。     

Differential controls by climate and substrate over the heterotrophic and rhizospheric components of soil respiration

The partitioning of soil respiration rates into the component processes of rhizospheric respiration (because of live roots and those microorganisms that subsist on root exudations) and heterotrophic respiration (because of decomposer microorganisms that subsist on the oxidation of soil organic matter) is difficult to accomplish through experimental observation. In order to minimize disturbance to the soil and maximize preservation of the natural relationships among roots, rhizospheric microorganisms, and decomposers, we conducted a girdling experiment in a subalpine forest dominated by lodgepole pine trees. In two separate years, we girdled trees in small forest plots (5–7 m in diameter) and trenched around the plots to sever invading roots in order to experimentally stop the transport of photosynthate from needles to roots, and eliminate rhizospheric respiration. Soil respiration rates in plots with trees girdled over 1 year prior to measurement were higher than those in plots with trees girdled 2–3 months prior to measurement. These results suggest that any stimulation of respiration because of the experimental artifact of fine root death and addition of labile carbon to the pool of decomposer substrates is slow, and occurs beyond the first growing season after girdling. Compared with control plots with nongirdled trees, soil respiration rates in plots with girdled trees were reduced by 31–44% at the mid‐summer respiratory maximum. An extreme drought during one of the 2 years used for observations caused greater reductions in the heterotrophic component of soil respiration compared with the rhizospheric component. In control plots, we observed a pulse in K₂SO₄‐extractable carbon during the spring snowmelt period, which was absent in plots with girdled trees. In control plots, soil microbial biomass increased from spring to summer, coincident with a seasonal increase in the rhizospheric component of soil respiration. In plots with girdled trees, the seasonal increase in microbial biomass was lower than in control plots. These results suggest that the observed seasonal increase in rhizospheric respiration rate in control plots was because of an increase in rhizospheric microbial biomass following ‘soil priming’ by a spring‐time pulse in dissolved organic carbon. Winter‐time, beneath‐snow microbial biomass was relatively high in control plots. Soil sucrose concentrations were approximately eight times higher during winter than during spring or summer, possibly being derived from the mechanical damage of shallow roots that use sucrose as protection against low‐temperature extremes. The winter‐time sucrose pulse was not observed in plots with girdled trees. The results of this study demonstrate that (1) the rhizospheric component of soil respiration rate at this site is significant in magnitude, (2) the heterotrophic component of soil respiration rate is more susceptible to seasonal drought than the rhizospheric component, and (3) the trees in this ecosystem exert a major control over soil carbon dynamics by ‘priming’ the soil with sugar exudates during the late‐spring snowmelt period and releasing high concentrations of sucrose to the soil during winter.     

Effects of population density on alienicolae of Aphis fabae Scop.

A technique for rearing aphids in dense populations is described. Apterae were reared in high (‘C’) and low (‘U’) population densities and the proportions of alatae among their progenies were compared. Proportions of alatae were larger among progenies of ‘C’ apterae, and the proportions also increased as the density of the population in which the progenies were reared increased. Progenies of alatae never became alatae.     

Translucent tissue defect in potato (Solanum tuberosum L.) tubers is associated with oxidative stress accompanying an accelerated aging phenotype

Translucent tissue defect (TTD) is an undesirable postharvest disorder of potato tubers characterized by the development of random pockets of semi-transparent tissue containing high concentrations of reducing sugars. Translucent areas turn dark during frying due to the Maillard reaction. The newly released cultivar, Premier Russet, is highly resistant to low temperature sweetening, but susceptible to TTD. Symptoms appeared as early as 170 days after harvest and worsened with time in storage (4–9 °C, 95 % RH). In addition to higher concentrations of glucose, fructose and sucrose, TTD resulted in lower dry matter, higher specific activities of starch phosphorylase and glc-6-phosphate dehydrogenase, higher protease activity, loss of protein, and increased concentrations of free amino acids (esp. asparagine and glutamine). The mechanism of TTD is unknown; however, the disorder has similarities with the irreversible senescent sweetening that occurs in tubers during long-term storage, where much of the decline in quality is a consequence of progressive increases in oxidative stress with advancing age. The respiration rate of non-TTD ‘Premier Russet’ tubers was inherently higher (ca. 40 %) than that of ‘Russet Burbank’ tubers (a non-TTD cultivar). Moreover, translucent tissue from ‘Premier Russet’ tubers had a 1.9-fold higher respiration rate than the average of non-translucent tissue and tissue from non-TTD tubers. Peroxidation of membrane lipids during TTD development resulted in increased levels of malondialdehyde and likely contributed to a measurable increase in membrane permeability. Superoxide dismutase and catalase activities and the ratio of oxidized to total glutathione were substantially higher in translucent tissue. TTD tubers also contained twofold less ascorbate than non-TTD tubers. TTD appears to be a consequence of oxidative stress associated with accelerated aging of ‘Premier Russet’ tubers.     

A smartphone based real-time daily activity monitoring system

A real-time activity monitoring system within an Android based smartphone is proposed and evaluated. Motion and motionless postures may be classified using principles of kinematical theory, which underpins hierarchical rule-based algorithms, based on accelerometer and orientation data. Falls detection was implemented by analyzing whether the postures classified as ‘lying’ or ‘sit-tilted’ posture are deemed normal or abnormal, based on the analysis of time, users’ current position and posture transition. Experimental results demonstrate that the approach can detect various types of falls efficiently (i.e., in real-time within a smart phone processor) and also correctly (95 % and 93 % true positives for falls ending with ‘lying’ and ‘sit-tilted’ respectively). The approach is reliable for different subjects and different situations, since it is not only based on empirical thresholds and subject-based training models, but in addition it is underpinned by theory.     

Cold storage to overcome dormancy affects the carbohydrate status and photosynthetic capacity of Rhododendron simsii

Global warming leads to increasing irregular and unexpected warm spells during autumn, and therefore natural chilling requirements to break dormancy are at risk. Controlled cold treatment can provide an answer to this problem. Nevertheless, artificial cold treatment will have consequences for carbon reserves and photosynthesis. In this paper, the effect of dark cold storage at 7 °C to break flower bud dormancy in the evergreen Rhododendron simsii was quantified. Carbohydrate and starch content in leaves and flower buds of an early (‘Nordlicht’), semi‐early (‘M. Marie’) and late (‘Mw. G. Kint’) flowering cultivar showed that carbon loss due to respiration was lowest in ‘M. Marie’, while ‘Mw. G. Kint’ was completely depleted of starch reserves at the end of cold treatment. Gene isolation resulted in a candidate gene for sucrose synthase (SUS) RsSus, which appears to be homologous to AtSus3 and had a clear increase in expression in leaves during cold treatment. Photosynthesis measurements on ‘Nordlicht’ and the late‐flowering cultivar ‘Thesla’ showed that during cold treatment, dark respiration decreased 58% and 63%, respectively. Immediately after cold treatment, dark respiration increased and stabilised after 3 days. The light compensation point followed the same trend as dark respiration. Quantum efficiency showed no significant changes during the first days after cold treatment, but was significantly higher than in plants with dormant flower buds at the start of cold treatment. In conclusion, photosynthesis stabilised 3 days after cold treatment and was improved compared to the level before cold treatment.     

Effects of fire on soil respiration,ATP content and enzyme activities in Mediterranean maquis

Question: Do low or high intensity fires affect micro‐organism activity in the upper soil layer of Mediterranean maquis? Location: 600 m from the sea in the Nature Reserve of Castel Volturno (Campania, southern Italy, 40°57’N; 13°55’E). Methods: Soil respiration was measured in situ on intact soil; enzyme activity (cellulase, xylanase, invertase, trehalase and protease) and ATP content were measured on soil samples collected under three species of maquis vegetation: Phillyrea angustifolia L., Myrtus communis L. and Cistus incanus L. Results: Soil microbial respiration showed no significant differences in CO₂ flux in treated and untreated plots, but the ATP content in the soil under C. incanus and M. communis was lower in the treated plots for most of the study period. In the soil under Ph. angustifolia, ATP content was low only for one week after fire. The reduction was more marked in the samples from ‘high fire intensity’ than from ‘low fire intensity’ plots. Soil respiration and ATP content exhibited seasonal variations linked to soil water content. Among the enzyme activity measured in the soil under the three plant covers, only invertase declined in burned plots throughout the study period, particularly in the ‘high fire intensity’ plots. Activity of the enzymes cellulase, xylanase, trehalase and protease had a different sensitivity depending on the respective shrub cover. Conclusions: Impact of fire on soil microbial activity is largely dependent on vegetation mosaic and species identity.     

Phaseolin-protein Variability in Wild Forms and Landraces of the Common Bean(Phaseolus vulgaris): Evidence for Multiple Centers of Domestication

A sample of 106 wild forms and 99 landraces of common bean (Thaseolus vulgaris) from Middle America and the Andean region of South America were screened for variability in phaseolin seed protein using one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS/PAGE) and two-dimensional isoelectric focusing SDS/PAGE. The Middle American wild forms exhibited phaseolin patterns similar to the ‘S’ pattern described previously in cultivated forms, as well as a wide variety of additional banding patterns—‘M’ (Middle America) types—not encountered among common bean cultivars. The Andean wild forms showed only the ‘T’ phaseolin pattern, also described previously among cultivated forms. Landraces from Middle America showed ‘S’ or ‘S’-like patterns with the exception of 2 lines with ‘T’ phaseolin. In Andean South America, a majority of landraces had the ‘T’ phaseolin. Additional types represented in that region were (in decreasing order of frequency) the ‘S’ and ‘C’ types (already described among cultivated forms) as well as the ‘H’ (Huevo de huanchaco) and ‘A’ (Ayacucho), (new patterns previously undescribed among wild and cultivated beans). In each region—Middle America and Andean South America—the seeds of landraces with ‘T’ phaseolin were significantly larger than those of landraces with ‘S’ phaseolin. No significant differences in seed size were observed among landraces with ‘T,’ ‘C,’ ‘H,’ and ‘A’ phaseolin types of the Andean region. Our data favor 2 primary areas of domestication, one in Middle America leading to small-seeded cultivars with ‘S’ phaseolin patterns and the other in the Andes giving rise to large-seeded cultivars with ‘T’ (and possibly ‘C,’ ‘H,’ and ‘A’) phaseolin patterns.     

基于高光谱遥感的小麦叶干重和叶面积指数监测

生物量和叶面积指数(LAI)是描述作物长势的重要参数, 叶干重和LAI的实时动态监测对小麦(Triticum aestivum)生长诊断和管理调控具有重要意义。为分析多种高光谱参数估算小麦叶干重和LAI的效果, 建立小麦叶干重和LAI的定量监测模型, 该研究连续3年采用不同小麦品种进行不同施氮水平的大田试验, 于小麦不同生育期采集田间冠层高光谱数据并测定叶片叶干重和LAI。试验结果显示, 小麦叶干重和LAI随施氮水平的提高而增加, 随生育进程呈单峰动态变化模式。小麦叶干重和LAI与光谱反射率间相关性较好的区域主要位于红光波段(590~710 nm, r<-0.60)和近红外波段(745~1 130 nm, r>0.69)。对于不同试验条件下的叶干重和LAI, 可以使用统一的光谱参数进行定量反演, 其中基于RVI (810, 560)、FD755、GM1、SARVI (MSS)和TC3等光谱参数的方程拟合效果较好。经不同年际独立试验数据的检验表明, 以参数RVI (810, 560)、GM1、SARVI (MSS)、PSSRb、(R_750-800/R_695-740) -1、VOG2和MSR705为变量建立的叶干重和LAI监测模型均给出较好的检验结果。因此, 利用关键特征光谱参数可以有效地评价小麦叶片生长状况, 尤其是光谱参数RVI (810, 560)、GM1和SARVI (MSS)可以对不同条件下小麦叶干重和LAI进行准确可靠的监测。     

Design and performance of a fracture monitoring transducer

The answer to the question, ‘when is a fracture healed?’ is not simple, since the healing process is progressive and it is not possible to specify a time when the fracture can be said to have healed. In the past the assessment of fracture healing has, in the main, been subjective, relying upon the skill of the interpreter. A more objective method would be an advantage for many reasons, and since the bone is intended to be load bearing it is reasonable to assess healing by measuring the mechanical integrity of the bone. to do this a ‘clamp on’ transducer has been developed which, when fitted to the support column of an external fixator, enables the stiffness of a fracture to be determined during the healing process. Over the past 6 years this system has been used for both clinical and research work. It has enabled various forms of treatment to be evaluated in terms of ‘rate of healing’ and it also indicates the safe point at which the fixator can be removed.     

Does nitrogen become limiting under high‐P conditions in detritus‐based tropical streams?

1. We examined effects of nutrients on leaf breakdown in interior forest streams at La Selva Biological Station, Costa Rica. We tested the hypothesis that dissolved inorganic nitrogen (DIN) becomes limiting when ambient phosphorus (P) concentration is high. We also compared the breakdown of relatively ‘low quality’ leaves (lower C : N, Trema integerrima) with that of ‘higher quality’ leaves (higher C : N, Ficus insipida) in a high‐P stream. 2. Litterbags were incubated in two streams: one enriched experimentally with P [target concentration 200 μg soluble reactive phosphorus (SRP) L^?1] and one control (naturally low P concentration approximately 10 μg SRP L^?1). Ammonium enrichment was achieved by adding fertiliser upstream of half of the litterbags in each stream. 3. Phosphorus addition stimulated leaf breakdown, microbial respiration, ergosterol and leaf %P. Leaf breakdown rate was consistent with those in La Selva streams with naturally high P concentration. 4. Nitrogen (N) addition had no effect on leaf breakdown, microbial respiration, ergosterol or leaf chemistry in either the P‐enriched or the reference stream, in spite of low N : P ratios. We conclude that N is probably not limiting in streams at La Selva that are naturally high in P. This may be due to moderately high ambient N concentration (>200 μg DIN L^?1) prevailing throughout the year. 5. The species with a lower C : N decomposed more rapidly and supported higher microbial activity than that with a higher C : N. Subtle differences in leaf N content, as well as dissolved P concentration, may be important in determining microbial colonisation and subsequent leaf breakdown.     

RABBIT SCIATIC NERVE FASCICLE AND''ENDONEURIAL''PREPARATIONS FOR IN VITRO STUDIES OF PERIPHERAL NERVE GLUCOSE METABOLISM

Abstract— Suitable preparations for in vitro studies of the composite glucose and energy metabolism of peripheral nerve axons and Schwann cells have not been available. Methods are described for the preparation and incubation of a defined segment of a rabbit sciatic nerve fascicle, free of epineurial contamination, but with an intact perineurial membrane; removing the perineurium provides in addition an‘endoneurial’preparation. Conditions were selected for incubating each preparation with glucose that maintained stable P-creatine and ATP concentrations and a stable rate of O₂ uptake; under these conditions the preparations retained an unaltered EM appearance during a 2-h incubation. Glucose diffusion into the endoneurial compartment of the fascicle is restricted, possibly by the perineurial membrane, and a higher medium glucose concentration (20 mM) was required to maintain a steady state of energy metabolism in this preparation than in the‘endoneurial’preparation, which was incubated with 5 mwglucose. The‘endoneurial’preparation required 0.50 mm -myoinositol in the medium to prevent a decrease in tissue free myoinositol and a slow decrease in O₂ uptake, which occurred when it was omitted. Under the incubation conditions selected the glucose concentrations in the‘endoneurial’preparation and in the endoneurial compartment of the fascicle were reasonably similar, and the preparations had similar rates of respiration, similar estimated rates of glucose utilization, and similar relative rates of respiration and lactate production. The preparations derive the major fraction of their energy requirements from respiration. Their rates of O₂ uptake are 60% higher than the previous indirect estimate of O₂ uptake in whole rabbit tibial nerve in situ. Constant rates of incorporation of ¹⁴C from [U-¹⁴C]glucose into CO₂ and total lipid were observed in the‘endoneurial’preparation after a 15-min equilibration period. The preparations reported provide suitable tools for in vitro studies of peripheral nerve metabolism not previously available.     

低温处理后4个越橘品种部分生理指标的比较及其抗寒性分析

以‘美登’(‘Blomidon ’)、‘北陆’(‘Northland ’)、‘蓝丰’(‘Bluecrop ’)和‘密斯梯’(‘Misty ’)4个越橘( Vaccinium spp.)品种为研究对象,对经-15℃、-20℃、-25℃、-30℃、-35℃和-40℃低温处理后各品种枝条的相对电导率( REC)、丙二醛( MDA)含量、过氧化物酶( POD)和过氧化氢酶( CAT)活性以及各指标的增长量进行比较;在此基础上,建立各品种REC值与温度的Logistic方程并获得各品种的低温半致死温度( LT50),初步确定各品种的抗寒性。结果表明：经不同低温处理后,各品种枝条的REC 值以及 POD 和 CAT 活性总体上极显著(P<0.01)高于对照(10℃),MDA含量极显著或显著(P<0.05)高于对照。随处理温度降低,各品种枝条的REC值和MDA含量逐渐升高,但不同品种间这2个指标的变幅不同;各品种枝条的POD和CAT活性随处理温度降低呈“单峰型”曲线,但不同品种枝条POD和CAT活性的峰值及其达到峰值的处理温度均存在差异,其中,经-25℃低温处理后品种‘密斯梯’枝条的POD和CAT活性最高,而其余3个品种的POD和CAT活性经-30℃低温处理后最高。总体上,品种‘密斯梯’枝条的REC值和MDA含量增长量处于较高水平,POD和CAT活性增长量处于较低水平;而品种‘美登’枝条的REC值和MDA含量增长量则处于较低水平,POD和CAT活性增长量处于较高水平。各品种的Logistic方程拟合度为0.8622~0.9778,且各品种间的拟合度差异均达到极显著或显著水平;REC值与温度的相关性极显著,其相关系数为0.9285~0.9888;品种‘密斯梯’、‘蓝丰’、‘北陆’和‘美登’的LT50值分别为-18.87℃、-26.85℃、-27.52℃和-30.83℃。综合分析结果显示：LT50值、MDA含量变化量、保护酶活性及其变化量均可作为越橘品种抗寒性的评价指标,据此初步确定供试4个越橘品种抗寒性由强至弱依次为‘美登’、‘北陆’、‘蓝丰’、‘密斯梯’。     

A multi-stakeholder participatory study identifies the priorities for the sustainability of the small ruminants farming sector in Europe

The European small ruminants (i.e. sheep and goats) farming sector (ESRS) provides economic, social and environmental benefits to society, but is also one of the most vulnerable livestock sectors in Europe. This sector has diverse livestock species, breeds, production systems and products, which makes difficult to have a clear vision of its challenges through using conventional analyses. A multi-stakeholder and multi-step approach, including 90 surveys, was used to identify and assess the main challenges for the sustainability of the ESRS to prioritize actions. These challenges and actions were identified by ESRS experts including farmers, cooperatives, breeding associations, advisers and researchers of six EU countries and Turkey. From the 30 identified challenges, the most relevant were economy-related challenges such as ‘uncertainty of meat and milk prices’, ‘volatility of commodity prices’, ‘low farm income’, ‘high subsidy dependency’ and ‘uncertainty in future changes in subsidies’ resulting in ‘a sector not attractive to young farmers’. Most of these challenges were beyond the farmer’s control and perceived as difficult to address. Challenges were prioritized using an index, calculated by multiplying the relevance and the feasibility to address measures. The identified challenges had a similar priority index across the whole sector with small differences across livestock species (sheep vs goats), type of products (meat vs dairy) and intensification levels (intensive vs semi-intensive vs extensive). The priorities were different, however, between socio-geographical regions (Southern vs Central Europe). Some of the top prioritized challenges were linked to aspects related to the production systems (‘low promotion of local breeds’ and ‘slow adaptability of high producing breeds’) and market practices (‘unfair trade/lack of traceability’). The majority of the priority challenges, however, were associated with a deficient knowledge or training at farm level (‘poor business management training’, ‘lack of professionalization’, ‘slow adoption of innovations’), academia (‘researchers do not address real problems’) and society as a whole (‘low consumer education in local products’, ‘low social knowledge about farming’, ‘poor recognition of farming public services’). Thus, improved collaboration among the different stakeholders across the food chain with special implication of farmers, associations of producers, academia and governments is needed to facilitate knowledge exchange and capacity building. These actions can contribute to make ESRS economically more sustainable and to adapt the production systems and policy to the current and future societal needs in a more region-contextualized framework.