The acceptability of meadow plants to the slug Deroceras reticulatum and implications for grassland restoration

Background and Aims

Despite the selective pressure slugs may exert on seedling recruitment there is a lack of information in this context within grassland restoration studies. Selective grazing is influenced by interspecific differences in acceptability. As part of a larger study of how slug–seedling interactions may influence upland hay meadow restoration, an assessment of relative acceptability is made for seedlings of meadow plants to the slug, Deroceras reticulatum.

Methods

Slug feeding damage to seedling monocultures of 23 meadow species and Brassica napus was assessed in microcosms over 14 d. The severity and rate of damage incurred by each plant species was analysed with a generalized additive mixed model. Plant species were then ranked for their relative acceptability.

Key Results

Interspecific variation in relative acceptability suggested seedlings of meadow species form a hierarchy of acceptability to D. reticulatum. The four most acceptable species were Achillea millefolium and the grasses Holcus lanatus, Poa trivialis and Festuca rubra. Trifolium pratense was acceptable to D. reticulatum and was the second highest ranking forb species. The most unacceptable species were mainly forbs associated with the target grassland, and included Geranium sylvaticum, Rumex acetosa, Leontodon hispidus and the grass Anthoxanthum odoratum. A strong positive correlation was found for mean cumulative feeding damage and cumulative seedling mortality at day 14.

Conclusions

Highly unacceptable species to D. reticulatum are unlikely to be selectively grazed by slugs during the seedling recruitment phase, and were predominantly target restoration species. Seedlings of highly acceptable species may be less likely to survive slug herbivory and contribute to seedling recruitment at restoration sites. Selective slug herbivory, influenced by acceptability, may influence community-level processes if seedling recruitment and establishment of key functional species, such as T. pratense is reduced.     

不同集雨种植方式对干旱区紫花苜蓿种植的影响

在甘肃省定西半干旱黄土丘陵区采用完全随机设计,研究不同覆盖材料(普通地膜CMR、生物可降解地膜BMR和土垄SR)和不同沟垄比(60 cm∶30 cm、60 cm∶45 cm和60 cm∶60 cm)对径流效率、土壤贮水量、土壤含水量、紫花苜蓿干草产量和水分利用效率的影响.结果表明：SR、BMR和CMR的平均径流效率分别为32.0%、90.7%和96.4%.在紫花苜蓿生育前期(4-6月),各处理之间土壤贮水量差异不显著;在紫花苜蓿生育后期(7-10月),BMR和CMR的土壤贮水量显著高于SR,SR的土壤贮水量显著高于平作,如在紫花苜蓿孕蕾期,平作、SR、BMR和CMR 0~140 cm土层土壤贮水量分别为223.27、248.56、277.81和284.16 mm.平作、SR、BMR和CMR全生育期实际干草产量分别为4112.1、3397.5、4317.8和4523.8 kg·hm^-2,水分利用效率分别为11.08、10.48、14.56、14.95 kg·mm^-1·hm^-2.在同一覆盖材料下,不同沟垄比对土壤贮水量和水分利用效率的影响不显著.当沟垄比为60 cm∶44 cm时,CMR和BMR处理的实际产量均达到最大.     

The Restoration of Phytophagous Beetles in Species‐Rich Chalk Grasslands

This study focuses on the restoration of chalk grasslands over a 6‐year period and tests the efficacy of two management practices, hay spreading and soil disturbance, in promoting this process for phytophagous beetles. Restoration success for the beetles, measured as similarity to target species–rich chalk grassland, was not found to be influenced by either management practice. In contrast, restoration success for the plants did increase in response to hay spreading management. Although the presence of suitable host plants was considered to dictate the earliest point at which phytophagous beetles could successfully colonized, few beetle species colonized as soon as their host plants became established. Morphological characteristics and feeding habits of 27 phytophagous beetle species were therefore tested to identify factors that limited their colonization and persistence. The lag time between host plant establishment and colonization was greatest for flightless beetles. Beetles with foliage‐feeding larvae both colonized at slower rates than seed‐, stem‐, or root‐feeding species and persisted within the swards for shorter periods. Although the use of hay spreading may benefit plant communities during chalk grassland restoration, it did not directly benefit phytophagous beetles. Without techniques for overcoming colonization limitation for invertebrate taxa, short‐term success of restoration may be limited to the plants only.     

Effects of varying proportions of concentrates on ruminal-reducing power and bacterial community structure in dry dairy cows fed hay-based diets

The objectives of this study were to evaluate the influence of diet composition on ruminal parameters, more particularly redox potential (Eh). Four Holstein dry dairy cows, fitted with ruminal cannulas, were allocated in a 4 × 4 Latin square design. They were given four experimental hay-based diets D0, D25, D42 and D56 consisting of 0%, 25%, 42% and 56% of ground wheat and barley concentrate mixture, respectively. They were fed at a daily feeding rate of 8.0 kg DM per cow during a 24-day experimental period (a 21-day diet adaptation, three consecutive days of measurement and sampling). The physicochemical parameters, such as pH and Eh, were measured and Clark's exponent (rH) was calculated from 1 h before feeding to 8 h after feeding at 1-h interval. Samples of ruminal fluid were taken at 0, 1, 2, 4, 6 and 8 h after feeding for the determination of volatile fatty acid (VFA) and ammonia N (NH3-N) concentrations. Ruminal bacterial populations were also studied by means of capillary electrophoresis single-strand conformation polymorphism (CE-SSCP) technique to focus on the structure of the ruminal microbiota and the diversity index was calculated. Mean ruminal Eh and rH were not modified by the concentrate-to-forage ratio and averaged - 210 mV and 6.30, respectively, across diets. The pH decreased slightly by 0.10 pH unit between treatments D0 and D56 with an average of 6.58. Nevertheless, the time during which physicochemical parameters remained at nadir value after feeding varied with diets: 2 and 7 h for D0 and 6 and 5 h for D56, respectively for pH and Eh. Moreover, fermentative parameters were altered by treatments: total VFA and NH3-N were greater in D56 (72.2 mM and 17.5 mg/100 ml) compared with D0 (65.2 mM and 14.2 mg/100 ml). However, neither the structure of bacterial populations of the rumen nor the diversity index (Shannon) was altered by treatments.     

Effects of Rate and Source Organo-Mineral Material on Forage Yield and Nutritive Value of Barley-Pea Mixed under Arid Conditions

Cereal-legume intercropping plays a vital role in the subsistence food production system that prevails in the arid regions. It not only provides profitable crop productivity for agricultural communities but also plays an important role in improving soil fertility. Therefore, the present research was conducted to assess the effect of the organic and mineral fertilizers on the forage yield and nutritional value in barley-pea intercropping system. The results revealed that the quality of forage grass is significantly influenced by both organic and inorganic fertilizer. Thus, organic fertilizer application has significantly influenced the dry matter (DM), crude ash (CA), crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF). Among the treatments, organic fertilizer added at rate of 35 m⁻³ ha⁻¹ produced the maximum fresh and dry matter in barley and peas. In addition, the same level of organic fertilizer also improved silage composition by significantly increasing the protein and fiber content and showed highest the values. Based on overall results, it is concluded that organic fertilizer treatment (35 m⁻³ ha⁻¹) has the potential as an effective strategy to improve the productivity and nutritional quality of the barley-pea intercropping system in arid areas. The results revealed that organic fertilizer can be utilized in sustainable agricultural as a source of nutrients for numerous various crops under arid conditions.     

不同播期对紫花苜蓿生长性状及越冬性的影响研究

采用随机试验设计方法,在宁南旱作农业区进行了不同播期对紫花苜蓿出苗率、生长发育、越冬率和产草量影响的研究。结果表明,在宁南地区人工种植紫花苜蓿的出苗率与播期温度存在极显著正相关关系,而不同播期土壤耕层含水量变化率较小,且基本能满足苜蓿萌发与生长的需要;播期越早,根颈越粗,入土越深,但4月份前播种,出苗率低,群体小且易形成“小老苗”;7月份以后播种。由于生长期短,植株根颈细嫩,越冬率很低或完全冻死。综合不同播期出苗率、产草量和越冬率等因素,认为在宁南地区紫花苜蓿的适宜播种期应在4月30日～6月30日。     

Aeroallergens and pollinosis: Molecular and immunological characteristics of cloned pollen allergens

Affecting almost twenty percent of thepopulation in industrialized countries,allergic diseases such as asthma and seasonalrhinitis result from the development ofimmediate hypersensitivity to otherwiseinnocuous components of the environment. Pollen, the male gametophyte of flowering plantspecies, is one of the most predominant sourcesof environmental allergens, and a significantcause of allergic diseases. This reviewdiscusses the nature of pollen proteins asallergens, their effect on the human immunesystem and their mode of environmentaltransmission, including effects of theinteraction between pollen aeroallergens andair pollution. The influence of cross-reactivepollen allergens to the incidence of foodsensitivities is also discussed. Floweringplant species that possess allergenic pollen,identified with allergens cloned from thesespecies, are also discussed.     

Nachweis von Fusarien und deren Mykotoxinen in Futterkonservaten aus Grünlandbeständen mit differenzierter Bewirtschaftungsintensität

Conservation forage (17 hay and 18 grass silage samples) from 15 farms with different intensities of grassland management in the Federal State of Brandenburg were examined for contamination with fusaria and their mycotoxins. The numbers of culturable filamentous fungi in hay were determined by plate counting andFusarium isolates were classified taxonomically. The mycotoxins Zearalenone (ZEA) and Deoxynivalenol (DON) were extracted from hay as well as silage by different procedures and detected chromatographically (HPLC). The numbers of filamentous fungi in the hay samples were 10² and 10⁶ CFU/g FM independently of intensive or extensive management. Only fourFusarium species were identified.Fusarium culmorum, a potential toxin producing species, was most frequently detected (52% of all isolates). ZEA was found in two hay and four silage samples (6-66 μg/kg), DON in three hay and seven silage samples (63–1290 μg/kg). There were no differences between forage samples of extensive and intensive cultivated grassland of the year 2003 regarding numbers of fusaria and the content of their mycotoxins.

Presented at the 26^th Mykotoxin-Workshop in Herrsching, Germany, May 17–19, 2004.     

Stress tolerance in the marsh plant Spartina patens: Impact of NaCl on growth and root plasma membrane lipid composition

The C‐4 salt marsh grass, Spartina patens , thrives in the upper portion of the marsh where soil salinities may be equal to coastal seawater. Spartina patens was grown in hydroponic culture in a greenhouse at 0, 340, and 510 m M NaCl, and measured for growth, tissue cation content, and root plasma membrane (PM) lipid composition. From 0 to 340 and 510 m M , the shoot growth decreased, but root growth was not affected. The Na⁺ content increased in both shoots and roots when plants were grown in salt, while the shoots had a decreased K⁺ content and the roots had a decreased Ca²⁺ content. Spartina patens root plasma membrane was isolated with an aqueous polymer two‐phase system. The purity of the plasma membrane was verified with cytochemical tests on membrane enzyme markers. Plasma membrane lipids were stable relative to the membrane protein content. Molar percentages of sterols (including free sterols) and phospholipid decreased with increasing salinity. However, glycolipid showed a statistically significant increase in the total lipid as salinity in the medium was increased from 0 to 510 m M . Even at a salinity of 510 m M , the plasma membrane sterol/phospholipid ratio was unaffected by NaCl. When the plants were grown in NaCl media, the plasma membrane had a decreased phosphatidylcholine (PC) and phosphatidylethanolamine (PE) content, but the PC/PE ratios were not affected. The plasma membrane molar percentage of sitosterol in total free sterol increased when plants were grown in salt media. The predominant membrane fatty acids were C11 and C14, and the major unsaturated one was C14:1. An increase in growth medium salinity resulted in a decreased root plasma membrane fluidity.