Determining the proper sowing time for the mixture of Hungarian vetch and triticale under continental climate conditions / Determinação da época de semeadura adequada para a mistura de ervilhaca Húngara e triticale em condições climáticas continentais

The research was conducted to determine forage yield and some quality characteristics of Hungarian vetch + triticale mixture, sowed in five different times under rainfed conditions of Central Anatolia, Turkey. The mixture was sowed in the second, third and fourth week of October, and the first and the second week of November in 2017 and 2018. Depending on the sowing times, plant height (PH) of Hungarian vetch and triticale was between 46.7 and 59.4 cm, and 85.9 and 93.4 cm, respectively. Green forage yield (GFY) was between 1746.2 and 2059.4 kg da-1, dry matter yield (DMY) was between 541.0 and 707.6 kg da-1, crude protein yield (CPY) was between 80.4 and 110.3 kg da-1, digestible dry matter yield (DDMY) was between 340.8 and 453.9 kg da-1, acid detergent fiber (ADF) ratio was between 31.8 and 33.7%, neutral detergent fiber (NDF) ratio was between 44.7 and 49.5%, total digestible nutrient (TDN) was between 57.9 and 60.4% and relative feed value (RFV) was between 118.6 and 133.8. Sowing time had a significant effect (P < 0.05) on PH of triticale, while it has a very significant effect (P < 0.01) on GFY, DMY, CPY, DDMY, NDF ratios and RFV. Delaying the sowing time caused a decrease in the GFY, DMY and quality of the mixture. Results revealed that the first week of October is the most appropriate sowing time to obtain high dry matter yield with high quality under continental climate conditions of the Central Anatolia.

A pesquisa foi conduzida para determinar a produção de forragem e algumas características de qualidade da mistura de ervilhaca húngara + triticale, semeada em cinco épocas diferentes em regime de sequeiro na região Central da Anatólia, Turquia. A mistura foi semeada na segunda, terceira e quarta semanas de outubro, e na primeira e segunda semanas de novembro de 2017 e 2018. Dependendo da época de semeadura, a altura da planta (PH) da ervilhaca e triticale húngara foi entre 46,7 e 59,4 cm e 85,9 e 93,4 cm, respectivamente. O rendimento de forragem verde (GFY) ficou entre 1746,2 e 2059,4 kg da-1, o rendimento de matéria seca (DMY) foi entre 541,0 e 707,6 kg da-1, o rendimento de proteína bruta (CPY) foi entre 80,4 e 110,3 kg da-1, digestível seco o rendimento de matéria (DDMY) estava entre 340,8 e 453,9 kg da-1, a proporção da fibra em detergente ácido (FDA) estava entre 31,8 e 33,7%, a proporção da fibra em detergente neutro (FDN) estava entre 44,7 e 49,5%, o nutriente digestível total (NDT) era entre 57,9 e 60,4% e o valor relativo da alimentação (RFV) foi entre 118,6 e 133,8. A época de semeadura teve um efeito significativo (P < 0,05) no PH do triticale, enquanto teve um efeito muito significativo (P < 0,01) nas relações GFY, DMY, CPY, DDMY, FDN e RFV. O atraso na semeadura ocasionou diminuição no GFY, DMY e na qualidade da mistura. Os resultados revelaram que a primeira semana de outubro é a época de semeadura mais adequada para a obtenção de alta produtividade de matéria seca com alta qualidade nas condições climáticas continentais da Anatólia Central.

Conservation Conundrum: At-risk Bumble Bees (Bombus spp.) Show Preference for Invasive Tufted Vetch (Vicia cracca) While Foraging in Protected Areas.

In recent decades, some bumble bee species have declined, including in North America. Declines have been reported in species of bumble bees historically present in Ontario, including: yellow bumble bee (Bombus fervidus) (Fabricus, 1798), American bumble bee (Bombus pensylvanicus) (DeGeer, 1773), and yellow-banded bumble bee (Bombus terricola) (Kirby, 1837). Threats contributing to bumble bee population declines include: land-use changes, habitat loss, climate change, pathogen spillover, and pesticide use. A response to the need for action on pollinator preservation in North America has been to encourage 'bee-friendly' plantings. Previous studies show differences in common and at-risk bumble bee foraging; however, similar data are unavailable for Ontario. Our research question is whether there is a difference in co-occurring at-risk and common bumble bee (Bombus spp.) floral use (including nectar and pollen collection) in protected areas in southern Ontario. We hypothesize that common and at-risk species forage differently, predicting that at-risk species forage on a limited selection of host plants. We conducted a field survey of sites in southern Ontario, using observational methods to determine bumble bee foraging by species. The results of a redundancy analysis show a difference in foraging between common and at-risk bumblebee species. At-risk bumble bee species show a preference for foraging on invasive, naturalized Vicia cracca (tufted vetch). This finding raises the question of how to preserve or provide forage for at-risk bumble bees, when they show an association with an invasive species often subject to control in protected areas.

Modeling long-term effects of hairy vetch cultivation on cotton production in Northwest Louisiana.

The use of hairy vetch as a winter cover crop for cotton production in Northwest Louisiana has contributed to sustaining cotton production as well as improving soil quality. To test the efficacy of hairy vetch (HV) cultivation as a natural N supplement for cotton production, a long-term field experiment lasting 27years was evaluated using the Denitrification-Decomposition (DNDC) model. Different N fertilization practices, including 0kgNha-1 (PL_1), HV alone (PL_2), 44.8kgNha-1 (PL_3), and 67.3kgNha-1 (PL_4), were compared to evaluate nitrogen (N) response to cotton yield. Measured crop yield from each treatment was used to calibrate and validate the model. The DNDC model was employed to test the effects of N application scenarios on cotton yields and HV incorporation on N balance under irrigated and non-irrigated conditions. In model calibration, statistical indices for the model performance on cotton seed yield showed that PL_1 had a normalized root mean square error (NRMSE) value of 24.5%, a model efficiency (ME) value of 0.51, and a correlation coefficient (r) of 0.87 (P<0.01). The DNDC model was validated with PL_2, PL_3, and PL_4. PL_2, PL_3 and PL_4 had a NRMSE of 18.6%, 16.4% and 15.8% respectively, ME value of 0.19, 0.47 and 0.52 respectively, and an r of 0.75, 0.83 and 0.85 (P<0.05) respectively. Estimates of soil organic carbon (SOC) for HV treatment showed double the SOC content during a 27-year long-term experiment, while both treatments of 44.8kgNha-1 and 67.3kgNha-1 showed similar levels of SOC of a 25% increase compared to the control. Based on the scenario analysis, sustainable cotton yields do not require N fertilizer application under HV cultivated fields, and no yield differences were observed between irrigated and non-irrigated conditions.

Immobilization of Lead Migrating from Contaminated Soil in Rhizosphere Soil of Barley (Hordeum vulgare L.) and Hairy Vetch (Vicia villosa) Using Hydroxyapatite.

This study conducted plant growth tests using a rhizobox system to quantitatively determine the distance of immobilization lead migrating from contaminated soil into uncontaminated rhizosphere soil, and to assess the lead phases accumulated in rhizosphere soil by sequential extraction. Without the hydroxyapatite, exchangeable lead fractions increased as the rhizosphere soil got closer to the contaminated soil. Exchangeable lead fractions were higher even in the rhizosphere soil that shares a boundary with the root surface than in the soil before being planted. Thus, plant growth of hairy vetch was lower in the soil without the hydroxyapatite than in the soil with the hydroxyapatite. The presence of hydroxyapatite may immobilize the majority of lead migrating from contaminated soil into the rhizosphere soil within 1 mm from the contaminated soil. The dominant lead fraction in the rhizosphere soil with the hydroxyapatite was residual. Thus, plant growth was not suppressed and the lead concentration of the plant shoot remained at the background level. These results indicate that the presence of hydroxyapatite in the rhizosphere soil at 5% wt may immobilize most of the lead migrating into the rhizosphere soil within 1 mm from the contaminated soil, resulting in the prevention of lead migration toward the root surface.

Factors influencing distribution and local coexistence of diploids and tetraploids of Vicia cracca: inferences from a common garden experiment.

Vicia cracca diploids and autotetraploids are highly parapatric in Europe; tetraploids reside in western and northern part, whereas diploids occupy much drier south-eastern part. They meet together in a Central European contact zone. This distribution pattern raised questions about a transformative effect of polyploidization on plant performance and environmental tolerances. We investigated plant survival, growth, and seed production in two water regimes in a common garden experiment using seeds collected from five localities in the Central European contact zone where diploids and tetraploids occur in sympatry. Obtained data imply that tetraploids of V. cracca are not generally superior in performance to diploids. Significantly larger seeds from tetraploid mother plants collected in the field were not correlated with greater stature of the seedlings. Nonetheless, tetraploids might have a potential to out-compete diploids in the long run due to the tetraploids' ability of greater growth which manifested in the second year of cultivation. Considering the response of diploids and tetraploids to water supply, drought stressed tetraploids but not diploids produced a higher proportion of aborted seeds than watered ones, which implies that tetraploids are more drought susceptible than diploids. On the other hand, decreased plant height in drought stresses tetraploids, which simultaneously increased total seed production, may suggest that tetraploids have a greater ability to avoid local extinction under unfavourable conditions by enhancing biomass allocation into production of seeds at the cost of lower growth. The significant interaction between ploidy level and locality in several traits suggests possible polyfyletic origin of tetraploids and the necessity to clarify the history of the tetraploids in Europe.

Habitat management of organic vineyard in Northern Italy: the role of cover plants management on arthropod functional biodiversity.

The effect of cover plants on arthropod functional biodiversity was investigated in a vineyard in Northern Italy, through a 3-year field experiment. The following six ground cover plants were tested: Sweet Alyssum; Phacelia; Buckwheat; Faba Bean; Vetch and Oat; control. Arthropods were sampled using different techniques, including collection of leaves, vacuum sampling and sweeping net. Ground cover plant management significantly affected arthropod fauna, including beneficial groups providing ecosystem services like biological control against pests. Many beneficial groups were attracted by ground cover treatments in comparison with control, showing an aggregative numerical response in the plots managed with some of the selected plant species. Alyssum, Buckwheat and 'Vetch and Oat' mixture showed attractiveness on some Hymenoptera parasitoid families, which represented 72.3% of the insects collected by sweeping net and 45.7 by vacuum sampling. Phytoseiidae mites showed a significant increase on leaves of the vineyard plots managed with ground covers, in comparison with control, although they did not show any difference among the treatments. In general, the tested ground cover treatments did not increase dangerous Homoptera populations in comparison with control, with the exception of Alyssum. The potential of ground cover plant management in Italian vineyards is discussed: the overall lack of potential negative effects of the plants tested, combined with an aggregative numerical response for many beneficials, seems to show a potential for their use in Northern Italy vineyards.

Genetic Diversity and Symbiotic Phenotype of Hairy Vetch Rhizobia in Japan.

Hairy vetch (Vicia villosa Roth) is a leguminous crop widely used as green manure and a cover crop in Japan. It exhibits strong weed-suppressing activity, high resistance to insect pests, and the ability to fix nitrogen through symbiotic interactions with soil bacteria known as rhizobia. Few studies have investigated the rhizobia that form nodules on hairy vetch in Japan, and the biological resources available for selecting high nitrogen-fixing rhizobia are limited. In the present study, we isolated 110 hairy vetch rhizobia from 13 different areas in Japan. Based on their 16S rRNA gene sequences, 73% of the isolates were identified as Rhizobium leguminosarum. A comparative analysis of nodC and 16S rRNA gene phylogenies revealed that several isolates possessed congruent nodC sequences despite having divergent 16S rRNA gene sequences, suggesting that the horizontal transfer of nod genes occurred during the evolution of rhizobia. Inoculation tests showed that isolates closely related to R. leguminosarum had better plant growth-promoting effects than other strains, thereby providing a promising agricultural resource for inoculating crops.

Shoot-derived abscisic acid promotes root growth.

The phytohormone abscisic acid (ABA) plays a major role in regulating root growth. Most work to date has investigated the influence of root-sourced ABA on root growth during water stress. Here, we tested whether foliage-derived ABA could be transported to the roots, and whether this foliage-derived ABA had an influence on root growth under well-watered conditions. Using both application studies of deuterium-labelled ABA and reciprocal grafting between wild-type and ABA-biosynthetic mutant plants, we show that both ABA levels in the roots and root growth in representative angiosperms are controlled by ABA synthesized in the leaves rather than sourced from the roots. Foliage-derived ABA was found to promote root growth relative to shoot growth but to inhibit the development of lateral roots. Increased root auxin (IAA) levels in plants with ABA-deficient scions suggest that foliage-derived ABA inhibits root growth through the root growth-inhibitor IAA. These results highlight the physiological and morphological importance, beyond the control of stomata, of foliage-derived ABA. The use of foliar ABA as a signal for root growth has important implications for regulating root to shoot growth under normal conditions and suggests that leaf rather than root hydration is the main signal for regulating plant responses to moisture.

MgtE From Rhizobium leguminosarum Is a Mg²âº Channel Essential for Growth at Low pH and N2 Fixation on Specific Plants.

MgtE is predicted to be a Rhizobium leguminosarum channel and is essential for growth when both Mg²âº is limiting and the pH is low. N2was only fixed at 8% of the rate of wild type when the crop legume Pisum sativum was inoculated with an mgtE mutant of R. leguminosarum and, although bacteroids were present, they were few in number and not fully developed. R. leguminosarum MgtE was also essential for N2fixation on the native legume Vicia hirsuta but not when in symbiosis with Vicia faba. The importance of MgtE and the relevance of the contrasting phenotypes is discussed.

Content of Zinc and Copper in Selected Plants Growing Along a Motorway.

In 2011 a study was carried out analyzing the effects of road traffic on bioaccumulation of zinc and copper in selected species of dicotyledonous plants growing on adjacent grasslands. To do the research the plants were sampled from the 9-km-long Siedlce bypass, a part of the international route E-30. They were collected during the flowering stage, at following distances from the road: 1, 5, 10, 15 m. The content of zinc and copper was determined with the AAS method, with dry mineralisation done before. The highest concentration of the elements, regardless of the distance from the road, was found in Taraxacum spec. Among the tested plants, the lowest zinc content was in Vicia cracca, and the lowest copper content in Rumex acetosa. The limit for copper content was exceeded in Taraxacum spec. and, slightly, in Achillea millefolium growing at the roadside, closest to the roadway.

Influence of Seeding Ratio, Planting Date, and Termination Date on Rye-Hairy Vetch Cover Crop Mixture Performance under Organic Management.

Cover crop benefits include nitrogen accumulation and retention, weed suppression, organic matter maintenance, and reduced erosion. Organic farmers need region-specific information on winter cover crop performance to effectively integrate cover crops into their crop rotations. Our research objective was to compare cover crop seeding mixtures, planting dates, and termination dates on performance of rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth) monocultures and mixtures in the maritime Pacific Northwest USA. The study included four seed mixtures (100% hairy vetch, 25% rye-75% hairy vetch, 50% rye-50% hairy vetch, and 100% rye by seed weight), two planting dates, and two termination dates, using a split-split plot design with four replications over six years. Measurements included winter ground cover; stand composition; cover crop biomass, N concentration, and N uptake; and June soil NO3(-)-N. Rye planted in mid-September and terminated in late April averaged 5.1 Mg ha(-1) biomass, whereas mixtures averaged 4.1 Mg ha(-1) and hairy vetch 2.3 Mg ha(-1). Delaying planting by 2.5 weeks reduced average winter ground cover by 65%, biomass by 50%, and cover crop N accumulation by 40%. Similar reductions in biomass and N accumulation occurred for late March termination, compared with late April termination. Mixtures had less annual biomass variability than rye. Mixtures accumulated 103 kg ha(-1) N and had mean C:N ratio <17:1 when planted in mid-September and terminated in late April. June soil NO3(-)-N (0 to 30 cm depth) averaged 62 kg ha(-1) for rye, 97 kg ha(-1) for the mixtures, and 119 kg ha(-1) for hairy vetch. Weeds comprised less of the mixtures biomass (20% weeds by weight at termination) compared with the monocultures (29%). Cover crop mixtures provided a balance between biomass accumulation and N concentration, more consistent biomass over the six-year study, and were more effective at reducing winter weeds compared with monocultures.

Cyanamide is biosynthesized from L-canavanine in plants.

Cyanamide had long been recognized as a synthetic compound but more recently has been found as a natural product from several leguminous plants. This compound's biosynthetic pathway, as yet unelaborated, has attracted attention because of its utility in many domains, such as agriculture, chemistry, and medicine. We noticed that the distribution of L-canavanine in the plant kingdom appeared to include that of cyanamide and that the guanidino group structure in L-canavanine contained the cyanamide skeleton. Here, quantification of these compounds in Vicia species suggested that cyanamide was biosynthesized from L-canavanine. Subsequent experiments involving L-[guanidineimino-(15)N2]canavanine addition to young Vicia villosa seedlings resulted in significant incorporation of (15)N-label into cyanamide, verifying its presumed biosynthetic pathway.

Cover crops influence soil microorganisms and phytoextraction of copper from a moderately contaminated vineyard.

We investigated the ability of summer (Avena sativa [oat], Trifolium incarnatum [crimson clover], Chenopodium [goosefoot]) and winter (Vicia villosa [hairy vetch], Secale Cereale L. [Rye], Brassica napus L. partim [rape]) cover crops, including a mixed species treatment, to extract copper from an organic vineyard soil in situ and the microbial communities that may support it. Clover had the highest copper content (14.3mgCukg(-1) DM). However, it was the amount of total biomass production that determined which species was most effective at overall copper removal per hectare. The winter crop rye produced significantly higher amounts of biomass (3532kgDMha(-1)) and, therefore, removed significantly higher amounts of copper (14,920mgCuha(-1)), despite less accumulation of copper in plant shoots. The maximum annual removal rate, a summation of best performing summer and winter crops, would be 0.033kgCuha(-1)y(-1). Due to this low annual extraction efficiency, which is less than the 6kgCuha(-1)y(-1) permitted for application, phytoextraction cannot be recommended as a general method of copper extraction from vineyards. Copper concentration did not influence aboveground or belowground properties, as indicated by sampling at two distances from the grapevine row with different soil copper concentrations. Soil microorganisms may have become tolerant to the copper levels at this site. Microbial biomass and soil enzyme activities (arylsulfatase and phosphatase) were instead driven by seasonal fluxes of resource pools. Gram+ bacteria were associated with high soil moisture, while fungi seemed to be driven by extractable carbon, which was linked to high plant biomass. There was no microbial group associated with the increased phytoextraction of copper. Moreover, treatment did not influence the abundance, activity or community structure of soil microorganisms.

Do cover crops enhance N2O, CO2 or CH4 emissions from soil in Mediterranean arable systems?

This study evaluates the effect of planting three cover crops (CCs) (barley, Hordeum vulgare L.; vetch, Vicia villosa L.; rape, Brassica napus L.) on the direct emission of N2O, CO2 and CH4 in the intercrop period and the impact of incorporating these CCs on the emission of greenhouse gas (GHG) from the forthcoming irrigated maize (Zea mays L.) crop. Vetch and barley were the CCs with the highest N2O and CO2 losses (75 and 47% increase compared with the control, respectively) in the fallow period. In all cases, fluxes of N2O were increased through N fertilization and the incorporation of barley and rape residues (40 and 17% increase, respectively). The combination of a high C:N ratio with the addition of an external source of mineral N increased the fluxes of N2O compared with -Ba and -Rp. The direct emissions of N2O were lower than expected for a fertilized crop (0.10% emission factor, EF) compared with other studies and the IPCC EF. These results are believed to be associated with a decreased NO3(-) pool due to highly denitrifying conditions and increased drainage. The fluxes of CO2 were in the range of other fertilized crops (i.e., 1118.71-1736.52 kg CO2-Cha(-1)). The incorporation of CC residues enhanced soil respiration in the range of 21-28% for barley and rape although no significant differences between treatments were detected. Negative CH4 fluxes were measured and displayed an overall sink effect for all incorporated CC (mean values of -0.12 and -0.10 kg CH4-Cha(-1) for plots with and without incorporated CCs, respectively).

Competition increases sensitivity of wheat (Triticum aestivum) to biotic plant-soil feedback.

Plant-soil feedback (PSF) and plant competition play an important role in structuring vegetation composition, but their interaction remains unclear. Recent studies suggest that competing plants could dilute pathogenic effects, whereas the standing view is that competition may increase the sensitivity of the focal plant to PSF. In agro-ecosystems each of these two options would yield contrasting outcomes: reduced versus enhanced effects of weeds on crop biomass production. To test the effect of competition on sensitivity to PSF, we grew Triticum aestivum (Common wheat) with and without competition from a weed community composed of Vicia villosa, Chenopodium album and Myosotis arvensis. Plants were grown in sterilized soil, with or without living field inoculum from 4 farms in the UK. In the conditioning phase, field inocula had both positive and negative effects on T. aestivum shoot biomass, depending on farm. In the feedback phase the differences between shoot biomass in T. aestivum monoculture on non-inoculated and inoculated soils had mostly disappeared. However, T. aestivum plants growing in mixtures in the feedback phase were larger on non-inoculated soil than on inoculated soil. Hence, T. aestivum was more sensitive to competition when the field soil biota was present. This was supported by the statistically significant negative correlation between shoot biomass of weeds and T. aestivum, which was absent on sterilized soil. In conclusion, competition in cereal crop-weed systems appears to increase cereal crop sensitivity to soil biota.

Systematics, biogeography, and character evolution of the legume tribe Fabeae with special focus on the middle-Atlantic island lineages.

BACKGROUND: Tribe Fabeae comprises about 380 legume species, including some of the most ancient and important crops like lentil, pea, and broad bean. Breeding efforts in legume crops rely on a detailed knowledge of closest wild relatives and geographic origin. Relationships within the tribe, however, are incompletely known and previous molecular results conflicted with the traditional morphology-based classification. Here we analyse the systematics, biogeography, and character evolution in the tribe based on plastid and nuclear DNA sequences. RESULTS: Phylogenetic analyses including c. 70% of the species in the tribe show that the genera Vicia and Lathyrus in their current circumscription are not monophyletic: Pisum and Vavilovia are nested in Lathyrus, the genus Lens is nested in Vicia. A small, well-supported clade including Vicia hirsuta, V. sylvatica, and some Mediterranean endemics, is the sister group to all remaining species in the tribe. Fabeae originated in the East Mediterranean region in the Miocene (23-16 million years ago (Ma)) and spread at least 39 times into Eurasia, seven times to the Americas, twice to tropical Africa and four times to Macaronesia. Broad bean (V. faba) and its sister V. paucijuga originated in Asia and might be sister to V. oroboides. Lentil (Lens culinaris ssp. culinaris) is of Mediterranean origin and together with eight very close relatives forms a clade that is nested in the core Vicia, where it evolved c. 14 Ma. The Pisum clade is nested in Lathyrus in a grade with the Mediterranean L. gloeosperma, L. neurolobus, and L. nissolia. The extinct Azorean endemic V. dennesiana belongs in section Cracca and is nested among Mediterranean species. According to our ancestral character state reconstruction results, ancestors of Fabeae had a basic chromosome number of 2n=14, an annual life form, and evenly hairy, dorsiventrally compressed styles. CONCLUSIONS: Fabeae evolved in the Eastern Mediterranean in the middle Miocene and spread from there across Eurasia, into Tropical Africa, and at least seven times to the Americas. The middle-Atlantic islands were colonized four times but apparently did not serve as stepping-stones for Atlantic crossings. Long-distance dispersal events are relatively common in Fabeae (seven per ten million years). Current generic and infrageneric circumscriptions in Fabeae do not reflect monophyletic groups and should be revised. Suggestions for generic level delimitation are offered.

[Effects of UV-B radiation on the growth and reproduction of Vicia angustifolia].

A simulation experiment with supplementation and exclusion of solar ultraviolet-B (UV-B) radiation was conducted to study the effects of enhanced and near ambient UV-B radiation on the growth and reproduction of alpine annual pasture Vicia angustifolia on Qinghai-Tibet Plateau. Enhanced UV-B decreased the plant height and biomass, biomass allocation to fruit, flower number, and 100-seed mass significantly, delayed flowering stage, increased the concentration degree of flowering and success rate of reproduction, but had little effect on seed yield. Near ambient UV-B radiation made the plant height increased after an initial decrease, decreased biomass allocation to fruit and 100-seed mass, but little affected flowering duration, flower number, and seed yield. Both enhanced and near ambient UV-B radiation could inhibit the growth and production of V. angustifolia, and the effect of enhanced UV-B radiation was even larger.

Using pilot test data to refine an alternative cover design in northern California.

Two instrumented test sections were constructed in summer 1999 at the Kiefer Landfill near Sacramento, California to test the hydraulic performance of two proposed alternative final covers. Both test sections simulated monolithic evapotranspiration (ET) designs that differed primarily in thickness. Both were seeded with a mix of two perennial and one annual grass species. Oleander seedlings were also planted in the thicker test section. Detailed hydrologic performance monitoring of the covers was conducted from 1999 through 2005, The thicker test section met the performance criterion (average percolation of <3 mm/y). The thinner test section transmitted considerably more percolation (average of 55 mm/y). Both test sections were decommissioned in summer 2005 to investigate changes in soil hydraulic properties, geomorphology, and vegetation and to collect data to support a revised design. Field data from hydrologic monitoring and the decommissioning study were subsequently included in a hydrologic modeling study to estimate the performance of an optimized cover system for full-scale application. The decommissioning study showed that properties of the soils changed over the monitoring period (saturated hydraulic conductivity and water holding capacity increased, density decreased) and that the perennial grasses and shrubs intended for the cover were out-competed by annual species with shallower roots and lesser capacity for water uptake. Of these changes, reduced ET from the shallow-rooted annual vegetation is believed to be the primary cause for the high percolation rate from the thinner test section. Hydrologic modeling suggests that the target hydraulic performance can be achieved using an ET cover with similar thickness to the thin test section if perennial vegetation species observed in surrounding grasslands can be established. This finding underscores the importance of establishing and maintaining the appropriate vegetation on ET covers in this climate.

The presence of co-flowering species facilitates reproductive success of Pedicularis monbeigiana (Orobanchaceae) through variation in bumble-bee foraging behaviour.

Background and Aims The presence of co-flowering species can alter pollinator foraging behaviour and, in turn, positively or negatively affect the reproductive success of the focal species. Such interactions were investigated between a focal species, Pedicularis monbeigiana, and a co-flowering species, Vicia dichroantha, which was mediated by behaviour alteration of the shared bumble-bee pollinator. Methods Floral display size and floral colour change of P. monbeigiana were compared between pure (P. monbeigiana only) and mixed (P. monbeigiana and V. dichroantha) plots in two populations. Pollinator visitation rates, interspecific floral switching and successive within-plant pollinator visits were recorded. In addition, supplemental pollination at plant level was performed, and the fruit set and seed set were analysed in pure and mixed plots with different densities of P. monbeigiana. Key Results Pollinator visitation rates were dramatically higher in mixed plots than in pure plots. The higher pollinator visitation rates were recorded in both low- and high-density plots. In particular, successive flower visits within an individual plant were significantly lower in mixed plots. Supplemental pollination significantly increased fruit set and seed set of individuals in pure plots, while it only marginally increased seed set per fruit of plants in mixed plots. Conclusions The presence of V. dichroantha can facilitate pollination and increase female reproductive success of P. monbeigiana via both quantity (mitigating pollinator limitation) and quality (reducing geitonogamy) effects. This study suggests that successive pollinator movements among flowers within a plant, as well as pollinator visitation rates and interspecific flower switching, may be important determinants of the direction and mechanisms of interaction between species.

[The assessment of no adverse effect doses for plant populations chronically exposed to radionuclides of uranium and thorium decay series].

Dose rates cause no adverse effects on natural populations of Pinus sylvestris L. and Vicia cracca L. inhabiting territories contaminated by uranium mill tailings and radium production wastes (Vodny settlement, Komi Republic) were determined. A significant increase in embryonic lethal mutation frequency in V. cracca legumes and decrease in seedlings survival rate as compared with control values were registered at dose rate equal to 1.67 mGy/day, that is 280 times higher than the one calculated for the reference site. The adverse effects in P. sylvestris expressed in increased frequency of chromosome aberrations in meristematic root tips and decreased reproductive capacity of seeds were determined at absorbed dose rate equal to 0.083 mGy/day. Data obtained show that the decrease in plant reproductive capacity in case of chronic exposure of radionuclides of uranium and thorium decay series can observe at lower weighted absorbed dose rates than in case of environmental contamination by artificial radionuclides.