BUSCADOR RECOLECTA

Comunicación presentada al XVI Congreso de la Sociedad Española de Malherbología, celebrado en la Universidad Pública de Navarra entre los días 25 y 27 de octubre de 2017., Concerns about a global decline in pollinators have called for more knowledge about the drivers of wild pollinator abundance and diversity. In this study we observed pollinator foraging activity in 27 field margins, from 2014-2016, in order to investigate the role of native weeds in supporting wild pollinators in Mediterranean cereal agroecosystems. In total, 175 different plant species were identified and 1,959 wild pollinators were observed foraging on margin flora. The most visited floral species were Papaver rhoeas L. (251 pollinator visits), Torilis arvensis (Huds.) (229 visits) and Malva sylvestris L. (141 visits). Pollinator abundance increased with flower abundance, vegetation height and floral diversity. Pollinator visits increased initially with open flower richness, but began to decrease when high richness likely resulted in lower densities of individual species., This work was supported by FEDER (European Regional Development Funds) and the Spanish Ministry of Economy and Competitiveness grants (projects number AGL2012-33736 and AGL2015-64130-R). The Natural Sciences and Engineering Research Council of Canada (NSERC) provided J.M. with a doctoral scholarship.

Concerns about a global decline in pollinators have called for more knowledge about the factors influencing wild pollinator abundance and diversity in agroecosystems. Agricultural intensification has been identified as the main cause of this “global pollinator crisis”, particularly due to reductions in natural areas holding critical floral and nesting resources. Maintaining native wild plants in agricultural landscapes (e.g., in field margins) is often recommended as a cost-effective and efficient method for pollinator conservation. In this study, the role of common wild flowers, often considered weeds, in supporting pollinators in a Mediterranean agroecosystem was investigated. This work involved a two-year field trial to compare five native weed species common in Mediterranean cereal agroecosystems: Convolvulus arvensis L., Daucus carota L., Malva sylvestris L., Papaver rhoeas L., and Sonchus oleraceus L. The goal was to compare the attractiveness of these species, and a mixture of all five, to different flower-visiting insect groups in order to assess their value in supporting wild pollinators. Overall, D. carota had the highest number of insect visits, followed by P. rhoeas. C. arvensis, M. sylvestris, and S. oleraceus, which had lower numbers of visits. On the basis of their overall attractiveness to pollinators and low risk for invasiveness, D. carota, P. rhoeas, and M. sylvestris are the most likely to contribute positively to the conservation of pollinators in agroecosystems. Our results also suggest that it is advantageous for wild flowers sown for the purpose of pollinator conservation to be grown in clumps, rather than highly intermingled, for improved visitation rates., This work was supported by FEDER (European Regional Development Funds) and the Spanish Ministry of Economy and Competitiveness (projects AGL2012-33736 and AGL2015-64130-R). The Natural Sciences and Engineering Research Council of Canada (NSERC) provided J.M. with a doctoral scholarship.

[Method] The study was carried out in 2013–2014 across 26 wheat fields (Triticum aestivum L. and Triticum turgidum subsp. durum Desf.) under a Mediterranean climate in Spain. Fields were either organically or conventionally managed and were located in cereal areas in four Spanish regions: Andalusia (15 fields), Madrid (3 fields), Castilla-La Mancha (4 fields) and Catalonia (4 fields). In each field, ten (1 m × 1 m) plots were established during crop tillering and maintained until harvest. Weeds were sampled at the end of the crop vegetative period (April with dates slightly varying depending on field location). In each plot we recorded the weed species present, and we visually assessed the cover (in cm2) of each weed species and the crop. We also measured plant height (cm). Immediately before crop harvest, we sampled the plots again to obtain crop yield. In each plot we counted the number of wheat stems with ears and cut 30 of them. We determined the dry weight (after 48 h at 65 °C) of the 30 stems, threshed the ears and weighed the grain for each sample. In doing this we obtained an average value for the grain weight of an ear. We calculated crop grain weight in each plot multiplying mean grain weight of each sample by the total number of fertile stems in the plot. In each plot, we obtained two measures of grain quality: the percentage of total dry protein content determined using the Kjeldahl standard method at the Laboratorio Agroalimentario de Córdoba (Córdoba, Spain) and the glutenin to gliadin ratio. The amount of glutenin and gliadin in each plot, was obtained from 100 mg of wheat flour. First, we ground the wheat grains of each sample using a ball mill to obtain flour of a 100 µm particle size. The extraction of gliadin and glutenin proteins was done using a modified classical Osborne procedure based on protein solubility. The method is described in detail in Wieser et al. (1998) and Pistón et al. (2011). Gliadin protein was extracted stepwise three times, samples were centrifuged, and the
supernatans were collected and pooled. The insoluble material from the previous step was used to obtain the glutenin fraction in a similar manner. Then, each of the extracts were filtered and they were applied to a 300SB-C8 reverse phase analytical column using a 1200 Series Quaternary LC System liquid chromatograph (Agilent Technologies) with a DAD UV-V detector. Absorbance was monitored with the DAD UV-V module at 210 nm. The amounts of both fractions were determined using bovine serum albumin as protein standard. Both fractions were expressed as μg/mg flour. The glutenin to gliadin ratio was calculated by dividing the amount of glutenins by gliadin content.
For each field we also recorded the crop species and the variety, and collected data on management practices: sowing date (month), fertilization rate (kg N/ha), preceding crop (legume, fallow, sunflower or cereal; categories depending on the nutrient demand of the crop), type of tillage and herbicides used. We also obtained data on the average monthly temperature (ºC) and total precipitation (mm) during crop growth season from the nearest meteorological stations.

[Methods for processing the data] Different plant community diversity indices were computed from data. Statistical analyses were performed to understand the relationship between crop quality and weeed community diversity as explained in: Paper accepted for publication., Weed community structure, including composition and taxonomic and functional diversity, may explain variability in crop quality, adding to the variability accounted for by management, climatic and genetic factors. Focusing on Mediterranean rainfed wheat crops, we sampled weed communities from 26 fields in Spain that were either organically or conventionally managed. Weed communities were characterized by their abundance and taxonomic, compositional and trait-based measures. Grain protein concentration and the glutenin-to-gliadin ratio were used as indicators of wheat grain quality. Linear mixed-effects models were used to analyze the relationship between crop quality and weed community variables, while accounting for environmental factors. Nitrogen fertilization, previous crop and precipitation explained an important part of wheat grain protein concentration (R2marginal = 0.39) and composition (R2marginal = 0.26). Weed community measures had limited effects on grain quality (increasing R2marginal of models by 1% on average). The weed effects were related to the composition and the functional structure of their communities but not to their abundance. Environmental conditions promoting higher protein concentration also selected for weed species with competitive attributes, whereas the role of weed functional diversity depended on the functional trait and on the resource limiting crop grain quality. Understanding the mechanisms of weed effects on crop quality could aid in designing sustainable weed management practices., Grants AGL2012-33736 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”., Peer reviewed

18 Pág., Weed community structure, including composition, taxonomic and functional diversity, may explain variability in crop quality, adding to the variability accounted by management, climatic and genetic factors. Focusing on Mediterranean rainfed wheat crops, we sampled weed communities from 26 fields in Spain that were either organically or conventionally managed. Weed communities were characterized by their abundance and taxonomic, compositional and trait-based measures. Grain protein concentration and the glutenin to gliadin ratio were used as indicators of wheat grain quality. Linear mixed effects models were used to analyze the relationship between crop quality and weed community variables, while accounting for environmental factors. Nitrogen fertilization, previous crop and precipitation explained a large portion of the variation in wheat grain protein concentration (R2marginal = 0.39) and composition (R2marginal = 0.26). Weed community measures had limited effects on grain quality (increasing R2marginal of models by 1% on average). The weed effects were related to the composition and the functional structure of their communities, but not to their abundance. Environmental conditions promoting higher protein concentration were also selecting for weed species with competitive attributes, whereas the role of weed functional diversity depended on the functional trait and on the resource limiting crop grain quality. Understanding the mechanisms of weed effects on crop quality could aid on designing sustainable weed management practices., This research was supported by grants AGL2012-33736 and AGL2015-64130-R funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”. D.J.G. was partially supported by the United States National Science Foundation (DUE 1758497 and DUE 1949969)., Peer reviewed

n this work, we aimed to test whether taxonomic diversity and functional diversity andthe values of functional traits of the weed seed bank varied across the field, from margins to thecore, and between fields embedded in distinct landscape structures. We sampled the seed bank of 47 conventionally managed cereal fields from two Mediterranean regions in Spain, This work was funded by FEDER (European Regional Development Funds) and the Spanish Ministry
of Economy and Competitiveness grants (projects AGL2012-33736 and AGL2015-64130-R). Y.P. was supported by
an FPI scholarship (Spanish Ministry of Economy and Competitiveness

Concerns about a global decline in pollinators have called for more knowledge about the factors influencing wild pollinator abundance and diversity in agroecosystems. Agricultural intensification has been identified as the main cause of this “global pollinator crisis”, particularly due to reductions in natural areas holding critical floral and nesting resources. Maintaining native wild plants in agricultural landscapes (e.g., in field margins) is often recommended as a cost-effective and efficient method for pollinator conservation. In this study, the role of common wild flowers, often considered weeds, in supporting pollinators in a Mediterranean agroecosystem was investigated.