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The increased interest in sustainable agricultural systems has led to significant developments in cropping practices that allow to preserve crop productivity and reduce the reliance on herbicides and nitrogen fertilizers. Relay intercropping of legumes in wheat may represent a proficient practice to maintain crop productivity, improve soil fertility and support weed control at crop rotation level, if appropriate associated legumes are used. The objective of this study is to select suited legumes for relay intercropping with durum wheat in central Italy among a wide range of taxa (Medicago sativa, Medicago varia, Medicago lupulina, Trifolium repens, Hedysarum coronarium, Trifolium alexandrinum, Trifolium incarnatum, Trifolium resupinatum, Vicia villosa, Medicago polymorpha, Medicago rotata, Medicago scutellata, Medicago truncatula, and, 3 subsp. of Trifolium subterraneum). This study was carried out at the Centre for Agro-Environmental Research “Enrico Avanzi” in Pisa (Italy) in 2017/18 and repeated in the 2018/19 cropping season. According to the results obtained during 2017/18, legumes were reduced in 2018/19 excluding the least performing ones. The experiment was organized in a randomized complete block design with four replicates and the sole wheat crop as control. No pesticides or fertilizers were used. The evaluation was focused on i) legume establishment in the already developed wheat, ii) grain production and quality, iii) weed control before and after the wheat harvest, iv) legume persistence and growth after wheat harvest and, v) effects on the following crop. Legumes, indeed, were incorporated into the soil the following spring and forage sorghum was seeded. Results of this study showed that relay intercropped legumes preserved wheat production and reduced weed biomass up to the 70% in comparison with the control. After wheat harvest legumes persisted in the field, as dead mulch or cover crop according to the different life cycle of the tested legumes, until the sowing of sorghum. Dead mulch of annual legumes resulted unsuitable to contrast weeds while, perennial and annual self-seeding legumes as M.polymorpha and T.subterraneum, showed overall good weed control and biomass accumulation. Legume biomass at spring soil incorporation, was the most important factor related with sorghum production. Sorghum, preceded by T. subterranum, H. coronarium and T. repens, had a higher biomass production than the control and was comparable with the productive level that can be obtained under conventional systems. The overall assessment of legumes used in this study, allows to select the most suited ones for relay intercropping with durum wheat for the local environmental condition.

The objective of this experiment is to screen perennial and annual self-reseeding legumes cover crops for investigating their potential role as permanent living mulch in organic vegetable systems. This study focuses on the screening of legumes based on their morphology, phenology and weed suppression capacity. This is the first phase of a trial in which 28 different legume cover crops are tested as sole crop in order to select the most interesting ones for the local environmental condition. A reduced number of selected legumes will then be tested as permanent living mulch in a vegetable cropping system. Both perennial and annual self-reseeding legumes may be suitable for the target system. Perennial legumes are expected to exert weed control all over the year as living mulch. Annual self-reseeding legumes are able to re-generate from the soil seed bank in autumn and therefore improve weed control during winter as living mulch, while during summer they act as dead mulch, hence limiting the potential water competition during this season. This preliminary experiment was necessary because one of the main challenges to establish successfully a permanent living mulch is the appropriate choice of legume species and/or varieties. Indeed, specific morphological, physiological and phenological traits are crucial in order to obtain the benefits of living mulch and avoid over-competition with the main crop (Ciaccia et al., 2017). Unfortunately, the availability of suitable legumes for this system seems limited, because the cultivars available on the market are normally selected for other uses, e.g. high biomass production and, hence, they are likely highly competitive with the main crop. A specific legume ideotype selection is therefore necessary.

L’effet concurrentiel des communautés d’adventices (CA) est mal connu. De plus, une des priorités de recherche en malherbologie consiste à caractériser les relations entre diversité des adventices et pertes de rendement (PR). Nous avons testé l’hypothèse que (i) toutes les CA ne sont pas responsables de PR et que (ii) les CA plus diversifiées réduisaient les PR grâce à une plus faible probabilité d’espèces dominantes et compétitives. Un essai au champ sur blé tendre a été mené pendant 3 ans sur 2 parcelles différentes chaque année. Sur chaque parcelle, 9 zones (6 non désherbées, 3 désherbées) présentant une flore contrastée ont été installées. Au sein de chaque zone, 5 quadrats ont été disposés (3 stades de la culture plus 1 à maturité couplé à 1 quadrat désherbage manuel). Un relevé initial ainsi que les prélèvements de biomasse aux 4 stades du blé nous ont permis de calculer des indices de biodiversité sur la densité et la biomasse. Sur les 6 CA identifiées, seulement 4 ont engendrées des PR significatives (19 à 56%) dans les zones non désherbées. Le nombre d’épis par pied fut la composante de rendement la plus affectée par la compétition avec les adventices. Nous avons également démontré que les CA diversifiées réduisaient les PR grâce à une production de biomasse moins importante. Les CA diversifiées ont limitées l’effet négatif des espèces dominantes et compétitives tout en potentiellement

Članek opisuje uporabo plevelnih vrst kot indikator-jev stanja tal, ki je povezano ali z lastnostmi tal (kot sta pH ali tekstura tal) ali z gospodarjenjem s tlemi (zastajanje vode v tleh, premalo ali preveč hranil, zbitost). Poudariti je treba, da: (i) Tovrstna analiza ne zagotavlja vedno doslednih rezultatov. Odnos med različnimi plevelnimi vrstami in stanjem tal namreč ni vedno jasno začrtan. (ii) Za izvajanje te metode vzorčenja je potrebno nekaj osnovnega botaničnega znanja za identifikacijo plevelov.

Esta ficha técnica describe cómo las especies de malas hierbas pueden ser utilizadas como bioindicadores de las condiciones del suelo, relacionándolas con las características del suelo (como pH o textura)y al manejo del suelo (como el uso del agua, falta o exceso de nutrientes o compactación. Debe destacarse que (i) este tipo de análisis no siempre proporciona resultados consistentes, porque la relación entre las malas hierbas y las condiciones del suelo no siempre es clara y que (ii) la metodología de muestreo sugerida requiere conocimientos botánicos básicos para la identificación de especies. English version available at https://orgprints.org/31696/

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. Abutilon theophrasti causes -severe yield losses in maize and soybean (70 % - 72%). A. theophrasti management is crucial for optimum crop production. Prevention is a pre-requisite to reduce weed pressure and investigation into weed bioecology is needed. This study characterized the morphological and genetic variation of eleven A. theophrasti accessions representative of a climatic gradient distribution range from north (47° N) to southeast Europe(39 ° N) and north America (43ºN). To evaluate interpopulation variability, seed were characterized with morphological parameters (length; width; thickness; weight and volume of 100 seeds) and biomolecular markers: trnL-trnF; trnH-trnK; trnT-psbC and matK. Multivariate and univariate analyses were performed to estimate genetic diversity within and among populations. Populations from north and southern Europe were separated in two groups according to seed morphology. However it was not possible to associate seed morphological traits to genetic variability. All gene sequences (cpDNA genome) presented the same nucleotide sequence.

This technical note shows how weed species can be used as indicators of soil conditions that are either linked to soil characteristics (such as soil pH or texture) or to soil management (such as water logging, lack or excess of nutrients, compaction). It should be stressed that (i) this kind of analysis does not always provide consistent results, because the relationship between weed species and soil conditions is not always clear cut and that (ii) the suggested sampling methodology requires some basic botanical skills for weed identification.

Cover crops are a fundamental tool for weed control, especially in organic and low input farming. Species with different functional traits can be combined in mixtures to enhance weed suppression. Our aim was to test the relative importance of functional diversity and functional composition (i.e. complementarity) in improving and stabilising the agroecosystem services expected from cover crops. Following a preliminary screening on cover crop functional traits (Step 1), we identified 8 species belonging to 4 functional groups: large seeded legumes, characterized by higher height (Pisum sativum L., Vicia sativa L.), small seeded legumes, able to cover quickly the soil (Trifolium incarnatum L., T. squarrosum L.), highly competitive grasses (Hordeum vulgare L., Avena sativa L.) and allelopathic brassicas (Raphanus sativus L., Brassica nigra L.). We designed 4 two-species mixtures, 4 four-species mixtures and 1 eighth-species mixtures and set a gradient of diversity: (i) pure stands; (ii) co-presence of 2 functional groups; (iii) diversity within 2 co-occurring functional groups, (iv) co-presence of 4 functional groups, (v) diversity within 4 co-occurring functional groups. The trial was conducted in an organic field located in Pisa, Italy. Experimental plots were seeded on 27 October 2014 following a randomized complete block design with three replicates, and devitalized on 6 May 2015. Weed biomass was significantly lower in mixtures with the higher level of diversity compared to the unweeded control (from -87% up to -97%). Cover crop mixtures proved to e more productive than pure stands, since Land Equivalent Ratio was >1 in all but one mixture. For some species, biomass production was higher in high diversity mixtures compared to pure stands. Functional diversity in cover crops can play a key role on biomass productivity and weed suppression. Data will be analysed to clarify the role of functional composition on cover crops agroecosystem services provision.

Cover crops play a key role in weed management strategy in no-till organic and low input vegetable systems. The ability of cover crops to reduce weed pressure can be linked to the amount of biomass produced at the time of cover crop devitalisation. Cover crop mixtures, in particular functional diversity in cover crop mixtures, can be managed to improve biomass production and weed suppressive ability of cover crops. We tested eight cover crop species pure stands and designed nine cover crop mixtures at increasing levels of functional diversity. The aim of this study was to highlight the effect of cover crops' functional diversity in controlling weeds before aubergine (Solanum melongena L.) transplanting. We showed that the functional composition (i.e. the presence of complementary cover crop species functional traits in mixtures) of cover crop mixtures is key to provide high biomass productivity and weed suppression.

Cover crops are an essential strategy in organic and low input arable and vegetable production, especially regarding weed reduction and N use efficiency, but their establishment and development can be unstable. A viable option to enhance and stabilise the agroecosystem services provided by cover crops is to sow mixtures of species having different functionality. Such mixtures have been reported to increase productivity, stability, resilience and resource use efficiency of cover crop communities. Therefore, our hypothesis is that weed reduction can also be improved by cover crops mixtures. However, it is not yet clear how diversity drives these mechanisms in arable and vegetable systems in Mediterranean climates.

The introduction of cover crops (CC) in crop rotations is a key tool to control weed and ameliorate soil conditions in low input arable systems. In 1992 a long term experiment (LTE) was set up at Centre for Agri-environmental Research “E. Avanzi (CIRAA), University of Pisa to determine the combined effect of tillage intensity, nitrogen fertilization levels and CC types on soil quality, crop yield and weed communities. The LTE is based on 4-year crop rotation (maize, durum wheat, sunflower, durum wheat) with cover crops grown twice, in between wheat and summer crops. Two tillage systems were compared: i) a conventional system (CS), with annual ploughing (30 cm depth); ii) a low input system (LIS), with chiseling (30 cm depth) for summer crops and no till for wheat. In both systems cover types were: control; Brassica juncea L.;Trifolium squarrosum L.; and Vicia villosa Roth.). Four Nitrogen levels (from 0 to a maximum rate, varying across crop type) were applied. The experiment was replicated in 4 blocks for a total of 128 plots (21 x 11 m). Weed and CC above-ground biomass were assessed at CC termination, while weed species cover and total biomass were assessed at harvest. Data collected in CC (2011, 2014), sunflower (2012), durum wheat (2012) were used to calculate species richness, weed community diversity indices (Shannon’s H’ and inverse Simpson index) and Pielou equitability. Weed biomass and cover were analyzed by split-split plot ANOVA. Weed community composition was analyzed by a permutational multivariate analysis of variance based on Bray Curtis dissimilarity and Non-metric Multidimensional Scaling.

Vicia villosa Roth, or hairy vetch, is one of the most productive cover crops (CC) in Mediterranean dry areas, with an interesting potential as dead mulch in no-tillage cropping systems. In low-input cropping systems, mechanical termination of hairy vetch could replace a glyphosate application to control weeds. Mechanical termination (e.g. with a roller crimper) of hairy vetch is ineffective until the late growing stages of vetch, leading to delayed sowing and yield reduction in the following crop. To find the best compromise in timing between effective termination of vetch and reasonable yield of no-till sunflower, an on-farm experiment was carried out in Pisa (Italy) in 2012/13 and 2013/14 to compare three termination techniques (roller crimper with no, half and full dose of glyphosate) and three termination dates (before flowering, beginning of flowering, 70% of flowering of vetch). Data on weed biomass, species density and soil cover were collected at CC termination and during sunflower growth. Weed diversity and composition were analyzed through ANOVA, PERMANOVA and NMDS.

The incorporation of conservation agriculture techniques (e.g. reduced tillage and green manures) in organic farming systems brings many benefits to the environment and reduces energy use (Holland, 2004). One of the main drawbacks of the use of reduced tillage is the potential increase in weed infestation and shifts in the weed community composition, sometimes to the benefit of more difficult-to-control species (Bàrberi, 2002; Peigné et al., 2007; Sans et al., 2011). However, weeds have an important role in maintaining farmland functional biodiversity (Bàrberi et al, 2010; Caballero et al., 2010), and this should be balanced with their potential negative impact on crop yield and quality. Within the frame of the European project “Reduced tillage and green manures for sustainable cropping systems” (TILMAN-ORG), in 2012 we started a study with the aim of evaluating the effects of conservation agricultural methods on functional attributes of weed communities, taking into account both the potential detrimental effects of weeds on crop growth and yield and the potential ecological services or dis-services. Knowledge on the outcome of positive and negative effects will be useful in the context of evaluating soil conservation practices in organic farming. In this paper we highlight the approach used to build the weed functional traits database, the first step in this study.