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In the past, the aquatic pteridophyte Marsilea quadrifolia L. was considered as a weed in paddy fields of southern Europe. The systematic use of herbicides as a crucial component of intensive agronomic approach has led to a dramatic decline in M. quadrifolia populations in European countries, mostly in the Mediterranean area. However, the introduction in recent years of sustainable rice cultivation practices has allowed partial recovery. We present here the results of a research aimed at analyzing the effects of farming typologies in respect to M. quadrifolia growth in the Po Valley area. After having transplanted M. quadrifolia swards in rice fields belonging to different farming systems, we monitored its growth and diffusion. Our results showed that M. quadrifolia has higher vegetative performance in organic farms, even though it can survive in conventional fields with reduced herbicide supply. Differences in water chemistry have limited effects on M. quadrifolia performance, because of its wide ecological amplitude. The shady conditions provided by rice canopy create micro-habitats suitable for M. quadrifolia growth. Cultivating M. quadrifolia in organic rice farms represents an important opportunity for preserving this endangered species in areas of intensive agriculture. This can, meanwhile, represent a valid opportunity to combine nature conservation and productivity offering a new possible income for farmers.

Peucedanum ostruthium (L.) W.D.J.Koch (Apiaceae) is an alpine medicinal plant traditionally used as a panacea to treat various ailments. For the first time, its phytotoxic and nematotoxic properties were investigated. The inhibitory activity toward germination and seedling growth of the weeds Echinochloa oryzoides (Ard.) Fritsch and Lolium multiflorum Lam. was evaluated by two in vitro assays, carried out on filter paper and soil, using different aqueous extract concentrations (1, 10, and 20 %) and 0.25 g of powder of P. ostruthium leaves, inflorescences, and rhizomes. The study showed that all samples were more effective on L. multiflorum than E. oryzoides with p-values = 0.000 on both substrate types. Nevertheless, in all cases, the soil mitigated the P. ostruthium effects. Regarding nematicidal activity, the leaf extract was the most active against larvae and adults of the nematode Panagrolaimus rigidus. According to the motility test, their death was 85.6 ± 2.7 % and 90.5 ± 3.1 % 24 h after treatment. Lastly, NMR and UPLC-HR-MS analyses led to the identification of several compounds in the aqueous extracts, including mono- and di-substituted chlorogenic acids, flavonol glycosides, coumarins, and furanocoumarin glycosides. 5-Caffeoylquinic acid was the most abundant phenolic component in all plant organs.

Rice cultivation, particularly prone to weed issues, requires practices able to effectively control them, however reducing the use of herbicides, responsible for damage to human health and ecosystem sustainability. Alternative strategies for weed management can be based on plant-plant interaction phenomena. In this context, a group of organic farmers has developed a pragmatic approach for weed containment using Lolium multiflorum Lam. as a cover crop before rice. The present study aimed to confirm the farmer field observations reporting a preferential inhibitory effect of L. multiflorum on Echinochloa oryzoides (Ard.) Fritsch, one of the most yield-damaging rice weed, compared with Oryza sativa L. The study showed that L. multiflorum was able to significantly reduce the seed germination of E. oryzoides. It was found to be more susceptible than O. sativa both to the effect of the aqueous extract and powder of L. multiflorum leaves (23-79% vs. 3-57% and 26-100% vs. 23-31%, respectively). In addition, the leaf extract was able to affect E. oryzoides growth starting from 20% concentration both in relation to the root and shoot length while O. sativa exhibited differences compared with the control only under the influence of extract 50%. The L. multiflorum leaf characterization by NMR and UPLC-HR-MS analyses led to the identification of 35 compounds including several polyphenols, glycosyl flavonoids and glycosyl terpenoids, as well as different amino acids and organic acids. Some of them (e.g. protocatechuic and gallic acids) are already known as allelochemicals confirming that L. multiflorum is a source of plant growth inhibitors.

Due to decades of loss of grassland diversity across Europe, there is a need to identify factors affecting species composition and diversity in managed meadows. The aim of the current study was to assess how ecological, landscape and management factors may affect plant species composition, biodiversity and forage value in Alpine hay meadows. Species composition, Shannon index and forage value were obtained from phytosociological relevés. Twenty explanatory variables were selected from a set of ecological, landscape and management factors. Their effects on plant species composition, Shannon index and forage value were analysed by applying the variation partitioning approach. Plant species composition was related to sixteen factors, explaining 35·6% of the variability. Shannon index and forage value were related to eleven factors, explaining 47·8 and 40·8% of their total variation respectively. Ecological factors were the main set explaining species composition and diversity, whereas none of the three individual groups of factors (ecological, landscape, management) significantly explained variability within forage value. Overall, the effects of the three groups of factors accounted for 70% of the total variability in plant species composition, but less than half that of Shannon index and of forage value. © 2012 John Wiley & Sons Ltd.