No abstract

Bitter vetch (Vicia ervilia L.) is an ancient grain legume used as animal feed in the Mediterranean basin. This legume has a large economical potential because of its high yield under low inputs and good protein content, as well as resistance to cold and drought. Nevertheless, its growth and production area are affected in the presence of the broomrape weed species Orobanche crenata. Due to the small bitter vetch size, infection by as few as two or three O. crenata per vetch plant can be devastating. There are no efficient methods of selectively controlling O. crenata in this crop, for which reason the development of varieties resistant and tolerant to O. crenata infection is needed. Phytogenetic resources are valuable reserves for species survival. They represent important genetic variability and allow the possibility of finding characters of interest, such as new resistance sources. A large-scale field screening of a collection of 102 bitter vetch accessions indicated that most bitter vetch accessions were susceptible but allowed us to select 16 accessions with low levels of O. crenata infection. Next, we used a combination of field and rhizotron experiments to investigate the resistant response of selected bitter vetch genotypes in detail by studying the performance and resistance mechanisms. These experiments led to the identification of three different mechanisms that block O. crenata parasitism. A pre-attachment mechanism of low induction of O.crenata germination was identified in two bitter vetch accession Ve.055 and Ve.155. In addition, a post-attachment mechanism of resistance to O. crenata penetration was identified inthe accession Ve.125. In addition, the field-resistant accession Ve.123 showed susceptible response in rhizotron, indicating that a late mechanism acting after vascular connection, most probably related with bitter vetch of escape due to fructification precocity was acting against O. crenata development.

The dodders (Cuscuta spp.) are parasitic plants that feed on the stems of their host plants. Cuscuta campestris is one of the most damaging parasitic plants for the worldwide agricultural production of broad-leaved crops. Its control is limited or non-existent, therefore resistance breeding is the best alternative both economically and environmentally. Common vetch (Vicia sativa) and bitter vetch (Vicia ervilia) are highly susceptible to C. campestris, but no resistant genotypes have been identified. Thus, the aim of this study was to identify in V. sativa and V.ervilia germplasm collections genotypes resistant to C. campestris infection for use in combating this parasitic plant. Three greenhouse screening were conducted to: (1) identify resistant responses in a collection of 154 accessions of bitter vetch and a collection of 135 accessions of common vetch genotypes against infection of C. campestris; (2) confirm the resistant response identified in common vetch accessions; and (3) characterize the effect of C. campestris infection on biomass of V. sativa resistant and susceptible accessions. Most common vetch and bitter vetch genotypes tested were susceptible to C. campestris. However, the V. sativa genotype Vs.1 exhibited high resistance. The resistant phenotype was characterized by a delay in the development of C. campestris posthaustorial growth and a darkening resembling a hypersensitive-like response at the penetration site. The resistant mechanism was effective in limiting the growth of C. campestris as the ratio of parasite/host shoot dry biomass was more significantly reduced than the rest of the accessions. To the best or our knowledge, this is the first identification of Cuscuta resistance in V. sativa genotypes.

Bitter vetch (Vicia ervilia (L.) Willd.) is a legume well adapted to cultivation in marginal areas, being an important source of protein for animal feed in low input cropping systems. Surprisingly, it is an underutilized crop as it could be a good alternative to increase the sustainability of extensive rainfed cropping systems. In Mediterranean rainfed cropping systems, the productivity of bitter vetch is severely reduced by the parasitic weed species Orobanche crenata (Forsk). To date, few resistant bitter vetch genotypes have been identified. O. crenata infection process initiates with the recognition of germination factors exuded by roots of susceptible hosts. In this work, the interaction of a collection of bitter vetch accessions and O. crenata has been analyzed in order to discover accessions with low germination induction activity. Through a combination of field and rhizotron experiments, two bitter vetch accessions were selected showing low germination-induction activity, which resulted in less infection. In addition, in vitro germination assays revealed that the low germination activity was due to low exudation of germination factors and not due to the exudation of germination inhibitors. The selected low germination-inducers genotypes could be the basis for a new breeding program generating locally adapted alternatives with resistance to O. crenata.

This study investigates the effect of different crop rotation systems on carbon (C) and nitrogen (N) in root biomass as well as on soil organic carbon (SOC). Soils under spring barley and spring barley/pea mixture were sampled both in organic and conventional crop rotations. The amounts of root biomass and SOC in fine (250–253 μm), medium (425–250 μm) and coarse (>425 μm) soil particulate organic matter (POM) were determined. Grain dry matter (DM) and the amount of N in harvested grain were also quantified. Organic systems with varying use of manure and catch crops had lower spring barley grain DM yield compared to those in conventional systems, whereas barley/pea showed no differences. The largest benefits were observed for grain N yields and grain DM yields for spring barley, where grain N yield was positively correlated with root N. The inclusion of catch crops in organic rotations resulted in higher root N and SOC (g C/m2) in fine POM in soils under barley/pea. Our results suggest that manure application and inclusion of catch crops improve crop N supply and reduce the yield gap between conventional and organic rotations. The observed positive correlation between root N and grain N imply that management practices aimed at increasing grain N could also increase root N and thus enhance N supply for subsequent crops.