No abstract

A universal germination stimulant for all broomrape species has not being identified to date. The synthetic stimulant GR24 is active against most of the weedy broomrape species, but fails with the non-weedy species tested in this study and with the very recent weedy species O. foetida. In addition, germination behaviour of broomrape species depends on the crop plant tested. Weedy broomrapes with a broad host spectrum respond better to the different exudates released by a wide range of crops and wild species than do non-weedy broomrapes, which have a narrow host spectrum and are more restricted to their host range. Root exudates of many plant species were active in stimulating germination of seeds of Orobanche and Phelipanche species for which they are not described as hosts, representing interesting examples of potential trap crops.

No abstract

Broomrape weeds (Orobanche and Phelipanche spp.) are root holoparasites that feed off a wide range of important crops. Among them, Orobanche crenata attacks legumes complicating their inclusion in cropping systems along the Mediterranean area and West Asia. The detrimental effect of broomrape parasitism in crop yield can reach up to 100% depending on infection severity and the broomrape-crop association. This work provides field data of the consequences of O. crenata infection severity in three legume crops, i.e., faba bean, field pea, and grass pea. Regression functions modeled productivity losses and revealed trends in dry matter allocation in relation to infection severity. The host species differentially limits parasitic sink strength indicating different levels of broomrape tolerance at equivalent infection severities. Reductions in host aboveground biomass were observed starting at low infection severity and half maximal inhibitory performance was predicted as 4.5, 8.2, and 1.5 parasites per faba bean, field pea, and grass pea plant, respectively. Reductions in host biomass occurred in both vegetative and reproductive organs, the latter resulting more affected. The increase of resources allocated within the parasite was concomitant to reduction of host seed yield indicating that parasite growth and host reproduction compete directly for resources within a host plant. However, the parasitic sink activity does not fully explain the total host biomass reduction because combined biomass of host–parasite complex was lower than the biomass of uninfected plants. In grass pea, the seed yield was negligible at severities higher than four parasites per plant. In contrast, faba bean and field pea sustained low but significant seed production at the highest infection severity. Data on seed yield and seed number indicated that the sensitivity of field pea to O. crenata limited the production of grain yield by reducing seed number but maintaining seed size. In contrast, the size of individual parasites was not genetically determined but dependent on the host species and resource availability as a consequence of competition between parasites at increasing infection severities.

No abstract

International audienc

Faba bean (Vicia faba L.) is a cool season grain legume whose acreage has constantly declined in traditional producer countries as it has been replaced by more productive cereal crops. However, faba bean is still considered to have great potential as rainfed crop. In order to satisfy the renewed interest in faba bean cultivation yield stability should be improved by exploiting different germplasm types and sowing seasons.In order to understand of genotype by environment interactions and to compare cultivar performance over years and locations a spring faba bean network was established with twenty cultivars grown over three crop seasons at thirteen contrasting locations covering most of Europe. Analysis was performed by heritability-adjusted genotype plus genotype × environment interaction (HA-GGE) biplot analysis. HA-GGE biplot analyses identified that the effect of genotype by environment interaction was higher than the effect of genotypes, allowing identification of three mega-environments, namely Continental, Oceanic, and Mediterranean, in which cultivars performed differently. This supports the need for specific breeding for each specific geoclimatic area. Espresso was the highest yielding cultivar, being also highly stable over the Oceanic and Continental mega-environments. Cultivars Fuego, Hobbit and SR-1060 had also good yield but with a moderate unstability in both Oceanic and Continental mega-environments. Baraca and Alameda yielded poorly at all environments although were the best yielders at Mediterranean locations. Environments as Sumperk and Premesques were identified as the best core test locations for Continental and Oceanic mega-enviroments, respectively, being the locations in which best genotypes could be most easily identified.

No abstract