Local vs. formal breeding and inbred line vs. synthetic cultivar for organic farming: Case of Vicia faba L.

As organic farming refrains from the use of agrochemical inputs, it is characterized by large environmental heterogeneity. Genotype × location interaction is expected to be larger across organic cropping areas than across conventional ones. When breeding for organic farming, it is important to identify an adequate breeding approach and type of cultivar. The objective was to investigate in the case of faba bean (Vicia faba L.) the effectiveness of local breeding (exploiting local adaptation) vs. formal breeding (exploiting broad adaptation) for grain yield in organic farming and to compare the performance of two types of cultivars: inbred lines and synthetics. A set of 18 inbred lines, their polycross progenies and 13 checks was tested in five locations in Germany from 2004 to 2006. Due to the large genotype × location interaction, local breeding generated higher gains from selection than formal breeding. Based on estimates of genotypic performance and variance of inbred lines and polycross progenies, the best synthetic cultivar at generation Syn-1 and the best inbred line cultivar were predicted. Despite the large variance among inbred lines available in local breeding, the highest performing entry in both breeding strategies was a synthetic, due to its partial realization of heterosis.     

Development of locally-adapted faba bean cultivars for organic conditions in Germany through a participatory breeding approach

Organic farming requires cultivars that are specifically adapted to this low input cropping system. Hence, organic farmers and scientists joined in a participatory breeding approach to develop region-specific genotypes of spring faba bean for organic conditions in Germany. A set of 49 genotypes with contrasting degrees of heterozygosity and heterogeneity was used in field trials across five locations in Germany during 3 years 2004, 2005 and 2006. The material involved 18 inbred lines, their 18 polycross progenies, one blend of inbred lines, one blend of polycross progenies, one blend of hybrids and ten checks. Inbred lines are uniform, thus giving the option to be specifically adapted; whereas the polycross progenies and synthetics (Syn-1; predicted from the inbred lines and polycross progenies performance) are partly heterogeneous and heterozygous, thus giving the option to evolve. Agronomic performance was assessed and a “personal appreciation” score of the material was assigned to each genotype by each partner. This personal appreciation was strongly influenced by biotic and abiotic constraints faced by the crop in each location and by the expected grain yield of the genotypes. Uniformity was apparently appreciated by organic farmers. In all locations, the highest yielding inbred line yielded slightly better than the predicted highest yielding synthetic. However, this slight disadvantage of the synthetic is very likely to disappear if the synthetic (Syn-1) is propagated during successive generations.     

Validation of simple sequence repeats associated with quality traits in durum wheat

Over recent years, quality has become an important commercial issue for durum wheat breeders. Modern breeding methods are most efficient for producing and supplying the best quality raw materials to the pasta industry. Here we assessed the effectiveness of molecular marker-assisted selection of quality traits in durum wheat. To this end, DNA and quality trait markers were jointly used to analyze quality-related traits in a durum wheat collection. A total of 132 durum wheat (Triticum turgidum ssp. durum) Mediterranean landraces, international lines, and Moroccan cultivars were analyzed for seven important qualityrelated traits including thousand-kernel weight (TKW), test weight (TW), gluten strength, yellow pigment (YP), and grain protein content (GPC). Additionally, 18 simple sequence repeat (SSR) markers previously reported to be associated with different quality traits were analyzed. Of these, 14 (78%) were polymorphic and four were monomorphic. There were between two and seven alleles per locus, with an average of four alleles per locus. The average phenotypic variation value (R²) ranged from 2.81 to 20.43%. Association analysis identified nine markers significantly associated with TKW, TW, and YP, followed by eight markers associated with GPC, six markers associated with yellow index b, four markers associated with brightness L, and three markers associated with SDS-sedimentation volume. This study highlights the efficiency of SSR technology, which holds promise for a wide range of applications in marker-assisted wheat breeding programs.     

Effect of competition between Vicia faba and Camelina sativa as a model weed in breeding for organic conditions

Weeds can have a detrimental effect on faba bean (Vicia faba) crops in organic farming. Breeding for competitive cultivars is one option for weed control in organic conditions. The aim of this study was to analyse the impact of heterozygosity and heterogeneity levels and plant height on the competitive ability of faba bean genotypes. A set of 24 genotypes, classified as genotype groups (eight inbred lines, eight polycross progenies, two inbred line bulks, two hybrid bulks and four controls), was tested under two treatments: with and without a model weed. Each group of genotypes was equally composed of tall and short genotypes. The competitive ability of the faba bean genotypes was tested with Camelina sativa (false flax) as the model weed in two German locations over the course of 2 years. Yield loss due to weed competition, as recorded per faba bean genotype, was mainly dependent on the heterozygosity level of the genotypes; hybrid bulks were the most competitive genotype group with an average loss of yield of only 6%, whereas the inbred lines were the least competitive genotype group and recorded an average yield loss of 35%. Within the genotype group, no correlations were found between either the yield performance of the genotypes or their plant height and their competitive responses. The competitive ability of faba bean against weeds was mainly determined by their level of heterozygosity; thus, highly heterozygous cultivars should be promoted for breeding.