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Genetic adaptation to local, organic growing conditions: comparison between the best pure line and genetically broader population example summer and winter field beans
Project
Project code: 2803OE438
Contract period: 15.01.2004
- 31.03.2007
Budget: 136,988 Euro
Purpose of research: Applied research
Faba bean (Vicia faba L.) as a grain legume is a low input crop that fits well to the organic farming and provides the organic cropping system with a number of advantages (e.g., break crop, positive N-balance, weed suppression). The use of chemical inputs in conventional farming partially buffers the effects of environmental variation on crops. In organic farming the use of genetic variation as a way to cope with agro-ecological, environmental variation and to reduce the risks of crop failure is of high importance. Therefore, organic farming requires cultivars that are specifically adapted to organic conditions. The main objectives of the present study were: (1) to develop locally adapted cultivars in faba bean for a set of organic farms in Germany through a participatory breeding approach, (2) to compare local versus formal breeding, and inbred line versus synthetic cultivars for organic farming, (3) to assess the effect of heterogeneity for inbreeding status and plant height on competition among faba bean genotypes and finally (4) to test the competitive ability against weeds of faba bean genotypes contrasting in their heterozygosity and heterogeneity and in their plant height. To fulfill the first objective, 49 spring bean genotypes and 56 winter genotypes with different genotypic structures (more or less heterozygous and heterogeneous), were tested in field trials across four organic farms and one conventional site in Germany across 2004, 2005 and 2006. The material involved in case of spring beans as well as for winter beans, was composed from 18 inbred lines, their 18 polycross progenies, polycross progenies blends, inbred lines blends, one hybrids blend (spring beans) and checks. Yield performance of synthetic cultivars was predicted through the yield performance of inbred lines and their polycross progenies. For the second objective, data of the genotypic performance of inbred lines and polycross progenies of spring bean genotypes over the five locations across the three years were considered. For the third objective, an experiment across three years (2004, 2005 and 2006) was conducted in one location where a tall hybrid, a tall hybrid blend, a short hybrid blend, a tall and a short inbred line were tested in all possible two component 'line plus hybrid' and 'line plus line' combinations. A sequence of five proportions of the two components was established per combination. Competition effects were recorded at both plot level and at the individual component level. Concerning the fourth objective, a set of 24 genotypes composed from different genotypic structures: eight inbred lines, eight polycross progenies, two inbred line blends, two hybrid blends and four checks were tested under two treatments with weeds and without weeds. The competitive ability of these faba bean genotypes against weeds was tested with a model weed Camelina sativa in two locations during two years (2005 and 2006). The outcome of these experiments showed that farmer's criteria of selection were strongly influenced by biotic and abiotic constraints faced by the crop in each location. Yield constituted for all partners an important trait for the evaluation of the genotypes. Unexpectedly, uniform rather than diverse genotypes were apparently appreciated by organic farmers. Due to the large genotype × location interaction in organic locations, local breeding proved to generate higher gains from selection and was obviously more efficient than formal breeding. Despite the large variance among inbred lines available in local breeding which allowed a high gain from selection, highest yielding synthetics were superior in both breeding strategies to highest yielding inbred lines due to their partially expressed heterosis. Through their heterogeneity and heterozygosity, synthetic cultivars have the advantage to be more stable and adaptable across years to a given environment. Besides, heterogeneity for inbreeding status, a characteristic of faba bean synthetic cultivars, proved to be advantageous and led to an increase in yield performance. Heterogeneity in plant height in the case of inbred lines was not found to be favorable for yield performance. As heterozygosity increased in the genotypes, the competitive ability against weeds increased, shown by the hybrid blends which were the most competitive genotypes, whereas inbred lines were least competitive. No correlation was found between the yield performance of genotypes and their competitive response within the genotypic structures (e.g., within lines). Competitive ability against weeds was improved by heterozygosity and high plant height, although some inbred lines were found to be as competitive to weed stress as the partially heterozygous and heterogeneous polycross progenies and checks. However, through the different aspects of this study, generally heterozygosity and heterogeneity appeared to be the required characteristics in a cultivar in order to match the conditions and constraints of organic farming. Hence, the synthetic cultivar seemed to be the adequate type of cultivar fitting the requirement of organic farming.
Section overview
Subjects
- Crop Production
Framework programme
Federal Organic Farming Scheme and other forms of sustainable agriculture (BÖLN)
