BIONÆR-Bionæringsprogram

European cereal production experiences an ongoing intensification and specialisation on wheat and barley production at the expense of minor cereals as oat, rye and spelt, and rye is today mainly grown in environments where climate- and soil conditions are unfavourable for wheat production. In order to improve the competitiveness of rye, enhanced plant breeding efforts are of strategic importance. Rye is the only cross-pollinated small-grain cereal, giving a unique complexity concerning the genetic improvement which underlines the need for rye-specific research activities. The overall goal of the RYE-SUS project, in which several European countries and Canada participated, was to make use of hybrid breeding technologies and genome-based precision breeding for the development of semi-dwarf rye varieties with improved lodging resistance, minimised risk of ergot infestations, improved drought- and frost tolerance, and a higher harvest index and yield potential. Three semidwarf genotypes with the Ddw1 dwarfing gene and their near-isogenic tall counterparts were used as seed parents for the establishment of 48 gibberellin-sensitive semidwarf prototypes and their 48 near-isogenic tall counterparts. They were evaluated in field trials under different climate and growing conditions for qualities related to winter survival, phenological development, agronomy, plant health, yield and grain quality. The results showed that semidwarf genotypes, in contrast to their near-isogenic tall counterparts, had a pronounced lodging resistance due to their shorter and more robust stems, and confirmed that the concept of genetic growth regulation using dominant dwarfing genes for the protection of yield loss due to lodging is feasible in rye. The strong lodging resistance of semidwarf rye hybrids enables farmers to produce more grain of better quality on finite arable land without increased use of fertilizers and water and hence also a lower environmental footprint. For a separate panel of genetically divergent rye lines, both with and without the dwarfing gene, more in-depth evaluations of qualities related to frost tolerance and winter survival was performed under both natural and controlled climatic conditions. This work identified 34 previously unknown genes significantly associated with winter survival and increased understanding of the genetic architecture of frost tolerance in rye. Process-based crop models have become essential tools in current agronomic research. While several crop models have been developed for wheat, only a few models with limited applications and/or accessibility exist for rye. A large dataset with almost 40 000 historical observations from more than 100 locations throughout Germany during 1983-2019 was used for calibration, adaptation and validation of the Ceres-Wheat crop growth model for rye. However, a specific challenge regarding crop models for winter cereals is the possibility to simulate winter survival and hence the remaining field plant coverage in spring. A pot experiment was therefore established at NIBIO Apelsvoll Research Station in the autumn of 2020 and 2021, where selected varieties were tested for vernalization requirement and development of frost tolerance during periods of hardening and dehardening. Data from these experiments were used to calibrate the FROSTOL model, developed to simulate course of frost tolerance and proportion of winter survival in winter wheat fields, to rye. The calibrated FROSTOL model was thereafter included as a winter survival module in the developed Ceres-Rye model. The Ceres-Rye model is made freely available in the Decision Support System for Agrotechnology Transfer and makes it possible to perform simulations of winter survival, growth and yield formation for rye under both present and future climatic conditions and evaluate different management strategies with a view both to yield production and environmental sustainability.

1) Establishment and field evaluations of 48 semidwarf genotypes and their near-isogenic tall counterparts. 2) The shown potential of genetic control of plant height in semidwarf rye will reduce the need of chemical plant growth regulators in rye production. The strong lodging resistance of semidwarf rye hybrids enables farmers to produce more grain of better quality on finite arable land without increased use of fertilizers and water and hence also a lower environmental footprint. 3) The CERES-Wheat crop growth model and the FROSTOL model, which simulates course of frost tolerance and proportion of surviving plants during winter, was adapted and calibrated to form a crop growth model for rye which also includes simulations of winter survival (CERES-Rye). The CERES-Rye model makes it possible to evaluate crop management methods under both present and future climatic conditions and is freely available in the Decision Support System for Agrotechnology Transfer. 4) Identification of 34 previously unknown genes significantly associated with winter survival. 5) Specific genes related to frost tolerance were tagged with gene-specific markers, enabling a more efficient marker-assisted introgression of favourable alleles from donor populations in the breeding of new, winter hardy rye cultivars. 6) Increased understanding of the genetic architecture of winter hardiness in rye will further promote rye as a model species to unravel the frost tolerance network in cereal crops.

Enhanced plant breeding efforts are of strategic importance to improve the competitiveness of minor cereals as rye in European agriculture. Rye is a traditional food grain and a valuable source of energy and protein for livestock. Like other minor cereals, rye is mainly grown in marginal environments where climate and soil conditions are unfavourable for wheat production. The overall goal of RYE-SUS is to develop and test gibberellin-sensitive semi-dwarf rye genotypes with an optimized harvest index, improved lodging resistance, high yield potential, minimised risk of ergot infestations, and high drought and frost tolerance, as well as to develop a crop model for simulations of winter survival, growth and yield formation under both optimal and potentially growth-limiting conditions. While the technology of hybrid breeding enables development and evaluation of prototypes of new rye genotypes, the knowledge gained within RYE-SUS will also be applicable for the genetic improvement of open pollinating cultivars with simpler and less expensive breeding procedures and shorter development cycles. An active exchange of ideas, concepts, knowledge and technology between participants of RYE-SUS will improve the coherence on marker assisted selection in European and Canadian rye breeding programs and generate synergies for more sustainable and resilient crop production through plant breeding. The collaborative research and activities within this transnational consortium develop and deliver unique opportunities for the European Research Area to increase and secure cereal production on finite arable land without increasing water and fertilizer use.