Characteristics of spring barley varieties for organic farming

Summary

Modern spring barley varieties have been developed with the aim of combining high productivity and standardised product quality under high-input conditions using pesticides for control of weeds, diseases and insects as well as heavy application of nutrient-rich and water-soluble inorganic fertilizers. In the organic growing system, biotic and abiotic stresses have to be overcome by growing the appropriate varieties and by practicing good farm management. The important spring barley traits to be considered in organic farming are related to the inherited viability and adaptation of plants to survive biotic and abiotic stresses and includes competitive ability (morphology, weed tolerance, growth rate, allelopathy), disease resistance (morphology, specific and non-specific resistance proporties, disease tolerance) and nutrient acquisition ability (root morphology, nutrient uptake and use efficiencies, low-nutrient tolerance, symbioses). An important question is whether modern spring barley varieties possess the right combinations of these characteristics to ensure a stable and acceptable yield of good quality when grown under different organic growing conditions. We know that varieties often perform and yield differently in different environments due to genotype-environment interactions, so it may be important to evaluate characteristics of varieties in organic as well as in conventional farming systems. However, it remains unclear to date whether the differences between the conventional and the organic growing systems are large enough to justify breeding and testing of varieties in both environments. Extensive field experiments and refined statistical methods are needed to clarify this. Characterisation of varieties as part of the official variety testing is at present done under conventional farming conditions in Denmark.
The aim of a newly started inter-institutional Danish research project within The Danish Research Center for Organic Farming (DARCOF) with project participants from The Royal Veterinary and Agricultural University, Danish Institute of Agricultural Sciences and Risø National Laboratory is to
Identify combinations of plant characteristics required for a barley crop to be successful in organic growing systems and develop methodologies for measuring these characteristics.
Evaluate, by investigating genotype-environment interactions, the need for specific variety trials for organic farming, and if necessary implement such trials.
Improve yield and yield stability in different organic farming systems by strategic use of the appropriate varieties and variety mixtures.
Investigate the potential of different variety mixtures for reducing diseases and weeds and increasing nutrient uptake efficiency.
Obtain new knowledge on plant competition, disease complexes, epidemiological models, nutrient acquisition and associations between molecular markers and agronomical traits.
The results of the first-year trials on three organic workshop areas and in two conventional fields with about 120 mostly modern varieties and a few variety mixtures will be discussed. The preliminary analyses indicate large variation in yield between the different varieties.