Euphytica

Lammerts van Bueren, Edith; Østergård, Hanne; Goldringer, Isabelle; Scholten, Olga

doi: 10.1007/s10681-008-9731-4pmid: N/A

Wolfe, M.; Baresel, J.; Desclaux, D.; Goldringer, I.; Hoad, S.; Kovacs, G.; Löschenberger, F.; Miedaner, T.; Østergård, H.; Lammerts van Bueren, E.

doi: 10.1007/s10681-008-9690-9pmid: N/A

The need for increased sustainability of performance in cereal varieties, particularly in organic agriculture (OA), is limited by the lack of varieties adapted to organic conditions. Here, the needs for breeding are reviewed in the context of three major marketing types, global, regional, local, in European OA. Currently, the effort is determined, partly, by the outcomes from trials that compare varieties under OA and CA (conventional agriculture) conditions. The differences are sufficiently large and important to warrant an increase in appropriate breeding. The wide range of environments within OA and between years, underlines the need to try to select for specific adaptation in target environments. The difficulty of doing so can be helped by decentralised breeding with farmer participation and the use of crops buffered by variety mixtures or populations. Varieties for OA need efficient nutrient uptake and use and weed competition. These and other characters need to be considered in relation to the OA cropping system over the whole rotation. Positive interactions are needed, such as early crop vigour for nutrient uptake, weed competition and disease resistance. Incorporation of all characteristics into the crop can be helped by diversification within the crop, allowing complementation and compensation among plants. Although the problems of breeding cereals for organic farming systems are large, there is encouraging progress. This lies in applications of ecology to organic crop production, innovations in plant sciences, and the realisation that such progress is central to both OA and CA, because of climate change and the increasing costs of fossil fuels.

Baresel, J.; Zimmermann, G.; Reents, H.

doi: 10.1007/s10681-008-9718-1pmid: N/A

Differences among six winter wheat varieties regarding N efficiency (NE) and its components were assessed in field trials in four locations over 3 years under conditions of organic farming (OF). N uptake and utilization efficiency, redistribution of N vs. direct N uptake during grain filling, N uptake in three periods (tillering, stem elongation/heading and grain filling) and the quantity of mineralized N during the same sub-periods were determined. Significant differences for these traits and significant interactions among varieties and environments could be detected for NE and its components. Limiting N availability during grain filling was typical for the more extensive organic environments. Under these conditions, differences of NE could be attributed to differences in pre-anthesis uptake and in translocation from vegetative tissues to the developing grain. Pre-anthesis uptake contributed more to N efficiency than translocation efficiency. Under more favourable conditions, differences became more evident and were mainly due to direct uptake during grain filling. This confirms, that different varieties are necessary in different environments and that breeding may contribute to improve baking quality to a certain extent. However, utilization of mineralized N is still unsatisfactory in OF systems in Germany. More N efficient varieties alone will help only little to resolve this problem; this can be achieved only by also improving the cropping systems.

Hoad, Stephen; Topp, Cairistiona; Davies, Ken

doi: 10.1007/s10681-008-9710-9pmid: N/A

Cereal cultivars conferring a high degree of crop competitive ability, especially against aggressive weeds, are highly beneficial in organic farming as well as other farming systems that aim to limit the use of herbicides. In this study, thirteen winter wheat cultivars, plus one spring wheat and one winter oat were assessed for their competitive ability at key growth stages, across three seasons. The natural population of weed species was allowed develop without agronomic intervention. Weed suppression ability for each cultivar (S var) was calculated as the difference between weed growth in plots for each cultivar and the maximal weed growth (W max) from adjacent uncropped areas. The sensitivity of S var in response to changes in weed growth (S var W ) was derived from the linear regression coefficient of S var plotted against W max. There was significant variation in S var between cultivars and strong evidence for cultivars to vary in S var W . Amongst groups of cultivars with similar levels of S var some could be defined as being of higher or lower sensitivity to changes in weed growth. Some cultivars also had relatively good S var at high levels of weed growth. The use of both weed suppression ability and sensitivity across different levels of weed growth or weed populations has considerable potential for selecting new cultivars suitable for organic agriculture. Ideally new cultivars will be selected on the basis of high S var and/or low S var W . This analysis provides the means to measure sensitivity of cultivar performance across a range of favourable and unfavourable conditions.

Kristensen, Kristian; Ericson, Lars

doi: 10.1007/s10681-008-9713-6pmid: N/A

The interest in organic grown cereals has increased the need for variety tests under organic growing systems and/or the knowledge on whether growth characteristics describe yield differently under conventional and organic conditions. This paper is a contribution to that question by examining the relationships between some important growth characteristics in barley trials in both systems in Northern Sweden and in Denmark. Mixed model analyses were used for regressions of growth characteristics (or transformations of those) on yield (and log-transformed yield), allowing the slope to depend on the growing system. The analyses showed that diseases seemed to have a less negative effect on yield in the organic growing system than in the conventional growing system if pesticides were not applied. For other characteristics the effect depended on the country. This was the case for grain characteristics where the effect of volume weight in the Swedish trials was much larger in the conventional growing system than in the organic growing system, while a non-significant difference in the opposite direction was found for the trails from Denmark. For the trials from Denmark the effect of grain weight was much larger in the organic growing system than in the conventional growing system, but there was only a small and non-significant difference in the Swedish trials. In both countries there was a significant interaction between the two grain characteristics.

Murphy, Kevin; Reeves, Philip; Jones, Stephen

doi: 10.1007/s10681-008-9681-xpmid: N/A

The diet of approximately three billion people worldwide is nutrient deficient and most of the world’s poorest people are dependent on staple food crops as their primary source of micronutrients. One component of the solution to nutrient deficiencies is collaboration among plant breeders, cereal chemists and nutritionists to produce staple crop cultivars with increased mineral nutrient concentration. Sixty-three historical and modern wheat cultivars were evaluated for grain yield and concentration of calcium, copper, iron, magnesium, manganese, phosphorus, selenium, and zinc. While grain yield has increased over time, the concentrations of all minerals except calcium have decreased. Thus a greater consumption of whole wheat bread from modern cultivars is required to achieve the same percentage of recommended dietary allowance levels contributed by most of the older cultivars. The decrease in mineral concentration over the past 120 years occurs primarily in the soft white wheat market class, whereas in the hard red market class it has remained largely constant over time. This suggests that plant breeders, through intentional selection of low ash content in soft white wheat cultivars, have contributed to the decreased mineral nutrient concentration in modern wheat cultivars. These results contradict the theory that there exists a genetically based, biological trade-off between yield and mineral concentrations. Therefore, using the abundant variation present in wheat cultivars, it should be possible to improve mineral concentrations in modern cultivars without negatively affecting yield.

Østergård, Hanne; Kristensen, Kristian; Pinnschmidt, Hans; Hansen, Preben; Hovmøller, Mogens

doi: 10.1007/s10681-008-9714-5pmid: N/A

For low-input crop production, well-characterised varieties increase the possibilities of managing diseases and weeds. This analysis aims at developing a framework for analyzing grain yield using external varietal information about disease resistance, weed competitiveness and yield potential and quantifying the impact of susceptibility grouping and straw length scores (as a measure for weed competitiveness) for predicting spring barley grain yield under variable biotic stress levels. The study comprised 52 spring barley varieties and 17 environments, i.e., combinations of location, growing system and year. Individual varieties and their interactions with environments were analysed by factorial regression of grain yield on external variety information combined with observed environmental disease loads and weed pressure. The external information was based on the official Danish VCU testing. The most parsimonious models explained about 50% of the yield variation among varieties including genotype-environment interactions. Disease resistance characteristics of varieties, weighted with disease loads of powdery mildew, leaf rust and net blotch, respectively, had a highly significant influence on grain yield. The extend to which increased susceptibility resulted in increased yield losses in environments with high disease loads of the respective diseases was predicted. The effect of externally determined straw length scores, weighted with weed pressure, was weaker although significant for weeds with creeping growth habit. Higher grain yield was thus predicted for taller plants under weed pressure. The results are discussed in relation to the model framework, impact of the considered traits and use of information from conventional variety testing in organic cropping systems.

Voorrips, Roeland; Steenhuis-Broers, Greet; Tiemens-Hulscher, Marjolein; Bueren, Edith

doi: 10.1007/s10681-008-9704-7pmid: N/A

Thrips tabaci is a major problem in the cultivation of cabbage for storage, as this pest causes symptoms that necessitate the removal of affected leaves from the product. Between cabbage varieties large differences in susceptibility occur. This study aimed to identify plant traits associated with these differences, in field experiments with natural infestation in 2005 and 2006. One factor affecting the amount of thrips damage was the timing of the development of the head. In an experiment with different planting dates especially the early maturing, more susceptible varieties were shown to benefit from later planting. In comparisons of multiple varieties in both years, regression studies showed that more advanced plant development in August and early September increased thrips damage at the final harvest. However, no single plant trait explained more than 25% (2005, Brix) or 48% (2006, compactness) of the variation in thrips damage. Optimal regression models, explaining up to 75% of the variation in thrips damage included Brix and leaf surface wax late in the season, as well as an indicator of plant development earlier in the season, and in 2005 also leaf thickness. The possible role of these plant traits in relation to thrips is discussed.

Przystalski, M.; Osman, A.; Thiemt, E.; Rolland, B.; Ericson, L.; Østergård, H.; Levy, L.; Wolfe, M.; Büchse, A.; Piepho, H.-P.; Krajewski, P.

doi: 10.1007/s10681-008-9715-4pmid: N/A

Top ranking varieties are tested in multiple environments before and after registration in order to assess their value for cultivation and use (VCU testing). Recently, interest has increased in obtaining varieties specifically adapted to organic farming conditions. This raised the question if an independent system of trials may be required for this purpose. To help answering this question, through the exchange network of European cereal researchers SUSVAR ( www.cost860.dk ), a number of data sets of agronomic traits from barley, wheat and winter triticale, from trials performed in Denmark, Sweden, The Netherlands, France, Switzerland, UK and Germany, were made available and analysed using an approach based on mixed models involving parameters describing genetic correlation between the two types of experiments, i.e., organic and non-organic (high or low input). Estimated variance components and correlations were used to evaluate response to selection and index selection. The response to index selection was analysed as a function of the fraction of available trials assigned to the organic system. The genetic correlations were interpreted in terms of ranking agreement. We found high genetic correlations between both systems for most traits in all countries. Despite high genetic correlations, the chances of very good agreement in observed rankings were moderate. Combining information from both organic and non-organic systems is shown to be beneficial. Further, ignoring information from non-organic trials when making decisions regarding performance under organic conditions is a sub-optimal strategy.

Pswarayi, A.; Eeuwijk, F.; Ceccarelli, S.; Grando, S.; Comadran, J.; Russell, J.; Pecchioni, N.; Tondelli, A.; Akar, T.; Al-Yassin, A.; Benbelkacem, A.; Ouabbou, H.; Thomas, W.; Romagosa, I.