Response of Root Properties to Tripartite Symbiosis between Lucerne (Medicago sativa L.), Rhizobia and Mycorrhiza Under Dry Organic Farming Conditions

It is generally considered that root turnover is a major contributor to organic matter and mineral nutrient cycles in organic managed agroecosystems. Approach: This study designed to investigate whether microbial activity could affect on root properties of lucerne in an organically managed field under dry weather conditions. The trial was laid out as a factorial experiment in the fields of the University of Natural Resources and Applied Life Sciences, Vienna-Austria at Raasdorf in 2007. The experimental factors of Sinorhizobium meliloti and arbuscular mycorrhiza (AM) including Glomus etunicatum, G. intraradices and G. claroideum and irrigation levels were tested. Results: Results showed that increasing water deficit affected root dry weigh, specific root mass and root length significantly at 1% level and co-inoculation of rhizobium and mycorrhiza with irrigation could increase all root parameters. Data’s of variance analysis for mycorrhizal colonization showed that main effect of using mycorrhiza had significant effects on root parameters at 5% and 1% probability level in first and second harvest, respectively. Results of mean comparisons by Duncan’s multiple range test showed that mycorrhizal colonization was higher in the inoculated treatments by rhizobium , mycorrhiza and irrigated plots in both harvests. Double interaction of mycorrhiza and irrigation was higher in both harvests (37.05% and 65.73%, respectively). Conclusion: Hence, it can be suggested that the tripartite symbiosis of S. meliloti, AM and lucerne can improve the performance of lucerne in organic farming and under dry conditions. Such traits could be incorporated into breeding programs to improve drought tolerance especially in organic fields

Genetic diversity and distance among Iranian and European alfalfa (Medicago sativa L.) genotypes

Alfalfa is the best known fodder crop with high ability of biological nitrogen fixation and drought tolerance in dry, Pannonian region of east Austria. Different morphological and physiological characteristics of 18 alfalfa genotypes from different geographical origins, 8 Iranian ecotypes and 10 European cultivars were evaluated under irrigated and rainfed conditions during 2006-08 cropping seasons. The objectives of this study were to measure genetic distance and divergence among genotypes and to classify them based on morphological and physiological characters. Cluster analysis differentiated Iranian ecotypes and European cultivars from each other under irrigated condition, and when data averaged across two environments (irrigated and rainfed). However, under rainfed conditions small changes occurred in grouping of genotypes due mainly to differential responses of the genotypes to rainfed condition. Considerable genetic distance observed between Iranian and European genotypes. Different crossing programs are recommended between Iranian and European genotypes to develop new alfalfa cultivars

Suitability of drought tolerance indices for selecting alfalfa (Medicago sativa L.) genotypes under organic farming in Austria

In eastern Austria, alfalfa is usually grown as a rainfed crop in crop rotations in organic farming systems, where year-to-year rainfall fluctuations cause different levels of drought stress. To identify the suitability of different alfalfa genotypes and drought tolerance indices, 18 contrasting alfalfa genotypes were evaluated under irrigated and rainfed conditions at the research station of the University of Natural Resources and Life Sciences (BOKU), Vienna, Austria, during 2006-08. The first study year (2006) was considered as the establishment year. Five drought tolerance selection indices were estimated based on shoot dry matter, total biomass yield and biological nitrogen fixation (BNF) data. The correlation between irrigated and rainfed performances increased (from r=-0.17 to 0.56) with decreasing stress intensity from the first to the second year. Genotypes Sitel, Plato ZS, Vlasta and NS-Banat were the best genotypes based on their performance under both conditions. Drought tolerance selection indices TOL and SSI showed high correlations (r = 0.32 to 0.81) only with rainfed performance, and SSI was the index that best identified genotypes with high yield potential under rainfed conditions. Indices STI and GMP were the ones that best identified genotypes with high performance under both conditions

Modellberechnungen für treibhausgasrelevante Emissionen und Senken in landwirtschaftlichen Betrieben Ost-Österreichs

Landwirtschaftliche Nutzungssysteme sind in unterschiedlicher Weise an der Emission und Speicherung von klimarelevanten Gasen (CO2, CH4 und N2O) beteiligt. Die wesentlichen Projektziel sind die Bereitstellung von Daten- und Berechnungsgrundlagen für eine umfassende Darstellung von Profilen treibhausgasrelevanter Emissionen und Senken landwirtschaftlicher Betriebe in den acht Hauptproduktionsgebieten Österreichs. In jeder Region werden die beiden vorherrschenden Betriebstypen mit dem Programm REPRO modelliert, da es die Analyse der C-, N- und Energieflüsse im System Boden-Pflanze-Tier-Umwelt kombiniert. Als Beispiel werden die Ergebnisse des Hauptproduktionsgebietes "Nordöstliches Flach- und Hügelland" im Anschluss präsentiert

Biological nitrogen fixation and growth parameters correlations of alfalfa (Medicago sativa L.) genotypes under organically managed fields with limited irrigation

To identify the effective characters and their relative importance in improvement of BNF, two separate field experiments were conducted under irrigated and rain-fed organic managements of dry, Pannonian region of east Austria. The experiments were laid out in an α-lattice design with two replications and 18 genotypes (eight Iranian ecotypes and ten European cultivars). Plant height was positively and significantly correlated with leaf area index (LAI) and shoot dry matter (DM) under both conditions. Positive correlations were found between biological nitrogen fixation (BNF) and shoot DM (r = 0.61** and 0.87**, irrigated and rain-fed management, respectively). Regarding correlation coefficients, high yielding genotypes had taller plants and denser stands, especially under rain-fed condition. In path analysis, all direct effects of BNF components were positive in both conditions, while some of the indirect effects were negative. These can be regarded in selection models to avoid undesirable negative effects. Plant height and LAI can be considered as primary selection criteria for improving shoot DM, while crop re-growth and plant height, with antonymous effects, were more important for improving root dry matter

AGTEC-Org Agronomy Handbook of Methods

A common handbook was conceived in the CORE Organic AGTEC-Org project in order to give some elements of field trial monitoring

Nitrogen fixation and yield of lucerne (Medicago sativa L.), as affected by co-inoculation with Sinorhizobium meliloti and arbuscular mycorrhiza under dry organic farming conditions

This study evaluated the effects of co-inoculation with Sinorhizobium meliloti and arbuscular mycorrhizal fungi on the growth, yield and biological nitrogen fixation (BNF) of lucerne (Medicago sativa L.) under organic farming and dry weather conditions. The trial was laid out as a factorial experiment in the fields of the University of Natural Resources and Applied Life Sciences, Vienna-Austria at Raasdorf in 2007. The experimental factors of S. meliloti and arbuscular mycorrhiza (AM) including Glomus etunicatum, G. intraradices and G. claroideum and irrigation levels were tested. Co-inoculation of lucerne with S. meliloti and AM increased shoot dry weight as well as BNF at the first and second harvest but for BNF it was not significant. Irrigation resulted in the enhanced growth of some growth parameters. Microbial activities in this organically managed field were high enough for establishing an effective symbiosis with lucerne without any necessity for inoculation. Hence, it can be suggested that the tripartite symbiosis of S. meliloti, AM and lucerne can improve the performance of lucerne in organic farming and under dry conditions

Management effects on nitrogen fixation and water use of lucerne under dry site conditions

Biological nitrogen fixation is the main source of nitrogen in organic farming systems. There is little known about the impacts of cultivation techniques in pannonic regions on the capacity of biological nitrogen fixation (BNF) and the water use efficiency (ETC: evapotranspiration coefficient) of lucerne. From 1999 to 2001, pure lucerne crops and lucerne-grass mixtures were investigated with respect to the effect of the utilization system (harvested = forage production; mulched = green manure; pure lucerne crops versus lucerne-grass mixtures) on yield, BNF, soil N balance and water use efficiency. The amount of total fixed N was 124-150 kg N ha-1 in 2000 and 178-197 kg N ha-1 in 2001. The proportion of N derived from the atmosphere (% Ndfa) ranged from 26 to 79%. When the proportion of grass yield in lucerne-grass mixtures was high enough (exceeding 20%), mixtures showed a higher water use efficiency than pure crops by using site resources more efficiently than the pure lucerne crops. The release of nitrogen from the legume mulch was inhibited due to unfavourable conditions for mineralization in both years. Therefore green manure legumes did not decrease nitrogen fixation and the proportion of nitrogen derived from the atmosphere. Nevertheless, mulching the legumes reduced the water consumption of the crops compared to the evapotranspiration of the forage legumes

Monitoring the Conversion to Organic Farming

A long term field monitoring concerning the development of Organic Farming is performed at the bio-farm “Rutzendorf “ of the BVW GmbH in the Marchfeld region east of Vienna. It is an interdisciplinary project of eleven research institutes, which started in 2003. The aims of the project are: examination of changes concerning soil and plant parameters accompanying the conversion to organic farming; investigation of the effects of different organic fertilisation systems (green manure, communal green forage compost, farmyard manure) on soil properties and on crop performances; analysis of existing biotopes (hedges and field stripes) on the farm, and planning and selective realization of new biotopes with the aim of enhancing the biodiversity of the area, offering habitats for beneficials and reducing wind erosion potential

Modeling growth of different lucerne cultivars and their effect on soil water dynamics

Lucerne (Medicago sativa L.) is a perennial legume with high importance as fodder crop under organic farming. Our study analyzes biomass growth and influence on soil water dynamics of three lucerne cultivars in a field experiment and using the simulation model CropSyst. The objective was to evaluate the model for a perennial legume crop, study the relation of cultivar traits with soil water relations and derive a lucerne ideotype for temperate, semi-arid conditions. Two cultivars of European origin (Sitel and Niva)were compared to an Iranian one (Mohajeran). Measurements were made under irrigated (non-water limited) and rain-fed (water limited) conditions. Sitel achieved a cumulative biomass (dry matter yield)of 36.8 t ha−1 (irrigated) and 25.3 t ha−1 (rain-fed) over six cuts during the two experimental years, being significantly higher compared to the other cultivars. It was depicted that for Sitel and Mohajeran biomass growth was determined by the ratio of rainfall-to-evapotranspiration. Niva on the contrary exhibited a distinct response of biomass growth to profile water content changes. Also the more even root distribution over the soil profile of Niva indicated an efficient water uptake for this cultivar. CropSyst simulated biomass growth (RMSE 0.58–3.52 t ha−1) and water content in the soil profile (RMSE 20.9–50.6 mm) satisfactorily. Indices of agreement revealed a better model performance for irrigated conditions compared to water-limited growth. Model deviations from measured biomass and profile water content were highest for Mohajeran and it can be attributed to an inadequate distribution of root water extraction over the soil profile in relation to rooting density. Scenario analysis revealed that for the temperate, semi-arid conditions at the site, a maximum root depth between 1.3 and 1.8 m is sufficient for optimum growth and water use. Optimization of growth is largely determined by leaf traits such as specific leaf area, but our analysis depicted that in a dry year the sustained water supply via the root system becomes decisive