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

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

Carbon isotope discrimination and water use efficiency relationships of alfalfa genotypes under irrigated and rain-fed organic farming

Carbon isotope discrimination (∆) has been proposed as a method for evaluating water use efficiency (WUE) in C3 plants and as a precise technique for screening plants with higher tolerance under water deficit conditions. In this research, 18 alfalfa genotypes from different geographical origins were evaluated under irrigated and rain-fed conditions in organically manged fields in Austria. Significant differences were found amongst harvests for ∆-shoot under both conditions while genotype by harvest interaction was only significant under irrigated condition. Drought stress under rain-fed condition reduced the overall mean of water use efficiency and carbon isotope discrimination responses(up to 34%), but the ratios of reduction differed for characters and genotypes. Narrow ranges were found for all traits especially for WUE-TBY (total biomass yield) (0.78 kg m-3) and ∆-shoot (0.53 ‰) based on genotype means over locations and years, although variation and ranges were higher under irrigated condition. Regarding the variable and low correlations, simultaneous assessment of genotypes for ∆-shoot and biomass production can ensure the selection of superior genotypes and minimize potential biomass reductions that may result from using ∆-shoot as the only selection criterion to improve WUE. Sitel was the most water use efficient genotype(2.79 and 4.48 kg m-3 based on shoot dry matter and total biomass,respectively) across two condition (widely adapted genotype) followed by Mohajeran, Fix232 and Verko under irrigated condition (as specific adapted genotypes) and Vlasta, Sanditi, Ghara-aghaj under rain-fed condition