Einfluß einer Bakterieninokulation auf die N- und P-Ernährung junger Weizenpflanzen bei unterschiedlichen Düngungsstufen

Abstract

Interactions between higher plants and microorganisms play an essential role in the nutrient supply of higher plants. Therefore bacterial strains which are able to fix atmospheric nitrogen, to mobilize soil nutrients and/or produce phytohormones are used as biofertilizers particularly in countries with limited mineral fertilizer use and unfavourable soil pH.

A pot experiment under green house conditions was conducted to answer the question, under which nutritional conditions bacterial inoculates can improve the nutrient supply of young wheat plants and which mechanisms are important for beneficial effects. The bacterial settlement was increased by inoculation in nearly all cases. The effective colonisation of two strains—‘D 5/23’ (Pantoea agglomerans, Germany) and ‘Mac 27’ (Azotobacter chroococcutn, India) was confirmed using DAS-ELISA. However, only under nitrogen deficiency the inoculation increased the dry matter production of young wheat plants. The nitrogen supply of the plants was improved by ‘D 5/23’ and ‘Mac 27’ in all treatments. Simultaneously the total nitrogen content of the rhizosphere soil was decreased. Besides a possible associative N₂ fixation the inoculation with these strains increased the nutrient uptake efficiency of the roots, presumable as a result of phytohormonal effects.

The phosphorus status of the plants was nearly not influenced by the strains we used in this experiment. Beneficial effects of bacterial inoculation depend on the nitrogen level of the plants, being mainly recognisable at insufficient nitrogen supply.