Nitrogen fixation in wheat (Triticum aestivum) : effect of Azotobacter salinestris CECT 9690 on N-accumulation

Sammanfattning: Biostimulants are products that can improve nutrient availability, nutrient uptake, nutrient use efficiency and tolerance to abiotic stress with the aim to increase plant growth and yield. During the last decades, the interest in, and market for biostimulants has grown and is expected to have a large compound annual growth rate. The number of products on the market increase every year and the sales agencies promote them as yield rising and profitable. This thesis aimed to investigate the effect of the product Vixeran (Azotobacter salinestris CECT 9690) on N-accumulation in spring wheat under different temperatures and N-levels. The study was conducted as a pot experiment where spring wheat was cultivated, with and without supply of Vixeran, in climate chambers in BioCentrum at Ultuna. The experiment had a three-factorial split-plot design with temperature regimes as main plots and N-rates and Vixeran treatment as sub plots. The effect of Vixeran treatment varied between the two temperature regimes. In the high temperature, there was significant higher N-accumulation corresponding to 4,09 kgN/ha in Vixeran treated plants compared to the untreated control. On the other hand in the low temperature there was significantly 5,90 kgN/ha higher N-accumulation in the untreated control compared to the Vixeran treated wheat. There was no significant interaction effect between N-level and Vixeran treatment in any of the temperatures. It is essential to conduct research on how the bacteria works under different environmental conditions. Parameters such as soil type, pH, temperature and cultivar can influence the effect of the bacteria and it is important to understand how the interaction between these parameters and the bacteria works. The result of this study shows that more research is needed to guarantee N-fixation from Azotobacter salinestris CECT 9690. Keywords: Biostimulants, Vixeran, N-uptake, N-concentration, yield, cereals