Application and effectiveness of Methylobacterium symbioticum as a biological inoculant in maize and strawberry crops

Abstract

The effectiveness of Methylobacterium symbioticum in maize and strawberry plants was measured under different doses of nitrogen fertilisation. The biostimulant effect of the bacteria was observed in maize and strawberry plants treated with the biological inoculant under different doses of nitrogen fertiliser compared to untreated plants (control). It was found that bacteria allowed a 50 and 25% decrease in the amount of nitrogen applied in maize and strawberry crops, respectively, and the photosynthetic capacity increased compared with the control plant under all nutritional conditions. A decrease in nitrate reductase activity in inoculated maize plants indicated that the bacteria affects the metabolism of the plant. In addition, inoculated strawberry plants grown with a 25% reduction in nitrogen had a higher concentration of nitrogen in leaves than control plants under optimal nutritional conditions. Again, this indicates that Methylobacterium symbioticum provide an additional supply of nitrogen.

Methylobacterium symbioticum Applied as a Foliar Inoculant Was Little Effective in Enhancing Nitrogen Fixation and Lettuce Dry Matter Yield

“…It remains to be better clarified whether the selected strain of M. symbioticum used in this study is more effective in N fixation than others under such diverse conditions. The results of this study showed that in lettuce, under these cultivation conditions, the N fixed by the microorganism was very modest, not matching the very favourable results reported in maize and strawberries by the team that developed the commercial product [28,39]. The observed N fixation values in this study were so low (<6.3 kg ha −1 at the highest N rate) that they would hardly justify farmers' application of this commercial product.…”

“…Also, the nitrate content in the tissues, sometimes seen as an indicator of high sensitivity to N availability because it is an unmetabolized form that accumulates in tissues [38], varied similarly to the total N concentration in the leaves (Figure 3). Thus, this variable also did not reveal any influence on the plant's N nutritional status due to the microorganism application, perhaps because in biological fixation, the plant accesses N in the form of ammonia [12,13,28].…”

“…M. nodulans and M. radiotolerans, for instance, are reported to be N-fixing bacteria, but by forming nodules on legume roots [27]. Regarding M. symbioticum, a recent study showed that the application of the inoculant resulted in decreases of 50% and 25% in the amount of N that would be required for maize and strawberry, respectively, accompanied by an increase in production compared to treatments of equivalent rates of nitrate-N applied, but without the application of the inoculant [28].…”