pH effects on nodulation and biological nitrogen fixation in Calopogonium mucunoides

Abstract

Calopogonium mucunoides Desv. is able to form nodules, root organs in which biological nitrogen fixation takes place, after a symbiotic interaction with soil bacteria known as rhizobia. Such distinct advantage of some legume species faces different environmental abiotic factors such as acid and alkaline pH conditions of soil. Nodulation and symbiotic nitrogen fixation response in different pH ranges were determined under greenhouse conditions. Plants were cultivated in vermiculite and treated with nutritive solution adjusted to pH 4.0, 5.5, and 7.0, and after three months, the following variables were measured: nodule number, nitrogen fixation, tissue protein, amino acids, total ureides, allantoin, and allantoate. The number of nodules and nitrogen fixation were enhanced under acidic conditions, but nitrogenase activity was drastically decreased at pH 7.0. Acidic conditions decreased the amount of protein, amino acids, total ureides, allantoate, and allantoin in leaves and nodules, but at pH 5.5, only protein content was decreased. Symbiosis with C. mucunoides and biological nitrogen fixation were kept under acidic conditions, but it was negatively affected under conditions that are near to neutral. It is reasonable to conclude that the association between C. mucunoides and nitrogen-fixing bacteria from ''Cerrado'' evolved in this context, which is supported by the difficulties faced to keep interaction under pH near neutrality.

Root symbioses in two legume-grass consortia inoculated with soils obtained from degraded coal mining areas in reclamation

“…Calopo seems to be a better alternative to be used in future recovery programs since 80% of the evaluated soils presented a microbiota that in symbiosis has the capacity to promote the growth of this legume. This fact is very positive considering that this is a legume native to South America adapted to low fertility soils and low pH, meanwhile vetch is a native legume from the temperate regions of the world (Ferreira et al, 2016;Camargos and Sodek, 2010). In the present study, there was no symbiotic association between vetch and any native rhizobia.…”

“…Other important characteristics of these plants are good adaptation to acid soils of low natural fertility containing high levels of aluminum. These plants are able to establish mutualistic relationships with symbiotic microorganisms such as rhizobia (in the case of leguminous plants) and arbuscular mycorrhizal fungi (AMF) (leguminous plants and brachiaria), which provide nutrients (such as phosphorous) to the plant (Ampomah and Huss-Danell, 2016;Ferreira et al, 2016;González et al, 2018). Besides rhizobial and mycorrhizal symbionts there is a great diversity of other microorganisms occupying the interior of the plant tissues, also known as endophytes.…”

Limitations and strategies to enhance biological nitrogen fixation in sub-humid tropics of Western Ethiopia

“…The activities of rhizobia in the legume root rhizosphere can be reduced by the extreme soil pH or low soil pH. The characteristics of highly acidic soils (pH < 4) are low level of phosphorus, calcium, and molybdenum along with aluminum and manganese toxicity, which affects both plant and the rhizobia (Bordeleau and Prevost, 1994;Ferreira et al, 2016). As a result, under low soil pH conditions, nodulation and N fixation are more severely affected than the plant growth.…”

Glyphosate Effect on Nitrogen Fixation and Metabolization in RR Soybean

“…Amino acids, total soluble protein, total ureides, allantoin and allantoic acid quantitation was carried according described in Ferreira et al (2016).…”