Establishment of inoculated Azospirillum spp. in the rhizosphere and in roots of field grown wheat and sorghum

• Published in: Plant and Soil [PLANT SOIL.]. 1986 1986-01, Vol.90 (1/3), p.35-46
• Main Authors: BALDANI, V.L.D., de B. ALVAREZ, M.A., BALDANI, J.I., DÖBEREINER, J.
• Format: Article
• Language: English
• Subjects: Antibiotics; Azospirillum; Inoculation; nitrogen fixation; Plant roots; Plants; Rhizosphere; roots; Session 1: Biology of interactions between plants and diazotrophic bacteria; Soil inoculation; Sorghum; Sorghum vulgare; Sterilization; Triticum aestivum; Wheat soils
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/BF02277385

Four field experiments were carried out with wheat or sorghum in different regions of Brazil. The aim was to study the establishment of inoculated Azospirillum strains, marked with resistance to various antibiotics, in the rhizosphere and in roots. The levels of the various antibiotics were chosen according to the resistance of the indigenous Azospirillum population. Azospirillum brasilense strains Sp 107 and Sp 245 could be established in all three wheat experiments and predominated within the Azospirillum population in washed, and especially in surface sterilized, roots. Strains Sp 7 and Cd established poorly in wheat roots. Azospirillum lipoferum Sp S82 represented 72% of the root isolates from sorghum inoculated with this strain. This strain and natural Azospirillum infection became concentrated in the upper parts of the root system. Improved methods for root surface sterilization in which the absence of Azospirillum on the root surface was established by pre-incubating roots with paraffin-capped ends in NFb medium confirmed the establishment of inoculated Azospirillum strains within sorghum roots in the field.