Abstract

Micropropagation offers important advantages for the vegetative propagation of species such as cassava because it allows the elimination of pathogens in infested areas, rejuvenates the planting material, regains vigor and productivity and offers a large number of seedlings within a short period. The objective of this study was to evaluate the effect of the in vitro inoculation of cassava seedlings with plant growth-promoting bacteria (PGPBs) during the acclimatization phase. The experiment was conducted under greenhouse conditions, and the studied cultivars were “BRA Pretinha III” and “BRS Poti Branca”. The PGPBs were Azospirillum amazonense (BR 11140),Herbaspirillum seropedicae (BR 11175), Paenibacillus brasiliensis (24), Paenibacillus graminis (MC 0421), Paenibacillus durus (V 2232), Gluconacetobacter diazotrophicus (BR 11284), and Streptomycessp(S 30). Electron microscopy analyses revealed satisfactory colonization of the roots, with the exception of plants that were inoculated with bacteria of the genus Paenibacillus, which exhibited a low level of colonization. Although the strains used were not homologous, the plant height, stem diameter, dry mass of shoots, dry mass of roots and accumulated nitrogen were optimized, and these features can provide greater tolerance to abiotic stresses that are promoted by the transfer of the plant from an in vitro to an ex vitro environment. The cultivar “BRS Poti Branca” showed a greater interaction with the strain Glucanoacetobacter diazotrophicus. The cultivar “BRA Pretinha III” showed a greater interaction with the strains G. diazotrophicus, Streptomyces sp., H, seropedicae andPaenibacillus brasiliensis. The PGPBs provided better performance in the cultivar “BRA Pretinha III” in relation to the cultivar “BRS Poti Branca”.

Keywords

Micropropagation, PGPB, Colonization, Cultivar, Cassava, Inoculation, Cassava, Sprouting, Contributing, Commercial, Tolerance, Abiotic, Microorganisms, Stimulating, Phosphates, Hypothesis