Isolation, characterization of rhizobacteria and analysis of indole acetic acid production aiming at the rooting of olive (Olea europaea L.) cuttings

Abstract

Plant growth-promoting rhizobacteria (PGPR) are capable of enhancing plant development through various mechanisms. One of them is the production of plant-growth regulators, e.g., indole acetic acid (IAA). On this basis, this study proposes to isolate, phenotypically characterize and evaluate the IAA production potential of rhizobacteria obtained from the rhizosphere of olive trees (Olea europaea L.), aiming at its application in the induction of rooting during seedling production. Samples of the rhizosphere of 17 olive cultivars from the germplasm bank of the Agricultural Research Corporation of Minas Gerais (EPAMIG), in Maria da Fé - MG, Brazil, were used for isolation of PGPR in JNFb, NFb and LGI culture media. Subsequently, they were characterized phenotypically in potato dextrose agar and subjected to an IAA production trial. There was an effect of cultivars on the number of PGPR in the different culture media. In phenotypic characterization, the PGPR isolates showed high similarity to each other (93% to 100%). These isolates showed relevant IAA production rates (0.16 and 29.08 μg mL^-1) when compared with reports of other studies, and the isolates obtained in JNFb medium had the highest IAA production. In conclusion, 11 isolates (KRJ2, GLJ2, G57J2, MFJ1, ADJ2, G57N1, AUSAL3, FTJ1, AUSAN1, AUSAJ2 and KRN1), with IAA production rates above 20 μg mL^-1, have potential for use in future rooting induction trials in olive cuttings.

Keywords:
Inoculant; Plant hormones; Seedlings