Effects of bioinoculation with Bacillus aryabhattai on adventitious rooting and nursery performance of clonal Eucalyptus

Abstract

The success of adventitious rooting in Eucalyptus mini-cuttings is influenced by the physiological state and juvenility of the propagules. In this context,bioinoculants containing microorganisms such as growth-promoting bacteria have been used to contribute to adventitious rooting and optimize plantlets production. Therefore, this study evaluated the effect of inoculation with B. aryabhattai on the rooting and growth of five Eucalyptus clones propagated by mini-cutting. As for adventitious rooting, the response to inoculation was genotype-dependent. Clone E. tereticornis × E. brassiana × E. urophylla showed greater responsiveness, with a reduction in rooting time and a significant increase of 20.5% in the final rate (88.88%), indicating the bacteria’s potential as a biostimulant to reduce the production cycle. In contrast, clones with a high intrinsic rooting capacity, such as E. urophylla × E. tereticornis genotype (92% in the control), the response to inoculation was negative, with a 14.4% reduction. Among the possible explanations for this inhibitory effect, the hypothesis of suboptimal auxin levels stands out; this should be tested in future studies involving hormone quantification. For growth in height, there was a significant interaction between genotype and inoculation, while the stem diameter was determined exclusively by the genotype. It can be concluded that B. aryabhattai has proved to be a promising tool for clonal forestry, especially for clones with poor rooting, as long as its application is adjusted according to the genetic material. The effect of B. aryabhattai on adventitious rooting of Eucalyptus is genotype-dependent. The inoculant resulted in up to a 20% increase in adventitious rooting. Clone 4 showed increased height when inoculated with B. aryabhattai. The use of bioinoculants is promising in genotypes with rooting below 75%. B. aryabhattai is a promising technological tool for forestry.