Rhizobacteria modify root architecture and improve nutrient uptake in oil palm seedlings despite reduced fertilizer

Abstract The oil palm (Elaeis guineensis Jacq.) is one of the most economically important oilseeds due to the production of two types of vegetable oils: palm oil and palm kernel oil. Due to the commercial plantations expansion, its necessary to produce seedling of agronomic quality, with low cost and proper management, which express all the productive potential of this culture. The objective was to evaluate the changes in the root system, in the nutrients acquisition and allocation in oil palm seedling inoculated with rhizobacteria. The study was carried out in the field in the seedling nursery of the company Agropalma Group S/A. Treatments was C-: no inoculation with ½ fertilizer; BRM 32113: Burkholderia pyrrocinia inoculated plants with ½ fertilizer; UFRA 92: Bacillus subtilis inoculated plants with ½ fertilizer; C+: no inoculation and complete fertilization. The inoculation positively influenced the root volume with an average increase of 46.7%, 28.4% total root length, 42.5% total surface area, 43.7% average diameter, 203% number of tips and 115% ramifications when comparing the mean of BRM 32113 and UFRA 92 against the mean of C- and C+. The results showed that inoculation modified the root architecture, increased the root system, and this favored the nutrients accumulation, in addition to obtaining quality seedlings for permanent planting with low production costs, highlighting the potential of rhizobacteria as a bioinoculant in agriculture. Rhizobacteria BRM 32113 and UFRA 92 also induced an increase in nutrient accumulation in the root, root dry mass, shoot and total dry mass in oil palm seedlings, with half the fertilizer compared to the controls. Rhizobacteria can be used as a mechanism to reduce the current high rates of synthetic fertilizers, without leaving chemical residues inherent to environmental problems and without compromising plant growth and productivity.