Beneficial cyanobacteria and eubacteria synergistically enhance bioavailability of soil nutrients and yield of okra

Abstract

Microorganisms in the rhizosphere mediate the cycling of nutrients, their enhanced mobilisation and facilitate their uptake, leading to increased root growth, biomass and yield of plants. We examined the promise of beneficial cyanobacteria and eubacteria as microbial inoculants, applied singly or in combination as consortia or biofilms, to improve growth and yields of okra. Interrelationships among the microbial activities and the micro/macro nutrient dynamics in soils and okra yield characteristics were assessed along with the changes in the soil microbiome. A significant effect of microbial inoculation on alkaline phosphatase activity was recorded both at the mid-crop and harvest stages. Microbial biomass carbon values were highest due to the Anabaena sp. - Providencia sp. (CR1 + PR3) application. The yield of okra ranged from 444.6–478.4 g−1 plant and a positive correlation (0.69) recorded between yield and root weight. The application of Azotobacter led to the highest root weight and yield. The concentration of Zn at mid-crop stage was 60–70% higher in the Azotobacter sp. and Calothrix sp. inoculated soils, as compared to uninoculated control. Iron concentration in soil was more than 2–3 folds higher than control at the mid-crop stage, especially due to the application of Anabaena-Azotobacter biofilm and Azotobacter sp. Both at the mid-crop and harvest stages, the PCR-DGGE profiles of eubacterial communities were similar among the uninoculated control, the Anabaena sp. - Providencia sp. (CW1 + PW5) and the Anabaena-Azotobacter biofilm treatments. Although the profiles of the Azotobacter, Calothrix and CR1 + PR3 treatments were identical at these stages of growth, the profile of CR1 + PR3 was clearly distinguishable. The performance of the inoculants, particularly Calothrix (T6) and consortium of Anabaena and Providencia (CR1 + PR3; T5), in terms of microbiological and nutrient data, along with generation of distinct PCR-DGGE profiles suggested their superiority and emphasized the utility of combining microbiological and molecular tools in the selection of effective microbial inoculants.

Bacterial Diversity and Interaction Networks of Agave lechuguilla Rhizosphere Differ Significantly From Bulk Soil in the Oligotrophic Basin of Cuatro Cienegas

“…In the rhizosphere, the hubs most affected by other members of the community are involved in nutrient acquisition or enhance bioavailability of soil nutrients, Bosea and Ensifer are well-known N fixers and denitrifiers (Shinwari et al, 2019) and Anabaena is a filamentous Cyanobacteria with the capacity to fix N (Manjunath et al, 2016). We hypothesize that they could be subject to predation.…”

Renewable Sources of Plant Biostimulation: Microalgae as a Sustainable Means to Improve Crop Performance

“…Microalgae-based plant biostimulation could be attributed also to the modulation of microbial communities residing in both the phyllosphere and the rhizosphere (Ranjan et al, 2016; Renuka et al, 2018). For instance, inoculation with blue-green algae such as Calothrix elenkinii stimulated the phyllosphere and rhizosphere microbiomes (Priya et al, 2015; Manjunath et al, 2016). One of the main mechanisms responsible for the improvement of soil microbial communities in response to inoculation with blue-green algae relates to the production of exopolysaccharides.…”

Recent Advances in the Chemistry of Bioactive Compounds from Plants and Soil Microbes: a Review

“… Heavy metals remediation Removal of Zn from contaminated soil [ 125 ] Variovorax paradoxus Crop improvement Increase shoot Fe and Zn and shoot dry weight [ 123 ] Fungal community Crop improvement Improve growth response of crop [ 126 ] Penicillium bilaiae Crop improvement Increase shoot Fe and Zn and shoot dry weight [ 123 ] Rhizobium Crop improvement Improve nodulation and nitrogen fixation of crops [ 127 – 130 ] Azotobacter sp . Crop improvement Increase root weight and yield [ 124 ] Flavobacterium sp. Nutrient availability Influence bioavailability of water-soluble Zn in soil [ 125 ] Calothrix sp.…”