Assessment of Bacterial Inoculant Delivery Methods for Cereal Crops

Abstract

Despite growing evidence that plant growth-promoting bacteria can be used to improve crop vigor, a comparison of the different methods of delivery to determine which is optimal has not been published. An optimal inoculation method ensures that the inoculant colonizes the host plant so that its potential for plant growth-promotion is fully evaluated. The objective of this study was to compare the efficacy of three seed coating methods, seedling priming, and soil drench for delivering three bacterial inoculants to the sorghum rhizosphere and root endosphere. The methods were compared across multiple time points under axenic conditions and colonization efficiency was determined by quantitative polymerase chain reaction (qPCR). Two seed coating methods were also assessed in the field to test the reproducibility of the greenhouse results under non-sterile conditions. In the greenhouse seed coating methods were more successful in delivering the Gram-positive inoculant (Terrabacter sp.) while better colonization from the Gram-negative bacteria (Chitinophaga pinensis and Caulobacter rhizosphaerae) was observed with seedling priming and soil drench. This suggested that Gram-positive bacteria may be more suitable for the seed coating methods possibly because of their thick peptidoglycan cell wall. We also demonstrated that prolonged seed coating for 12 h could effectively enhance the colonization of C. pinensis, an endophytic bacterium, but not the rhizosphere colonizing C. rhizosphaerae. In the field only a small amount of inoculant was detected in the rhizosphere. This comparison demonstrates the importance of using the appropriate inoculation method for testing different types of bacteria for their plant growth-promotion potential.

Bioprospecting for Isoetes cangae Endophytes with Potential to Promote Plant Growth

“…Thus, in the present study, techniques were applied to identify bacterial isolates with an important role in the construction of an inoculant consortium to be implemented in the I. cangae preservation, according to Chai et al [ 87 ] and Olanrewaju and Babalola [ 88 ]. In addition, the activities presented by the bacterial isolates deserve to be investigated from the perspective of biotechnology resources.…”

Impact of inoculation practices on microbiota assembly and community stability in a fabricated ecosystem

“…This points out the importance of implementing different inoculation methods into experimental designs and to the need of comparing multiple inoculation methods when studying plant-microbe interactions. A recent study on sorghum (Sorghum bicolor) also showed that inoculation practices impacted the total abundance of different bacterial species at an earlier harvesting point, but not at a later harvesting point (Chai et al 2022).…”

Phytomicrobiomes: A Potential Approach for Sustainable Pesticide Biodegradation

“…Seed coating, seed priming, root colonization, foliar application, and soil drenching are the popular methods of microbial inoculation. Chai et al (2022) observed that prolonged seed coating could efficiently boost the colonization of the endophytic bacterium C. pinensis in cereal crops [93]. On the contrary, Inoculation of Ochrobactrum spp.…”