Rapid Bioassay for Inhibitory Rhizobacteria Using Digital Image Analysis

Abstract

Current methods for assaying the potential effects of rhizobacteria on plant growth are tedious and time consuming. A rapid, automated bioassay has been developed using a flatbed scanner and digital image analysis. Comparisons were made between manual measurements of root length and computed values based on an edge discrimination image analysis procedure. The assay consisted of bacterial cultures of filtrates added to 18 mL of 0.9% agar in square petri plates. Seeds were planted along a marked axis and incubated for 4 d at 15°C, and then the roots were measured. Total root length measurements for the two methods, manual and image analysis, were well correlated (r2 = 0.94), and both were equally able to identify bacteria inhibitory to plant growth. Root measurements by the scan method were five times faster than the manual method. Each sample required 53 s to read with the scan method vs. 250 s with the manual method. The scan method provides a quick and accurate method for screening inhibitory activity of rhizobacteria based on seedling root length and has potential in the screening of toxic substances of other origin.

Monitoring of root growth and redox conditions in paddy soil rhizotrons by redox electrodes and image analysis

“…Recently, the application of flat bed scanners attached to glass walls or external rhizotrons was proven as a highquality method taking images with high resolution from rhizotrons (Pan et al 1998;Kuchenbuch and Ingram 2002). Constantly improved image analysis software allow extensive automatic evaluation of these images such as root length (Doty et al 1994;Vamerali et al 1999;Devienne-Barret et al 2006;Pietola and Smucker 2006), soil porosity (Dathe et al 2001;Bruneau et al 2004) or soil moisture (Kuchenbuch and Ingram 2002).…”

Microbial Weed Control and Microbial Herbicides

“…A quick substitute bioassay will reduce the length of time needed for the initial screenings. In many cases, a quick screen is not possible (Kennedy et al, 1991), but automating data recording can often make data collection easier (Doty et al, 1994). Fig.…”

Monitoring Russian Thistle (Salsola iberica) Root Growth Using a Scanner-Based, Portable Mesorhizotron1

“…However, these instruments are useful to measure root turnover (Cheng et al 1991). Computer-linked color line scanners, originally designed for desktop publishing purposes, offer affordable (Ͻ $5,000) and superior imaging capability for generating digitized plant root images (Doty et al 1995;Pan and Bolton 1991). A low cost, portable mesorhizotron system has been developed for in-field imaging of potato (Solanum tuberosum L.) roots (Pan et al 1998).…”