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Digital imaging to investigate root architectural changes associated with a root rot disease

Chakradhar Mattupalli: Noble Research Institute, LLC

<div><em>Phymatotrichopsis omnivora</em> is the causal agent of Phymatotrichopsis Root Rot (PRR) disease that severely limits alfalfa production in southern Oklahoma. The disease manifests as circular to irregular shaped areas in the field categorized into three zones based upon plant status: asymptomatic, disease front and survivor. To study root architectural changes associated with PRR, a four-year old 23.8 hectare alfalfa stand infested with PRR was selected at the Red River Farm, Burneyville, OK during October 2017. Line transect sampling was conducted from four actively growing PRR disease rings. At each disease ring, six line transects were positioned spanning ~15 m on either side of the disease front with one alfalfa root sampled at every ~3 m interval. Each root was imaged using the RhizoVision-Crown platform using a backlight and a high-resolution monochrome CMOS camera. The platform’s image analysis software automatically segmented images, skeletonized, and extracted a suite of features. Total root length ranged from 211.7±133.2 cm for survivors to 170.6±104.2 cm for roots sampled from the asymptomatic zone. Survivor plants compensated for damage or loss to the taproot through the development of more lateral and crown roots. The mean time to extract 24 root morphological features from an alfalfa root image was 8.4±6.0 s. This study demonstrates the benefits of a low-cost, efficient and high-throughput digital imaging approach to study root architectural changes.</div>