Limitations with X-Ray CT include the complicated equipment required for the survey and the extensive job of distinguishing roots against soils. Consequently, the images obtained were not exceptionally clear but did give a broad depiction of the area covered. For example, small roots were not distinguishable from the soil matrix . Similarly, shovelomics will generate a general structure of the root area, but the results lack detailed information on individual root parts . Mathematical models employing fractural geometry create a reasonable estimate of root architecture measurements and aid in viewing root systems . Measurements from 2-dimensional, planar models or images obtained from soil cores may serve as a base for 3D model construction. Although mathematical models can provide insight into root formation patterns, a failure results in accounting for natural recourses that significantly affect a plant’s root structure .
Field observations of root systems are time-consuming and tedious but do garner useful general information . There is a vital need for an accurate visual root architecture method. Three-dimensional imaging software combined with MRI scanning techniques advances the prospect of using rice as an experimental subject for studying root structure . The complete unique development of RSA can be obtained through 3D imaging techniques; additionally,vertical grow system this digital phenotypic data can be analyzed repeatedly for various traits The limitations with these methods include the equipment needed, finding compatible soil media for these methods, and image processing time and software ability to distinguish soil from the root Efforts to create bioassays for herbicide dose responses or observe root growth patterns gave way to germination pouches. This method is rapid, cost-efficient, reproducible, accurate, non-invasive, and easily controlled . Germination pouches allow visualization of seedling growth patterns and have been utilized for various crops and purposes . These transparent bags make it possible to promptly and practically observe and image roots at any growth stage. Screening in a lab setting allows for a uniform and controlled environment as well as sterile conditions.
Images obtained can be analyzed and screened through publicly available user-friendly software programs. Adeleke et al. made germination pouches at an even lower cost than those purchased for this study and were able to successfully germinate seedlings and obtain photographs at the end of the study in less than five minutes per plant, producing fast and effective results . This phenotyping strategy can increase non-invasive screenings by saving time and space in the seedling stage of development, leading to exploring traits in the accessions screened . This study aimed to characterize root morphological traits of allelopathic and non-allelopathic weedy rice and identify root traits related to allelopathyFrom Shrestha et al. , seeds of the five most barnyard grass-suppressive and four least barnyard grass-suppressive weedy rice accession were selected. Cultivated rice lines Rex, Rondo, PI312777, CL163, and PI388046 were also included in this study for comparison. All seeds were surface-sterilized by soaking in 70% ethanol for 30 seconds and 5% bleach for 20 minutes and rinsed six times with distilled water. Sterilized seeds were germinated in plastic 9-cm Petri dishes lined with What man No. 1 filter paper and soaked with 5 ml distilled water.After germination, four seedlings of equal height were selected for each accession and placed using forceps into germination pouches .
Pouches holding the seedlings were placed in the growth chamber in the Weed Physiology Laboratory at Mississippi State University, set at 30˚C/21˚C day/night for 28 days after germination . Plants were watered with 20 ml half-strength Hoagland’s No. 2 basal salts every two days to keep the roots damp until 28 DAG. At 28 DAG, the bags were cut open, and the roots were removed and placed directly onto an Epson Perfection V370 Photo scanner . Black paper was placed over the root to contrast the image. Four images were obtained for each accession serving as individual replications. Root images were measured using Image J® software . Each image was cropped to encompass the area each root covered and converted into an 8-bit grayscale format. The length of each root was recorded in cm, and to obtain the total area covered by each root, the images were first converted to a binary format to remove the background and create a contrast. Weedy rice was characterized as allelopathic or non-allelopathic based on data from a screening performed in a prior study .