Evaluation of heterogeneity and hidden defects of wheat (Triticum aestivum L.) seeds by instrumental physical methods

For quality control of seed material, there are a number of standard tests adopted by ISTA (International Seed Testing Association, Switzerland) as well as promising instrumental methods evaluating the characteristics of seed surface, structural integrity and integral electrophysical parameters. The aim of the study was to evaluate the efficiency of instrumental physical methods in detection of latent defects of ecologically heterogeneous wheat seeds of various genetic origin. Diversity and latent defectiveness of wheat seeds ( Triticum aestivum L.) were evaluated using optical imaging, microfocus radiography, and electrophotography. It was found that the optical imaging method combined with automatic analysis of digital scanned images is statistically reliable to distinguish wheat seeds of different varieties and genetic lines by color characteristics of the RGB (red, green, blue) model, e.g., Hue and Saturation. Differences were also found between the seeds of the same variety and genetic line grown under field and regulated conditions. E.g., the Hue values varied from 0.081±0.0005 to 0.090±0.0006 for regulated conditions (the phytopolygon of the Agrophysical Research Institute) and from 0.084±0.0005 to 0.088±0.0005 for field conditions, the Saturation values - from 0.326±0.0005 to 0.419±0.0006 and from 0.371±0.0005 to 0.444±0.0005, respectively. With an increase in the number of cracks in the X-ray projections of wheat grains, their sowing qualities decrease. Microfocus radiography combined with automatic analysis of digital X-ray images successfully detects the damage to wheat seeds by the corn bug, and with the increase of the damage score the sowing quality of seeds in general decreases. Parameters of the digital X-ray images of seeds (Average Intensity, Shape Coefficient, and Entropy) differed between wheat varieties. The Average Intensity varied from 53.30±1.00 to 60.60±1.17, the Form coefficient from 6.67±0.35 to 8.28±0.48, and Entropy from 1.84±0.06 to 1.98±0.03. The research data indicate the effectiveness of the approaches we propose based on instrumental physical methods in the assessment of different quality and latent defectiveness of wheat seeds. Our findings make a background for the functional non-invasive diagnosis of seed quality based on the complex evaluation of external and internal anomalies and defects, significantly affecting both the biological quality of seeds and their economic suitability. This is a methodologically new tool to be used in breeding and controlled seed production.