Evaluating the effect of light exposure and seed coat on lentil cotyledon color by computer vision

Abstract A computer vision system and color analysis algorithms were employed to study the influence of UVA (ultraviolet‐A) and visible light on the color of lentils with red, green, and yellow cotyledons. Twenty samples of cotyledons from each of the three‐color classes were subjected to six light treatments (ultraviolet, full‐spectrum visible, red, green, blue, and dark control) for 7 days at room temperature. The International Commission on Illumination L*a*b* (CIE L*a*b*) color values of the individual seeds were obtained before and after each treatment using the computer vision and image analysis system. Results of the analysis showed that light exposure had a statistically significant effect on all three cotyledon color classes. The effect size was largest for green lentils, smaller in yellow, and least in red lentils. By having established that light exposure affects the color of lentil cotyledons, it was hypothesized that seed coats may protect cotyledons against the effects of light exposure and that the degree of protection would vary with seed coat color classification. This hypothesis was tested using green‐cotyledon lentil varieties with different seed coat classes. Results confirmed that light‐induced color loss in the cotyledons was significantly influenced by seed‐coat color class. The order of protective effect of lentil seed coat from least to highest was found to be as follows: gray‐zero tannin, green, normal gray, and black. Thus, breeding for seed coat protection may improve the overall quality of green lentils. The results from this study will be informative to breeding programs that focus on enhancing the cotyledon color of lentils, and in making decisions regarding the dehulling of lentils and the design of dehulled lentil materials handling.