Image‐based phenotyping and genetic analysis of potato skin set and color
Maria V. Caraza‐Harter, Jeffrey B. Endelman
Abstract
Abstract Image‐based phenotyping offers new opportunities for fast, objective, and reliable measurement for breeding and genetics research. In the current study, image analysis was used to quantify potato ( Solanum tuberosum L.) skin color and skin set, which are critical for the marketability of new varieties. A set of 15 red potato varieties and advanced breeding lines was evaluated over 2 yr at a single location, with two harvest times in the second year. After mechanical harvest and grading, seven to eight representative tubers per plot were photographed, and the photos were analyzed with ImageJ to measure skinning (as percentage surface area) and skin color using the hue, chroma, and lightness (HCL) representation. The plot‐based heritability was consistently high (> .77) across traits and environments; the genetic correlation between environments was also high, ranging from .81–.98. Significant increases in lightness and chroma, as well as a decrease in skinning, were observed at the late compared with early harvest, whereas the opposite trends for color were observed after 6 wk of storage. The three color traits were unexpectedly collinear in this study, with the first principal component explaining 86% of the variation. This result may reflect the physiology of red color in potato, but the highly selected nature of the 15 genotypes may also be a factor. Image‐based phenotyping offers new opportunities to advance genetic gain and understanding for tuber appearance traits that have been difficult to precisely measure in the past.