Fine Phenotyping of Pod and Seed Traits in Arachis Germplasm Accessions Using Digital Image Analysis

Abstract

Reliable and objective phenotyping of peanut pod and seed traits is important for cultivar selection and genetic mapping of grade components. To develop useful and efficient methods to quantitatively define peanut pod and seed traits, a group of peanut germplasm with high levels of phenotypic variation was included in this study. Digital image analysis was employed to quantify peanut pod volume using projected 2-dimensional pod area as an effective surrogate parameter. Strong correlation between pod volume measured by water displacement and image analysis was established (R2 = 0.891). Pod volume, pod density and kernel percent were observed to vary significantly among the germplasm lines. To define testa color, hue angle analysis was performed on a subset of germplasm with solid testa color. It was determined that hue angle can sufficiently differentiate genotypic differences based on testa color variation.