Approaches to improve the determination of eligibility for plant variety protection: II. Identification and evaluation of a core set of morphological characteristics.

We compared the discriminational abilities of two sets of morphological characteristics among 210 inbred lines of maize (Zea mays L). One set of 62 characteristics comprised those required by UPOV and individual PVP authorities. A second core set of 28 characteristics was selected based upon an iterative process where characteristics were examined for their contribution according to three categories (Variabiity, Power, and Genotype by Environment [GxE] interaction) partitioned among nine parameters. An iterative peeling process involving cycles of 1) multivariate analysis to reveal contributions of characteristics to providing discrimination and 2) removal of characteristics to reveal underlying contributions of remaining characteristics was used to select a core set of 28 characteristics. The core set provided slightly less discrimination among inbred lines that were closely similar but was able to discriminate among inbred lines with use of less resources by removing characteristics that were duplicative, had little power of discrimination, or were particularly affected by GxE interactions.