Usefulness of quantitative morphological and phenological characteristics of maize (Zea mays L.) in preparating national guidelines of tests for distinctness, uniformity and stability (DUS)

Selecting quantitative characteristics, division of their expression ranges and selecting the check varieties are key issues on preparation of DUS test guidelines,so that based on these characteristics can evaluate three conditionsof a new variety; distinctness, uniformity and stability (DUS). To prepare national DUS test guidelines in maize (Zea mays L.), a randomized complete block design was conducted with three replications and 28 varieties and lines at Seed and Plant Certification and Registration Institute(SPCRI), Karaj, Iran,during 2014 and 2015. First, a total of 49 qualitative and quantitative morphological and phenological characteristics proposed by international union for the protection of new varieties of plants (UPOV), community plant variety office (CPVO), India (PPV&FRA) and Philippines (PVPO),were selected and evaluated.Then,ten quantitative characteristics based on within-variety uniformity by usingcoefficient of variation, correlation among characteristics, heritability,stability in two years and principal component analysis, were selected for the national DUS test guidelines. The expression ranges of these ten selected quantitative characteristics were divided into different situationsusing the descriptive statistics and frequency distribution of the varieties. The plant height with two peaks in the frequency distribution chart of the varieties was categorized as grouping characteristic, whileothernine selected quantitative characteristics had only one peak andwere selected as standard characteristics. Finally, KSC704 hybrid and two maternal lines Fajr and Mobin were determined as the check varieties for plant heightusing boxplot. It is also proposed to use this method as an efficient method for preparingDUS guidelines for other plant genera.