Evaluation of the USDA Core Safflower Collection for Seven Quantitative Traits

R.C. Johnson, P.B. Ghorpade, and V.L. Bradley

Abstract

The United States Department of Agriculture maintains a safflower (Carthamus tinctorius L.) germplasm collection of more than 2,300 accessions from which a core collection of 207 accessions was developed.  To enhance characterization and determine diversity, the core collection was evaluated for numerous crop descriptors at the Western Regional Plant Introduction Station in Pullman, Washington USA.   This paper reports evaluation results for seven quantitative factors: outer involucral bract (OIB) width, OIB length, primary head diameter, date of 50% flowering, plant height, weight per seed, and yield per plant.  Accessions were highly variable for all factors measured indicating considerable diversity within the core collection.  Correlation analysis showed the strongest associations were between plant height and flowering (r = 0.62), and between OIB width and OIB length (r = 0.54) (P<0.05).  To test regional differences, accessions in the core collection were partitioned into ten major regions (the Americas, Australia, China, E. Africa, Europe, Japan, the Mediterranean, S. Central Asia, and S. West Asia, and Thailand).  Significant differences were found among regions for all factors except OIB length and yield per plant.  Canonical discriminant functions showed that the first and second functions explained 83% of the total variation.  Among the regions, accessions from SW Asia were the most distant from other regions, but S. Central Asia and E. Africa grouped closely together.  The results showed that the core collection was a highly diverse germplasm source, and that agronomic attributes could often distinguish regional differences.

Key words:  quantitative traits, international testing