Variability of Seedling Growth Characteristics among Oat Genotypes1

Abstract

The objectives of this investigation were to (i) estimate the range of variability present for the oat (Avena sativa L.) seedling characteristics, including shoot length and weight and root length, weight, and volume; and (ii) to determine how these characters vary among groups of cultivars representing different breeding eras.Fifty‐two cultivars were chosen to represent a wide range of genetic backgrounds and breeding eras. The cultivars were classified as belonging to one, or more, of the following categories: I—spring‐sown, II—fall‐sown, III—sources of crown rust resistance, IV—earliest introductions, V—early selections, VI—early hybrid selections, VII—intermediate hybrid selections, VIII—modern hybrid selections, IX—sources of straw strength, X—diploid, XI—dwarfs, and XII—very tall. Comparisons were made between cultivar categories.Ranges in cultivar means expressed as a percentage of the grand mean for the five characters were: shoot length, 101.9 % ; root length, 81.5%; root volume, 81.8%; shoot weight, 113.3%; and root weight, 75.0%. Simple correlations were relatively high among all characters, ranging from 0.48 for shoot length and root volume to 0.84 for root volume and root weight (determined over all 52 cultivar means).The spring‐sown genotypes gave consistently higher values for the five growth characters than did the fall‐sown genotypes. Lines that are sources of crown rust resistance were genetically inferior in their seedling growth responses. The effects of selection pressure (for other characters) during the time progression from the earliest introductions to the modern hybrid selections were pronounced. The most obvious trend was toward greater root development in the modern selections. Shoot lengths were slightly reduced over the time span.