Genotypic Variability in Response of Oat to Delayed Sowing1

Abstract

AbstractA classification of oat (Avena sativa L.) genotypes for reaction to delayed sowing could be used for developing cultivars that either escape the effects of or tolerate high temperatures. The effects of delayed sowing on duration of growth of nine genotypes of oat were studied in field experiments grown on a Coland loam (Cumulic Haplaquoll) soil at the Hinds Experiment Farm near Ames, IA. Sowing dates were 18 March, 2 April, 17 April, and 30 April in 1981; and 14 April, 28 April and 11 May in 1982. Number of growing degree days (GDD) and number of days to reach emergence, tiller initiation, fourth‐, fifth‐, and flag‐leaf stages, heading, and 80% panicle ripe were recorded. Plant height, biological and grain yields, and test weight were measured, and straw yield was calculated. Days and GDD required to reach each developmental stage varied significantly among genotypes. Genotypic differences occurred for plant height, biological and grain yields, harvest index, and test weight, but the differences were not associated with maturity differences. Significant variation occurred across sowing dates for plant height, grain yield, and test weight for most genotypes. Number of GDD required to reach any developmental stage across sowing dates generally was less variable than was number of days for all genotypes, indicating that GDD is a better predictor of oat cultivar development than is number of days. Thus, GDD for oat would be used much as corn heat units (CHU) are used in maize (Zea mays L.).