YIELD AND PRIMARY CULM YIELD COMPONENTS OF TWO SPRING BARLEY CULTIVARS AS INFLUENCED BY TEMPERATURE, DAYLENGTH AND GROWTH STAGE

Abstract

Olli, a photoperiod-insensitive and Vantage, a photoperiod-sensitive cultivar of spring barley (Hordeum vulgare L.) were raised in growth chambers at 13 and 24 °C under all combinations of 8-, 16- and 24-hr daylengths during the following three growth stages: seeding to internode elongation (stage I), internode elongation to heading (stage II), and heading to maturity (stage III). Days to maturity at 24 °C were about 60% and yields around 15% of those at 13 °C. Longer daylengths always reduced time to maturity, but decreased final yield only when applied during stage I. Earliest maturity occurred at 24 °C with continuous light, while highest yield resulted at 13 °C following an 8-hr daylength during stage I and 24-hr daylengths during stages II and III. Three primary culm yield components, fertile primary heads per plant, seeds per head, and seed size, were examined at 13 °C. Shortening the daylength caused: (1) during stage I, an increase in all three components, especially seeds per head; (2) during stage II, a decrease of all three components and greatly reduced percent fertile florets (8 hr produced none); and (3) during stage III, only a seed size decrease. The component most closely associated with yield was seeds per head. Applications of these results for the efficient reproduction of material in cereal breeding programs are suggested.