Phytohormone Levels in the Florets of a Single Wheat Spikelet during Pre-Anthesis Development and Relationships to Grain Set

Abstract

Lee, B. T., Martin, P. and Bangerth, F. 1988. Phytohormone levels in the florets of a single wheat spikelet during pre-anthesis development and relationships to grain set.—J. exp. Bot. 39: 927–933. The gradient in grain number found within a single spikelet of wheat (higher grain numbers in proximal positions than in distal positions) was investigated with respect to endogenous levels of hormones in anthers and carpels. Auxins, abscisic acid and cytokinins were measured using radioimmunoassay. Measurements were made on both whole ears and floral organs (anthers and carpels) of a single spikelet during pre-anthesis development. Similar hormonal trends in whole ears compared to those of anthers and carpels were only found for anther abscisic acid and indole acetic acid levels and carpel zeatin/zeatin riboside levels. In the distal floret positions of the spikelet where fewer or no grains were set, anther abscisic acid levels were higher than in those of the proximal positions.