The vascular system of the spikelet in wheat (Triticum aestivum)

Abstract

The lower three florets in a spikelet of wheat cv. Aotea were found to be supplied by the principal vascular bundles of the rachilla, while the system of more distal florets consisted of subvascular elements derived from the vascular cylinder formed at the disc of insertion of these florets. This pattern appeared to be the same in all spikelets irrespective of position, apart from the terminal one, nor was it altered by raising the supply of nitrogen. The apparent constancy of the vascular system is contrasted with considerable variability in the number of grain-bearing florets depending on genotype and environment. If a floret is connected directly with the main vascular system and if assimilates are not limiting, then competition for assimilates does not appear to be the main factor preventing grain formation.