Floret initiation and development in spring wheat (Triticum aestivum L.)

The number and developmental stages of florets were determined in each spikelet of the spike in the main shoots of spring wheat. Samples were taken frequently from plants grown in a phytotron and in a nitrogen application field-test. Ten stages of development, from floret initiation until anthesis, were recognized and described.Inter-spikelet variation in the total number of initiated florets was rather small. However, the number of florets at advanced stages of development, as well as the number of grains, was highest in the central spikelets in which florets initiated first. Floret initiation did not proceed beyond spike emergence, whereafter the distal florets and the spikelet apex degenerated. Grain-set was restricted to florets which had developed at least to the stage of visible anther lobes at spike emergence. The number of these florets was increased significantly by nitrogen application.