LAUSR

Abstract Genetic gains in wheat yield are required to meet future demand. In order to design strategic crosses, it is essential to quantify the genetic variation among elite cultivars on traits responsible for the adaptation and the generation of yield components. We explored the degree of variation within well-adapted commercial cultivars on developmental phases (vegetative, early reproductive and late reproductive), final leaf number and phyllochron, leaf and spikelet plastochron, number of spikelets, florets, and dynamics of floret primordia development. Variation in flowering time among cultivars was minor but they differed in the partitioning of that time into particular phases. Main differences were found for the length of the late reproductive phase, partly linked to those in final leaf number. Variations on number of fertile florets at anthesis were mostly explained by floret survival, due to differential ability of labile florets to maintain normal development between cultivars. These differences were related to the duration of the floret development, but not to the synchrony of development among florets. These findings provide useful information for breeders when selecting genotypes for strategic crosses, as considering floret survival through duration of floret development in one of the parents (for which these processes shall be characterised in the elite germplasm) might increase the likelihood of transgressive segregation towards high-yielding offspring.