Vernalisation and photoperiod sensitivity in wheat: the response of floret fertility and grain number is affected by vernalisation status

•Reproductive development of wheat near isogenic lines combining VRN1 and PPD-D1 studied.•More fertile florets with longer stem elongation and higher anthesis spike biomass if plants vernalised.•Vernalised plants had more grains in main shoot and tiller spikes than non-vernalised plants.•Non vernalised winter lines had slow growing apex, shorter spikes, high spikelet density and less grains per spike.•Regulation of grain set and synchrony as influenced by VRN1 and PPD-D1 deserve further study.