Determinants of grain number responding to environmental and genetic factors in two- and six-rowed barley types

•We quantified grain number components depending on source of variation in barley.•Spike number (SN) explaining grain number regardless of the source of variation.•Spike dry weight (SDWF) was the most relevant component for environment factor.•Fruiting efficiency was more relevant for genotypic factor.•Grain number was more related to SDWF in two-rowed, while FE in six-rowed type.