Old and modern durum wheat varieties from Italy and Spain differ in main spike components

Four field experiments comparing 24 durum wheat varieties grown at different periods during the 20th century in Italy and Spain were carried out to assess the changes caused by breeding activities on the number of grains per main spike and its determinants: number of spikelets per spike, number of grains per spikelet, fertile flowering and grain setting. Increases of 0.14 grains spike−1 year−1 (0.43% year−1 in relative terms) and 0.08 grains...