title: Floret development and grain setting differences between modern durum wheats under contrasting nitrogen availability.
abstract: Wheat yield depends on the number of grains per square metre, which in turn is related to the number of fertile  florets at anthesis. The dynamics of floret generation/degeneration were studied in contrasting conditions of nitrogen (N) and water availability of modern, well-adapted, durum wheats in order to understand further the bases for grain number determination. Experiments were carried out during the 2008-2009 and 2009-2010 growing seasons at Lleida (NE Spain). The first experiment involved four cultivars (Claudio, Donduro, Simeto, and Vitron) and two contrasting N availabilities (50 kgN ha(-1) and 250 kgN ha(-1); N50 and N250) while experiment 2 included the two cultivars most contrasting in grain setting responsiveness to N in experiment 1, and two levels of N (N50 and N250), under irrigated (IR) and rainfed (RF) conditions. In addition, a detillering treatment was imposed on both cultivars under the IR+N250 condition. The number of fertile florets at anthesis was increased by ~30% in response to N fertilization (averaging across treatments and spikelet positions). The effect of N and water availability was evident on floret developmental rates from the third floret primordium onwards, as these florets in the central spikelets of all genotypes reached the stage of a fertile floret in N250 while in N50 they did not. In this study, clear differences were found between the cultivars in their responsiveness to N by producing more fertile florets at anthesis (through accelerating developmental rates of floret primordia), by increasing the likelihood of particular grains to be set, or by both traits.
authors.affiliation: Department of Crop and Forest Sciences and AGROTECNIO (Centre for Research in Agrotechnology), University of Lleida, Av. Rovira Roure 191, 25198 Lleida, Spain. ariel.ferrante@pvcf.udl.cat
authors.forename: Ariel
authors.initials: A
authors.lastname: Ferrante
authors.forename: Roxana
authors.initials: R
authors.lastname: Savin
authors.forename: Gustavo A
authors.initials: GA
authors.lastname: Slafer
mesh_terms: D005298:Fertility / Q000187:drug effects; D035264:Flowers / Q000187:drug effects* / Q000254:growth & development*; D009584:Nitrogen / Q000494:pharmacology*; D018520:Plant Shoots / Q000033:anatomy & histology / Q000187:drug effects; D012639:Seeds / Q000187:drug effects* / Q000254:growth & development*; D013030:Spain; D014908:Triticum / Q000187:drug effects* / Q000254:growth & development*
chemical_list: D009584:Nitrogen