Nitrogen by radiation interaction on floret development and biomass partitioning during the acrtive spike growth phase in two and six rowed near isogenic barley lines.

ARISNABARRETA SEBASTIAN; MIRALLES D J

Rosario

Congreso; XIII Reunion Latinoamericana y XXVII Reunion Argentina de Fisiología Vegetal,; 2008

It is well known, in wheat and barley, the important role of assimilates allocated in the spikes on fertile floret survival and grain setting per unit area. Other evidences also suggested the role of nitrogen on floret fertility. However, only few reports analyze the interaction between nitrogen and radiation on grain number establishment. This work aims to understand the possible genotype by radiation by nitrogen interaction on (i) development of floret structures within the spike, and (ii) the dynamic of biomass and nitrogen partitioning between vegetative and reproductive structures during the active spike growth phase and its impact on the survival of floret primordia. The experiment was carried out under field conditions in the experimental field of the Department of Plant Production, University of Buenos Aires. The experiment consisted on a factorial combination of two nitrogen fertilizer rates, two radiation levels and two near isogenic barley lines which only differ in the lateral spikelet fertility gene (Vrs1). Floret development and biomass partitioning between vegetative and reproductive organs were measured. Results showed a significant genotype x nitrogen x shading interaction on the dynamic of floret initiation and mortality. When nitrogen was not a limiting factor, shading treatments strongly reduced floret survival, in relation to the low nitrogen treatment. Shading and nitrogen treatments altered floret development during the active spike growth phase. Floret development was affected by treatments in apical spikelet positions. Nitrogen altered floret development as early as the maximum number of spikelet primordia phase was achieved. It was observed an indirect effect of nitrogen on floret development due to a higher (i) RUE, (ii) radiation interception, and (iii) biomass partitioning to the spike during the spike growth phase.