CARACTERÍSTICAS ESTRUTURAIS E MORFOGÊNESE DE AZEVÉM ANUAL EM RESPOSTA AO NITROGÊNIO

Abstract

The leaf morfogenesis of the Italian ryegrass, in other words, its leaf appearance dynamics, elongation and senescence and, the adjustment of a nitrogen dilution model, were evaluated under five levels of nitrogen (O, 75, 150, 225 and 300 kg N.ha-1), during May to October of 1998. To evaluate morfogenetic parameters, twenty marked tillers were used by experimental unit, in a completely randomized design with three replicates. For the adjustment of the dilution model, cuts were done weekly nearby portions to the soil. Nitrogen promoted more pronounced increases in leaf appearance and elongation rates during the establishment period, which resulted in the reduction of the phyllochron. The leaf senescence rate was affected mainly by the reduction in the readiness of nitrogen. The leaf area index was the variable that best characterized the effects of the applied nitrogen. The tratament 225 kg N.ha-1 didnt limit the development of the italian ryegrass. Considering there were no hydric and nutritional limitations, then the applied nitrogen conditioned the aerial development and the forage accumulation of the italian ryegrass.