Variáveis fisiológicas, valor nutricional e cinética de degradação ruminal da aveia branca (Avena sativa L.) sob diferentes níveis de adubação nitrogenada.

Abstract

We determined the physiological variables (experiment 1) of three oat genotypes (Avena sativa L) and the nutritional value and the gas production kinetics of cultivar IPR 126 (experiment 2), fertilized at levels of 0, 180, 360 and 720 kg N/ha. In experiment 1 we evaluated the assimilation and the rate of intracellular CO2 concentration, photosynthesis, chlorophyll content, leaf/stem ratio, number of tillers/plant, number of leaves/tiller, leaf area, and the production of biomass of the three genotypes. The experimental design was a factorial 3 x 4 (species and nitrogen dose), with three repetitions, performing variance analysis and comparison of means by Duncan test at 5% significance level. There was no statistical difference between the three cultivars for any variable, but cutting time showed statistical significance, and the best conditions were obtained in the second cut. In experiment 2 were determined the chemical composition of cultivar IPR 126 and the estimation parameters of the two-compartment logistic model for gas production kinetics (Vf1, Vf2, K1, K2 and λ). The experimental design was randomized blocks, and the Corrected Akaike Information Criterion (AICC) was used for choosing the best matrix of variance and covariance. The level of fertilization caused a linear increase in the CP content and linear reduction in TC content. The parameter λ varied in a quadratic pattern according to the level of fertilization. The other nutrient contents and kinetic parameters did not show significant variance in the treatments. The asymptotic phase of protein concentration was not reached, even using high doses of nitrogen.