The Use of Thermal Time to Describe and Predict the Growth and Nutritive Value of Lolium perenne L. and Bromus valdivianus Phil

The thermal time, expressed in accumulated growing degree-days (AGDD), was used as a predictor to describe and simulate the independent growth of two pasture crops, Lolium perenne L. Bromus valdivianus Phil. Two sinusoidal models (four-parameter Logistic Gompertz) were applied variables (total leaf blade length per tiller—LBL, herbage mass—AHM). nutritive value pastures predicted modeled using regression equations (linear quadratic), depending on each nutrient. Data for modeling collected from two-year study, which LBL, AHM, B. measured at three-day intervals. Defoliation determined according AGDD, such that swards defoliated 90, 180, 270, 360, 450 AGDD. Gompertz presented similar values rate (GR) parameters, superior asymptote (Asup), inferior (Ainf), point maximum (Pmax). In both species, 260 GR species different seasons year, but AHM varied, with presenting higher (+1500 kg DM ha−1) than during spring. regressions accurately described value, demonstrating positive linear relationship between AGDD concentrations neutral acid detergent fiber (NDF, ADF), an inverse crude protein (CP), quadratic metabolizable energy (ME) water-soluble carbohydrate (WSC) concentration.