GROWTH CURVE OF A TROPICAL MIXED-GRASS PASTURE IN A HOT AND HUMID CLIMATE

<p><strong>Background. </strong>Pasture growth rate (PGR, kg/ha/day) depends on climatic and management practices. However, studies the influence of environment pasture production productivity dry matter are scarce in tropical, hot, humid regions México. <strong>Objective.</strong> To estimate curve using time variables. <strong>Methodology.</strong> We related, through nonlinear models, accumulated a composed native grasses mixed with exotic grasses, variables temperature day length as independent variables, latter integrated into single variable called thermal photo units (PTU). estimated daily rates five divisions; from these, forage yields for ten days until completing 29 periods. The best-fit models had largest coefficients determination lowest Akaike’s information criterion. <strong>Results.</strong> model that best described relationship between cumulative yield (Y) growing (X) was reciprocal-quadratic: y = x/(0.097535 – 0.0000881x + 0.0000006810x<sup>2</sup>) R<sup>2</sup><sub>Adj,</sub> 0.9988 an AIC<sub>C</sub> 222.6. performance PTU rational: (- 317.8 1.594x 0.00001307x<sup>2</sup>)/(1 0.001059x 0.00000001964x<sup>2</sup>), R<sup>2</sup><sub>Adjt</sub>.=0.9985 AIC<sub>C</sub>=233.4. Likewise, two-segment showed close fit. logarithmic first segment: y<sub>1</sub> -2268 417.2*(ln(x)), when y<sub>2</sub> =1079.3e<sup>0.00003932X</sup>, if x > 8415; R<sup>2</sup><sub>Adj.</sub> 0.9975 AICc 245.1. value 8415 derivative both coincided. <strong>Implications.</strong> generated is useful because it allows grazing system adjustment concerning correct stocking application designing more efficient rotations. <strong>Conclusions. </strong>The conversion to ten-day periods produced smooth allowed fitting high-precision predict accumulation variables.</p>