Modelos para estimativa da taxa de desidratação para produção de feno em híbridos de Urochloa

Abstract

Haymaking is a potential strategy that allows for year-round food availability. However, there is a lack of studies on predictive models to estimate the dehydration rate after cutting. This study aimed to evaluate different models for estimating the dehydration rate in four hybrids of Urochloa, as well as to determine which of these have the greatest potential for hay production.The experiment was conducted at the Agrostological Field - Faculty of Agricultural Sciences of the Federal University of Grande Dourados. Four hybrids of Urochloa were evaluated: Cayman (CV, IATTC BR02/1752), Camello (GP3025), Cobra (CV, CIAT BR02/1794), and Mestizo (CV, CIAT BR02/36087), distributed in a completely randomized design, in 32 beds, with 8 repetitions per treatment. The beds were cut when the canopy average was 0.4 m. Collection times were 0; 0.5; 1; 1.5; 2; 3; 4; 5; 6; 21; 25; 29; 45; 49; 53; 69; 73 and 77 hours after the cut when the plants were exposed to the sun. The data obtained were evaluated using the Gompertz, Logistic, and Bicompartimental Logistic models. For all four cultivars, the icompartimental logistic model had the best fit. The Gompertz model is not a good estimator of the dehydration rate for use in hays, as it generates negative parameters that cannot be biologically explained. The logistic and bicompartimental logistic models are good estimators of the dehydration rate. For the Cobra cultivar, the Bicompartimental Logistic model was not a good estimator, as it generated parameters without biological interpretation, making it necessary to seek other models that can better explain the behavior of water loss in this cultivar. Among the other cultivars, the Camello cultivar had the lowest dehydration rate in the rapid phase (0,085% of DM h-1), this fact shows that this genetic material has a greater resistance to water loss, while for the slow dehydration phase it had the highest value (0,0015% of DM h -1), showing that at this stage this cultivar has less resistance of the leaf cuticle. Given the above, it can be concluded that: the evaluated models are not the best predictors of the dehydration rate for hay production and among the cultivars the one that had a slower dehydration rate is the Camello hybrid.