Nonlinear modeling proposal for the germination performance of Paspalum regnellii seeds: a species with forage potential in Brazil

Finding qualified standard plants is an essential requirement in the search for high-quality pasture, fact that involves knowledge about the performance of the assessed seeds. Therefore, the aim of the present study was to evaluate the influence of seed weight on the germination behavior of Paspalum regnellii seeds through the logistic growth model. The adopted values were taken from an experiment conducted in 2016 under laboratory conditions. A pneumatic separator was used to select four seed classes, depending on the weight of one thousand seeds namely: Extra light, light, middle and weighted. The logistic model was adjusted to data about the germination rate of each class, and the parameters were compared through the F test. Germination rates between classes were compared based on recorded parameters and on model critical points. The logistic model adjusted well to the values and made it possible to use the parameters and critical points of the curve to describe the germination process. In addition to have low germination rate, seeds in the light-weight batch demanded longer to complete this process. Based on estimates about the parameters and the critical points of the model, the weighted-weight seeds were superior in terms of quality than seeds in the other batches, since they recorded higher germination rate in a shorter period-of-time.