Demografía y dinámica poblacional de Conyza bonariensis (l.) cronq

Laburpena

Conyza bonariensis (L.) Cronquist is an annual Asteraceae, a native of South America and widely spread over tropical and temperate-hot areas, including the Mediterranean basin. It mainly behaves like a ruderal plant, colonizing disturbed habitats like road borders, boundaries, and open ground. C. bonariensis has become one of those most difficult weed to control in agricultural systems, particularly in conservation ones. The knowledge of the weed ecology can contribute to a more rational control. A more detailed knowledge of their demography and population dynamics allow us the development of predictive models and the evaluation of long-term management strategies. Under these context, the aims of this work were: 1) to study the demography (emergence, survival and fecundity) of C. bonariensis 2) to develop and evaluate a model for predicting the emergence of C. bonariensis; 3) to develop a stochastic population dynamic model based on cohorts to simulate the long-term dynamics of the seed bank under different management scenarios. The seedling emergence rate was 61 %, and highly dependent on the rainfall. The mean survival rate of the plants was 33%. Fecundity reached a mean value of 86066 achenes plant-1. In general, the earliest cohorts presented higher survival and fecundity values, contributing more to the following generation and, consequently, they should preferably be controlled for an effective management of C. bonariensis. This species showed a regulation of its populations through a density-dependence process system at a fecundity level. A hydrothermal seed germination model was fitted to time course germination data from germination tests carried out at different constant temperatures and water potentials to establish the hydrothermal parameters characterizing C. bonariensis seed germination. The relationship between cumulative seedling emergence and cumulative hydrothermal time under field conditions was analyzed through the Gompertz function. Base temperature and base water potential for seed germination were estimated at 10.6 ºC and -0.70MPa, respectively. The emergence model showed a very good fit to the experimental data. According to this model, seedling emergence starts at 15 accumulated hydrothermal time (HTT) after sowing, and 50 and 95% emergence is completed at 53 HTT and 105 HTT, respectively. The model was validated with...