A hydrothermal seedling emergence model for Conyza bonariensis

Abstract

Summary Conyza bonariensis is a South American native annual Asteraceae that has been introduced to the Mediterranean, where it behaves as a ruderal plant and a weed that is difficult to control in several crops. The development of predictive models can contribute to control measures at early growth stages, but currently there are no studies to predict seedling emergence of Conyza species. Our objectives were to develop and evaluate a model for predicting emergence response of C. bonariensis to the soil hydrothermal environment. A hydrothermal seed germination model was fitted to time course germination data from germination tests carried out at different constant temperatures and water potentials with the aim of establishing the hydrothermal parameters characterising C. bonariensis seed germination. The relationship between cumulative seedling emergence and cumulative hydrothermal time under field conditions was analysed using the Gompertz function. Model development was based on 2 years' data from a field experiment. Base temperature and base water potential for seed germination were estimated at 10.6°C and −0.70 ± 0.151 MPa, 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. For model evaluation, independent field experiments were carried out in two localities. Cumulative seedling emergence was accurately predicted by the model. Results indicate that this model can be useful as a predictive tool contributing to effective control of C. bonariensis populations.

A comparative study between nonlinear regression and nonparametric approaches for modelling Phalaris paradoxa seedling emergence

“…PNR models have been fitted for a range of species, for example Galium spp. (Royo‐Esnal et al ., ), Bromus diandrus Roth (Garcia et al ., ) and Conyza bonariensis (L.) Cronquist (Zambrano‐Navea et al ., ).…”

Base temperatures for germination of selected weed species in Iran

“…These models are often based on the hydrothermal time concept (Bradford 2002) and require the estimation of biological parameters, base temperature, and base water potential for germination (t b and Y b hereinafter), to simulate seedling emergence according to weather trends. Adopting inaccurate values of t b and Y b could notably influence the precision of model prediction, so several procedures have been proposed to estimate these parameters, such as linear or nonlinear regression with resampling methods (Masin et al 2010;Onofri et al 2014), population-based threshold models (Dorado et al 2009b), probit analysis (Zambrano-Navea et al 2013) or survival analysis (Onofri et al 2010).…”

“…(1) logistic model of germination time course plus linear regression of germination rate against incubation temperature with resampling bootstrap methods (Masin et al 2010), (2) probit analysis Zambrano-Navea et al 2013) were adopted independently, starting with the same germination data, to calculate t b of all studied species in order to assess potential differences between the results obtained by the two procedures.…”

Vicia villosa ssp. villosa Roth field emergence model in a semiarid agroecosystem

“…Following, each “non‐dormant” fraction of the seedbank accumulates a certain amount of hydrothermal time to achieve germination and pre‐emergence growth in order to finally emergence. Thus, cumulative emergence ( E T, ψ ) was represented as where is the cumulative percentage of germination of the seed population at a given dormancy level (i.e., PY + PD status) after incubation for a given time ( t ) and temperature ( T ) (Equation ); indicates whether soil water potential allows for hydrothermal‐time accumulation ( = 1) for seed germination or not ( = 0) according to the dormancy status of the seed population (adapted from Zambrano‐Navea, Bastida, & Gonzalez‐Andujar, ). RE ( T ,ψ) is the hypocotyl elongation rate according to the soil temperature and moisture content.…”