Development and evaluation of a model for predicting Lolium rigidum emergence in winter cereal crops in the Mediterranean area

Abstract

Summary Lolium rigidum is an extremely competitive and prevalent grass weed in cereal fields of Mediterranean areas. The proper timing of control measures is a prerequisite to maximising herbicide efficacy, in terms of both improved control and reduced herbicide inputs. The development of models to predict emergence flushes will contribute to this goal. Pooled cumulative emergence data obtained during three seasons from a cereal field were used to develop a Gompertz model. This explained relative seedling emergence from crop sowing onwards as a function of: (i) standard soil thermal time accumulation (TT) with a base temperature of 1.8°C and (ii) soil thermal time accumulation corrected for soil moisture (cTT). For the latter, no thermal time accumulation was computed for days in which the soil water balance within the upper 10‐cm soil layer indicated no water available for plants, because evapotranspiration was greater than rainfall plus the stored water remaining from the previous day. The model was validated with six datasets from four different sites and seasons. Compared with TT, the model based on cTT showed better performance in predicting L. rigidum emergence, particularly in predicting the end of emergence. Complemented with in‐field observations to minimise deviations, the model may be used as a predictive tool to better control this weed in dryland cereal fields of Mediterranean climate areas.

Base temperatures for germination of selected weed species in Iran

“…This awareness induced increasing interest in the development of models that can simulate seedling emergence and the potential benefits, but also challenges, of their adoption were recognised and thoroughly reviewed (Forcella et al 2000;Grundy 2003). Several models have been created for seedling emergence of various weed species in the main crops such as maize (Dorado et al 2009a;Masin et al 2012), soybean Werle et al 2014) or winter cereals (Royo-Esnal et al 2010, 2015García et al 2013;Izquierdo et al 2013). 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.…”

Short communication: Evaluation of a model for predicting Avena fatua and Descurainia sophia seed emergence in winter rapeseed

“…From the farmer's point of view, seedlings that emerge at the onset of the rainy season, in autumn, are of minor importance, as they are suppressed by cultivation during seedbed preparation for sowing. However, this cultivation stimulates germination and new seedlings emerge simultaneously with the crop (Izquierdo et al, 2013). A wide range of days for maximum wild oat emergence have been reported.…”

“…Weibull and Gompertz distributions have been used commonly in the development of weed emergence models (Izquierdo et al, 2013;Royo-Esnal et al, 2015). Model parameters of both species were estimated with SigmaPlot 12.0 using a non-linear regression fitting routine.…”

“…The cumulative soil thermal time (CTT) was estimated daily during the growing season with the following equation (Leblanc et al, 2003;Leguizamon et al, 2005;Izquierdo et al, 2013):…”

Modelagem matemática do fluxo de emergência de plantas daninhas: ferramenta para decisão no manejo de cultivos

“…Em cereais de inverno esses padrões de emergência não foram observados, mas em condições de inverno quente e úmido a emergência de planta daninha ocorre em períodos mais cedo e em fluxos menores, porém em invernos frios e secos a emergência ocorre no final do ciclo (Izquierdo et al, 2013;Royo-Esnal et al, 2012). Determinou-se que Conyza bonariensis exige acúmulo de 15TH para iniciar a emergência e até a sexta semana após a semeadura ocorre 95% da emergência, tanto no outono quanto na primavera (Zambrano-Navea et al, 2013).…”