engleski

Validation of hydrothermal model AlertInf for barnyardgrass emergence in Croatia maize crop

Barnyardgrass (Echinochloa crus-galli L.) is the most common grass weed in maize fields in Croatia and an important weed in many crops worldwide. Since weed species can differ in the time and duration of emergence, to achieve appropriately weed control timing, it is necessary to determine the field emergence period of the largest proportion of the weed population. Soil temperature and soil moisture are the two main factors driving weed emergence. Therefore, hydrothermal models can be used to predict weed emergence in agricultural crops. AlertInf is an Italian hydrothermal time (HTT) model for weed emergence prediction in maize. The possibility of validating this model for Croatian maize crops was tested with barnyardgrass. Prior the validation, AlertInf model was calibrated with the values of germination parameters of the Croatian population (base temperature 10.8°C and base water potential -0.97 MPa). Field experiments were conducted in maize crops in continental Croatia to quantify barnyardgrass emergence pattern from natural seedbanks. Barnyardgrass emergence was monitored in a 2-yr experiment in an experimental maize field Šašinovečki Lug (45°50'59.6 "N 16°09'53.9 "E). Emergence monitoring was carried out three times a week in 12 squares (0.3 x 0.3 m2) between maize rows. The first visible true leaves of barnyardgrass were counted and removed. Monitoring of emergence ended when no emerged seedling was observed for at least two weeks after closing the maize canopy. Soil temperature and soil moisture were recorded daily during experimentation. The obtained emergence data was used for the validation of the Italian HTT model. Results showed the successful applicability of the AlertInf model for simulating the emergence of barnyardgrass in maize (EF =0.97 and EF = 0.98in 2019 and 2020, respectively), although a slight underestimation of the onset of emergence in 2019 and overestimation in 2020 was observed. However, the model successfully predicted the mid- and end of emergence in both years. According to the model, the onset of emergence needed 29 and 27 HTT units in 2019 and 2020, respectively ; 93 HT units for the middle emergence in both years ; and 312 and 342 HT units for end of emergence in 2019 and 2020, respectively. Our findings showed the potential use of the AlertInf model for the simulation of barnyardgrass emergence in Croatian maize crops and in similar geographic areas.

germination parameters, seed, emergence, precision weed management

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