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

Hairy vetch (Vicia villosa Roth) is a winter annual legume cultivated for pasture and hay with the capability for natural reseeding. Vicia villosa increases N concentrations in the soil, thus contributing to the sustainability of semiarid regions. However, under rotations of 1-2years of pasture followed by 1year of crop (1:1-2:1), hairy vetch could become a problematic volunteer weed in the winter cereal crop phase. This study aimed to develop a mechanistic model for hairy vetch seedling emergence in order to (i) estimate the natural reseeding of hairy vetch in the pasture phase of the field rotation, or (ii) develop control strategies considering hairy vetch as a volunteer weed in the winter cereal phase. The proposed model simulates the pattern of field emergence of hairy vetch after natural seed dispersal by integrating four submodels: (i) physical (PY) dormancy release dynamics, (ii) physiological dormancy (PD) release and germination thermal requirements, (iii) hydro-time requirements for germination, and (iv) pre-emergence growth respectively. The developed field emergence model was validated with independent field emergence data during 2013, 2014 and 2015. The model adequately predicted the timing and magnitude of field emergence flushes (RMSE<10.1) despite the environmental variability among years. The additive effect of each submodel clearly improved the explanatory capacity of the field emergence patterns. The alleviation of PD synchronizes the timing for hairy vetch germination, while the PY determines the seedbank persistence. These outcomes suggest the potential applicability of the proposed modelling approach within management decision support systems.