Development and validation of a simulation model for hairy vetch (Vicia villosa Roth) self-regeneration under different crop rotations

Abstract

Hairy vetch (Vicia villosa Roth) is a winter annual legume cultivated for both seed production and pasture grazing in rotation with cereal crops. Vicia villosa increases N concentrations in the soil, thus contributing to the sustainability of semiarid regions. Other important advantage of hairy vetch is associated with the capability for natural reseeding in the pasture phase. Although the benefits of hairy vetch can be significant, its adoption could become a problematic volunteer weed in the cereal phase. This study aimed to develop and validate a simulation model to evaluate hairy vetch selfregeneration capacity considering different ley farming scenarios under vetch -winter cereal crop rotation (pasture-crop phase). Predicted hairy vetch density for all sequence agreed with observed values. Vicia villosa yield and seed rain were the most important variables affecting seedbank replenishment and self-regeneration capacity. Under pasture phase, monoculture of vetch it is feasible to obtain a productive pasture by successive natural reseeding (base threshold ≥ 30 plants m -2 ). For a vetch-cereal-vetch sequence, the base thresholds of seed yield required at the end of 1 st season to achieve V. villosa regeneration capacity were 185 and 240 kg ha -1 for conventional tillage and no tillage, respectively. Natural seedbank replenishment would not be enough to establish a productive plants density pasture by self-regeneration after two or more successive years of cereals, due to higher rates of release dormancy during the summer season after dispersal. From a low impact perspective in crop phase, hairy vetch weed control should not be a considerable problem if management practices tend to avoid seed production and seedbank replenishment for at least three consecutive years. These outcomes suggest the potential applicability of the proposed modelling approach within management decision support systems.

Diversity of Naturalized Hairy Vetch (Vicia villosa Roth) Populations in Central Argentina as a Source of Potential Adaptive Traits for Breeding

“…An additional challenge of HV is seed dormancy control, which can lead to incomplete emergence after seeding (Jacobsen et al, 2010;Maul et al, 2011). On the contrary, in agroecosystems of semiarid regions, HV natural reseeding capacity is a desirable trait reducing establishment costs (Renzi et al, 2017;Renzi et al, 2019), especially when used as forage crop by livestock farmers.…”

Spontaneous Gene Flow between Cultivated and Naturalized Vicia villosa Roth Populations Increases the Physical Dormancy Seed in a Semiarid Agroecosystem

“…However, these genotypes would not be suitable in ley farming practice, in which the success of annual crop rotation depends on the ability to provide an adequate plant density for seed/forage production by self-regeneration from the soil seedbank. On the contrary, from a weed management perspective, we observed that in HV genotypes with more than 70% of initial PY, the problem of "volunteer plants" can be avoided if management practices avoid seed production and seedbank replenishment for at least three consecutive years [17]. The selection breeding of cultivars with <14% and <8% of initial PY could reduce this period further to one year and 6 months, respectively.…”

“…The most important traits for which HV has been selected include biomass production and a low level of seed dormancy [13]. Low PY is a desirable trait for stand establishment [8], while incomplete germination related to PY can result in soil seed bank formation and emergence in subsequent crop rotations as a problematic weed [8,16,17].…”

“…On the contrary, in the agroecosystems of semiarid regions, HV's natural reseeding capacity with high PY is a desirable trait. The adoption of HV is associated with its high self-regeneration potential, which is known in ley farming in Australian systems and helps to reduce production costs, minimalizing the seed and sowing operations [17][18][19][20].…”

How Could the Use of Crop Wild Relatives in Breeding Increase the Adaptation of Crops to Marginal Environments?

“…In many Mediterranean CWR seed physical dormancy has been selected as bet-hedging against false breaks (heavy rainfall that precedes the growing season start and which would expose the recently germinated seedling to extreme heat and drought) and other disturbances such as catastrophic herbivory ( Piano et al, 1996 ; Norman et al, 2002 ; Smýkal et al, 2014 ; Berger et al, 2017 ). Typically, there is wide ranging dormancy within populations ( Berger et al, 2017 ; Hradilová et al, 2019 ; Renzi et al, 2019 ), that in combination with variable seed placement will drive staggered germination across the CWR population over the growing season, exposing individuals to different micro-habitats in space and time.…”