Seed survival and predation of Anoda cristata in soyabean crops

Abstract

Anoda cristata is a troublesome annual broad-leaved weed in summer crops in the rolling Pampa in Argentina; seeds are the only source of regeneration of this species. Seed persistence or depletion is the result of survival and loss processes, including predation. The objective of this study was to determine survival at two burial depths in undisturbed soil and predation rates of A. cristata seeds in soyabean crops in different rotations and tillage systems. Survival was discontinuous and decreased to 25% after 35 months, after which no further reduction in survival was observed to the end of the experiment at 96 months. No differences in seed survival between seeds placed on the soil surface and buried 5 cm below the soil surface were found at 80 months, but at later times survival was lower for seeds placed on the soil surface. Predation rates ranged between 0.3% day )1 and 6.7% day )1 . Of the models tested, a polynomial regression of the rate of predation with time gave the best representation of seed predation. From January to July, predation was higher in nontillage plots in the wheat/soyabean rotation. There was no significant difference in predation rates between tillage systems in the soyabean monoculture and no difference between planting densities. Higher crop residue levels in non-tillage plots in the wheat/soyabean rotation was the dominant factor influencing seed predation, probably because such habitat favours the presence of seed predators.

Burial rates of surrogate seeds in arable fields

“…So far, contrasting effects have been reported with regard to the role of plant litter and mulches on seed predation rates (e.g. Reader, 1993; Brust, 1994; Puricelli et al. , 2005; Pullaro et al.…”

“…The soil surface is an extremely dangerous place for a seed because of the presence and activity of post‐dispersal seed predators. This danger diminishes when seeds are covered by soil or plant litter, because covered seeds are less likely to be consumed by seed predators than are exposed seeds (Thompson, 1987; Hulme, 1994; Hulme & Borelli, 1999; Puricelli et al. , 2005), although some predators will dig for buried seeds (Reichman, 1979; Abramsky, 1983;White et al.…”

Which model species for weed seedbank and emergence studies? A review

“…Inversion operations bury weed seeds at a depth where the seeds are less prone to predation and germination (e.g. Puricelli et al. , 2005) and thus persist longer (Mohler & Galford, 1997; Omami et al.…”

Preventive Weed Management in Direct-Seeded Rice

“…In general, surface residue or vegetation has been shown to be an important factor promoting predation. For example, Puricelli et al (2005) suggested that the major factors influencing seed predation in zero-tillage wheat/soybean rotation were the higher crop residue levels which provided a favorable habitat for seed predators. Shelter is crucial for hiding from predators and affects predator behavioral decisions such as microhabitat choice, feeding activity, and movement (Lima and Dill, 1990).…”