No abstract

Foxtail sophora is a widely distributed problematic weed in western Iranian dryland farming systems. Little information is available on seed germination and seedling emergence of this weed species in response to environmental and agronomic factors. This study was conducted to address this knowledge gap. Maximum seed germination (80%) occurred at 25 C and decreased at lower temperatures (<1% at 5 C) or under fluctuating temperature regimes. Light and pH did not have any substantial effect on seed germination. Foxtail sophora was tolerant to osmotic stress and moderately tolerant to sodium chloride. It was tolerant to salinity and drought stress during germination, which suggests that the population of this weed may increase in western farmlands of Iran. No seedlings emerged when seeds were buried at depths greater than 6 cm, which indicates that minimum- and no-till systems would increase seedling emergence of this species. Therefore, using sweep cultivators would be beneficial in management of foxtail sophora seedlings in the drylands of west of Iran.

No abstract

The enemy release hypothesis (ERH) of plant invasion asserts that natural enemies limit populations of invasive plants more strongly in native ranges than in non‐native ranges. Despite considerable empirical attention, few studies have directly tested this idea, especially with respect to generalist herbivores. This knowledge gap is important because escaping the effects of generalists is a critical aspect of the ERH that may help explain successful plant invasions. Here, we used consumer exclosures and seed addition experiments to contrast the effects of granivorous rodents (an important guild of generalists) on the establishment of cheatgrass ( Bromus tectorum ) in western Asia, where cheatgrass is native, versus the Great Basin Desert, USA, where cheatgrass is exotic and highly invasive. Consistent with the ERH, rodent foraging reduced cheatgrass establishment by nearly 60% in western Asia but had no effect in the Great Basin. This main result corresponded with a region‐specific foraging pattern: rodents in the Great Basin but not western Asia generally avoided seeds from cheatgrass relative to seeds from native competitors. Our results suggest that enemy release from the effects of an important guild of generalists may contribute to the explosive success of cheatgrass in the Great Basin. These findings corroborate classic theory on enemy release and expand our understanding of how generalists can influence the trajectory of exotic plant invasions.

No abstract