Erodium cicutarium is a globally distributed annual herb and is known as a weed that can cause substantial reductions in crop yield in agricultural lands. Effective weed management requires an understanding of how environmental factors in agricultural...
Erodium cicutarium is a globally distributed annual herb and is known as a weed that can cause substantial reductions in crop yield in agricultural lands. Effective weed management requires an understanding of how environmental factors in agricultural lands influence weed performance. Accordingly, this study examined the survival and phenotypic variation of E. cicutarium by focusing on soil phosphorus, which can accumulate in soils and exert long-term effects, and light availability, a key factor affecting early weed growth. In the field survey, plant height was affected only by light and showed a negative relationship with light, whereas stem diameter and dry mass were positively associated only with soil phosphorus. In the mesocosm experiment, phosphorus was the primary driver of variation in most phenotypic traits of E. cicutarium, while light mainly influenced traits related to light acquisition (e.g., SLA and internode length) and total dry mass. The interaction between phosphorus and light was detected only for belowground biomass (BGB) and total dry mass, and total dry mass increased by up to 580% under their interaction. Survival of E. cicutarium was 100% at 0 ppm phosphorus and approximately 30% at 160 ppm, whereas all individuals died at 800 ppm, a level designed to mimic lands in South Korea. Taken together, these results suggest that E. cicutarium can grow rapidly during the early cultivation period when canopies are open in fertile agricultural lands, highlighting the importance of early-season control. In agricultural lands with very high phosphorus levels, such as those in South Korea, E. cicutarium may be less likely to cause yield losses within fields and may instead persist along field margins, where it could engage in different interactions with other weeds.