Submitted to: Weed Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/25/2003
Publication Date: 2/25/2003
Citation: GRUNDY, A., PETERS, N., RASMUSSEN, I., HARTMANN, K., SATTIN, M., ANDERSSON, L., MEAD, A., MURDOCK, A.J., FORCELLA, F. EMERGENCE OF CHENOPODIUM ALBUM AND STELLARIA MEDIA OF DIFFERENT ORIGINS UNDER DIFFERENT CLIMATIC CONDITIONS. WEED RESEARCH. 2003. V. 43. P. 163-176.
Interpretive Summary: Understanding the emergence behavior of weeds in relation to management and weather events allows weed scientists to better help farmers control weeds. However, dissimilarities among weed populations in terms of seed dormancy, germination, weather, soils, and so forth all contribute to making predictions of weed behavior a difficult task. For this reason, seeds of common chickweed and common lambsquarters were collected from three locations (Italy, Sweden and UK) during both 1999 and 2000, and then buried in the autumn of the same year of seed maturation. Burial occurred in identical substrates at eight sites, seven of which were located in Europe and one in the USA. Seedling emergence was monitored at least weekly. Synchronous timing of emergence occurred for different populations within a given location. Also, the extent of emergence from the three populations at a given burial site in a given year was similar across the study sites, regardless of burial location. A simple weed emergence model was developed, which was tested for its application to the range of different burial environments and populations. The study demonstrated (a) the possibility of using a simple model based on growing-degree-days to describe emergence behavior across sites, seed populations and seasons and (b) a simple winter chilling relationship to adjust for the magnitude of the flush of emergence at a given site. This first example suggests the possibility for developing robust generic models for simple predictions of emergence timing across populations. These results will help other scientists to develop emergence models for other important weed species with wide-ranging distributions. Ultimately, these models of weed behavior will ease the burdens (financial, labor, managerial, etc.) of weed control experienced by farmers.
Technical Abstract: A better understanding of the emergence behavior of weed species in relation to cultural and meteorological events presents a number of opportunities. However, dissimilarities between populations in dormancy and germination ecology, between-year maturation conditions and seed quality and burial site climate, all contribute to potentially unpredictable variability. A weed emergence dataset was produced for weed seeds of Stellaria media (L.) Vill. and Chenopodium album L. whose seeds had matured and were collected from three main study populations (Italy, Sweden and UK). The seeds were collected in two consecutive seasons (1999 and 2000) and subsequently buried in the autumn of the same year of maturation in eight contrasting climatic locations throughout Europe and the USA. The experiment sought to explore and explain differences between the study populations in their emergence behavior. Evidence was demonstrated of synchrony in the timing of the emergence of different populations of a species at a given burial location. The relative magnitudes of emergence from the three populations at a given burial site in a given year were generally similar across the study sites, regardless of burial location. The resulting dataset also was used to construct a simple weed emergence model, which was tested for its application to the range of different burial environments and populations. The study demonstrated the possibility of using a simple thermal-time-based model to describe the emergence behavior across sites, seed populations and seasons, and a simple winter chilling relationship to adjust for the magnitude of the flush of emergence at a given site. This first example demonstrates the possibility for developing robust generic models for simple predictions of emergence timing across populations.