Spatial relationships between seed bank and seedling populations of Hordeum spontaneum and Cardaria draba in saffron (Crocus sativus L.) fields

Geostatistical techniques were used to characterize the spatial relationship between Hordeum spontaneum and Cardaria draba seedling and seed bank over the course of one growing season (2004-2005) in three saffron fields, located in Southern Khorasan, Iran. The density and spatial distribution of weeds varied widely with fields. The emergence percentage was higher for Cardaria draba than for H. spontaneum in all fields. Semivariograms showed spatial autocorrelation in seed bank and seedling populations of H. spontaneum and C. draba in all fields. Cross-semivariograms showed moderate to strong (63.3 to 94.7%) and strong spatial continuity (78.4 to 95.4 %.) between seed bank and seedling population densities of H. spontaneum and C. draba, respectively. Grey-scale field maps of C. draba seed banks corresponded visually to maps of seedling populations and could have been used to target control efforts, but visual correspondence between H. spontaneum seed bank and seedling maps was poor. Seed bank and seedling mapping may be useful for site-specific management, but additional information is needed to understand variation in the relationships between these two populations over time and space.