Variability in germination fractions of Amaranthus albus in response to weed management and abiotic maternal conditions

Abstract

Understanding the effects of abiotic, biotic, and management factors on weed germination is vital for optimizing weed control in agricultural fields. Nevertheless, the considerable variability among weed populations may undermine the reliability of these efforts. This study explores the intra-specific variability of Amaranthus albus populations obtained from agricultural fields across a climate gradient, ranging from semi-arid to Mediterranean. We explore the influence of temperature on germination, characterize A. albus seed morphology and assess seedling growth rate, while considering maternal effects. Nine populations were collected in northern Israel, and F2 generation seeds were produced under uniform conditions. Seed traits, germination patterns and growth rate of both maternal and progeny populations were characterized and compared. The estimated parameters of time-to-event models of populations and generations were compared using a meta-analytic approach. There were significant seed weight differences among the F1 populations, with eastern populations having the highest mean weights (28.6–38.5 mg per 50 seeds). Overall, F1 populations had higher seed weight than F2 populations (25.5 vs. 23.4 mg; p < 0.001). Two distinct germination patterns were observed in F1 populations: For the early-season planting areas, germination was rapid and uniform, with higher germination percentages at lower temperatures; in contrast, for the late-planting areas, germination was delayed and variable, with higher percentages under more favorable conditions (30 °C). F2 populations exhibited nearly identical germination patterns in response to temperature. The initial growth rate over time was similar across populations and generations, indicating that maternal conditions had no effect beyond the germination phase. The plasticity in the germination response to temperature suggests that modeling A. albus behavior is possible but requires a thorough understanding of underlying system components. The study emphasizes the importance of incorporating location-specific factors into weed management strategies, considering both natural processes and anthropogenic influences shaping weed populations.