Seed germination requirements of Amaranthus retroflexus L. populations exposed to environmental factors

Seed germination studies are often used to predict the potential of plants to extend their global distribution. In this research, the effect of gibberellic acid (GA₃ ) concentrations, pre-chilling, temperature, water and salt stresses, pH, high-temperature pretreatment, planting depth, and flooding on seed germination and seedling emergence of three Amaranthus retroflexus L. populations was investigated. GA₃ concentration significantly affected seed germination of all three A. retroflexus populations grown under light/dark conditions. All three populations germinated under constant (10, 15, 20, 25, and 30^◦C) and alternating (20/15, 25/18, and 35/25^◦C (day/night)) temperatures. The optimum alternating temperature for germination of all three populations was 18/25^◦C day/night. Seed germination was severely reduced under moisture and salt stresses. Seedling emergence was reduced on the soil surface by increasing the planting depth from 2.5 to 7.5 cm, and no seedlings emerged when the planting depth of seeds was more than 10 cm. The results of this research help us to understand the germination capacity and requirements of A. retroflexus in different environments and also provide information to help better control the weed.