PhD: Biology of Amarathus retroflexus and Amaranthus viridis

This PhD project studies the phenology (cyclic and seasonal natural phenomena) of two weedy Amaranthus species (A. retroflexus and A. viridis), that are very competitive and produce many seeds. Results so far suggest: 1. that seeds planted on the soil surface have the highest in-field germination; 2. delayed sowing reduces height, above-ground biomass, root biomass, and seed production; 3. Amaranthus infestation in a water-limited environment may reduce cotton yield sharply; and 4. some populations of these weeds have no resistance to glyphosate.