Germination response of slender amaranth to temperature, solution pH, moisture stress, and depth of emergence was evaluated under controlled environmental conditions. Results indicated that 30 C was the optimum constant temperature for germination. Germination of slender amaranth seed at 21 d was similar, with 35/25, 35/20, 30/25, and 30/20 alternating temperature regimes. As temperatures in alternating regimes increased, time to onset of germination decreased and rate of germination increased. Slender amaranth germination was greater with acidic than with basic pH conditions. Germination declined with increasing water stress and was completely inhibited at water potentials below −0.6 MPa. Slender amaranth emergence was greatest at depths of 0.5 to 2 cm, but some seeds emerged from as deep as 6 cm. Information gained in this study will contribute to an integrated control program for slender amaranth.
Nomenclature: Slender amaranth, Amaranthus viridis L. AMAVI.