Germination Requirements and Management Implications for Kyllinga gracillima (False Green Kyllinga)

Understanding weed biology, particularly factors influencing seed germination, can help develop effective weed management strategies. This research evaluated the effects of temperature, light, and water stress on the germination of Kyllinga gracillima (false green kyllinga). Seeds collected in Indiana (IN) and New Jersey (NJ) were subjected to constant (20°C) and alternating temperatures (15/5°C, 20/10°C, 25/15°C, 30/20°C, and 35/25°C; day/night) and different water potential conditions in germination chambers. By 42 days after initiation (DAI), total germination exceeded 90% at 20/10°C, 25/15°C, 30/20°C, and 35/25°C, but no seeds germinated at 15/5°C in either population. At a constant 20°C, germination was reduced compared to seeds germinating in alternating temperatures (25/15°C). Seeds subjected to 21 days of dark had 46% (IN) and 2% (NJ) germination compared to > 94% (IN and NJ) germination of seeds exposed to light. Water stress significantly reduced germination, with no germination occurring at −0.4 MPa. By 42 DAI, germination was 97% at 0.0 MPa, 96% at −0.1 MPa, 77% at −0.2 MPa, and 16% at −0.3 MPa. The results indicate that alternating temperatures and light exposure promote germination, while reduced water potential suppresses it. Results suggest that management practices that create dense turfgrass swards coupled with infrequent irrigation will reduce K. gracillima establishment from seeds. These findings support integrated management strategies combining cultural practices with chemical control, and they warrant field validation of these approaches.