Competition for Nitrogen Between Eastern Black Nightshade and Fresh Market Tomatoes

129 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2001.This study was conducted to differentiate how eastern black nightshade (Solanum ptycanthum) (SOLPT) and tomato ( Lycopersicon esculentum) differ in nitrogen (N) utilization, and to determine if N fertilization in a tomato crop can be altered to control weedy SOLPT. Greenhouse hydroponics and field studies found SOLPT and tomato respond to high levels of N and that growth can be limited by reduced levels of N. Tomato and SOLPT were grown in four hydroponic solutions ranging from 0.2 to 10.0 mM nitrate. Both SOLPT and tomato reached their maximum shoot dry mass accumulation at 5 or 10 mM nitrate, but tomato reached the exponential stage of shoot and root growth earlier. A replacement series field study using 15N was conducted with staked fresh market tomatoes and SOLPT, which included two plant populations, and four N treatments. Overall, tomato grew taller faster, and gained more shoot mass than SOLPT regardless of N rate or population density. When grown together both species produced taller plants, with less fresh shoot mass at in the higher plant population. Population density did not affect internal N levels or the percentage of N from applied fertilizer for SOLPT or tomato. This suggest both species adjust their growth to maintain an internal N concentration when N is not limited. The ratio of SOLPT to tomato also did not affect internal N rate or the percentage of N from applied fertilizer. Both SOLPT and tomato benefitted from added N, and in most cases the high and low late did not significantly differ. The percentage of N coming from applied 15N fertilizer was significantly higher with 336 kg N ha-1, the highest rate used in the study. This study eliminated N rate or population density as possible control measures for SOLPT in tomatoes.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD