Research observation: Nitrogen effects on Arizona cottontop and Lehmann lovegrass seedlings

Abstract

We compared the responses of seedlings of introduced Lehmann lovegrass (Eragrostis Lehmanniana Nees) and a native perennial grass, Arizona cottontop (Digitaria californica (Benth.) Henr.) to 7 nitrogen and 2 water treatments to determine if Lehmann lovegrass displayed greater growth or nitrogen use efficiency than Arizona cottontop. After 8 weeks, the lovegrass seedlings had greater shoot N concentrations (2.07 vs. 1.20%), and lower C:N ratios (27.7 vs. 49.6) than Arizona cottontop seedlings. Arizona cottontop seedlings produced more biomass per plant (1.09 vs. 0.31g), exhibited greater nitrogen use efficiency (63 vs. 39%), and tolerated high N levels better. Arizona cottontop may be a superior N competitor under both N-limited and high N conditions, while Lehmann lovegrass may outcompete Arizona cottontop at moderate N levels.