Effects of Macronutrient and Micronutrient Additions on Photosynthesis, Growth Parameters, and Leaf Nutrient Concentrations of Uniola paniculata and Panicum amarum

Uniola paniculata (sea oats) and Panicum amarum (bitter panicum) seedlings were grown under green-house conditions in Louisiana dune sand and subjected to four macronutrient/micronutrient combinations. Macronutrient additions (N, P, K) resulted in significantly greater leaf-elongation rates, number of stems, and aboveground biomass. Net CO2 exchange rate was also increased, although significantly only for P. amarum. Micronutrient additions (Fe, Mn, Cu, and Zn) in conjunction with macronutrient additions reduced leaf-elongation rates and number of stems of both species. In U. paniculata, leaf Zn was negatively correlated with aboveground and below-ground biomass, whereas in P. amarum leaf Zn was negatively correlated with rhizome biomass but positively correlated with root biomass and net CO2 exchange rate. Leaf Mn in P. amarum was negatively correlated with number of stems and rhizome biomass. Species differences in leaf Na, Ca, K, Cu, and Mn concentrations were particularly large; U. paniculata accumulated more Na and Cu and less Ca, K, and Mn than P. amarum.