Effects of Nitrogen Forms on the Growth and Nitrogen Accumulation in Buchloe dactyloides Seedlings.

Buffalograss [ Buchloe dactyloides (Nutt.) Engelm.] has become the most widely cultivated warm-season turfgrass in northern China because of its low-maintenance requirements. Nitrogen (N) can be applied to plants in a range of formulations. However, preference of nitrogen uptake and the effects of N form on plant growth and nitrogen accumulation has not been established in buffalograss. In this study, we evaluated the effects of different inorganic nitrogen forms (NO 3 - -N, NH 4 + -N, and NO 3 - -N: NH 4 + -N = 1:1) on growth and nitrogen accumulation in buffalograss seedlings. Results showed that supply of three N forms significantly increased buffalograss seedlings growth, biomass, and N contents of all plant organs compared with the seedlings receiving free nitrogen. Plants achieved better growth performance when they received nitrate as the sole N source, which stimulated stolon growth and increased the biomass of ramets, spacers, and aboveground and total plant biomass, and also allocated more biomass to ramets and more N to spacers. Meanwhile, those plants supplied with the treatment +NH 4 NO 3 displayed a significantly greater N content in the ramet, 15 N abundance, and 15 N accumulation amount in all organs. These data suggest NO 3 - -N supplied either singly or in mixture increased vegetative propagation and thus facilitates buffalograss establishment. However, applications of ammonium caused detrimental effects on buffalograss seedlings growth, but +NO 3 - could alleviate NH 4 + -induced morphological disorders. Thus, recommendations to increase vegetative propagation and biomass accumulation in buffalograss seedlings should consider increasing NO 3 - -N in a fertility program and avoiding applications of nitrogen as NH 4 + -N.