Response of Four Tall Fescue Cultivars Grown at Two Nitrogen Levels to Low Soil Water Availability1

Four cultivars of tall fescue (Festuca arundinacea, Schreb.) ‘Ky‐31 (GA)’, ‘Fawn’, ‘Kenhy’, ‘G1‐306’ were grown in controlled environments to evaluate the interactive effect of N and soil water availability on biomass production, leaf water potential (ψL), as well as Kjeldahl N, NO3‐N and the amino acid proline. Two N fertility regimes [0 kg N/ha (O N) and 200 kg N/ha (200 N)], and two successive drought stress and recovery cycles were imposed in controlled environment chambers with a third and final stress period imposed in the greenhouse. Drought stress reduced biomass production in all cultivars. Application of 200 N improved dry matter production of all cultivars under drought stress except G1‐306. Leaf roll was apparent in most cases of drought stress. Leaf water potential responses were not consistent over successive drought stress cycles; that is, preconditioning minimized the change in ψL, indicating that some adjustment to stress conditions were being made by the plant. Nitrogenous components including Kjeldahl N, NO3‐N and proline were distinctly affected by drought stress. Kjeldahl N was significantly increased by drought stress in all cultivars but especially in Kenhy and G1‐306 at the 200 N level. Proline concentrations were increased by drought stress in all cultivars, with Fawn containing the highest and G1‐306 the lowest concentration of proline. Since there is a specific response of nitrogenous components to drought stress these responses may represent fundamental alterations in N metabolism and may not be similar for all cultivars. Our findings indicate the need for further analysis of the distribution and composition of the nitrogenous fractions of drought‐stressed tall fescue.