The response of Whitegrass [Cortaderia pilosa (D'Urv.) Hack.] to nitrogen nutrition
2001
Wilson, F.E.A. | Harvey, B.M.R. | McAdam, J.H. | Walton, D.W.H.
To investigate the potential for increasing Falkland Island Whitegrass [Cortaderia pilosa (D'Urv.) Hack.] pasture production through application of nitrogen (N) fertilizer, two hydroponic experiments were conducted. First, 5 mg l(-1) N was supplied to plants as nitrate (NO3-), urea [CO (NH2)2], ammonium (NH4+), or a nine parts NH4+: one part NO3- mixture. At harvest, plants grown in a NO3- medium had about half the biomass of plants grown in a NH4+ medium. In the second experiment plants were supplied with 1, 3, 10, 30 or 100 mg l(-1) Nh4+-N. Plants at 1 and 3 mg l(-1) N had the largest biomass of young root and the lowest shoot-root ratios. Leaf extension rate was low in the 1 mg l(-1) N treatment. Plants given 10 mg l(-1) N had the greatest proportion of green shoot material but little root growth; while those at 100 mg l(-1) N produced very little shoot and root biomass. Preferential assimilation of NH4+-N and a low N requirement make Whitegrass well adapted to dominating vegetation on much of the Falkland Islands.
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