Brennan, Mariann Phyllis2018-03-132018-03-132017http://hdl.handle.net/10092/15070http://dx.doi.org/10.26021/7663Agriculture accounts for almost 50 % of New Zealand’s greenhouse gas emissions. The high level of nitrogenous fertilisers used to stimulate plant growth causes emissions of NO2 and leaching of N into waterways. In order to address these issues and improve N uptake efficiency in Lolium perenne L., a widely used forage grass, the effect of the day (postdefoliation) of N application, in conjunction with the addition of GA3, on plant growth was observed. Parameters measured included N uptake and fructan levels which are the main storage carbohydrate of grasses. Results indicate that the application of fertiliser between day 6 and 11 post‐defoliation may be beneficial in increasing N uptake and reducing leaching of N as carbohydrate levels have been restored in leaves, leaving the plant less C starved and more able to take up N. The application of GA3 was not found to have an effect on N uptake. The effect of N form and concentration on root system architecture in vitro, indicates that arginine, an organic form of nitrogen, may be beneficial in improving N uptake and growth of plants if used as a fertiliser, compared to nitrate, a commonly used inorganic form of fertiliser.enAll Rights ReservedTheses / Dissertations