Selecting forage grasses for improved nitrate retention - a progress report


  • S.N. Nichols
  • J.R. Crush



Significant variation for both root diameter and shoot dry weight was found among 20 commercially available hybrid and Italian ryegrass cultivars screened for root diameter. Nitrate interception by four selected cultivars was then compared with perennial ryegrass in a lysimeter trial. The shoot size of selected cultivars was significantly higher than perennial ryegrass. Drainage volumes from hybrid/Italian ryegrasses were half that of perennial ryegrass and contained significantly less nitrate. 15N absorption was also significantly higher for thin (79- 80%) and thick rooted (75-76%) hybrid/Italian cultivars than for the perennial ryegrass (63%). Root diameter of the different hybrid/Italian cultivars did not have a major impact on nitrogen interception and leaching. However the concept of a large, winter active grass with high nitrogen demand during periods of high leaching activity is supported by this study. Further selection for finer roots could increase the nitrogen interception ability of these plants without compromising shoot growth. Keywords: leaching, nitrate, roots, ryegrass







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