Microclimate, Photosynthesis and Growth of Lucerne (Medicago sativa L.). II. Canopy Structure and Growth

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Abstract
The growth of lucerne var. Europe was examined in the field during 1976. The annual dry matter production of unirrigated lucerne during 1976, with no nitrogen fertilizer application, was 82.5 per cent greater than unirrigated S.24 perennial ryegrass, with a nitrogen application of 384 kg ha −1 . The mean above ground growth rate of lucerne was 7.3 g DM m −2 day −1 between March and early June, of which stem material contributed a maximum of 76.5 per cent. Significant losses of leaves and stems occurred from the end of April, indicating a loss of potential forage material. Nitrogen analyses of the above ground crop suggested that in 56 days lucerne yielded 10.7 per cent more nitrogen than did S.24 annually with a nitrogen fertilizer addition of 280 kg ha −1 . Between 13 and 57 per cent of the daily photosynthate is translocated below ground.