The influence of irradiance distribution on the growth of white clover (Trifolium repens L.) in differently managed canopies of permanent grassland
1986
Schwank, O. | Blum, H. | Nosberger, J.
Growth of white clover was investigated in permanent grassland cut three or five times per year. The influence of cutting frequency and nitrogen fertilization on dry-matter yield, leaf-area distribution and the distribution of photosynthetically active radiation within the canopy were examined. In the five cut treatments, total dry-matter yield was nearly equal, with and without nitrogen. However, nitrogen practically eliminated white clover. Leaf-area distribution showed characteristic patterns for the different treatments. The small proportion of white clover in the treatment with nitrogen fertilization was thought to be due to the large leaf area of the other species at heights which white clover could not attain. This conclusion was supported additionally by the radiation measurements within the canopy. The sunlit fractional area within canopy layers was measured with ‘quantum sensors’ and calculated from canopy transmission measured with tube solarimeters. The leaf area index of white clover was highly correlated (r2 = 0.68) with the sunlit fractional area above the canopy layers where white clover was present. This response of white clover leaf growth to the light regime is discussed in relation to the potential petiole growth.
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