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Book: Proceedings of the Second International Turfgrass Research Conference
Published by: American Society of Agronomy, Crop Science Society of America



  1.  p. 186-195
    Proceedings of the Second International Turfgrass Research Conference

    Eliot C. Roberts (ed.)

    ISBN: 978-0-89118-573-4


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Photosynthate translocation and metabolism in Kentucky bluegrass turf as a function of fertility1

  1. R. J. Hull and
  2. L. M. Smith


The influence of fertilizer practices on carbon transfer through bluegrass (Poa pratensis L.) turf was the subject of this investigation. ‘Merion’ Kentucky bluegrass plots were established in 1966 and subjected to four fertilizer ratios: N-O-O, N-P-O, N-O-K, and N-P-K. In 1970, the plots were subdivided and each ratio was applied at three rates: 2.5-1-1, 5-2-2, and 10-4-4 kg/200 m2 per year. The test was replicated four times. Soil samples were analyzed for N, P, and K in early summer and midautumn of 1971 and 1972. Midsummer clippings were analyzed for the same elements each year.

Assimilate translocation and metabolism were measured by exposing 15-cm diameter circles of turf to 14CO2 and harvesting the turf at selected times following exposure. Individual grass plants were separated into deep and shallow roots, stems, and leaves. Plant tissue was freeze-dried and the 14C analyzed quantitatively and characterized biochemically.

Mineral analysis of soil and plant tissue indicated that the fertilizer treatments had produced marked differences in soil fertility and in the mineral content and yield of grass. During the growing season, carbon fixed by leaves was translocated into stems and roots within 2 hours. Roots received maximum photosynthate during early winter and spring, although translocation rates were slower during the cool seasons. During the warm seasons, photosynthate translocated more rapidly in low fertility grass than in heavily fertilized turf. Turf grown under high fertility maintained smaller carbohydrate pools, but the turnover rate of these pools was greater than in low fertility turf. Additional index words: Nitrogen, Phosphorus, Potassium, Carbon-14.

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Copyright © 1974. Copyright 1974 by the American Society of Agronomy, Inc. and the Crop Science Society of America, Inc., 5585 Guilford Rd., Madison, WI 53711 USA