Effect of Alfalfa Ploidy on Nitrogen Fixation1
- Walter T. Leps,
- Winston J. Brill and
- E. T. Bingham2
Genetically similar families of alfalfa (Medicago sativa L.) at diploid (2×), tetraploid (4×), and octaploid (8×) ploidy levels were assayed for acetylene-reduction activity to determine the effect of ploidy on N2 fixation by nodulated plants. Tetraploids had higher rates of acetylene reduction than diploids during the first 10 days of growth. After that time, both tetraploid and diploid plants reduced acetylene at the same rate. The higher acetylenereduction activity found during the first 10 days may reflect the ability of the tetraploids to fix more N2 than the diploids early in growth and may explain why tetraploids had higher N contents than the diploids when the plants obtained their N from N2 fixation. Increasing the ploidy of alfalfa plants from tetraploid to octaploid did not result in increased acetylene-reduction activities or N content.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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