Nitrogen fixation and transfer from red clover (Trifolium pratense L.) cultivars to companion bluegrass (Poa pratensis L.) under field conditions

R. M. M. S. Thilakarathna1, Y. A. Papadopoulos1*, A. V. Rodd3, S. A. E. Fillmore4, A. N. Gunawardena1 and B. Prithiviraj5


In the current study, nitrogen (N) transfer capacity of three diploid (AC Christie, Tapani, CRS15) and three tetraploid (Tempus, CRS18, CRS39) red clover (RC) cultivars were evaluated under field conditions. Plants from each cultivar were transplanted into established bluegrass stands at two sites in 2009. Three harvests were taken during the 2010 growing season and N fixation-transfer from the RC cultivars to the companion bluegrass was measured using the isotope dilution technique.

There were significant yield differences between the RC cultivars with Tempus and Tapani having the highest seasonal yields (93.2 and 91.4 g plant-1, respectively). In general tetraploid cultivars had significantly higher tissue N concentrations compared to the diploid cultivars (3.25 vs 3.06%, respectively). On average 98% of the clover N was derived from N fixation. There was no N-transfer from RC to companion bluegrass during the first harvest, but N-transfer was observed during the second and third harvests averaging 5.7 and 4.2%, respectively. The greatest N-transfer was observed in ACChristie (15.2%) and CRS18 (8.4%) during the second and third harvests, respectively.

The results of this investigation demonstrate the presence of significant variability in N-transfer from RC to companion crops, suggesting that selection for this trait is an important consideration.


Proceedings of the CSA-CSH-CAA-AIC Conference 2012. 16-19 July 2012. Saskatoon, SK.

Author Locations and Affiliations

(1) Department of Biology, Dalhousie University, Halifax, NS, Canada B3H 4J1
(2) Agriculture and Agri-Food Canada, Nova Scotia Agricultural College, Truro, Nova Scotia, Canada B2N 5E3
(3) Agriculture and Agri-Food Canada, Charlottetown, Prince Edward Island, Canada CIA 4N6
(4) Agriculture and Agri-Food Canada, Kentville, Nova Scotia, Canada B4N 1J5
(5) Department of Environmental Sciences, Nova Scotia Agricultural College, Truro, Nova Scotia, Canada B2N 5E3
* Corresponding author, E-mail

Posted May 2013