Nitrogen Critical Level Determination in The Woody Ornamental Shrub Euonymus fortunei
2008
Evans, Richard Y. | Smith, Samantha J. | Paul, J.L.
We determined the critical nitrogen (N) level on greenhouse-grown winter creeper (Euonymus fortunei Hand. Mazz. 'Colorata') in one-gallon containers by adding N in doses of 0 to 400 mg/pot as ammonium nitrate (NH4NO3) and growing plants for 50 days without leaching. At harvest, leaf N concentrations were similar in all treatments up to 150 mg/pot, but increased with applied N above 150 mg/pot. Yield increased with increasing leaf N up to about 1% N, but was relatively constant at higher leaf N. The leaf N critical level was 1.03%. Shoot:root ratio, based on new growth, decreased with applied N. This method for critical level determination provides an accurate description of the relationship between leaf N and growth and may be used by growers to improve fertilizer use efficiency.
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