Nitrogen Critical Level Determination in The Woody Ornamental Shrub Euonymus fortunei

ABSTRACT

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.

Keywords:

• nitrogen deficiency
• foliar analysis
• nutrition
• critical level
• nursery production
• winter creeper

Notes

^xTreatment means in a column followed by the same letter are not significantly different based on Tukey's HSD Test at P < 0.05.

 ^ySix representative rooted cuttings were used to determine initial dry weight (2.97 g).

 ^zRatio based on net dry weight accumulation.

 *Significant effect at P < 0.05.

^zTreatment means in a column followed by the same letter are not significantly different based on Tukey's HSD Test at P < 0.05.

 *Significant effect at P < 0.05.

^zTreatment means in a column followed by the same letter are not significantly different based on Tukey's HSD Test at P < 0.05.

 *Significant effect at P < 0.05.

 *Significant effect at P < 0.05; NS indicates no significant effect.