Effects of Nitrogen fertilization on foliar nutrient dynamics in Ginkgo seedlings

A fertilization experiment was established in three-year-old ginkgo (Ginkgo biloba L.) seedlings in central Korea. Four levels of nitrogen (N) in the form of ammonium sulfate were applied. Foliar nutrient concentrations were similar to those reported for angiosperms. Application of N fertilizer increased foliar N, potassium (K), calcium (Ca), and magnesium (Mg) concentrations. Foliar N, phosphorus (P), and K concentrations decreased through foliage senescence whereas Ca and Mg concentrations increased. During autumn 25-45% of N, 30-75% of P, and 28-55% of K from foliage were retranslocated, respectively. Nitrogen and K retranslocation decreased after fertilization while P retranslocation increased. Senescent foliar Ca and Mg concentrations increased by 205-526% and 93-160%, respectively, and the ratio increased after fertilization. However, there were no consistent patterns in foliar nutrient retranslocation with the levels of N fertilization. Ginkgo seedlings showed high foliar nutrient concentrations and relatively low nutrient retranslocation compared to other gymnosperms.