NUTRITION OF CONTAINER-GROWN RADERMACHERA-SINICA HEMSL

Seedlings of Radermachera sinica Hemsl. were grown in peat/composted b ark (7:3, v/v) medium to evaluate their response to five levels of nit rogen (N), phosphorus (P), potassium (K), and lime. R. sinica proved t o be an adaptable species quite tolerant of nutrient extremes. There w as a strong response to added N with an optimum at 300 g N/m(3), equiv alent to 85 g N/m(3) per month and a leaf N content of 2.5%. P, and mo re noticeably K, had little influence on foliage growth and consequent ly there were few nutrient interactions. Optimum P additions were at c . 200 g P/m(3) or a leaf P content of 0.35%, whereas high P fertilisat ion depressed foliage growth. The lime rate for optimum growth was at 6 kg/m(3) and pH 4.8.