Influence of N, P and K Fertilizer Interactions on Growth of Ilex crenata Thunb. ‘Helleri’

Ilex crenata ‘Helleri’ was greenhouse-grown in sand culture for 8 weeks at 4 levels of N, P and K in a factorial arrangement. Nitrogen and K levels were maintained at 0, 25, 75, and 200 ppm and P at 0, 5, 15, and 40 ppm in the irrigation water. The lowest level of each nutrient required for optimal growth was 75 ppm N, 5-15 ppm P and 25 ppm K. When levels of P were maintained at 40 ppm, then 200 ppm K was required for maximum growth. The same trend occurred for N and P in that higher levels of N were required to promote maximum growth when P levels were at 40 rather than 15 ppm.