Growth of Ilex crenata Thunb. 'Helleri' in response to properly timed fertilizer applications

Abstract

Multiple branched liners of Ilex crenata “Helleri” growing in a pine bark medium were fertilized at the beginning of active root growth at 300, 400, 500, or 600 ppm N with a 20N-8.7P-16.7K water soluble fertilizer. The treatments were repeated during the next two periods of root growth which occurred approximately 6 weeks apart. The above soluble fertilizer was applied weekly at 300 ppm N as a control. Shoot growth of plants fertilized twice at 500 ppm N was comparable to growth of the control plants. Further, these plants receive 44 percent less fertilizer and utilized a larger percentage of the total fertilizer applied. Root growth decreased with increasing fertility levels with 300 ppm N weekly resulting in the least amount of root growth. Extract nutrient and soluble salt levels were high during root growth and low during shoot growth except for treatment 300 weekly, demonstrating the plant’s need for fertilizer only during periods of active root growth. Tissue nutrient levels increased with increasing fertilizer rates and number of applications when applied during root growth.