Effects of two nitrogen application methods on growth of Eucalyptus urophylla × E. grandis container seedlings cultivated with light media

The effects of nitrogen treatments with the exponential fertilization,mean fertilization and non-fertilization on the growth and chlorophyll contents of Eucalyptus urophylla × E. grandis clone DH 32-29 tissue culture seedlings in container with light media were studied during a three-month period. The results suggested that N supply could significantly increase the growth and chlorophyll contents of seedlings( p 0. 05). The increase of height from the exponential fertilization was faster than that from mean fertilization at the late stage of experiment. When N supply were 20 and 40 mg per seedling,the growth indices of seedlings from the exponential fertilization were significantly higher than those from mean fertilization in the same N concentration,and when N supply were 20 and 60 mg per seedling,the chlorophyll contents of seedlings from exponential fertilization were significantly higher than those from mean fertilization in the same N concentration,but the other N concentrations had no obvious differences. The ground diameter,root volume,leaf area,leaf length,leaf width and chlorophyll contents of seedlings from the exponential fertilization with 60 mg N per seedling were significantly higher than other treatments,their growth vigor was the best among all treatments,so the exponential fertilization was the best treatment in this experiment. We concluded that the effect of exponential fertilization was superior to that of the mean fertilization both in growth and chlorophyll contents of E. urophylla × E. grandis seedlings.