Effects of nitrogen fertilization on growth, yield and quality of Chrysanthemum morifolium

Nitrogen (N) is an element of life and plays an important role on the quality of crops, vegetables and fruits. Recently, N has also been found to have an important effect on the secondary metabolism in plant, such as flavonoids and chlorogenic acid. The effects of different N application rates on growth, active ingredient accumulation and correlative physiological index of Chrysanthemum morifolium were studied by using a pot culture experiment. The results show that the uptake and accumulation of N element and the flower bud differentiation are promoted, and the contents of chlorophyll of C. morifolium and yields of the flowers are significantly increased under the applications of N nitrogen. When the N application rate is 0.5069 g/kg soil, the fresh flower yield is highest, and reaches to 542.01 g/plant. The P, K and Ca contents of C. morifolium and activity of PAL which is a key enzyme in the secondary metabolism of the plant are significantly decreased under the high N application rate. In fact, the contents of chlorogenic acid, total flavonoids and soluble sugar are significantly decreased with the increase of N application rate, which are declined by 35.48%45.26%, 28.58%35.58% and 6.42%9.51%, respectively. With the high N application rate, it increases the N content, decreases the PAL activity and soluble sugar content of C.morifolium, and restrains the anabolism of chlorogenic acid and total flavonoids. Furthermore, the accumulations of total flavonoid, chlorogenic acid and soluble sugar of C. morifolium flower are highest when the N application rates are from 0.4180 to 0.4598 g/kg soil. The overall results suggested that the appropriate N application rate is 0.30.4 g/kg soil in production of C. morifolium.