Effects of different N feritilization modes and rates on the production and quality of king grass

In order to provide the reference about nitrogen rational use in king grass （Pennisetum purpureum P.typhoideum）production, effects of different nitrogen levels and application methods on king grass growth and quality were studied by using pot culture experiment. The results indicated that N could improve yield and quality of king grass remarkably. The dry weight, plant height, the chlorophyll SPAD value, nitrogen (%) and crude protein contents (%) of the king grass had positive correlation with N application. The contents of phosphorus (%), potassium (%) and coarse fibre (%) had negative correlation with N application. The effect of N application at different periods on yield and crude protein content was not synchronization. Application N three times at different growth periods instead of one time at the beginning of growth period could remarkably increase the crude protein content. Further more, only application N three times with equal amount at different growth periods could conspicuously improved the dry weight of king grass. The most suitable N amount for king grass in our experiment was 3.48 gpot-1 (about 180 kgha-1 nitrogen). However, between 1.74～6.95 gpot-1 （90～360 kgha-1）the king grass could grow normally, less than 0.87 gpot-1 （45 kgha-1）or more than 13.91 gpot-1 （720 kgha-1）the growth was restricted; and no fertilization the growth was seriously retarded. Thus, the best fertilization way of king grass is to fertilize N with equal amount at stages of initial growth, tillering and jointing.