Effects of different amount of nitrogen fertilizer on yield and nutrient quality of green asparagus

In experimental farm of Inner Mongolia University for Nationalities from March to July in 2007, using three-year Asparagus officinalis L. cv. Grande as experimental material, we studied the effect of different amount of nitrogen fertilizer on yield and nutrient quality of green asparagus. The results are as the following: the yield of green asparagus and rate of qualified green asparagus goes up with the increase of the amount of nitrogen fertilizer during the harvesting time when the amount of nitrogen fertilizer is within N 0~360 kg/ha. The occurance number of tender stem and the increase of the amount of chlorophyll are the major reason for the increase of the yield of green asparagus, while applying nitrogen fertilizer can make thin asparagus (whose diameter is less than 0.5 cm) long and wide thus decreases the rate of unqualified asparagus. With the increase of amount of nitrogen fertilizer, the content of chlorophyll a and b increase, and the content of carotenoid have no obvious change. The content of crude protein, soluble protein and soluble sugar all increase with the increase of amount of nitrogen fertilizer. The content of mineral elements are much higher when the amount of nitrogen fertilizer is appropriate, but which is lower when the amount of nitrogen is too much or little. Before harvesting time, the content of rutin are much higher and decreases with the increase of amount of nitrogen fertilizer, while after harvesting time, the content of rutin decreases and the difference among each treatment was not obvious. Under this experimental condition, when the amount of nitrogen fertilizer is about N 240 kg/ha, green asparagus not only has higher yield and better nutrient quality, but also its yield has obvious lifted with the increasing of the nitrogen fertilizer.