Research On Nitrate Accumulation Of Vegetable And Reduce And Control Nitrate Of Vegetable Agronomic Measures In Facilities Vegetable Field

Vegetables occupy a very important position on peple's diets. Green and organic vegetables have been growing concern and attention. Nitrate content of greenhouse vegetables is much higher than that in the field. Reducing the Nitrate content of vegetables has a significant impact on improving the quality of vegetable and ensuring the health of human.The Nitrate accumulation of vegetables is directly related to Nitrogen fertilization.In this paper, conventional methods combined with the isotope tracer technique are used to research the fertilizer's impact on nitrate and quality of vegetables, the relationship between nitrogen sources and nitrate accumulation,distribution of vegetables.The results are as follows:1. The results showed that:On the basis of 20% reduction of chemical fertilizer, it reduce2.93%-22.05% of the nitrate and 9.09%-53.17% of the nitrite content of vegetables through agricultural technical measures such as the combined application of organic manure,application of nitrification inhibitors and trace elements in urinary inhibitors;The nitrate accumulation peak of summer vegetables are earlier than winter vegetables,the nitrate content of the late period of Vegetable growth less than the period of rapid growth significantly; Under the same nitrogen, it increase the Vc and Soluble sugar content of vegetables and the chlorophyll SPAD values in vegetables change implicitly by using the organic fertilizer, distribution and application of microelements, nitrification inhibitor and urease inhibitor and other agronomic measures.2. Vegetables is an easy plant for nitrate accumulation. The nitrate content of vegetables in stem is about 1.5 times for leaf. The vitamin C content of vegetables in leaf is much higher than stems, meanwhile the nitrate reductases activity in roots and leaves is far outweigh the stems of Vegetables. Different types of nitrogen on the accumulation of nitrate in vegetables were as follows: sodium nitrate maximum, ammonium sulfate, urea and ammonium bicarbonate smaller.The more nitrate content in vegetables,the more content of Vc.3.more than 80% vegetables nitrate comes from soil, while less than 20% from the fertilizers.Vegetables demand is high of soil nutrients in vegetable production should be paid special attention in part of soil, reducing vegetables reduce control on the soil of nitrate, and then to reduce vegetables absorb the purpose of nitrate.4.When urea is added to soils, the rate of its fertilizer utilization has reached 46.27% and the rate of its soil residual nitrogen has reached 17.01%, which are higher than those of ammonium sulfate and sodium nitrate. The loss rate of urea is 40.32%, which is much lower than those of ammonium sulfate 52.67% and sodium nitrate54.15%.