Effects Of Rare Earth Element, Micronutrient Fertilizers And Nitrification Inhibitors On Nitrate, Nitrite Contents And Other Qualities In Leaf Vegetable

Vegetable is a crop being easy to accumulate nitrate in its tissue. Nitrate can be transformed into nitrite in return when it is absorbed by people' s bodies. After nitrite combinating with secondary amines, nitrosamines be formed, which would lead to cancer. Recently, the study on how to decrease nitrate accumulation in vegetable is becoming more and more concerned topic. So the effects of applying rare earth element, 5 micronutrient fertilizers and 3 nitrification inhibitors on nitrate, nitrite contents and other qualities in pakchoi were studied with plot experiment at 2 sites. The experimental soils were red vegetable soil and alluvial vegetable soil. The experimental vegetables were winter pakchoi and summer pakchoi. The main results were showed as following:1. In the experimental rare earth element and 5 micronutrient fertilizers, spraying Molybdenum fertilizer and Manganese fertilizer could decrease nitrate contents and increase nitrate reductase activity in pakchoi significantly. Also, Boron, Zinc and rare earth element fertilizers could decrease nitrate contents in pakchoi to some extent. Of them Molybdenum and Manganese fertilizers had the best effects. Copper fertilizer had the worst effect. The nitrate reductase activity was correlated with nitrate contents in pakchoi negatively at the significant level of P0.05.2.Nitrification inhibitors,HQ, DCD and TU, could all decrease nitrate contents in pakchoi significantly in three stages of pakchoi. But the effect varies with the test soil. Nitrification inhibitors, HQ, DCD and TU, could decrease nitrate contents in soils in different stages . They could all keep higher NH4+-N concentration in soil and reduce excessive NO3--N accumulation and NO3--N pollution in ground water which lead to excessive NO4--N accumulation in pakchoi.3.Spraying rare earth element or micronutrient fertilizers had nosignificant effect on the nitrite contents in pakchoi. But the nitrite in pakchoi didn' t exceed cri terion in every experiment. As well as, the nitrite contents in pakchoi decreased with its growth gradually. Treatments with nitrification inhibitors had the similarly effect. Nitrification inhibitors, HQ,DCD and TU, could all decrease nitrite contents in pakchoi to different extent.4.Nitrification inhibitors, HQ, DCD and TU, could all increase N and P uptake obviously, but had not effect on K uptake. They could increase yield of pakchoi to some extent in all, of them DCD was the best. Spraying rare earth element or micronutrient fertilizers could not affect the yield of pakchoi and the uptake of N, PA and K2O by pakchoi obviously.