【作者】 余光辉；

【导师】 张杨珠；

【作者基本信息】 湖南农业大学 ， 土壤学， 2004， 硕士

【摘要】 蔬菜是一种极易富集硝酸盐的作物。而硝酸盐在人体中可转化为亚硝酸盐，其与二级胺结合可形成强致癌物亚硝胺。因而，降低蔬菜硝酸盐积累技术的研究已成为当前人们越来越关注的热点。本论文通过田间试验，研究了稀土、微肥和硝化抑制剂对叶菜类蔬菜硝酸盐和亚硝酸盐含量、产量和养分吸收以及维生素C和可溶性糖含量等品质指标的影响。供试土壤为红菜园土和冲积菜园土。供试蔬菜为冬季小白菜和夏季小白菜。得到的结果如下： 1．在供试的5种微肥和稀土肥种，喷施钼肥和锰肥降低蔬菜硝酸盐含量效果最佳，显著增强了硝酸还原酶活性。微肥B、Zn和稀土肥叶不同程度的降低了蔬菜硝酸盐含量，但其效果次于微肥Mo和Mn肥。而微肥Cu的效果最差。硝酸还原酶活性与蔬菜硝酸盐含量之间呈现显著的负相关性。 2．三种硝化抑制剂HQ(氢醌)、DCD(双氰胺)和TU(硫脲)在蔬菜的不同时期均不同程度的降低了蔬菜硝酸盐含量，但是不同供试土壤上的试验反映的情况不完全一致。三种硝化抑制剂在试验的不同时期均降低了土壤硝酸盐含量，使施入的氮肥中的氮较长时间以硝态氮形式存在，从而降低蔬菜在一定时期内对硝酸盐的吸收和积累，减少地下水硝酸盐的污染。 3．稀土和微肥对蔬菜亚硝酸盐含量的影响不明显，且无明显规律性。但每次试验蔬菜的亚硝酸盐含量很低，均没有超过卫生标准。随着蔬菜的生育期进展，蔬菜体内亚硝酸盐含量逐渐减少。硝化抑制剂处理的蔬菜也表现出这样的趋势。且三种硝化抑制剂能够不同程度的降低蔬菜亚硝酸盐含量。 4．三种硝化抑制剂均明显的提高了蔬菜对氮肥和磷肥的吸收，对钾肥的影响不大，其中DCD提高的效果最好。三种硝化抑制剂均能不同程度的提高蔬菜产量，其中效果最好的是DCD。稀土和微肥对蔬菜产量和养分吸收没有明显的影响。更多还原

【Abstract】 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.更多还原