【作者】 罗金葵；

【导师】 陈巍； 沈其荣；

【作者基本信息】 南京农业大学 ， 植物营养学， 2006， 硕士

【摘要】 蔬菜在其组织及液泡内累积了大量的硝酸盐，对人体的健康构成了危害。如能从蔬菜自身出发降低其组织及液泡内硝酸盐含量，则不仅能提高蔬菜的品质，还能提高硝态氮肥的利用率。 实验选择了两个硝酸盐含量显著不同的小白菜品种上海青(低硝酸盐累积品种)及亮白叶1号(高硝酸盐累积品种)作为供试对象，测定了这两个品种小白菜的生物量、光合能力、碳氮含量、硝态氮吸收量、不同器官(叶片、叶柄及根系)组织及液泡硝酸盐含量、硝酸还原酶活性(NRA)及其基因的相对表达量。实验还测定了氮亏缺条件下不同器官组织硝酸盐含量变化情况、叶片及根系亚细胞(液泡及细胞质)硝酸盐含量变化情况以及叶片NRA变化情况。探讨硝酸盐在不同品种小白菜体内不同器官的分布、调配及同化规律，希望能为蔬菜硝酸盐累积研究提供理论基础。 实验结果如下。 亮白叶1号单株生物量仅较上海青大2.8％。上海青叶片SPAD值和光合速率分别较亮白叶1号高12％和5％。亮白叶1号单位干重含氮量较上海青大6.6％，其单位纯氮产生的干物量较上海青小。上海青单位干重含碳量较亮白叶1号大5.4％。上海青具有较高的光合速率，能为氮的同化提供较多的碳架和能量，其氮的利用效率较亮白叶1号高。 叶片、叶柄及根系液泡硝酸盐活度分别是组织硝酸盐含量的4.6、2.0和7.4倍，液泡硝酸盐活度远高于细胞质硝酸盐活度。亮白叶1号叶片、叶柄、根系液泡硝酸盐活度分别是上海青的2.4、1.7和4.3倍。不同器官组织硝酸盐含量呈叶柄＞叶片＞根系，而液泡硝酸盐活度则不存在显著差异。 亮白叶1号单位鲜重吸收的硝态氮较上海青高12.7％，但两品种差异不显著。上海青叶片、叶柄及根系NRA分别较亮白叶1号大34％、161％及32％，上海青具有较高的硝态氮还原能力。两品种硝酸盐累积差异主要取决于NRA的差异。 小白菜各器官NRA呈现叶片＞根系＞叶柄，硝酸还原酶主要在叶片中工作。更多还原

【Abstract】 Nitrate accumulated in vegetable plant tissues and vacuoles is known harmful to humanbeing health especially when people eat a lot of vegetables with high content of nitratre. Thus, increase of nitrate utilization efficiency could not only increase vegetable quality, but also increase nitrogen fertilizer use efficiency.Two pakchoi cultivars significantly different in nitrate content, Shanghaiqing with low nitrate content and Liangbaiye 1 with high nitrate content screened from twelve cultivars in previous experiments were used in this experiment. The biomass, photosynthesis capacity, carbon and nitrogen content, nitrate uptake amount of these two cultivars, tissue and vacuolar nitrate content, nitrate reductase activity (NRA) and nitrate reductase gene (Nia) relative expression amount in different organs (leaf blade, petiole and root) were measured. The time courses of tissue nitrate content of different organs, sub-cell (vacuolar and cytosolic) nitrate content and leaf blade NRA after these two cultivar plants were transferred to nutrient solution without nitrogen were also measured. Distribution, remobilization and metabolism of nitrate in different organs of the two cultivars were discussed to propose mechanisms of nitrate behave in vegetable plants.Results obtained were as followed.Biomass of Liangbaiye 1 per plant was only 2.8% higher than that of Shanghaiqing. Vacuolar nitrate activities in leaf blade, petiole and root were 4.6, 2.0 and 7.4 times of tissue nitrate contents in the respective organs, and vacuolar nitrate activity was much higher than cytosolic nitrate activity. Vacuolar nitrate activities of Liangbaiye 1 were 2.4, 1.7 and 4.3 times of those of Shanghaiqing in leaf blade, petiole and root. Tissue nitrate contents of更多还原