【作者】 栗娜娜；

【导师】 郭世荣；

【作者基本信息】 南京农业大学 ， 蔬菜学， 2008， 硕士

【摘要】 青花菜含有丰富的类胡萝卜素、抗坏血酸（维生素C）和生育酚（维生素E）,同时还具有天然抑制诱变剂（吲哚类和酚类物质）,可以广泛抑制癌变和肿瘤的发生。本文以青花菜为试验材料,采用无机基质盆栽方式,在生长适应氮浓度范围内,研究氮素营养对青花菜生长、品质、矿质元素含量、叶片光合特性、活性物质含量以及抗氧化能力的影响,为人们有效合理施用肥料,生产出高营养且具食疗功效的高档青花菜产品提供理论依据。主要结果如下:低氮水平显著降低了青花菜株高、叶片数以及花球直径和干重,适当提高氮素水平可以有效的提高青花菜的花的生长指标,提高氮素水平增加了花球中的Vc、可溶性蛋白、游离氨基酸含量以及矿质元素含量的升高,碳水化合物含量总体呈降低趋势。增加氮素浓度,青花菜叶片的叶绿素、类胡萝卜素含量以及Pn、Gs均呈升高趋势,Ci呈降低趋势。氮素处理对叶绿素荧光参数的影响不显著,但在较高供氮处理下,有利于PSⅡ光合电子传递量子效率（ΦPSⅡ）、光化学淬灭系数（qP）及PSⅡ光化学效率（Fv/Fm）的提高,同时降低非光化学淬灭系数（qN）。由此表明适当增加氮素营养有利于青花菜叶片光合能力的提高。两品种花球的总酚含量随着氮浓度的增加呈降低的变化趋势,当供氮浓度高于10mmol·L^-1,总酚含量显著降低;花球中主要含有槲皮素和山萘黄素两种黄酮醇物质,而且山萘黄素含量是槲皮素的1.48倍,在低氮(5 mmol·L^-1)处理下,两品种花球的槲皮素含量和绿优2号的山萘黄素含量显著高于其他处理。提高供氮水平可以有效提高青花菜抗氧化色素的含量,当氮浓度为15 mmol·L^-1时,β-胡萝卜素和叶黄素含量最高,且花球抗氧化物质与总N含量之间呈显著正相关。增加供氮浓度,花球的DPPH自由基清除率和FRAP值呈降低的变化趋势,限制了抗氧化能力。通过相关性分析发现,两品种花球的FRAP值与酚类物质的正相关性显著高于DPPH自由基清除率。以上结果表明偏高的氮素水平15 mmol·L^-1有利于提高青花菜抗氧化色素的含量。由以上结果说明,通过氮营养水平能够调控青花菜酚类物质合成和抗氧化能力,从而为生产高营养品质的青花菜产品提供了可能的途径。青花菜叶片中黄酮类物质只含有山萘黄素,在缺氮（NO）处理下,山萘黄素、PAL和PPO酶的活性含量显著高于N15、N40水平。更多还原

【Abstract】 Broccoli inflorescence is a good source of health promoting compounds since it contains carotenoids, vitamin C, tocopherols （vitamin E）, glucosinolates, polyphenolics and other minor compounds. Recent studies have shown the relevant bioactive components against various types of cancer and cardiovascular diseases. This paper studied the effects of different nitrogen supply on quality and antioxidant activity in heads of broccoli, the objectives are to know how nitrogen affect the nutritional quality and antioxidant activity in heads of broccoli. The results are summarized as follows:The effects of (5, 10, 15 and 20 mmol·L^-1) on the head growth, nutrition quality were investigated in two broccoli （Brassica olerecea var. italica） cultivars （late maturity cv. Malasong and middle early maturity cv. Lüyou No.2 ） by inorganic medium culture.The results showed that plant height, head diameter, head fresh and dry weight increased with increasing nitrogen supply, simultaneously also improved soluble protein, free amino acid and nitrate accumulation, but the Mg content, the Vc, the soluble total sugar decreased, these suggeated that the suitable level is advantageous to enhances the broccoli nutrition quality and the antioxidant ability.The results showed that the content of chlorophyll, carotenoid, net photosynthetic rate （Pn） and stomatal conductance （Gs） increased significantly with increasing the supply of nitrogen nutrition, but intercellular CO₂ concentration （Ci） decreased. Nitrogen application was little affected on chlorophyll fluorescence characteristics in leaves of broccoli, however, in comparison with the lower nitrogen supply, the actual efficiency of PSII （ΦpsII）, photochmical quenching （qP）, maximal photochemical efficient （Fv/Fm） was promoted in higher nitrogen supply, at the same time non-photochemical quenching （qN） was inhibited. These results suggested that increased nitrogen applied was benefical to promote photosynthetic capacity in broccoli to a certain extent.The results showed that total phenolic content decreased with increasing nitrogen supply in heads of broccoli, especially when applied nitrogen level was higher than 10 mmol·L^-1. Quercetin and kaempferol were identified in broccoli head, and kaempferol content was 1.48 times higher than quercetin content, and their contents reached highest level when applied nitrogen concentration was 5 mmol·L^-1. Increasing nitrogen supply decreased DPPH radical scaveging and FRAP value, and markedly inhibited the antioxidant activity in broccoli head when nitrogen supply level was 20 mmol·L^-1 . A significantly positive correlation was found between FRAP value and the phenolic content in two cultivars. Compared with two cultivars, the head growth of cv. Malasong was better than that of cv. Lüyou No.2, but was contrary to total phenolic and antioxidant activity. These results clearly demonstrated the phenolic substances and antioxidant activity in broccoli were strongly affected by fertilizer regimes especially nitrogen application level. The antioxidant matters availably advanced with increasing nitrogen supply. The content ofβ-carotene and lutein were the highest on the higher nitrogen level 15mmol·L^-1.the antioxidant matters were positively correlated with the total N content of head in broccoli at significant level. These suggested that the higher nitrogen level 15 mmol·L^-1 is advantageous to enhance the broccoli nutrition quality and the antioxidant matter.The effects of nitrogen deficiency (0 mmol·L^-1) and excessive nitrogen supply (40 mmol·L^-1) on the flavonoids, PAL and PPO activity were investigated in two broccoli cultivars leaves （early maturity cv. Qingfeng and middle maturity cv. Liiyou No.2 ） by inorganic medium culture. The results showed that flavonoid content on deficiency treatment was signific4ntly higher than excessice nitrogen treatment and control (15 mmol·L^-1), Increasing nitrogen supply level significantly decreased the activity of PAL and PPO.更多还原