【作者】 徐加林；

【导师】 别之龙；

【作者基本信息】 华中农业大学 ， 蔬菜学， 2005， 硕士

【摘要】 本试验利用水培方式研究了营养液调控对生菜（Lactuca sativa L.）生长、产量及品质的影响。试验由采收前不同停止营养液供应时间、营养液浓度分段管理、不同氮素形态配比和不同营养液浓度四部分组成。 1.研究了采收前停止营养液供液时间（12天,8天,4天,0天）对生菜（品种为‘弘农’和‘青丰’）的生长和品质影响。结果表明,采收前停止营养液供液时间超过8天时,地上部的鲜重、干重、叶片数、叶长、叶宽、叶片含水量均随着停液时间的延长而显著降低,而根的鲜重、干重和根冠比则显著增加;与对照（停液0天）处理相比,采收前4天停止营养液供应对生菜的生长无显著影响。生菜叶片中的硝酸还原酶活性、可溶性糖含量随着采收前停止营养液供应时间的延长而显著增加,而生菜体内硝酸盐含量则显著降低,采收前4天停止营养液对可溶性蛋白和维生素C含量没有显著影响,但停止营养液时间超过8天时则显著降低了生菜体内可溶性蛋白和维生素C含量,表明采收前停液4天处理是比较适合生菜水培的方法。随着停止营养液时间的加长,生菜叶片和根中的有机氮、磷、钾、钙、镁含量都逐渐降低。 2.采用营养液浓度分段管理（1s-1s-1s;2s-1/2s-1s;1s-2s-1/2s;1/2s-1s-2s）即采用了四种浓度管理模型（对照;高-低-中;中-高-低;低-中-高）对生菜（品种为‘弘农’和‘青丰’）研究了其对生菜生长和品质的影响。结果表明,“中-高-低”和“低-中-高”浓度管理模型显著增加了地上部和根的鲜重和干重,而“高-低-中”浓度管理则显著抑制了生菜地上部和根的生长。在生菜的三个不同生长发育时期,早期低营养液浓度管理可促进生长,高浓度不利于鲜重、干重和叶面积的增加,中期和后期高浓度管理显著促进地上部鲜重、干重和叶面积的增加。“中-高-低”浓度管理模型显著降低了生菜采收期叶片的硝酸盐含量并增加了硝酸还原酶活性,而“低-中-高”浓度管理则极显著提高了生菜体内硝酸盐含量。“中-高-低”和“低-中-高”浓度管理显著提高了生菜的可溶性糖、可溶性蛋白和维生素C的含量,地上部和根中氮和磷的含量也显著增加,但降低钾、钙和镁的含量。“中-高-低”浓度分段管理是适合生菜水培的浓度管理模式。 3.利用4种不同氮素形态配比（NO₃^-—N∶NH₄⁺—N分别为100∶0,75∶25,50∶50和0∶100）研究了不同氮素形态对水培生菜（品种为“弘农”和“绿领”）生长和品质的影响。结果表明,随着氮素中氨态氮比例的增加,地上部和根的鲜重、干重逐渐降低,叶片数、叶长、叶宽、叶片含水量均显著降低,而根冠比则随着氨态氮比例的增加而上升;不同氮素形态配比处理对地上部生长的影响在定植10天后才表现出显著差异。随着氨态氮比例的增加,生菜中硝酸盐含量逐渐降低,硝酸还原酶活性则逐渐增加。叶绿素含量也随着铵态氮比例的增加而增加。随着氮素中氨态氮比例的增加,SOD和POD活性逐渐增加,完全氨态氮处理下SOD和POD活性最高。更多还原

【Abstract】 The effects of nutrient solution supply on the growth, nitrate accumulate and quality of lettuce （Lactuca sativa L.） were studied by means of water culture in this paper. The research includes four parts: The effect of different stop solution concentration supply times on lettuce before harvest; The effect of The effect of different N forms on lettuce; The effect of different solution concentration on lettuce. The results are as follows:1. Effects of four stopping nutrient solution times before harvest （0d;4d;8d;12d） on the lettuce （cv. Hongnong and Lvling） growth , nitrate accumulate, quality and mineral nutrient were investigated. The results showed that the times of stop the nutrition solution over 8 days, the fresh and dry weights of shoot, leaf s number , leaf length , leaf width and Shoot water content decreased gradually, whereas the fresh and dry weights of root, root/shoot ratio increased significantly. The times of stop the nutrition solution is 4 days, no effect significantly on growth of lettuce. The nitrate content and soluble sugar decreased significantly with increasing of times of stop the nutrition solution, whereas the nitrate reductase increasing significantly. When the times of stop the nutrition solution over 8 days, the soluble protein and vitamin C decreased significantly, whereas the times of stop the nutrition solution is 4 day, no effect significantly on the soluble protein and vitamin C of lettuce. N, P, K, Ca, Mg of shoot and root decreased significantly with increasing of times of stop the nutrition solution.2. Effect of different solution concentration in different stage （1s-1s-1s; 2s-1/2s-1s; 1s-2s-1/2s;1/2s-1s-2s） mean three nutrition solution concentration models （H-L-M; M-H-L; L-M-H） and the control on the lettuce （cv. Hongnong and Lvling） growth, nitrate accumulate, quality and mineral nutrient were investigated. The results showed that "M-H-L; L-M-H" made fresh weight and dry weight of shoot and root increase significantly, whereas "H-L-M" decrease significantly. The nitrate content of "M-H-L" decrease significantly, but the nitrate reductase increase significantly, whereas the nitrate content and the nitrate reductase all increase significantly. soluble sugar, soluble protein , vitamin C, N and P of "M-H-L; L-M-H" increase significantly, but K , Ca and Mg decreased significantly,whereas nutrition solution concentration models "H-L-M" was contrast with "M-H-L; L-M-H".3. Effects of four nitrogen forms （NO₃^-—N:NH4⁺—N were 100:0, 75:25, 50:50 and 0:100, respectively）on the lettuce （cv. Hongnong and Lvling） growth and the activity of protectiase enzymes were investigated. The results showed that the fresh and dryweights of shoot and root decreased with increasing of ammonium nitrogen form, leaf number, leaf length, leaf width and leaf water content also decreased significantly, whereas root/shoot ratio increased, difference between different treatments on the shoot growth was only significant ten days after transplanting. SOD and POD activities increased with increasing of ammonium nitrogen form. Different nitrogen forms had no significant influence on the MDA content 13 days within transplanting, but for the treatments of complete ammonium nitrogen and NO"3 — N:NH+4 — N（50:50）, MDA content increased sharply 10 days after transplanting. The leaf nitrate content was the highest in the complete nitrate nitrogen treatment, and it decreased with increasing of ammonium nitrogen form, the contents of soluble sugar and soluble protein were the highest in the treatment of NO3"-N:NH4+-N（75:25）.4. Effect of four nutrient solution concentration （l/4s, l/2s, Is, 2s） on the lettuce （cv. Hongnong and Lvling） growth, nitrate accumulate, quality, mineral nutrient and the activity of protectiase enzymes were investigated. l/2s made the fresh and dry weights of shoot and root, leafs number, leaf length, leaf width and Shoot water content increasing gradually. The rest are Is, l/4s and 2s. The nitrate content and the chlorophyll content increasing significantly with increasing of the nutrition solution concentration. TTie SOD activities of 2s changed low into high from the seedling period to harvest period. The MDA content of 2s was more significantly than the control, whereas the MDA content l/2s was less than the control. The nitrate content, soluble sugar, soluble protein and vitamin C of lettuce of 2s increasing significantly, whereas l/2s decreased significantly. N, P, K, Ca of l/2s in shoot and root increasing significantly, Mg of shoot and root decreased significantly with increasing of the nutrition solution concentration.更多还原