不同氮素形态配比对生菜生长、品质和保护酶活性的影响

研究了4种氮素形态配比(NO3^--N^2NH4^ -N分别为100：0，75：25，50：50和0：100)对生菜(品种为“弘农”和“绿领”)生长、品质和叶片保护酶活性的影响。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10d后才表现出显著差异。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。定植后13d内各处理叶片中的(MDA含量无显著差异，其后对于完全氨态氮处理和NO3^--N^2NH4^ -N为50：50处理，MDA含量迅速增加。完全硝态氮处理下硝酸盐含量最高，随着氨态氮比例的增加，生菜中硝酸盐含量逐渐降低，NO3^--N^2NH4^ -N为75：25处理下的可溶性糖和可溶性蛋白质的含量最高。

Effects of Nitrogen Form Ratios on the Lettuce Growth and Activity of Protective Enzymes

Effects of four nitrogen forms ratios(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 protec-tiase enzymes were investigated. The results showed that the fresh and dry weight of shoot and root decreased with increasing of ammonium nitrogen form ratio, number, length, leaf width and water content decreased significantly whereas root/shoot ratio increased. The difference between different treatments on the shoot growth was significant at ten days only after transplanting. SOD and POD activities increased with increasing of ammonium nitrogen form ratio. Different nitrogen form ratios had no significant influence on the MDA content at 13 days within transplanting, but for complete ammonium nitrogen and NO3--N:NH4 + -N(50: 50), MDA content increased sharply at 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 ratio, the contents of soluble sugar and soluble protein were the highest with the treatment of NO3--N:NH4 + -N(75 : 25).