紫色土施氮对莴笋营养效应的研究

3种紫色土施用化学氮肥盆栽莴笋的研究结果表明,石灰性紫色土莴笋生长状况最差,施中、高氮明显降低其株高、根重和茎、叶产量,而中性紫色土施氮的生物效应最佳。酸性紫色土莴笋叶片((NO3--N)/(TN)100)值最低、((AAN)/(TN)100)值最高;植株氮素表观利用率为中性土酸性土石灰性紫色土。中性、酸性和石灰性紫色土施氮分别为133、67、67mg/kg土时,莴笋3个生长期叶片N/P、N/K、K/P值变异系数(C.V％)小,生物量高。施氮显著提高中性和石灰性紫色土莴笋叶片NRA(r值0.9275*～0.9956* *),降低CAT活性和Vc含量,使茎中(△NO3-)/(△FN)值高于酸性紫色土2～5倍,但却提高酸性紫色土莴笋水溶性氨基酸、粗蛋白和可溶性糖含量,改善其食用价值。

EFFECT OF NITROGEN FERTILIZER ON LETTUCE NUTRITION IN PURPLE SOILS

Effects of nitrogen fertilizer on lettuce plant growth, nutrient metabolism and quality were studied in a pot experiment with three purple soils. Lettuce growth traits, such as plant height, root weight", stem and leaf yield, all of which were decreased obviously by applying high and medium levels nitrogen fertilizer in calcareous purple soil, whereas the best response of lettuce to nitrogen fertilizer appeared in neutral purple soil. The percentage of NO₃^--N/TN and AAN/TN in lettuce leaf in acid purple soil, the former was the lowest, but the latter was the highest. The apparent recovery rate of nitrogen for lettuce order was neutral purple soil>acid purple soil. >calcareous purple soil. The coefficeient of variation of N/P, N/K and K/P ratio value in lettuce leaf at three growth stages were minimum and plant biomass were maximum at 133, 67 and 67 mgN/kg in neutral, acid and calcareous purple soils, respectively. The application of nitrogen fertilizer to neutral and calcareous purple soils could increase significantly the NRA of lettuce leaf (r values 0.9275^* -0.9956^{* *}) and reduce the CAT as well as Vitamine C content, the NO₃^-/FN ratio values in lettuce stem were inhanced about 2~5 times, relative to that of acid purple soil. Nitrogen fertilizer could raise lettuce soluble amino acid, crude protein and soluble sugar content and improved the quality of lettuce in acid pruple soil.