用^(15)N示踪研究不同氮水平下剑麻的氮素吸收利用特性

Nitrogen Utilization Characteristics of Sisal on Different Nitrogen Rates, Using ^(15)N Isotope Tracer Technique

采用盆栽试验和15N示踪技术,研究4个不同氮(N)水平对剑麻生长及氮素吸收利用特性的影响。结果表明,施氮显著提高剑麻株高、叶长、叶宽和根粗。施氮处理地上部鲜重、含水量、全氮含量和吸氮量均有所增加,但施氮处理之间差异不显著。剑麻地上部和根系吸收的肥料N随着氮水平增加而增加,各处理整株肥料N比例,以示踪法计算为24.2%~32.6%,差减法计算为34.6%~53.1%。不同氮水平下剑麻氮素利用率变化不明显,整株氮素利用率,示踪法计算为20.0%~22.0%,差减法计算为30.0%~35.7%。可见,剑麻吸收的肥料氮低于土壤氮;剑麻的氮素利用率偏低;以示踪法求得的肥料N比例和氮素利用率均低于以差减法求得的结果。

Pot experiment and15 N tracer technique were used to explore the effects of different nitrogen levels on the growth and nitrogen utilization characteristics of sisal. Four levels of nitrogen fertilizer were： none, low（0.69 g）,medium（0.98 g） and high（1.24 g）. The results showed that plant height, leaf length, leaf width, leaf fresh weight and water content of the leaf increased significantly when using nitrogen fertilizers. The content of N and the amount of N accumulation of the aboveground parts and roots increased as the application of nitrogen fertilizers increased. The uptake of N from the fertilizer（ Ndff） by above-ground parts and roots all increased with the N rates. The percentage of N from the fertilizer（%Ndff） ranged between 24.2% and 32.6% when calculated by the tracer method, and 34.6%-53.1% when calculated by the difference method. N uptake efficiency of plants ranged between 20.0% and 22.0% when calculated by the tracer method, and 30.0%-35.7% when calculated by difference method, whereas no significant differences were found between the treatments. The results showed that（1） the uptake of N from the fertilizer was higher than from soil,（2） the N uptake efficiency of sisal was low,（3）the values of the percentage of N from the fertilizer and N uptake efficiency that calculated by the tracer method were lower than that calculated by the difference method.