Effect of irrigation rate on absorption and translocation of nitrogen under different nitrogen fertilizer rate in wheat

Chino. 【目的】研究灌溉量和施氮量对氮素吸收转运特性的影响及其与籽粒蛋白质含量的关系。【方法】试验在山东农业大学实验农场防雨池栽条件下进行，选取高产强筋小麦品种济麦20为试验材料。利用. 5N同位素示踪技术，于开花期和收获期分别测定各器官中不同来源氮素的吸收量与分配比例、成熟期籽粒产量、水分利用率等。【结果】施氮量和灌溉量对植株吸氮量、籽粒产量、籽粒蛋白质含量的影响存在互作，其中灌溉量的效应大于施氮量的效应，是影响以上诸项指标的主导因素。同一施氮量条件下，增加灌溉量，成熟期氮素吸收总量增加，但籽粒蛋白质含量降低；随灌溉量增加，土壤氮的吸收量和占总氮量的比例增大，肥料氮的吸收量和占总氮量的比例减小，表明增加灌溉量导致氮素吸收总量的增加主要是通过提高土壤氮的吸收量和占总氮量的比例实现的；增加灌溉量对籽粒蛋白质含量的稀释效应则主要表现为，增加灌溉量抑制开花后营养器官中积累的氮素向籽粒的转移，最终不利于籽粒蛋白质含量的提高。灌溉量不变，施氮量由120 kg・ha. 1增加到240 kg・ha. 1，各营养器官中氮素的积累量增加，但开花后营养器官中积累的氮素向籽粒的转移率降低，最终籽粒蛋白质含量亦不高。【结论】施氮量为120 kg・ha. 1，全生育期灌溉底墒水和拔节水（W2N1）的处理，小麦植株吸收的氮素向籽粒分配量大，开花前营养器官中积累的氮素向籽粒转移率高，籽粒蛋白质含量最高，水分利用率亦最高，但籽粒产量仅为5 534.26 kg・ha. 1；施氮量为120 kg・ha. 1，全生育期灌溉底墒水、拔节水和开花水（W3N1）的处理，小麦植株吸收的氮素向籽粒分配量、氮素向籽粒转移率、水分利用率均较高，籽粒蛋白质含量达14.54%，籽粒产量达7 411.37 kg・ha. 1，是本试验的最佳处理。

Inglés. [Objective] The objective of this study was to determine the effects of irrigation rate and N fertilizer rate on the absorption and translocation of N in wheat and their relationship to grain protein content. [Method] Research was carried out at the Experiment Station of Shandong Agriculture University by . 5N isotope tracing technique, under a rain-proof trough shelter. A winter wheat cultivar with high grain yield and strong gluten, viz. Jimai20, was selected in the study. The amount and proportion of N from different sources, grain yield at maturity, and water use efficiency were measured. [Result] The results were as follows. Both irrigation rate and N fertilizer rate affected N absorption amount （NAA）, grain yield （GY）, and grain protein content （GPC） significantly and there was a correlation between irrigation rate and N fertilizer rate. Irrigation rate played a more important role than N fertilizer rate and was the dominant factor. When increasing irrigation rate with identical fertilizer rate, the total NAA increased, but the GPC decreased. At the same time, when improving irrigation rate, the absorption amount and proportion of soil N increased and those of fertilizer N decreased correspondingly, indicating that the increase of NAA mostly came from soil N. The results also indicated that the increased irrigation rate inhibited the translocation of N from vegetable organs to grain and then decreased GPC, and that was the diluting effect of irrigation. When N rate increased from 120 kg・ha. 1 to 240 kg・ha. 1, the N amount accumulated in the vegetable organs increased, but the translocation proportion and GPC decreased. [Conclusion] Under the conditions of this experiment, the NAA in grain, the N translocation proportion, the GPC and the water utilization efficiency of W2N1（the treatment with 120 kg N・ha. 1 and basal-irrigation ＋ jointing-irrigation） were highest, but the GY was as low as 5534.26 kg・ha. 1. W3N1 （the treatment with 120 kg N・ha. 1 and basal-irrigation ＋ jointing-irrigation ＋anthesis-irrigation） was the best treatment in this experiment,with 14.54% of GPC and 7411.37kg・ha. 1 of GY.