春大豆生长中对不同氮源的吸收利用

ABSORPTION AND UTILIZATION OF DIFFERENT NITROGEN SOURCES DURING THE GROWTH OF SOYBEAN PLANT

利用^15N示踪技术和框栽方法，对大豆不同生育期（苗期V4，初花期R1，盛花期R2，结荚初期R4，鼓粒期R5，成熟期R6，收获期R8）各部位及全株氮素来源进行系统的研究。结果表明，在大豆生育前期土壤氮和肥料氮是根、茎、叶片氮素的主要来源，在生育后期根瘤固氮开始增加；随生长大豆荚果氮素中土壤氮所占比例逐渐减小，根瘤固氮所占比例逐渐增加，并在收获期（R8）达到总量的70．6％，肥料氮所占比例一直很低。苗期至初花期（V4～R1）是无机氮营养期，大豆主要依靠土壤氮和肥料氮；初花期至鼓粒期（R1～R5）是无机氮营养与根瘤固氮并行期，既依靠土壤氮和肥料氮，又有根瘤固氮的供应；鼓粒期至收获期（R5～R8）是根瘤固氮营养期，主要依靠根瘤固氮。

^15N tracer technique and frame-planting method were applied to investigate the absorption and utilization of nitrogen source in soybean plant in different growth stage （seedling stage V4, early-bloom stage R1, full-bloom stage R2, early-poding stage R4, pod-peak stage R5, muture stage R6, harvest stage R8 ） . The results indicated： the nitrogen of root, stem and leaf was mainly from soil and fertilizer nitrogen at growth stage, and the nitrogen from root nodule azotification started and increased at later growth stage. In the nitric proportion of bean pods, the soil nitrogen was decreasing and root nodule azotification was increasing with the growth in later stage, and 70.6 % of total nitrogen at Rs stage was from root nodule azotification, the proportion of fertilizer nitrogen stayed at low level all the time. At the vegetative period of inorganic nitrogen lasted from V4 to R4, soybean was mainly depending on soil nitrogen and fertilizer nitrogen; but in the period of R1- R5, inorganic nitrogen nutrition was parallel to root nodule azotification, the soybean depended not only on soil nitrogen and fertilizer nitrogen, but also on the supply of root nodule azotification; when it came to the root nodule azotification stage of R5- R8, soybean mainly relied on root nodule azotification.