Studies on the systems and controlling factors in translocation and destribution of absorbed nitrogen in gramineous crops.

为明确水稻氮素吸收和运转的控制因素，采用田间施氮试验，研究了氮素在水稻体内的分配规律<15>。水稻吸收氮素的分配因叶位和内外半叶的不同而不同。外半叶氮素含量高于内半叶的原因可能是外半叶宽度较窄，外半叶上的节根体积较大，外半叶上的节根吸收的氮素只能转移到外半叶，不能直接再转移到另一侧。氮素含量与叶色强度呈高度正相关。叶色强度最稳定的叶斑位于最上部完全展开的第二片叶的中脉两侧中央。在小麦植株中，内外半叶的叶色差异不明显。小麦和玉米叶色强度叶位变异程度大于水稻，但叶色强度叶位变异的基本趋势与水稻一致。研究了豆科植物作为绿色肥料、大麻和花生对小麦氮素营养的影响。花生全氮含量高于笋麻。各豆科作物吸收的氮素占后茬小麦全氮的贡献率，花生区为11.2%，胡麻区为9.4%。花生对后茬小麦的氮素贡献量大于大麻。

To clarify the controlling factors in absorption and translocation of nitrogen in rice plant, the distribution of nitrogen was researched by using ^<15>N fertilizer. The destribution of absorbed nitrogen was varied with the leaf positions and the inside and outside half-leaves in rice plant. The reasons of the fact that the nitrogen contents of an outside half-leaf was higher than that of an inside half-leaf were considered that the width of outside half-leaf was narrower, the volume of nodal roots on an outside half-leaf was larger, and the nitrogenabsorbed by outside nodal roots was translocated only to outside half-leaves and could not retranslocate directly to another side. The aitrogen contents showed a high positive correlation with the leaf color intensity. The most stable leaf spots in leaf color intensity were at the center of lateral sides of a midrib of leaf blade on uppermost fully expanded second leaf. In wheat plant, the defferences in leaf color between outside and inside half-leaf were not recognized. The degrees of variation in leaf color intensity on leaf positions in wheat plant and corn plant were larger than that of rice plant, but, basic tendency of variation in leaf color intensity in leaf positions corresponded to that of rice plant. The effects of legumes incorporated as green manures, sunn hemp and peanut, was examined for nitrogen contribution to the succeeding wheat. Total nitrogen content was higher in peanut compared with sunn hemp. The contribution percentage of nitrogen accumlated by each legume to total nitrogen of the succeeding wheat was 11.2% on the peanut plot and 9.4% on the sunn hemp plot. Peanut crop contribated more nitrogen to the succeeding wheat compared with sunn hemp.