氮在水稻中的行为及其品种间的差别

目前氮肥的利用效率很低，很多研究重点放在氮肥在土壤过程中的损失，对植物本身的氮素损失较少注意。作者利用^15NH4^ 和^15NO3^-双标记，对Indica和Japonica水稻亚种进行水培，在分蘖期、幼穗分化期、开花期施用，将培养液ρ(N)20mg／L的NH4NO3换成相同质量浓度的^15NH4^ NO3或NH^15NO3^；部分水稻在一周后收获，其他分别在分蘖期、幼穗分化期、开花期、成熟期收获。植株分成根系、地上部和穗部，对各自的全氮、^15N进行测定，计算植物的总吸收量。从施用量、植株总吸收量以及三部分总和的植株氮残存量的比较来研究氮素在两种水稻亚种中的行为。研究结果表明，两种植物都近100％吸收了所施用的^15NH4NO3或NH4^15NO3，但^15NH4^ 和^15NO3^-在Japonica的残存量要比Indica多，损失的部分可能往大气中散失了，意味着两种水稻亚种有着明显不同的氮素利用率。比较^15NH4^ 和^15NO3^-的残存量，结果表明^15NH4^ 留在植株体内要比^15NO3^-多，尤其在抽穗期施用的情况下，植物体在后期对^15NO3^-的转化能力大大减弱，但这部分的氮如何损失掉尚不清楚。比较植株体内各部分的氮素含量，发现Japonica的穗部比Indica含有更多的氮素，表明氮在前者的体内转化效率和利用效率高。试验结果表明，不同水稻亚种对氮素的利用以及不同氮素形态在其体内的行为不同。

Behavior of N within Rice Plants, Comparing between Japonica and Indica Varieties

To investigate the behavior of N within rice plants, Japonica (Hinohikari) and Indica (Hadsaduri) types were grown in the culture solution in a green house. The nitrate nitrogen (NO-3-N) or ammonium nitrogen (NH4 -N) labeled with N were supplied to + 15 both plants for one week at tillering, panicle initiation and heading stages. The rice plant was harvested immediately after application of Nat panicle initiation and heading stage respectively. By the determination of NO-3-N and NH4 -N in the solution culture, the N 15 + 15 amount absorbed from the root during one week was calculated. All harvested plants were separated into the roots, vegetative parts or ears. After the total nitrogen in each plant part was determined by the Kjeldahl method, the Nwas analyzed by emission method. 15 By comparing between Japonica and Indica plants in all growth stages, it is shown that the N amount absorbed with both 15 NH4 -N and NO-3-N remained more in the Japonica than in the Indica, while comparing between NH4 -N and NO-3-N treatments, N + + 15 amount absorbed with NH4 -N remained more in the both plants than that with NO-3-N. At maturity stage, Namount absorbed with + 15 both N forms, observed in ears, remained more in Japonica than in Indica. The result suggests that N amount remained in rice 15 plants were different between varieties and supplying N form and among N supplying period.