氮素形态对小麦花后不同器官内源激素含量的影响

 采用盆栽方法，研究了酰胺态氮、铵态氮和硝态氮对小麦（Triticum aestivum） 花后根系、旗叶和籽粒内源激素IAA、GA₃、ABA和ZR含量的影响。结果表明，小麦不同器官的内源激素含量对3种氮素形态的响应不同。氮素形态调节籽粒灌浆是通过根系、旗叶和籽粒中内源激素的协同作用而实现的。酰胺态氮与硝态氮处理相比，小麦花后5～15 d，旗叶GA₃含量、籽粒IAA和ABA含量较高，籽粒灌浆速率（Grain-filling rate, GFR）较高；花后15～25 d，根系GA₃含量、旗叶IAA和GA₃含量、籽粒ABA含量较高，籽粒IAA含量较低，GFR较低。铵态氮与硝态氮处理相比，小麦花后5 d，籽粒ZR含量较高；花后15 d前后，籽粒IAA、ABA含量较低，GFR 较低；花后20～25 d，根系ZR、GA₃含量较低，旗叶IAA、GA₃含量较低，ABA含量较高，籽粒 ABA、GA₃含量较低，IAA含量较高，GFR较高。铵态氮比硝态氮处理的小麦籽粒粒重显著增加。 铵态氮和酰胺态氮处理比硝态氮处理增产显著。建议在‘豫麦49’施肥时，使用铵态氮或酰胺态氮并配施硝化抑制剂。

EFFECTS OF NITROGEN FORMS ON ENDOGENOUS PLANT HORMONES CONTENT IN DIFFERENT ORGANS OF WHEAT AFTER ANTHESIS

Background and Aims Applying different forms of nitrogen is an important method to regulate nitrogen metabolism of wheat. Endogenous plant hormones play an important role in grain filling of wheat. The objectives of this study were to 1) elucidate the effects of nitrogen forms on endogenous hormones content in roots, flag leaves and grains of wheat after anthesis, and 2) find nitrogen application methods for the wheat cultivar `Yumai 49’. Methods Pot experiments utilizing a sandy loam soil and wheat cultivar‘Yumai 49’were completed during 2003-2005. Nitrogen forms were CONH₄-N (urea), NH₄- N(NH₄HCO₃) and NO₃-N(NaNO₃), and nitrification inhibitor dicyandiamide (DCD) was applied in CONH₄-N and NH₄-N treatments. Spikes of wheat which flowered on same day were marked and roots, flag leaves and grains were sampled at fixed dates. Each sample weighed 0.5 g FW and was stored at -40 ℃. The enzyme-linked immunosorbent assay (ELISA) method was used to determine the content of IAA, GA₃, ABA and ZR. Key Results Compared with NO₃-N treatment, GA₃ content in CONH₄-N treated flag leaves and IAA and ABA content in grains were higher 5-15 days after anthesis, and the grain-filling rate (GFR) was higher in this period. GA₃ content in CONH₄-N treated roots, IAA and GA₃ content in flag leaves, and ABA content in grains were higher, IAA content in grains was lower 15-25 days after anthesis, and the GFR was lower in this period. Compared with NO₃-N treatment, ZR content in grains was higher 5 days after anthesis in all NH₄-N treatments. IAA and ABA content in grains was lower about 15 days after anthesis, and the GFR was lower in this period. ZR and GA₃ content in roots, IAA and GA₃ content in flag leaves, and ABA and GA₃ content in grains were lower, ABA content in flag leaves and IAA content in grains were higher 15-25 days after anthesis and the GFR was higher in this period. Compared with NO₃-N treatment, the grain weight of wheat was significantly greater in NH₄-N treatment, and grain yield was increased significantly either in NH₄-N or CONH₄-N treatments.  Conclusions This study showed that endogenous hormones in wheat responded differently to nitrogen forms after anthesis. The GFR of wheat regulated by nitrogen forms was realized through the balance of endogenous hormones in roots, flag leaves and grains. We recommend that CONH₄-N or NH₄-N mixed with DCD be applied to wheat cultivar‘Yumai 49’.