获得目前玉米杂交种高额产量的主要策略是选择对高N肥供应反应良好的品种(Hageman,1979)。但是,N肥的消耗和因过量施肥产生环境污染的担心,促使人们渴望找到既能获得最高产量又能减少高N投入的另一种办法。选育更有效地吸收和利用土壤N的玉米品种,便是这种方法之一。在硝化作用不受抑制的大多数农业土壤中,硝酸盐是植物可利用的主要形式(Haynes等,1978),它的吸收、还原和以营养性还原 The primary strategy for obtaining the current high yields of maize hybrids is to choose varieties that respond well to high N fertilizer supply (Hageman, 1979). However, the depletion of N fertilizer and fears of environmental pollution due to over-fertilization have led to an eagerness to find another way to achieve the highest yields and reduce the high N investment. Breeding of maize varieties that more efficiently absorb and utilize soil N is one such method. In most agricultural soils where the nitrification is not inhibited, nitrate is the dominant form of plant available (Haynes et al., 1978), and its uptake, reduction and nutrient reduction