Nitrogen uptake and use of two contrasting maize hybrids differing in leaf senescence

Author: Ma B.L.   Dwyer L.M.  

Publisher: Springer Publishing Company

ISSN: 0032-079X

Source: Plant and Soil, Vol.199, Iss.2, 1998-02, pp. : 283-291

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Abstract

In eastern Canada, the use of fertilizer N has been identified as the most energy-consuming component of maize (Zea mays L.) grain production. As the economic and environmental costs of excessive N fertilization rise, there is an increased emphasis on selection of hybrids with greater N use efficiency (NUE; defined as the ratio of the amount of ^15N recovered in grain or stover dry matter to the amount of fertilizer ^15N applied to the soil in this study). Using an ^15N-labelling approach, a field study was conducted on a tile-drained Brandon loam soil (Typic Endoaquoll) on the Central Experimental Farm at Ottawa, Canada (45°22′ N, 75°43′ W) in 1993 and 1994. Fertilizer N uptake and partitioning within the plant in relation to dry matter changes were monitored during development of a current stay-green maize hybrid and an older early-senescing hybrid grown with three fertilizer N levels (0, 100, 200 kg N ha^-1). Dry matter, N concentration and ^15N atom% enrichment of plant components were determined at five growth stages. The current stay-green hybrid, `Pioneer 3902' had greater NUE than the old early-senescing hybrid, `Pride 5', which was associated with 24% more dry matter production and 20% more N uptake during grain fill for Pioneer 3902. There was no indication of greater allocation of N to the grain in Pioneer 3902. Our data suggest that prolonged maintenance of green leaf area for photosynthate production during grain fill and the ability to take up available soil N later in grain filling are characteristics of maize hybrids with greater NUE.

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