Grain Nitrogen Source Changes over Time in Maize: A Review
- Ignacio A. Ciampitti * and
- Tony J. Vyn *
Understanding the sources of grain N uptake (Grain N) in maize (Zea mays L.) and especially the trade-off between reproductive-stage shoot N remobilization (Remobilized N) and reproductive-stage whole-plant N uptake (Reproductive N) is needed to help guide future improvements in yield and N use efficiency (NUE). Therefore, a literature review was performed to investigate the knowledge gap concerning changes over time in Grain N sources and on N partitioning to the grain and stover plant fractions at maturity. The synthesis–analysis was based on 100 reports, which were divided into two time intervals: (i) research conducted from 1940 to 1990—“Old Era”—and (ii) research conducted from 1991 to 2011—“New Era.” The most remarkable results were (i) Grain N concentration was the main parameter that has changed over time, (ii) Reproductive N contributed proportionally more to Grain N for the New Era while Reproductive N and Remobilized N contributed equally to Grain N for the Old Era, (iii) Remobilized N was primarily associated with vegetative-stage whole-plant N uptake (Vegetative N), which was constant across eras, although the proportion of the Remobilized N itself seems to be driven by the ear demand, (iv) complex plant regulation processes (source:sink) appeared to influence Reproductive N, and (v) stover N concentration gains mirrored the grain N concentration as the plant N uptake increased at maturity in both eras. This new appreciation for the changes over time may assist directed selection for yield and NUE improvements.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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