Dry root weights of narrow spaced plants were significantly
lower in the shallow soil layer, and root reductive activity in
each soil layer was markedly reduced, along with lower root
biomass and plant nitrogen uptake. Narrow spacing led to
higher nitrogen use efficiency in grain, harvest index and dry
matter production capacity. The nitrogen translocation rates
of roots, leaves and stem-sheaths were higher during grain
formation. However, these increases did not compensate for
the impact of decreased nitrogen accumulation on production.
Thus grain yield increases in summer maize could be
achieved with modest increases in plant density.