(DSB[WSB), and water regime (NF[F) at the early
growth stage.
One of the most interesting findings, however, was that
older seedlings, after transplanting fared relatively better in
flooded soil, which was more conducive to their developing
greater root length density. However, their root growth was
mostly at shallow soil depths, not going as deep as the roots
of younger seedlings in NF soil (Table 1). Better and
deeper root growth was exhibited by the younger seedlings
raised in a dry seedbed after being transplanted into nonflooded
soil. This differentiation in responses could be due
to a preference in older seedlings for shoot growth over
root growth and to a dominance of NH4
? in the soil
solution (Sah and Mikkelsen 1983). Non-flooded soil, it
was seen, generally improved plants’ root growth in the
subsoil layer, with this effect seen more in seedlings that
were transplanted at a younger age (12 days) than in older
ones (30 days). Also, there was better uptake of N by
younger seedlings grown in a dry seedbed. This could
contribute to their greater root length density and to a
greater number of lateral roots that would improve the
plants’ acquisition of nutrients from the soil.