Management of rice production systems to increase productivity

Figure 12. Number of New Roots Re‐growth and Bulk Root Length of
cv ITA 306 and IET 3137
The higher the quantity of new roots and bulk root produced within a
specific time span, the better the quality of the seedling. Although the number
of new roots produced was higher with age because more rooting buds are
produced with age, the bulk density at 21 days was lower than at 7 days for cv
IET 3137, and the number of new roots regrowth was not significantly
different between 7 and 14 days old seedlings.
This further validates the fact that younger seedlings are more viable
and have higher vigor after uprooting and transplanting. Older seedlings
have less vigor after being uprooted and transplanted, even though they will
eventually produce a relatively higher bulk root density, they have a relatively
much higher above‐ground biomass to support. Before adequate root system
is re‐established after uprooting and transplanting of an older seedling, almost
all its leaves will die back. The ratio of total new root regrowth to above‐
ground biomass for 7‐days old seedlings is much lower than that of older
seedlings. This is essential to support faster recovery after uprooting and
transplanting.
In practice, when younger seedlings are uprooted, less damage is done
to the root system than for older seedlings. Thus there is less die‐back of the
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