Figure 1. Distribution of permafrost in the Northern Hemisphere (after Pw 1983).
the primary roots slows down after the initiation
of nodal roots. When the formation of crown roots
is delayed, the plants rely entirely on the seminal
root system for acquisition of water and nutrients
during the seedling establishment stage.
There is a continuous spectrum between the
two extremes of fibrous and tap root systems (Ren-
dig and Taylor 1989). Monocot plants have fibrous
root systems, and dicots have some variant tap
root system.
Monocots
Under favorable conditions, monocot root ex-
Figure 2. Gross morphology of two root types; a fibrous
tension rates are rapid. During the vegetative
root system (left) and a tap root system (right) in soil
phase of plant growth, root depth and root length
density (m roots m3 soil) increase with time.
(after Stem 1982).
2
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