|
The
development cycle of sweetpotato from crop establishment to harvesting the
storage roots takes place in three phases within a time span of 90-150 days. The
growth duration depends on the variety and on the environmental conditions. The
three phases of a variety maturing in four months under tropical conditions are
presented below:
|
Week |
Development Phase |
Characteristics |
|
1
2
3
4 |
I
Establishment phase
|
-
Planting
-
Fast growth of roots
-
Slow growth of vines
|
|
5
6
7
8 |
II
Intermediate phase
(storage root initiation)
|
|
|
9
10
11
12
13
14
15
16
17 |
III Final
phase
(storage root bulking) |
-
Growth of vines slows and
finally stops
-
Rapid bulking of storage
roots
-
Transportation of
substances from leaves to storage roots
-
Reduction of leaf area as
old leaves yellow and fall
-
Harvesting
|
Storage
root formation may begin as early as four weeks after planting, and on average
between 4-6 weeks, depending on the variety and the environmental conditions.
Favourable conditions during the first month after planting are of vital
importance for storage root initiation. At seven weeks after planting, 80%
of the storage roots have already been formed, and between 8-12 weeks after
planting the plant will stop forming new storage roots. After that, all energy
is devoted to the bulking of the storage roots. When many storage roots are
formed on a plant, the weight per root is normally low, while few roots per
plant normally results in big roots.
Vine growth of a
healthy sweetpotato crop, in which all requirements for maximum development are
fulfilled, is extremely abundant and less susceptible to problems such as losses
due to insects, diseases and nutritional disorders. Although parts of the leaves
may be eaten by certain pests, such as leaffolders, tortoise beetles and
grasshoppers, a healthy plant is able to compensate for such damage. Vine growth
normally reaches a maximum half way through the final phase. At that stage the
foliage of the crop looks most lush. After that, vine density decreases, because
the plant uses more and more energy to fill the storage roots rather than to
form and maintain the leaves. Moreover, the substances produced in the leaves
are transported to the storage roots. Vines attacked by pests are no longer
replaced. Some leaves become old, yellow and fall off.
Source:
van de Fliert, E. and Braun, A. 1999. Farmer field school for integrated crop
management of sweetpotato. Field guides and technical
manual. International Potato Center. Lima, Peru. 266 p.
|
Growth
habit
Root
system
Stem
Leaves
Flowers
Fruit
and seeds
Storage
root |
