Agriculture Reference
In-Depth Information
5
Plant Growth and Development
Carrie H. Wohleb,
1
* N. Richard Knowles
2
and Mark J. Pavek
2
1
Washington State University, Ephrata, USA;
2
Department of
Horticulture, Washington State University, Pullman, USA
Potatoes are classified as a C
3
plant and are
members of the nightshade family (Solanaceae).
The cultivated species most commonly grown
for human consumption is
Solanum tuberosum
.
Botanically, potatoes are considered perennials,
because clones of the mother plant can develop
via daughter tubers that are left unharvested.
Depending on the cultivar and environment,
daughter tubers may sprout while the mother
plant is still alive; however, the daughter tubers
typically transition through a dormancy phase
prior to initiating new growth. The dormancy
phase usually extends beyond the natural life of
the mother plant. When potatoes are grown com-
mercially, the vines of the mother plant senesce
naturally or are killed and the daughter tubers
harvested; therefore, potatoes are an annual crop.
This chapter focuses on the growth and devel-
opment of
S. tuberosum
under commercial produc-
tion and describes how potato plant morphology
changes as plants grow and develop. To simplify
the discussion on potato development over time,
we separated this chapter into a logical series
of growth and developmental stages including
propagation, seed tuber dormancy and physio-
logical age, tuber anatomy and sprout development,
tuber initiation, canopy development, tuber bulking,
and plant and tuber maturation.
Plant and tuber development are influenced
largely by environment, particularly at key growth
stages. To produce high-quality tubers with ideal
yields, tuber size profile, shape, storability, and
palatability, commercial agronomists routinely
manipulate soil moisture and fertility, planting
date and depth, plant population and intra- and
inter-row plant spacing, source-sink relationships,
vine kill date, and harvest date. Additionally,
producing potatoes in the appropriate region and
climate zone reduces the chances of a nature-
induced crop failure. Ideal production regions have
well-drained, fertile soils,
100-180
consecutive
frost-free days, between
50
and 60 cm of rainfall or
irrigation between plant establishment and matur-
ation, a broad day/night temperature differential,
absence of extreme heat and cold during the grow-
ing season, and proximity to market, temperature-
controlled storage, and mass transportation.
5.1
Propagation: True Seed
versus Seed Tubers
Potatoes are most often propagated from vegeta-
tive tissue, either whole tubers or cut pieces of
tubers. Tubers used for propagation are typically
called seed tubers, seed potatoes, or seed pieces.
In some regions, tubers left uncut and planted
whole are referred to as “single-drop” seed potatoes.
Potato plants can be produced from botanical or
sexual seeds, but these “true” potato seeds (TPS)
