Download Vegetative Growth/Development

Chapter 7 - Plant Growth and Development
Germination and Early Seedling Growth
• In general, seed germination occurs in three stages:
– Imbibition (water uptake).
– Increase in biological activity.
– Radicle (root) and shoot emergence.
Figure 7-1
The seed on the left has not begun to germinate.
The center seed has imbibed water.
The seed on the right has the radicle & plumule emerging.
tab
Practical Horticulture 5th edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
© 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Chapter 7 - Plant Growth and Development
Germination and Early Seedling Growth
• Germination starts with the seed imibing water.
– This causes cells to swell and the seed increases in size.
• Cells elongate and begin to divide and differentiate.
• Leaves start to photosynthesize & the new plant is
then independent of energy reserves in the seed.
tab
Practical Horticulture 5th edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
© 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Chapter 7 - Plant Growth and Development
Vegetative Growth/Development - Shoots & Roots
• Strictly speaking, vegetative growth includes roots,
shoots, and leaves, but not reproductive structures.
tab
Practical Horticulture 5th edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
© 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Chapter 7 - Plant Growth and Development
Vegetative Growth/Development - Shoots & Roots
• Four principal functions of roots in higher plants are:
–
–
–
–
Anchoring plants in the soil.
Absorbing water and mineral nutrients.
Conducting water and dissolved minerals
Storing food materials
• The roots of some plants can also function in
vegetative reproduction, as in root cuttings.
• Once the radicle emerges & enters the soil, the root
grows through the soil, bringing it in contact with
water and nutrients.
tab
Practical Horticulture 5th edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
© 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Chapter 7 - Plant Growth and Development
Vegetative Growth/Development - Shoots & Roots
• The root system and the shoot system maintain a
balance—as the top of the plant grows larger, leaf
area & water loss through transpiration increases.
– Increased water loss is made up by water absorption from
an increasing root system.
• The enlarging shoot and root systems also requires
greater amounts of water and mineral absorption.
• The spring flush of root growth results from the
accumulated foods stored the previous year.
tab
Practical Horticulture 5th edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
© 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Chapter 7 - Plant Growth and Development
Vegetative Growth/Development - Shoots & Roots
• Shoot growth is determinate or indeterminate.
– Determinate growth - after a period of vegetative growth,
flower bud clusters form at shoot terminals so most shoot
elongation stops.
– Indeterminate growth plants bear flower clusters laterally
along the stems in the axils of the leaves.
tab
Practical Horticulture 5th edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
© 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Chapter 7 - Plant Growth and Development
Vegetative Growth/Development - Shoots & Roots
Stem growth is limited in the first growing season.
Plants remain alive (dormant) through the winter.
Figure 7-13 Hollyhocks are a biennial plant. The plant on the right is two years old and flowering.
The one on the left is in its first growing season and will remain vegetative.
tab
Practical Horticulture 5th edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
© 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Chapter 7 - Plant Growth and Development
Vegetative Growth/Development - Shoots & Roots
• Exposure to chilling temperatures triggers hormonal
changes leading to stem elongation, flowering, fruit
• Most annual and biennial plants flower and fruit only
once before dying.
–In woody perennial plants, shoot & root systems
remain alive indefinitely, growing to the ultimate size
for the particular plant.
–Magnitude of growth can vary considerably from
season to season.
tab
Practical Horticulture 5th edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
© 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Chapter 7 - Plant Growth and Development
Phase Change: Juvenility, Maturation, Senescence
• A newly seedling undergoes a phasic development
throughout life—essentially the same as in animals.
– Embryonic growth; juvenility; a transition stage; maturity
or adult phase; senescence; and death.
• The juvenile phase is characterized by the inability
to reproduce sexually.
– The duration of the juvenile phase varies from a week or
two up to thirty or forty years in some tree species.
tab
Practical Horticulture 5th edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
© 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
Chapter 7 - Plant Growth and Development
Phase Change: Juvenility, Maturation, Senescence
The morphology of
juvenile and adult plants
is often quite different.
Juvenile acacia leaves are
bipinnately compound, while
the adult form appears linear
tab
Practical Horticulture 5th edition
By Margaret J. McMahon, Anton M. Kofranek and Vincent E. Rubatsky
© 2011, 2007, 2002, 1988 Pearson Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458