Historic note
 Front Cover

Title: Rooting medium air space critical for rooting pentas
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00065275/00001
 Material Information
Title: Rooting medium air space critical for rooting pentas
Series Title: Bradenton GCREC research report
Physical Description: 3 p. : ill. ; 28 cm
Language: English
Creator: Harbaugh, B. K ( Brent Kalen )
Gulf Coast Research and Education Center (Bradenton, Fla.)
Publisher: Gulf Coast Research and Education Center
Place of Publication: Bradenton FL
Publication Date: 1995
Subject: Flowers -- Propagation -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
Statement of Responsibility: Brent K. Harbaugh.
General Note: Cover title.
General Note: "February, 1995"
 Record Information
Bibliographic ID: UF00065275
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 68652802

Table of Contents
    Historic note
        Historic note
    Front Cover
        Front cover
        Page 1
        Page 2
        Page 3
        Page 4
Full Text


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source

site maintained by the Florida
Cooperative Extension Service.

Copyright 2005, Board of Trustees, University
of Florida



Marston Science
APR 2 01995

University of Florida

Gulf Coast Research and Education Center
5007 60th St. E., Bradenton, FL 34203
Bradenton GCREC Research Report
BRA-1995-6 (February 1995)


Bradenton GCREC Research Report BRA1995-6


Brent K. Harbaugh'
Gulf Coast Research and Education Center
University of Florida, IFAS
5007 60th St. East
Bradenton, FL 34203

Pentas (Pentas lanceolata) have become quite popular recently due to the
availability of new flower colors, improved vegetative characteristics and a
demand for drought tolerant plants. In addition, pentas are excellent plants for
butterfly gardens.

While seed pentas are starting to become available, propagation of pentas is
primarily by rooting vegetative cuttings. Poor root development or a lengthy
period for rooting are common problems associated with rooting pentas. Often
"pop corn" callus will form at the base of a cutting and roots fail to develop
for weeks after other cuttings of the same cultivar and age have rooted. The
purpose of this research was to test the hypothesis that poor root development
in pentas cuttings is associated with rooting medium with low percentage air
Materials and Methods

Combinations of sand and perlite were used to develop five rooting media with
a range of air space from 3 to 55% The five media (v/v) and percent air space
were: 1.) 1 course sand : 0 perlite = 3% ; 2.) 1 sand : 1.25 perlite = 16% ;
3.) 1 sand : 2.5 perlite= 29% ; 4.) 1 sand : 5 perlite=42% ; 5.) 0 sand : 1
perlite=55%. Air space was determined by the following method. A 1.5 inch
pyramidal cell of a propagation flat was filled with each medium and the drainage
holes were plugged. Water was added to the top of the medium (100% saturation).
The drainage holes were then unplugged and the water was drained for one hour and
measured. Percent air space was then calculated as the volume of drained water
divided by the total cell volume, times 100%.

Single-node cuttings approximately 2 inches in length of 'Ruby Red' and 'Pink
Rose' pentas were used in this study. Cuttings were dipped in a solution
containing 0.1% IBA and 0.05% NAA. One cutting was placed in each 1.5-inch
pyramidal cell filled with one of the 5 media. Cuttings were misted for 1
minute every 30 minutes from 8AM to 5PM. After 21 ('Ruby Red') or 34 ('Pink
Rose') days, cuttings were given a subjective ranking for root production and
growth from 1 (no roots produced) to 10 (highest root production and growth).


A correlation of rooting medium air space with root development was evident for
both cultivars. The highest root ranking was with 29% air space for 'Ruby Red'
and 42% air space for 'Pink Rose' (Fig. 1). Root production and growth were poor
with 3% air space for both cultivars, and also with 16% air space for 'Pink

'Professor (Floriculture)

February 1995

Root rankings were less at 55% air space than at 42% for both cultivars due
to poor root growth. Medium components used for the purposes of this study had
very poor water retention capabilities. More frequent misting probably would have
been necessary for cuttings in the 55% air space treatment to prevent root stress
associated with drying between mist cycles.

It is a well known, often forgotten, fact that oxygen is essential for root
production and development. One of the functions of a rooting medium is to
permit penetration of air to the base of the cutting, and in general, there is
increased movement of oxygen to the roots with increased rooting medium air
space. Research on many crops has shown that there is quite a variation in oxygen
requirements for root development between plant species. Pentas would appear
to be categorized with those plants that have high oxygen requirements for

Since rooting medium air space is critical for rooting pentas, a quick review
of factors affecting it might be beneficial for those propagating pentas. Three
major factors affect air space: the rooting medium, the container size, and
handling of the rooting medium. The effect of medium components on air space can
easily be seen with the five media developed for this study. Water retention
decreased with increased air space in this study since the rooting medium
components (sand and perlite) do not have internal water-holding capacities and
primarily affect medium texture. Peat or other components which affect structure
and have high internal moisture retention properties should be combined with
substrates providing good air space and water-holding capacity for ideal
commercial rooting media.

The size of the propagation container influences drainage and thus air space.
In brief, the shorter the propagation container or cells within a propagation
tray, the less drainage that will occur, resulting in less air space. A medium
which may be ideal for growing pentas in a 6-inch pot will not drain adequately
if used in a plug tray for rooting.

And finally, handling the rooting medium is important. Increased compaction
results in less air space. If small-celled propagation trays are used, there is
a tendency to pack the rooting medium into the cells, or stack filled trays,
resulting in poor air space for even the "best" rooting medium. Increasing the
moisture content of the rooting medium prior to filling small containers is
beneficial because it causes the organic particles to swell. This technique will
result in increased air space if the rooting medium is not compressed after
filling the containers.

In summary, rooting medium air space is critical for rooting pentas. While
misting cycles can be adjusted in an attempt to prevent waterlogging in a rooting
medium which already has poor air space, the potential of overwatering remains
high with this type of rooting medium. Successful rooted cutting production will
be enhanced with the choice of a rooting medium with high percentage air space,
consideration of container size, and proper handling of the rooting medium.



5 -


Pink Rose Ruby Red

2 J-------------------------------
3 16 29 42 55
Percent Air Space
Fig. 1. Response of 'Ruby Red' and 'Pink Rose' pentas cuttings to root medium
air space. Cuttings were evaluated after 21 ('Ruby Red') or 34 ('Pink Rose') days
and given a subjective ranking for root production and growth from 1 (no roots
produced) to 10 (highest root production and growth).

The Gulf Coast Research and Education Center

The Gulf Coast Research and Education Center is
a unit of the Institute of Food and Agricultural Sci-
ences, University of Florida. The Research Center
originated in the fall of 1925 as the Tomato
Disease Laboratory with the primary objective of
developing control procedures for an epidemic out-
break of nailhead spot of tomato. Research was ex-
panded in subsequent years to include study of sev-
eral other tomato diseases.

In 1937, new research facilities were established
in the town of Manatee, and the Center scope was
enlarged to include horticultural, entomological, and
soil science studies of several vegetable crops. The
ornamental program was a natural addition to the
Center's responsibilities because of the emerging in-
dustry in the area in the early 1940's.

The Center's current location was established in
1965 where a comprehensive research and extension
program on vegetable crops and ornamental plants is
conducted. Three state extension specialists posi-
tions, 16 state research scientists, and two grant
supported scientists from various disciplines of
training participate in all phases of vegetable and
ornamental horticultural programs. This interdisci-
plinary team approach, combining several research
disciplines and a wide range of industry and faculty
contacts, often is more productive than could be ac-
complished with limited investments in independent

The Center's primary mission is to develop new
and expand existing knowledge and technology, and
to disseminate new scientific knowledge in Florida, so
that agriculture remains efficient and economically

The secondary mission of the Center is to assist
the Cooperative Extension Service, IFAS campus
departments, in which Center faculty hold appropri-
ate liaison appointments, and other research centers
in extension, educational training, and cooperative
research programs for the benefit of Florida's pro-
ducers, students, and citizens.

Program areas of emphasis include: (1) genetics,
breeding, and variety development and evaluation;
(2) biological, chemical, and mechanical pest manage-
ment in entomology, plant pathology, nematology,
bacteriology, virology, and weed science; (3) produc-
tion efficiency, culture, management, and counteract-
ing environmental stress; (4) water management and
natural resource protection; (5) post-harvest physiol-
ogy, harvesting, handling and food quality of horti-
cultural crops; (6) technical support and assistance to
the Florida Cooperative Extension Service; and (7)
advancement of fundamental knowledge of disciplines
represented by faculty and (8) directing graduate
student training and teaching special undergraduate

Location of
GCREC Bradenton

" The Institute of Food and Agricultural Sciences,
University of Florida.
Q A statewide organization dedicated to teaching,
research and extension.
O Faculty located in Gainesville and at 13 research
and education centers, 67 county extension
offices and four demonstration units throughout
the state.
O A partnership in food and agriculture, and natural
and renewable resource research and education,
funded by state, federal and local government,
and by gifts and grants from individuals, founda-
tions, government and industry.
" An organization whose mission is:
Educating students in the food, agricultural,
and related sciences and natural resources.
Strengthening Florida's diverse food and
agricultural industry and its environment
through research.
Enhancing for all Floridians, the application
of research and knowledge to improve the
quality of life statewide through IFAS exten-
sion programs.

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