Principles of Horticulture

426 Pages·2008·7.97 MB·English

Principles of Horticulture
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Principles of
Horticulture
Fifth edition
C.R. Adams, K.M. Bamford and M.P. Early
AMSTERDAM • BOSTON • HEIDELBERG • LONDON
NEW YORK • OXFORD • PARIS • SAN DIEGO
SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO
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First published 1984
Reprinted 1985, 1987, 1988, 1990, 1991, 1992
Second edition 1993
Third edition 1998
Reprinted 1999
Fourth edition 2004
Fifth edition 2008
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08 09 10 11 12 10 9 8 7 6 5 4 3 2 1
Contents
Preface vii
Acknowledgements xi
Chapter 1 Horticulture in context 1
Chapter 2 Climate and microclimate 25
Chapter 3 Environment and ecology 45
Chapter 4 Classification and naming 63
Chapter 5 External characteristics of the plant 77
Chapter 6 Plant cells and tissues 87
Chapter 7 Plant reproduction 99
Chapter 8 Plant growth 109
Chapter 9 Transport in the plant 121
Chapter 10 Pollination and fertilization 133
Chapter 11 Plant development 149
Chapter 12 Plant propagation 165
Chapter 13 Weeds 181
Chapter 14 Horticultural pests 197
Chapter 15 Horticultural diseases and disorders 233
Chapter 16 Plant protection 263
Chapter 17 Physical properties of soil 295
Chapter 18 Soil organic matter 319
Chapter 19 Soil water 337
Chapter 20 Soil pH 355
Chapter 21 Plant nutrition 365
Chapter 22 Alternatives to growing in the soil 383
Index 401
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Preface
By studying the principles of horticulture, one is able to learn
how and why plants grow and develop. In this way, horticulturists
are better able to understand the responses of the plant to various
conditions, and therefore to perform their function more effi ciently.
They are able to manipulate the plant so that they achieve their own
particular requirements of maximum yield and/or quality at the
correct time. The text therefore introduces t he plant in its own right,
and explains how a correct naming method is vital for distinguishing
one plant from another. The internal structure of the plant is studied
in relation to the functions performed in order that we can understand
why the plant takes it particular form. The environment of a plant
contains many variable factors, all of which have their effects, and
some of which can dramatically modify growth and development.
It is therefore important to distinguish the effects of these factors
in order to have precise control of growth. The environment which
surrounds the parts of the plant above the ground includes factors
such as light, day-length, temperature, carbon dioxide and oxygen,
and all of these must ideally be provided in the correct proportions to
achieve the type of growth and development required. The growing
medium is the means of providing nutrients, water, air and usually
anchorage for the plants.
In the wild, a plant will interact with other plants, often to different
species and other organisms to create a balanced community. Ecology
is the study of this balance. In growing plants for our own ends we
have created a new type of community which creates problems –
problems of competition for the environmental factors between one
plant and another of the same species, between the crop plant and
a weed, or between the plant and a pest or disease organism. These
latter two competitive aspects create the need for crop protection .
It is only by identifi cation of these competitive organisms (weeds,
pests and diseases) that the horticulturist may select the correct
method of control. With the larger pests there is little problem of
recognition, but the smaller insects, mites, nematodes, fungi and
bacteria are invisible to the naked eye and, in this situation, the
grower must rely on the symptoms produced (type of damage).
For this reason, the pests are covered under major headings of the
organism, whereas the diseases are described under symptoms.
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viii
Preface
Symptoms (other than those caused by an organism) such as frost
damage, herbicide damage and mineral defi ciencies may be confused
with pest or disease damage, and reference is made in the text to this
problem. Weeds are broadly identifi ed as perennial or annual problems.
References at the end of each chapter encourage students to expand their
knowledge of symptoms. In an understanding of crop protection, the
structure and life cycle of the organism must be emphasized in order
that specifi c measures, e.g. chemical control, may be used at the correct
time and place to avoid complications such as phytotoxicity, resistant
pest production or death of benefi cial organisms. For this reason, each
weed, pest and disease is described in such a way that control measures
follow logically from an understanding of its biology. More detailed
explanations of specifi c types of control, such as biological control,
are contained in a separate chapter where concepts such as economic
damage are discussed.
This book is not intended to be a reference source of weeds, pests and
diseases; its aim is to show the range of these organisms in horticulture.
References are given to texts which cover symptoms and life cycle
stages of a wider range of organisms. Latin names of species are
included in order that confusion about the varied common names may
be avoided.
Growing media include soils and soil substitutes such as composts,
aggregate culture and nutrient fi lm technique. Usually the plant’s water
and mineral requirements are taken up from the growing medium by
roots. Active roots need a supply of oxygen, and therefore the root
environment must be managed to include aeration as well as to supply
water and minerals. The growing medium must also provide anchorage
and stability, to avoid soils that ‘ blow ’ , trees that uproot in shallow soils
or tall pot plants that topple in lightweight composts.
The components of the soil are described to enable satisfactory root
environments to be produced and maintained where practicable. Soil
conditions are modifi ed by cultivations, irrigation, drainage and liming,
while fertilizers are used to adjust the nutrient status to achieve the type
of growth required.
The use of soil substitutes, and the management of plants grown in
pots, troughs, peat bags and other containers where there is a restricted
rooting zone, are also discussed in the fi nal chapter.
The importance of the plant’s aerial environment is given due
consideration as a background to growing all plants notably their
microclimate , its measurement and methods of modifying it. This is
put in context by the inclusion of a full discussion of the climate , the
underlying factors that drive the weather systems and the nature of local
climates in the British Isles.
There has been an expansion of the genetics section to accommodate
the need for more details especially with regard to genetic modifi cation
(GM) to refl ect the interest in this topic in the industry. The changes
in the classifi cation system have been accommodated and the plant
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Preface
divisions revised without losing the familiar names of plant groups,
such as monocotyledon, in the text. Concerns about biodiversity and
the interest in plant conservation are addressed along with more detail
on ecology and companion planting. More examples of plant adaptions
have been provided and more emphasis has been given to the practical
application of plant form in the leisure use of plants. The use of
pesticides has been revised in the light of continued regulations about
their use. More details have been included on the use of inert growing
media such asrockwool .
Essential defi nitions have been picked out in tinted boxes alongside
appropriate points in the text. Further details of some of the science
associated with the principles of growing have been included for those
who require more backgound; these topics have been identifi ed by
boxing off and tinting in grey.
The fi fth edition is in full colour and has been reorganized to align
closely with the syllabus of the very popular RHS Certifi cate of
Horticulture . To this end, the chapters have been linked directly to the
learning outcomes of the modules that cover The Plant, Horticultural
Plant Health Problems, the Root Environment and Plant Nutrition.
Introductions to Outdoor Food Production, Protected Cultivation,
Garden Planning, Horticultural Plant Selection, Establishment
and Maintenance have been expanded and a new chapter on Plant
Propagation has been added. The expansion of these areas has made
the essential relationship between scientifi c principles and horticultural
practice more comprehensive with the essential extensive to help relate
topics across the text.
This edition of the book continues to support not only the RHS
Certifi cate of Horticulture and other Level Two qualifi cations, such
as the National Certifi cates in Horticulture, but also provides an
introduction to Level Three qualifi cations including the RHS Advanced
Certifi cate and Diploma in Horticulture, Advanced National Certifi cates
in Horticulture, National Diplomas in Horticulture and the associated
Technical Certifi cates. The book continues to be an instructive source of
information for keen gardeners, especially those studying Certifi cate in
Gardening modules and wish to learn more of the underlying principles.
Each chapter is fully supported with‘ Further Reading ’ and self-
assessment ( ‘ Check your Learning ’ ) sections.
Charles R Adams
Katherine M Bamford
Micheal P Early