Tree Physiology 6,347-350
0 1990 Heron Publishing-Victoria,
Canada
BOOK REVIEW
Sexual reproduction
John N. Owens, Department
Canada, V8W 2Y2
of Biology,
University of Victoria, Victoria, B.C.,
Sexual reproduction of tree crops
M. SEDGLEY and A.R. GRIFFIN
Academic Press, London, New York: 1989.378 Pages, hardcover, $85.00 US
The book successfully brings together the very diverse literature dealing with
horticultural and forest tree crops. The task is difficult because it includes the
reproductively diverse flowering plants and gymnosperms and because it includes
horticultural crops, in which the goal is enhanced reproduction, and forest crops, in
which the goal in enhanced vegetative growth. The authors carefully maintain this
distinction throughout the nine chapters. The result is a well written, informative
book which includes many new and useful tables, about 1400 references and a
comprehensive index. The authors’ extensive experience with tropical and southern
hemisphere species adds a refreshing approach to topics generally discussed only in
the context of north temperate regions. The book will be a valuable reference for the
expert, an essential introduction to the newcomer and a useful resource to the
biotechnologist and tree breeder.
Chapters cover diverse areas from floral initiation to crop management and tree
breeding. The first chapter accurately sets the tone by placing reproductive biology
and tree-crop research in the context of tree cultivation. Chapter 2 discusses floral
initiation and development. Here, coverage of angiosperms is quite complete but that
of conifers is sparse. A few, but not serious, inaccuracies occur regarding development of conifer pollen and megagametophytes and there is a tendency to refer to
general reviews rather than individual papers, although some of these papers are in
the references. The tables of floral and pollen structure are useful.
Extensive tables are again helpful in Chapter 3 covering floral physiology and
breeding, but problems are encountered when angiosperms and gymnosperms are
both included and terms applying to one group are inaccurate for the other. Nevertheless, the tables contain much useful information but the reader must be cautious
regarding strict adherence to some of the terms used. The chapter gives a good
treatment of complex terminology, mostly developed for angiosperms and to be
cautiously applied to gymnosperms. Topics such as growth regulator control of sex
expression are covered although generalizations are premature. Gametophytic and
sporophytic self-incompatibility
are explained for prezygotic self-incompatibility
mechanisms. The authors acknowledge this information comes primarily from
herbaceous species but several good examples of tree crops are discussed. The
chapter is not so much one on floral physiology but rather floral development and
breeding systems. It is refreshing to see the authors realize the importance of
development rather than relegating it to a minor component of physiology.
Chapter 4 emphasizes the critical importance of pollination and pollination man-
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agement for all trees except some omamentals in which flowers are of no consequence or the flower is the product. Pollen vectors are discussed and a table is
included that summarizes the abiotic and biotic agents in a wide variety of genera.
Floral characteristics of anemophilous (wind) pollinated species are reiterated and
the calculation for pollen dispersion away from a point source explained. Under
biotic pollinations the complex association between the floral characteristics and the
vector is discussed in terms of benefit to the vector, the primary attractants (pollen,
nectar, etc.), secondary attractants (odor, visual) and blossom architecture. The
complexity of plant-pollinator interactions is discussed with regard to characteristics
of effective pollinators and the variety of pollinators in north temperate and tropical
regions. Wind pollinated trees are treated briefly under the heading of environmental
effects (climate and weather) on pollination, particularly the relationship between
pollen shed and receptivity. The authors emphasize that under cultivation many tree
crops are removed from the ecosystem in which the pollination system has evolved.
Therefore, it is important to understand the pollination system for any tree crop in
order to manage pollination effectively.
Chapter 5 deals with the female-male interactions during pollen germination,
pollen tube growth and fertilization. There are some inaccuracies regarding conifer
fertilization but the coverage of angiosperms is more complete and demonstrates the
interesting but rather spotty information available for tree crops. Aspects of self-incompatibility are considered again regarding pistil physiology and mentor pollen and
their relation to interspecific and intergeneric hybridization. The authors point out
the many reasons for the lag in experimental results with tree crops. They conclude
that we cannot assume that tree crops are the same as the more thoroughly studied
herbaceous species.
Seed and fruit development are discussed in Chapter 6, which deals mostly with
angiosperms because of the abundance of literature from the 1940s and 1950s.
Several interesting examples are presented that reiterate earlier discussion of incompatibility. There is little included on gymnosperms since cone loss is a problem
primarily of certain general (e.g., Pinus) and there has been little research in this area.
Some inaccurate or outdated terms are used for conifers and some subtle distinctions
between cone drop due to lack of pollen or environmental causes in pine are missed.
Intermediate examples, such as spruce, are not included. The discussion of embryology is brief and adds less than the subject warrants in understanding seed and fruit
development.
Ripening and dispersal are covered in Chapter 7. Here the authors wrestle with the
definition of a fruit and come up with a general definition for angiosperms and
gymnosperms which is appropriate for pines but not for those conifers where seed
cones mature even though seeds do not. Most aspects of ripening, as they apply to
fruit crops, are covered as are the applied aspects of harvest indices using physical
and biochemical features and heat units. Abscission is dealt with anatomically,
physiologically and in terms of environmental and internal regulation. The authors
rightly point out that for these subjects little is known about conifers. Dispersal is
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discussed using van der Pijl’s treatment based on agents of transport both biotic and
physical.
Chapter 8 deals with genetic consequences of variation in reproductive biology
and successfully puts reproductive biology into a genetic framework using examples
of inbreeding and outcrossing, inbreeding depression, heterosis, hybridization and
hybrid vigor. The implications to breeding programs, seed orchard design and natural
populations are discussed. There is extensive reference to conifers including a
discussion of the relationship between genetic load and polyembryony and between
inbreeding and vigor. Discussions of coefficients of inbreeding and changes in rate
of increase in inbreeding may not be clear to the non-geneticist.
The final chapter effectively places many of the topics covered in chapters 1-8 in
the context of fruit- and seed-production management and tree breeding. The contrast
between forest-tree seed and horticultural crops is emphasized in terms of orchard
siting, design and management of flowering, pollination, fruit set and harvesting. The
reproductive biology of tree-crop breeding nicely contrasts the opposing goals of
increased reproductive development in horticultural crops and increased vegetative
growth for forest-tree species. Described in some detail, including a table, are several
aspects of pollen management including pollen collection, extraction, storage, viability testing and briefly pollination techniques in diverse wind, insect, outcross and
self-pollinating species. There is brief mention of developments in molecular biology
and tissue culture and a reminder that the new biotechnology should be used as an
adjunct to conventional techniques and will not replace the sexual process. The
authors rightly conclude that we must strike a balance between sexual and vegetative
propagation. This balance will differ between forest and horticultural tree crops and
among species, depending in each case on the desired end product, the species and
its reproductive biology.
NEW BOOKS
Process modeling of forest growth responses to environmental
stress
ROBERT
WILLIAM
K. DIXON, RALPH S. MELDAHL,
G. WARREN (editors)
Timber Press, Inc., 9999 SW Wilshire, Portland,
hardcover, $54.95 US plus shipping.
GREGORY
A. RUARK
and
OR 97225: 1990. 447 Pages,
Atmospheric pollutants and global climate change may significantly influence the
growth and health of forests worldwide. Unfortunately, our understanding of these
potential impacts is limited. This book was developed in response to the rapidly
proliferating interest in modeling the impact of environmental stresses, principally
atmospheric pollutants, on forest growth. A contemporary review of tree and forest
process model development, structure, and evaluation in relation to tree structure and
metabolism is presented in this comprehensive treatise. Quantitative methods in the
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assessment and prediction of forest growth in response to environmental stress are
emphasized.
The chapters in this book were prepared by participants in the conference “Forest
growth: process modeling of responses to environmental stress” held at Gulf Shores,
Alabama, April 1988.
Forest tree physiology
Supplement to the Annales des Sciences Forestihes, Volume 46 (ISSN 0003-43 12)
E. DREYER, G. AUSSENAC, M. BONNET-MASIMBERT,
P. DIZENGREMEL,
J.M. FAVRE, J.P. GARREC, F. Le TACON and F. MARTIN (editors)
Elsevier, Paris, New York: 1989.875 Pages, softcover, FF850, $142 US
This volume includes almost 200 short papers summarizing oral presentations or
posters given at an international symposium held at Nancy, France in September
1988. The proceedings are divided into three sections. The first is entitled “Developmental physiology of forest trees,” and is introduced with a review by P. Champagnat. The second section is entitled: “Ecophysiology of forest trees” and is
introduced with a review by T.M. Hinckley and R. Ceulemans. The third section is
entitled: “Primary and secondary metabolism of forest trees,” and is introduced with
a review by R.E. Dickson. There is a foreward by F. Le Tacon and a final address by
G.B. Sweet.