Seed biology and yield of grain crops

233 Pages·2017·2.04 MB·English

by  Dennis B. Egli

Seed Biology and Yield of Grain Crops,
2nd Edition
This book is dedicated to four people who, in one way or another, made it
possible. My mother Florence Egli, my major professor Dr J.W. Pendleton,
University of Illinois, and two long-term colleagues at the University of
Kentucky – the late W.G. Duncan and J.E. Leggett.
Seed Biology and Yield of Grain
Crops, 2nd Edition
Dennis B. Egli
University of Kentucky
USA
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© Dennis B. Egli 2017. All rights reserved. No part of this publication may be reproduced
in any form or by any means, electronically, mechanically, by photocopying, recording or
otherwise, without the prior permission of the copyright owners.
A catalogue record for this book is available from the British Library, London, UK.
Library of Congress Cataloging-in-Publication Data
Names: Egli, Dennis B.
Title: Seed biology and yield of grain crops / Dennis B. Egli.
Description: 2nd edition. | Wallingford, Oxfordshire : CAB International,
[2017] | Includes bibliographical references and index.
Identifiers: LCCN 2016035557| ISBN 9781780647708 (hbk : alk. paper) | ISBN
9781780647722 (epub)
Subjects: LCSH: Grain--Seeds--Physiology. | Grain--Yields.
Classification: LCC SB189.4 .E45 2017 | DDC 633.1/04--dc23 LC record available at
https://lccn.loc.gov/2016035557
ISBN-13: 978 1 78064 770 8
Commissioning editor: Rachael Russell
Editorial assistant: Emma McCann
Production editor: Shankari Wilford
Typeset by SPi, Pondicherry, India
Printed and bound in the UK by CPI Group (UK) Ltd, Croydon, CR0 4YY, UK
Contents
Preface vii
Acknowledgements to First Edition ix
Acknowledgements to Second Edition xi
1 Introduction 1
Seeds as a Food Source 1
Increasing Food Supplies: Historical Trends in Seed Yield 5
Crop Physiology and Yield Improvement 10
The Seed: an Integral Component of the Yield Production Process 15
2 Seed Growth and Development 18
Seed Structure, Composition and Size 18
The Three Phases of Seed Development 21
Development of seed structures (Phase I) 26
The linear phase of seed development (Phase II) 28
The end of seed growth – physiological maturity (Phase III) 33
Summary 41
3 Seed Growth Rate and Seed-fill Duration: Variation
and Regulation 42
Species and Cultivar Variation 45
Seed Growth Rate (SGR) 48
Genetic variation 48
Environmental and physiological variation 50
Regulation of seed growth rate 56
Summary 62
Seed-Fill Duration (SFD) 63
Genetic variation 63
Environmental and physiological variation 64
Regulation of seed-fill duration 70
Summary 76
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vi Contents
4 Yield Components – Regulation by the Seed 77
Yield Components – Seeds per Unit Area and Seed Size 78
Historical use and misuse 78
Yield components and plant development 81
Yield components and yield 87
Determination of Seed Number 91
Components of seed number 91
Summary 96
Environmental effects 98
Modelling seed number and assimilate supply relationships 103
Determination of Seed Size 111
Potential seed size 112
Components of seed size – seed growth rate and seed-fill duration 113
Summary 117
5 The Seed, Crop Management and Yield 119
Size of the Yield Container 121
Canopy photosynthesis 122
Length of Murata’s Stage Two 124
Partitioning 128
Characteristics of the seed 129
Summary 130
Filling the Yield Container 131
Seed growth rate (SGR) 133
Seed-fill duration (SFD) 133
The enigma 135
Seed size and yield 137
Source–Sink Limitations of Yield 139
Partitioning and Harvest Index 143
Time and Yield 150
Potential productivity 150
Utilization of potential productivity 153
Summary 161
Summary 161
6 The Way Forward 162
Yield Improvement 162
Food Availability for the Future 168
General Summary 178
References 181
Index 215
Preface
The world’s food supply depends on crops harvested for their seeds. Roughly half
of the calories available from plant sources in recent years came from just four
crops harvested for their seeds – maize, rice, wheat and soybean. Seeds are har-
vested because they are rich in carbohydrate, protein and oil stored in the seed as
reserves for germination and the beginning of the next generation. Dry seeds are
easy to transport and store; characteristics that contribute to their usefulness and
popularity.
The unique carbohydrates, proteins and oils in the seed result from a complex
series of biochemical processes, starting with the capture of light energy and the
fixation of carbon in the leaf and ending with the synthesis of storage compounds
in the seed. The mother plant produces the raw materials, primarily sucrose and
various amino acids that are used by the seed to synthesize the complex molecules
we use as food or feed. Understanding the production of yield by a crop commu-
nity requires consideration of both the assimilatory and the synthesis processes.
Crop physiologists historically focused on the assimilatory processes.
Investigations of dry matter accumulation by plants and plant communities
and photosynthesis and other primary assimilatory processes were considered
important because these processes are fundamental to the production of yield.
However, the production of dry matter by a crop community is only part of the
story in a grain crop where the economic yield is the seed. Utilization by the seed
of raw materials translocated from the source is an equally important part of the
yield production process. That is what this book is about.
My objectives in this book are, first, to gain an understanding of the growth
and development of seeds, the processes involved, the regulation of these pro-
cesses and the effect of plant and environmental factors. The second objective is
to use this knowledge of seed growth and development to define the role of the
seed in the yield production process.
What will we gain from such considerations? By approaching the produc-
tion of yield from the viewpoint of the accumulation of dry matter by the seed
(the sink), we will be able to integrate the source and the sink, assimilatory and
synthesis processes, into a unified description or model of yield production. This
model will be better than one that considers only the assimilatory processes in the
vii
viii Preface
source and relegates sink activity to a black box. A unified model including the
seed will help us understand many important questions in yield physiology, in-
cluding the determination of seed number, the relationship between seed size and
yield, partitioning and source-sink relations. We cannot hope to answer all ques-
tions about the regulation of yield in a single book, but a thorough consideration
of the seed sink will contribute to that goal.
Acknowledgements to First Edition
Preparation of a book purporting to cover such a broad topic as seed growth
and development and the involvement of the seed in the production of yield of
grain crops relies primarily on the published and unpublished research of others.
Synthesis of information from the literature into principles and concepts occurs
over a period of many years and it is frequently difficult to remember where cer-
tain ideas or concepts originated – did they come from a long-forgotten paper
or talk at a conference, or are they mine? I find it sometimes difficult to answer
this question and therefore can only issue a blanket acknowledgment and express
my thanks to those whose ideas I inadvertently expropriated and used and could
not cite specifically. This book also draws heavily on my own research over the
past 20 years and that research was made possible by the able assistance of many
graduate students, technicians, visiting professors and colleagues. My heartfelt
thanks go to this group.
A number of individuals made specific contributions to this book and I greatly
appreciate their efforts. Dr Steve Crafts-Brandner, USDA-ARS, Western Cotton
Research Laboratory, my valued colleague for many years at the University of
Kentucky, graciously made it possible for me to spend a six-month sabbatical
with him in Phoenix, Arizona, where I had the solitude to concentrate on writing.
The final version of this book was completed during my stay in Phoenix. My
thanks also goes to the other scientists and staff at the Western Cotton Research
Laboratory for making my stay there most enjoyable. Mr Bill Bruening ably man-
aged my lab in Lexington during my absence and prepared most of the figures in
this book. Brenda Wilson prepared most of the tables. I thank Lynn Forlow Jech,
Western Cotton Research Laboratory, for preparing Fig. 4.6. Individuals that re-
viewed chapters include Steve Crafts-Brandner, Jim Heitholt, Miller MacDonald,
Dennis TeKrony and Ian Wardlaw. Their comments were insightful and very
helpful and I appreciate their efforts, but the opinions expressed in this book are
solely the responsibility of the author.
Dennis B. Egli
September 1997
Lexington, Kentucky
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