Table Of ContentPHYTOHORMONES
IN
SOILS
BOOKS IN SOILS, PLANTS, AND THE ENVIRONMENT
. . . .
SoilBiochemistry,Volume 1,editedby A D McLaren and G H Peterson
SoilBiochemistry,Volume 2,editedby A.D.McLaren andJ.Skujin§
SoilBiochemistry, Volume3,edited by E. A.Paul and A.D. McLaren
SoilBiochemistry,Volume4,edited by E. A.Paul and A.D. McLaren
SoilBiochemistry,Volume 5,edited by E. A. Paul and J.N. Ladd
.
SoilBiochemistry,Volume6,edited by Jean-Marc Bollag and G Stotzky
.
SoilBiochemistry, Volume 7,edited by G Stotzky and Jean-Marc Bollag
Soil Biochemistry,Volume8, editedby Jean-Marc Bollag andG. Stotzky
Organic Chemicals in the Soil Environment, Volumes 1 and 2,edited by C. A. I.
. .
Goring and J W Hamaker
Humic Substancesin theEnvironment,M. Schnitzer and S.U.Khan
.
Microbial Lifein theSoil: AnIntroduction,T Hattori
Principles of SoilChemistry,KimH. Tan
SoilAnalysis:InstrumentalTechniquesandRelatedProcedures,editedby KeithA.
Smith
SoilReclamation Processes: MicrobiologicalAnalysesandApplications,editedby
. .
Robert L TateIIIand Donald A Klein
.
Symbiotic NitrogenFixation Technology,editedby Gerald H Elkan
Soil-Water Interactions: Mechanisms andApplications, ShingoIwata and Toshio
.
Tabuchi withBennoP Warkentin
SoilAnalysis: ModernInstrumental Techniques,SecondEdition,edited by Keith
.
A Smith
SoilAnalysis: Physical Methods,edited by Keith A. Smithand Chris E.Mullins
Growth and Mineral Nutrition of Field Crops, N. K. Fageria, V. C. Baligar, and
Charles Allan Jones
SemiaridLandsandDeserts: SoilResourceandReclamation,editedby J.SkujinS
PlantRoots:TheHiddenHalf,editedbyYoavWaisel,AmramEshel,andUziKafkafi
Plant Biochemical Regulators,edited by Harold W.Gausman
Maximizing Crop Yields, N. K. Fageria
Transgenic Plants: Fundamentals andApplications, edited by Andrew Hiatt
Soil Microbial Ecology: Applications in Agricultural and Environmental Manage-
ment, edited by F.BlaineMetting,Jr.
.
Principles of SoilChemistry:SecondEdition,KimH Tan
Water Flow inSoils,edited by TsuyoshiMiyazaki
Handbook of Plant andCropStress,editedby Mohammad Pessarakli
.
Genetic Improvement of Field Crops,editedby Gustavo A Slafer
AgriculturalField Experiments: Design andAnalysis,Roger G.Petersen
.
EnvironmentalSoilScience,KimH Tan
Mechanisms of Plant Growth and Improved Productivity: Modern Approaches,
edited by Amarjit S.Basra
. . .
SeleniumintheEnvironment,editedbyW T Frankenberger,Jr,andSally Benson
.
Plant-Environment Interactions,edited byRobert E Wilkinson
Handbook of Plant andCropPhysiology, editedby Mohammad Pessarakli
Handbook of Phytoalexin Metabolism and Action, edited by M. Daniel and R. P.
Purkayastha
Soil-Water Interactions: Mechanisms and Applications, Second Edition,Revised
andExpanded,ShingoIwata,Toshio Tabuchi,and BennoP. Warkentin
Stored-GrainEcosystems,editedbyDigvir S.Jayas,NoelD.G.White,andWilliam
.
E Muir
Agrochemicals fromNaturalProducts,editedby C.R. A.Godfrey
SeedDevelopment and Germination, edited by Jaime Kigel and Gad Galili
Nitrogen Fertilization in theEnvironment,edited by Peter Edward Bacon
.
PhytohormonesinSoils:MicrobialProductionandFunction,W T.Frankenberger,
.
Jr ,and Muhammad Arshad
Additional Volumes inPreparation
SoilErosion,Conservation,andRehabilitation, edited by Menachem Agassi
Handbook of Weed Management Systems,edited by A. E. Smith
PHYTOHORMONES
IN
SOILS
MICROBIAL PRODUCTION
AND FUNCTION
W.T. FRANKENBERGER, JR
,
Universityof California
Riverside,California
MUHAMMADARSHAD
UniversityofAgriculture
Faisaiabad,Pakistan
CRC Press
Taylor&FrancisGroup
Boca Raton London New York
CRC Press is an imprint of the
Taylor & Francis Group, an informa business
Firstpublished1995byMarcelDekker,Inc
Published2019byCRCPress
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NoclaimtooriginalU.S.Governmentworks
ISBN13:978-0-8247-9442-2(hbk)
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Library of Congress Cataloging-in-Publication Data
Frankenberger, W. T. (William T.)
Phytohormones in soils : microbial productionand function / W.T.
Frankenberger, Jr., Muhammad Arshad.
p. cm. — (Books in soils, plants, and the environment ; 43)
Includes bibliographical references and index.
ISBN 0-8247-9442-7(hbk.)
1. Soil microbiology. 2. Plant regulators. I. Arshad, Muhammad.
II. Title. III. Series
,
QR111.F73 1995
—
576’.190948 dc20 94-48505
CIP
The publisher offers discounts on this book when ordered in bulk quantities. For more
information, write toSpecial Sales/Professional Marketingat the address below.
To my sons, Grant, Spencer, and Ryan, and my parents,
Norma-Jean and William T., Sr.
WTF, Jr.
To my parents, Khursid and Ali, and my wife, Talat.
M A
Preface
Although plant physiologists have recognizedfor many years that soil microorga-
nismscanproduceplantgrowth-regulatingsubstances(PGRs),verylittleempha-
sis has been given toexploiting theirinfluenceon plant growthanddevelopment.
The application of beneficial soil microorganisms can promote consistent im-
proved crop yields, suppression of plant pathogens, and improved soil quality.
Theprimaryfocusofthisbookisacomprehensivepresentationofcurrentinforma-
tionon microbiallyderived PGRs,theireffectson plantgrowthand development,
and recommendations regardingfuture research needs.
Therootsystemsofallhigherplantsareassociated withadistinctcommunity
of beneficial soil microorganisms capable of synthesizingfive primary classes of
plant hormones: auxins, gibberellins, cytokinins, ethylene, and abscisic acid.
Many of these microorganisms have mutualistic relationships with plant roots,
beinghighlydependentfortheirsurvivalonpreformedsubstratesexcretedinplant
root exudates, such as amino acids, organic acids, carbohydrates, nucleic acid
derivatives, vitamins, and other growth substances. In turn, the indigenous soil
microflorasynthesizeandexcretePGRsintotherhizosphere,thesoilzoneadjoin-
ingliving plant roots, bringingaboutdramaticchangesin plantgrowth and devel-
opment. Typically, PGRs do not act alone. The final outcome of plant growth,
suppression, or enhanced development represents the net effect of a hormonal
balance.
Exogenous supplementation of PGRs to plant roots is a relatively new ap-
proachtomaximizecropyield. Plantsthemselvessynthesizeauxins,gibberellins,
cytokinins,ethylene,andabscisicacid,butunderless-than-idealclimaticandenvi-
ronmentalconditions,plantsmaynotsynthesizesufficientendogenousconcentra-
tions tosustainoptimalgrowthand development.Scientists haveshown recently
that plant growth can be improved when specific microbial strains are used to
“inoculate” seeds or roots of agricultural cropsdue to the microbes’ production
of PGRs. At present, the use of microbial inoculants, often referred to as plant
growth-promoting rhizobacteria (PGPR), is a common practice in many regions
of the world, but it is often difficult to achieve consistent and reproducible yield
increases under field or greenhouse conditions due to the lack of understanding
ofthemechanismsbywhichaparticularinoculumpromotesplantgrowth.Littleis
knownabouthowthesoiltype,hostplantgenotype,andenvironmentalconditions
affecttheabilityof theinoculatocolonizeand persistonplant roots.Toeliminate
inconsistencies and to enhance reproducibility of the beneficial effects by the
PGR-producing microorganisms, we have investigated and reported recently the
IV
Preface v
successof precursor-inoculum interactions,in which physiological precursorsof
PGRs alone or precursors plus microbial inocula are added to the rhizosphere.
This novel technique and its potential economic and agricultural advantages in
producing PGRs are addressed throughout the text.
Several excellent books have been published on the biochemistry of plant
hormones, but none, to date, have taken into account the involvement of soil
microbiotaasexternalsourcesof thesechemicalstothe root zone.Toourknowl-
edge, this is thefirst book that offers a comprehensive presentation on microbial
productionof thefiveprimaryclassesofplant hormonesand theireffectson plant
growthanddevelopment.Thebookisorganizedwithsixchapters,anintroductory
chapterthatprovidesanoverviewofmicroorganism-plantinteractionsandasepa-
ratechapteroneachof themajorplant hormones:auxins(Chapter2),gibberellins
(Chapter3),cytokinins(Chapter4),ethylene(Chapter5),andabscisicacid(Chap-
ter 6). For each of the five classes of plant hormones, the chapters provide a
-
historical review of their discovery, physiological actions, biochemistry, biosyn
thesisandmetabolisminplantsandrhizospheremicroorganisms,modesofaction,
production in purecultureand in soil, role in pathogenesis, and the physiological
effectsof microbiallyderived PGRs.The bookisintendedprimarilyforsoilscien-
tistsworkinginsoilmicrobiologyandbiochemistry,butwillalsointerestuniversi-
ty-andindustry-basedresearcherswhowillhavevariedopportunitiestoapplythis
information in microbiology, plant physiology,genetics, botany, plant pathology,
forestry, and horticulture.
We wish toexpressoursincereappreciation toSharonCondittfor the manu-
script preparation, LindaBobbittfortheartworkand DeborahSilvaforheredito-
rial assistance.
W. T. Frankenberger, Jr.
Muhammad Arshad
