effects of high nighttime temperature and role of plant growth regulators on growth, development ...

144 Pages·2009·1.07 MB·English

EFFECTS OF HIGH NIGHTTIME TEMPERATURE AND ROLE OF
PLANT GROWTH REGULATORS ON GROWTH,
DEVELOPMENT AND PHYSIOLOGY OF RICE PLANTS

A Dissertation
by
ABDUL RAZACK MOHAMMED

Submitted to the Office of Graduate Studies of
Texas A&M University
in partial fulfillment of the requirements for the degree of
DOCTOR OF PHILOSOPHY

May 2009

Major Subject: Molecular and Environmental Plant Sciences
EFFECTS OF HIGH NIGHTTIME TEMPERATURE AND ROLE OF
PLANT GROWTH REGULATORS ON GROWTH,
DEVELOPMENT AND PHYSIOLOGY OF RICE PLANTS

A Dissertation
by
ABDUL RAZACK MOHAMMED

Submitted to the Office of Graduate Studies of
Texas A&M University
in partial fulfillment of the requirements for the degree of
DOCTOR OF PHILOSOPHY

Approved by:
Co-Chairs of the Committee, Lee Tarpley
J. Tom Cothren
Committee Members, William D. Park
Lloyd T. (Ted) Wilson
Chair of Intercollegiate Faculty, Jean H. Gould

May 2009

Major Subject: Molecular and Environmental Plant Sciences
iii

ABSTRACT

Effects of High Nighttime Temperature and Role of Plant Growth Regulators on
Growth, Development and Physiology of Rice Plants. (May 2009)
Abdul Razack Mohammed, B.S., Acharya N.G. Ranga Agricultural University; M.S.,
Mississippi State University
Co-Chairs of Advisory Committee: Dr. Lee Tarpley
Dr. J. Tom Cothren

Seasonally high nighttime temperatures (HNT) along the United States Gulf
Coast and in regions of similar climate, during the critical stages of development, could
reduce rice yield and quality. To study the effects of HNT on plant physiology, a method
for applying a controlled heating treatment to plant canopies was developed using
overhead infrared heaters, which are relatively inexpensive and are accurate, precise and
reliable in rapidly controlling the temperature. The apparatus successfully maintained air
temperatures within the set points + 0.5 oC, and was used for all the experiments. Several
experiments were conducted to determine the response of various physiological
parameters during and following exposure of rice plants to HNT (32 oC) or ambient
nighttime temperature (ANT) (27 oC) starting from 2000 h until 0600 h, and with or
without plant growth regulator treatments. The plant growth regulator treatments
included α-tocopherol (vitamin E), glycine betaine (GB), and salicylic acid (SA), which
play different roles in inducing thermo-tolerance in plants.
High nighttime temperature had no effect on plant height, number of tillers and
panicles, or rice net leaf photosynthetic rates. However, HNT increased leaf respiration
iv

(dark respiration in the night) (21%) and decreased membrane thermo-stability (60%),
pollen germination (20%), spikelet fertility (18% as a % of total spikelets), grain length
(2%), and grain width (2%). The HNT also hastened plant development. The
combinations of these effects decreased rice yield by 90%. Moreover, under HNT, there
were decreases in leaf chlorophyll concentration (7%) and nitrogen concentration (18%).
Application of GB and SA increased total antioxidant capacity of the rice plants by 17%,
thereby decreasing the leaf respiration rates, increasing membrane thermo-stability,
pollen germination, and spikelet fertility, thus increasing the yield. High nighttime
temperature decreased leaf starch concentration (14%), grain total nonstructural
carbohydrate (TNC) concentration (9%), and grain extractable invertase activity (20%).
Vitamin E- or GB-treated plants had greater grain soluble-sugar concentrations, whereas
SA-treated plants had greater leaf soluble-sugar concentrations and lower grain TNC
concentrations. Invertase activity was shown to be not rate limiting or required for
sucrose degradation for starch synthesis in grain of ‘Cocodrie’ rice under short-term high
nighttime temperatures exposures during grain filling.
In conclusion, HNT decreased rice yield by increasing plant respiration, rate of crop
development, and decreasing membrane thermo-stability, pollen germination, spikelet
fertility and grain dimensions. Exogenous application of GB and SA increased yields
under HNT, possibly acting through increased antioxidant levels, which might have
protected the membranes and enzymes against heat-induced ROS-mediated degradation.
v

DEDICATION

I would like to dedicate this research to my parents,
MARYAM BEE and ABDUL GHANI MOHAMMED
vi

ACKNOWLEDGEMENTS

I would like to express my gratitude to all the people without whose relentless support
this work would not have been possible. I would like to extend a special thank you to the
following people:
• Dr. Lee Tarpley, my major professor, for his patience, enthusiastic guidance,
invaluable advice, continual encouragement, and financial support throughout the
years of study
• Drs. J. Tom Cothren, William D. Park and Lloyd T. (Ted) Wilson, my graduate
committee members, for their help and suggestions during the course of my study
and research
• Dr. Charles Long with the Texas A&M University System, AgriLife Research
and Extension Center for providing me the use of a LiCor 6400
• Dr. Ming-Hsuan Chen and Ms. Janis T. Delgado for their advice and technical
assistance with antioxidant analysis
• Mr. James Medley for his technical assistance with leaf nitrogen analysis
• Mr. Robert Freeman for his help with electrical setup and power connections of
the infrared heating system
• Mr. Ronnie Porter, Elliott Rounds, Marcus McCabe, Casey Hall, Bo Dixon,
Wilbert Moore, Randy Valcin, and Patrick Huff for their great support,
encouragement, and friendship during the course of my study
vii

• Texas Rice Belt Warehouse for providing a graduate fellowship and Texas Rice
Research Foundation for partial financial support of the research
• Horizon Ag, RiceTec, and the Texas Rice Improvement Association for the
provision of seed
• My mother, Maryam Bee, family members, and all my friends for their love,
endless encouragement, and unwavering belief in my abilities
• My wife, Huma Firdous Mohammed, for her ever-present cheerfulness,
unlimited patience and never-ending support and encouragement that has allowed
me to keep things in perspective and bring this project to completion
• GOD, my eternal source of inspiration, encouragement, and strength
viii

TABLE OF CONTENTS
Page
ABSTRACT................................................................................................. iii
DEDICATION.............................................................................................. v
ACKNOWLEDGEMENTS.......................................................................... vi
TABLE OF CONTENTS............................................................................. viii
LIST OF TABLES....................................................................................... x
LIST OF FIGURES...................................................................................... xi
CHAPTER
I INTRODUCTION................................................................ 1
II INSTRUMENTATION ENABLING STUDY OF PLANT
PHYSIOLOGICAL RESPONSE TO ELEVATED
NIGHTTIME TEMPERATURE……………… 5

Introduction………………………………………….. 5
Materials and Methods……………………………… 9
Results and Discussion……………………………… 18
Conclusions………………………………………...... 21
III IMPACT OF HIGH NIGHTTIME TEMPERATURE ON
RESPIRATION, MEMBRANE STABILITY,
ANTIOXIDANT CAPACITY AND YIELD OF RICE
PLANTS…………………………………………………... 22

Introduction………………………………………….. 22
Materials and Methods……………………………… 25
Results….…………………………………………..... 32
Discussion ………………………………………....... 41

IV HIGH NIGHTTIME TEMPERATURES AFFECT RICE
PRODUCTIVITY THROUGH ALTERED POLLEN
GERMINATION AND SPIKELET
FERTILITY……………………………………………...... 45
ix

CHAPTER Page

Introduction………………………………………….. 45
Materials and Methods……………………………… 49
Results….…………………………………………..... 57
Discussion ………………………………………....... 68
V NIGHTTIME TEMPERATURE EFFECTS ON
PRODUCTIVE TILLERS, SPIKELET FERTILITY,
GRAIN CHARACTERISTICS AND YIELD OF
RICE (ORYZA SATIVA L.) PLANTS…………………….. 72

Introduction………………………………………….. 72
Materials and Methods……………………………… 76
Results….…………………………………………..... 82
Discussion ………………………………………....... 92

VI SOLUBLE SUGARS AND STARCH BIOSYNTHESIS
AND INVERTASE ACTIVITY OF RICE PLANTS
SUBJECTED TO HIGH NIGHTTIME
TEMPERATURES DURING EARLY-GRAIN FILLING
STAGE……………………………………………………. 95

Introduction………………………………………….. 95
Materials and Methods……………………………… 98
Results….…………………………………………..... 108
Discussion ………………………………………....... 113

VII SUMMARY………………………….................................. 116
REFERENCES……………………………………………………………. 118
VITA………………………………………………………………………. 132
x

LIST OF TABLES
TABLE Page
3.1. Effects of experiment (Exp.), nighttime temperature (NT) and
plant growth regulators (PGR) on respiration rates (RR),
membrane thermal stability (MTS), total antioxidant capacity
(TAC) and yield…………………………………………................ 34

5.1. Effects of nighttime temperatures and plant growth regulators on
main-stem panicle length and number of primary branches per
panicle………………………………………………....................... 84

5.2. Effects of nighttime temperatures and plant growth regulators on
grain length, width, grain nitrogen concentration and grain yield… 86