UNIVERSITI PUTRA MALAYSIA

IMPACT OF PLANTING DATE AND DENSITY

ON GROWTH OF MAIZE IN NORTHERN IRAN

HASSAN MOKHTARPOUR

FP 2011 17

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IMPACT OF PLANTING DATE AND DENSITY ON GROWTH OF MAIZE

IN NORTHERN IRAN

By

HASSAN MOKHTARPOUR

Thesis Submitted to the School of Graduate Studies, University Putra Malaysia,

in Fulfilment of the Requirements for the Degree of Doctor of Philosophy

April 2011

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DEDICATION

To

My beloved people in my life

My father, my mother, my wife and my lovely daughter Rozhan

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Abstract of thesis to be presented to the Senate of University Putra Malaysia in

fulfilment of the requirements for the degree of Doctor of Philosophy

IMPACT OF PLANTING DATE AND DENSITY ON GROWTH OF MAIZE

IN NORTHERN IRAN

By

HASSAN MOKHTARPOUR

April 2011

Chairman: Christopher Teh Boon Sung, PhD

Faculty: Agriculture

Planting date and density are two major factors affecting maize growth and yield.

Although many worldwide studies were done to evaluate the effect of planting date

and density on maize, it is still necessary to do more studies to add the knowledge in

this area because environmental factors affect planting date and density. During the

last four decades, many simulation studies were conducted to evaluate maize growth.

A robust simulation model can help researchers to understand, predict and control a

system. Despite the importance of modeling studies on maize, no simulation study

was done in Golestan-Iran. The purpose of this study was to investigate maize

growth and yield response to planting date and density in field and simulation studies

in Golestan-Iran.

The field studies were conducted at the Agricultural Research Center of Golestan,

Iran in 2007 and 2008. In the first experiment, the effects of eight planting dates and

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three planting densities (0.16, 4.5, and 6.5 plants m-2

) were investigated in 2007. The

experiment was replicated in 2008 by adding another planting density (8.5 plants m-

2). In the second experiment, maize yield response to a wide range of planting

densities (0.16, 2.5, 4.5, 6.5, 8.5, 10.5 and 12.5 plants m-2

) was evaluated for two

seasons in 2008. In the third study, empirical equations were developed to estimate

leaf area and leaf weight using the data from different treatments of the first

experiment in 2008. Simulation studies were done using two specific maize models:

CERES-Maize and IXIM. To calibrate the models, the data of the first five planting

dates in optimum planting densities (6.5 plants m-2

) from the first field experiments

in 2007 were used. Using stepwise approach and sensitivity analysis, genetic

coefficients were calibrated for both models. To evaluate the accuracy of the models,

the data from different treatments from the first and second experiments in 2008

were used. The models’ validity was tested using three goodness of fit indicators

namely, root mean square error, index of agreement (d) and mean error.

Results of the first experiment showed planting date, planting density and the

interaction between them had significant effect on yield and yield components. The

highest yield was produced in the first planting date (10659 kg ha-1

). The best

planting density among early and middle planting dates was 6.5 plants m-2

while for

late plantings no significant differences were observed in yield among the different

planting densities. Results of the second experiment showed that in the first season

the highest yield was observed in planting density 6.5 plants m-2

(9470 kg ha-1

).

However, in the second season, no significant difference in yield was observed

among the different planting densities (~4500 kg ha-1

). Empirical equations were

fitted to the observed data to show the relationship of each of the parameters, yield,

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total dry matter (TDM), leaf area index (LAI) and harvest index (HI) to planting

density. Results of the third study showed that the empirical equations developed to

estimate leaf area, fresh weight and dry weight could predict their values with a high

degree of accuracy in different situations. The results of simulation study showed

that both CERE-Maize and IXIM models predicted days to anthesis, days to

physiological maturity, LAI, and kernel weight with high accuracy in different

planting dates and densities although the IXIM showed a better performance

comparing to CERES-Maize model. IXIM model simulated TDM, kernel number

and yield with higher accuracy comparing to CERES-Maize model in the first five

planting dates. However, both models could not give accurate predictions of these

traits in the last three planting dates. Evaluating response of CERES-Maize and

IXIM models to planting density showed that both models could predict different

traits accurately in the middle planting densities (4.5-8.5 m-2

). However, both models

overestimated most traits in high planting densities (10.5-12.5 plants m-2

).

In conclusion, maize should be planted in early planting dates with planting density

6.5 plants m-2

in Golestan-Iran. However, to obtain high yield in late planting dates,

planting density should be decreased to 4.5 plants m-2

. In simulation study, both

models could not predict yield and yield component with high accuracy in the late

planting dates and high planting densities therefore, it seems some modification are

needed to be done in the functions that calculate daily crop growth rate, kernel

number m-2

, and LAI. These modifications may improve the accuracy of the models

to estimate these traits.

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Abstrak tesis yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai

memenuhi keperluan untuk ijazah Sarjana Sains Doktor Falsafah

IMPAK TARIKH PENANAMAN DAN KEPADATAN TANAMAN

TERHADAP PERTUMBUHAN JAGUNG DI UTARA IRAN

Oleh

HASSAN MOKHTARPOUR

April 2011

Pengerusi: Christopher Teh Boon Sung, PhD

Fakulti: Pertanian

Tarikh penanaman dan kepadatan tanaman adalah dua faktor utama yang

menpengaruhi pertumbuhan dan hasil jagung. Walaupun terdapat banyak kajian yang

giat dijalankan untuk mengkaji kesan tarikh penanaman dan kepadatan tanaman bagi

jagung, namun adalah amat penting untuk mendalami kajian kerana faktor alam

sekitar sangat mempengaruhi. Selama empat dekat yang lalu, banyak kajian simulasi

telah dijalankan untuk mengkaji pertumbuhan jagung. Model yang tepat boleh

membantu para penyelidik untuk memahami, meramal, dan mengawal sesebuah

sistem. Walaupun kajian ini penting, namun tiada kajian simulasi telah dilakukan di

Golestan-Iran. Kajian lapangan ini melibatkan tiga eksperimen yang telah dijalankan

di Pusat Penyelidikan Pertanian Golestan-Iran pada tahun 2007 dan 2008. Untuk

eksperimen pertama, kesan untuk lapan tarikh tanaman dan tiga kepadatan tanaman

(0.16, 4.5, dan 6.5 pokok m-2

) dikaji pada tahun 2007. Eksperimen ini diulangi pada

tahun 2008 dengan menambah satu lagi kepadatan tanaman (8.5 pokok m-2

). Untuk

eksperimen kedua, tindakbalas hasil tuai jagung untuk kepadatan tanaman yang

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lebih banyak ( 0.16, 2.5, 4.5, 8.5, dan 12.5 pokok per m-2

) telah dikaji dalam dua

musim pada tahun 2008. Untuk eksperimen ketiga, persamaan empirikal telah

dibangunkan untuk mengganggar keluasan daun dan berat daun dengan mengunakan

data yang diperolehi daripada rawatan pada eksperimen pertama pada tahun 2008.

Kajian simulasi telah dijalankan dengan menggunakan dua model spesifik untuk

tanaman jagung iaitu CERES-Maize dan IXIM. Untuk menguji model, data untuk

lima traikh tanaman pertama bagi kepadatan tanaman yang optimum (6.5 pokok m-2

)

untuk eksperimen pertama pada tahun 2007 telah digunakan. Dengan menggunakan

kaedah stepwise dan analisis sensitivity, koefisien genetic telah dikalibrasi untuk

kedua-dua model. Untuk mengenalpasti ketepatan model, data daripada eksperimen

pertama dan eksperimen kedua telah digunakan. Kesahihan model telah diuji dengan

menggunakan 3 penunjuk: roots mean square error, indeks kesamaan (d) dan purata

ralat. Hasil daripada eksperimen pertama menunjukkan tarikh tanaman, kepadatan

tanaman dan interaksi dintara hasil tuai, tarikh tanaman dan kepadatan tanaman

menunjukkan kesan yang nyata.

Hasil tuai tertinggi dicatatkan pada tarikh terawal tanaman (10659 kg ha-1

).

Kepadatan tanaman yang paling baik untuk tarikh tanaman awal dan pertengahan

adalah 6.5 pokok m-2

sementara untuk tarikh akhiran tanaman tidak menunjukkan

perbezaan yang ketara untuk kepadatan tanaman yang berbeza. Eksperimen kedua

menunjukkan bahawa pada musim pertama, hasil tuai yang teringgi dicatatkan untuk

kepadatan tanaman 6.5 pokok m-2

(9470kg ha-1

). Walau bagaimanapun, untuk musim

kedua, tiada perbezaan ketara dicatatkan untuk kepadatan tanaman yang berbeza

(~4500 kg ha-1

). Persamaan empirikal telah digunakan untuk mengetahui hubungan

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diantara kepadatan tanaman, hasil tuai, jumlah berat kering (TDM), indek keluasan

daun (LAI), dan index tuaian (HI).Untuk eksperimen ketiga, keputusan menunjukkan

bahawa persamaan yang dibangunkan untuk mengira luas daun, berat daun dan berat

kering daun dapat digunakan untuk meramal nilai yang lebih tepat. Hasil dari

simulasi, kedua-dua model CEREZ- Maize dan IXIM boleh meramal sehingga dari

hari pengeluaran bunga jagung, hari sehingga kematangan fizikal jagung, LAI dan

berat biji jagung dengan ketepatan yang tinggi untuk kepadatan tanaman yang

berbeza dimana IXIM lebih menunjukkan pretasi cemerlang berbanding CERES-

maize dalam lima kepadatan tarikh tanaman pertama. Walau bagaimanapun, kedua-

dua model tidak dapat menganggar simulasi hasil tuai yang baik untuk tiga tarikh

penanaman yang terakhir. Evaluasi tindakbalas model menggunakan CERES-maize

dan IXIM terhadap tarikh penanaman menunjukkan kedua-dua model tidak dapat

meramal kesan yang lebih tepat untuk kepadatan tanaman sederhana (4.5-8.5 pokok

m-2

). Namun, untuk kepadatan tanaman yang lebih tinggi (10.5-12.5 m-2

) model telah

terlebih anggaran.

Sebagai kesimpulannya, jagung harus ditanam pada tarikh tanaman yang awal

dengan kepadatan tanaman 6.5 pokok m-2

di Golestan, Iran. Untuk mencapai hasil

tuai yang tinggi, pada tarikh tanaman yang kemudian, kepadatan tanaman seharusnya

dikurangkan sehingga 4.5 pokok m-2

. Dalam kajian simulasi, kedua-dua model tidak

dapat meramal hasil tuai dan komponen tuaian dengan ketepatan tinggi dan oleh itu

beberapa modifikasi perlu dilakukan dalam fungsi yang mengira kadar pertumbuhan

harian, bilangan biji benih dan LAI. Modifikasi ini perlu untuk meramal dengan

lebih tepat.

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ACKNOWLEDGEMENTS

First and foremost, I am greatly indebted to my supervisor, Dr. Christopher Teh

Boon Sung, for his insightful guidance, continuous encouragement, and unselfish

support in my research over the past four years. His thoughtful coaching with all

aspects of my research was a guarantee of the success of this endeavor. His

enthusiasm and preciseness have left an everlasting impression on me.

I would like to express my deep gratitude to the members of my dissertation

committee, Prof. Dr. Ghizan B Saleh, Dr. Ahmad B Selamat, Dr. Behnam Kamkar,

and Dr. Mohammad Esmaeil Asadi for their invaluable comments, critiques, and

advice that enriched this dissertation.

My warm thanks are due to Dr. Noriniya head of Agricultural and Natural Resources

Research Center of Golestan, Iran and Mr. Kalateh head of Gorgan Agricultural

Research Station for providing the facilities to conduct my field experiments.

My sincere thanks go to my colleagues Mr. Faizbakhsh and Mr. Heydari at

Department of SEED and Plant Improvement, Agricultural and Natural Resources

Research Center of Golestan, Iran for their assistance in field data collection.

Agricultural Research Extension and Education Organization, Seed and Plant

Improvement institute, and Agricultural and Natural Resources Research Center of

Golestan, Iran gave me this opportunity to continue my study in PhD at the

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University Putra Malaysia (UPM). They provided the funds and facilities to continue

my study and carry out this research. Their contribution is gratefully acknowledged.

Special thanks to my fellow student Jane Iba at the University Putra Malaysia for her

help to improve my general knowledge in computer science during the last four

years. Her assistance in the translation of the abstract of the current study into Bahasa

Malayu is also greatly appreciated.

I owe my loving thanks to my wife, and my daughter Rozhan. They have lost a lot

due to my research. Without their encouragement and understanding it would have

been impossible for me to finish this work.

Hassan Mokhtarpour

UPM, Malaysia, April 2011

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I certify that an Examination Committee met on 1 April of 2011 to conduct the final

examination of Hassan Mokhtarpour on his doctor of philosophy thesis entitled

“Experimental and Modeling Studies to Determine the Impact of Planting Date and

Plant Density on Growth of Maize in Northern Iran” in accordance with Universities

and University College Act 1971 and the Constitution of Universiti Putra Malaysia

[P.U.(A) 106] 15 march 1998. The Committee recommends that the student be

awarded the relevant degree.

Members of the Thesis Examination Committee were as follows:

Hemdan Jol, PhD

Associate Professor

Faculty of Agriculture

University Putra Malaysia

(Chairman)

Anuar Abd. Rahim, PhD

Associate Professor

Faculty of Agriculture

University Putra Malaysia

(Internal Examiner)

Wan Sulaiman Wan Harun, PhD

Professor

Faculty of Agriculture

University Putra Malaysia

(Internal Examiner)

Gerrit Hoogenboom, PhD

Professor

Agricultural Weather Net Program

Washington State University

United States of America

(External Examiner)

______________________________

SHAMSUDDIN SULAIMAN, PhD Professor and Deputy Dean

School of Graduate Studies

Universiti Putra Malaysia

Date:

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This thesis was submitted to the Senate of Universiti Putra Malaysia and has been

accepted as fulfillment of the requirement for the degree of doctor of philosophy.

The members of the Supervisory Committee were as follows:

Christopher Teh Boon Sung, PhD

Senior Lecturer

Faculty of Agriculture

University Putra Malaysia

(Chairman)

Gizhan B Saleh, PhD

Professor

Faculty of Agriculture

University Putra Malaysia

(Member)

Ahmad B Selamat, PhD

Associate Professor

Faculty of Agriculture

University Putra Malaysia

(Member)

Behnam Kamkar, PhD

Associate Professor

Faculty of Agriculture

University of Agriculture Science and

Natural Resources of Gorgan, Iran

(External Member)

Mohammad Esmaeil Asadi

Assistant Professor

Agricultural and Natural Resources Research

Center of Golestan, Iran

(External Member)

______________________________

HASANAH MOHD GHAZALI, PhD Professor and Dean

School of Graduate Studies

Universiti Putra Malaysia

Date:

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DECLARATION

I declare that the thesis is my original work except for quotations and citations which

have been duly acknowledged. I also declare that it has not been previously, and is

not concurrently, submitted for any other degree at Universiti Putra Malaysia or at

any other institutions.

______________________________

HASSAN MOKHTARPOUR

Date: 1 April 2011

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TABLE OF CONTENTS

Page

DEDICATION ii

ABSTRACT iii

ABSTRAK vi

ACKNOWLEDGEMENTS ix

APPROVAL SHEETS xi

DECLARATION xiii

LIST OF TABLES xvii

LIST OF FIGURES xxiii

LIST OF VARIABLES xxvi

CHAPTER

1 INTRODUCTION .................................................................................... 1

1.1 Maize production in the world and Iran ............................................. 1

1.2 Statement of the problem................................................................... 2

1.2.1 Planting date and planting density effects ............................... 2

1.2.2 Non-destructive leaf area, leaf fresh weight, and leaf dry

weight measurement .............................................................. 5

1.2.3 Crop simulation models ......................................................... 6

1.3 Objectives of the study ...................................................................... 8

1.3.1 Objectives of field studies ...................................................... 8

1.3.2 Objectives of the model simulation ........................................ 9

2 LITERATURE REVIEW ...................................................................... 10

2.1 Planting density ............................................................................... 10

2.2 Planting date ................................................................................... 16

2.3 Temperature effect on growth and yield of maize ............................ 20

2.3.1 Effect of temperature on maize photosynthesis..................... 20

2.3.2 Temperature effects on maize vegetative growth and

development ........................................................................ 21

2.3.3 Temperature effect during grain filling period ...................... 23

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2.3.4 Effect of temperature on total dry matter and yield production

............................................................................................ 25

2.3.5 Evaluation of temperature effect on maize in simulation studies

............................................................................................ 26

2.4 The effect of relative humidity on maize ......................................... 27

2.5 Non destructive leaf area, leaf fresh weight and leaf dry weight

estimation of maize ......................................................................... 30

2.6 Crop simulation models and their important role in agriculture ........ 31

2.6.1 Introduction ......................................................................... 31

2.6.2 Types of mathematical models ............................................. 33

2.6.3 Limitations of models .......................................................... 34

2.6.4 Model uses........................................................................... 35

2.7 Decision support system for agro-technology transfer (DSSAT v4.5)

........................................................................................................ 35

2.7.1 Introduction ......................................................................... 35

2.7.2 Components of DSSAT ....................................................... 37

2.7.3 Applications of DSSAT ....................................................... 41

2.7.4 CERES-Maize model ........................................................... 42

2.7.5 IXIM model ......................................................................... 51

3 METHODOLOGY ................................................................................. 56

3.1 Field studies .................................................................................... 56

3.1.1 The first field experiment: Maize growth and yield response to

different planting dates and densities ................................... 56

3.1.2 The second field experiment: Maize yield and yield

components response to planting density ............................. 68

3.1.3 The third field study: Non-destructive estimation of maize leaf

area, fresh weight, and dry weight using leaf length and leaf

width ................................................................................... 72

3.2 Description of CERES-Maize and IXIM models ............................. 76

3.2.1 CERES-Maize Model description ........................................ 76

3.2.2 Description of IXIM model .................................................. 94

3.2.3 Calibration of CERES-Maize and IXIM models................. 114

3.2.4 Evaluation of CERES-Maize and IXIM models ................. 122

4 RESULTS AND DISCUSSION ........................................................... 125

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4.1 The first field experiment: Maize growth and yield response to

different planting dates and densities ............................................. 125

4.1.1 Planting density effect........................................................ 127

4.1.2 Analysis of weather data for different planting dates .......... 129

4.1.3 Planting date effect ............................................................ 140

4.1.4 Interaction effect between planting date and density on some

traits .................................................................................. 143

4.2 The second field experiment: Maize yield and yield components

response to different planting densities .......................................... 153

4.2.1 Planting density effect........................................................ 153

4.2.2 Effect of season ................................................................. 156

4.2.3 Interaction effect ................................................................ 161

4.3 The third field study: Non-destructive estimation of maize leaf area,

fresh weight, and dry weight using leaf length and leaf width ........ 169

4.3.1 Equation development ....................................................... 169

4.3.2 Equation evaluation ........................................................... 170

4.4 Results of CERES-Maize model calibration .................................. 177

4.5 Results of IXIM model calibration ................................................ 180

4.6 Evaluation of CERES-Maize and IXIM models ............................. 182

4.6.1 Evaluation of CERES-Maize and IXIM models to simulate

different traits in different planting dates ........................... 182

4.6.2 Evaluating the response of CERES-Maize and IXIM models to

plant density ...................................................................... 225

5 SUMMARY, CONCLUSION AND RECOMMENDATIONS

FOR FUTURE RESERCH .................................................................. 243

5.1 Summary ....................................................................................... 243

5.1.1 Field studies ....................................................................... 243

5.1.2 Simulation studies .............................................................. 245

5.2 Conclusion .................................................................................... 246

5.3 Recommendations for future research............................................ 248

REFERENCES…………………………………………………………………....249

BIODATA OF STUDENT……………………………………………………….264

LIST OF PUBLICATIONS…………... ……………………………………….265