EFFECT OF WEEDY RICE (Oryza sativa L.) ON THE YIELD OF ...

EFFECT OF WEEDY RICE (Oryza sativa L.)

ON THE YIELD OF CULTIVATED RICE (Oryza

sativa L.) IN GREENHOUSE AND FIELD

ENVIRONMENT

SALMAH BINTI TAJUDDIN

UNIVERSITI SAINS MALAYSIA

2014

EFFECT OF WEEDY RICE (Oryza sativa L.) ON THE YIELD OF

CULTIVATED RICE (Oryza sativa L.) IN GREENHOUSE AND FIELD

ENVIRONMENT

by

SALMAH BINTI TAJUDDIN

Thesis submitted in fulfilment of the requirements for the degree of

Master of Science

AUGUST 2014

ii

ACKNOWLEDGEMENTS

My postgraduate (MSc) study at the Universiti Sains Malaysia (School of

Biological Sciences) was a great challenge. It was made possible with the kind

assistance of many individuals, either directly or indirectly, to whom I am indebted,

not all of whom are mentioned in this page.

First and foremost, my deepest appreciation goes to Prof. Mashhor Mansor for

his strong support, unweary supervision and motivating guidance during the course

of my study. In addition, I was also trained in writing scientific papers and had the

opportunity to present scientific papers in seminars and conferences.

Other academicians had also given support through inspirational motivations

and guidance, particularly Dr. Azmi Man, Prof. Nashriyah Mat and Dr. Asyraf

Mansor, my co-supervisors, to all of whom I am very grateful.

I wish to thank the staff of the Malaysian Meteorological Department Pulau

Pinang for providing me the necessary meteorological data needed for my thesis. The

staff of MARDI (Seberang Perai) had been very helpful in my experimental work,

especially En. Awang, En. Ebnil, En. Mustafa, Pn. Norhayati and Pn. Aqilah. The

staff of USM for help me solve statistics analysis problems, particularly Dr. Zarul

Hazrin Hashim, En. Safian Bin Uda (The Advisory Statistician USM), and Dr. Nik

Fadzly Nik Rosely.

The grant of this study was provided Universiti Sains Malaysia under the TNC

Incentive and PRGS Grant. Universiti Sultan Zainal Abidin (UNISZA) provided the

fellowship to enable me to do my postgraduate study at Universiti Sains Malaysia.

Last but not least, my heartfelt thanks go to members of my family who had

given me continuous support an encouragement without which this study might not

be completed. Cik Nur Diana Salihi, Cik Minah Muda, Dr. Fadzilah Hamzah, Cik

iii

Mastika Suhaila and all my family members that lended me a hand during my study.

Muhammad Fadzli (husband) and En. Tajuddin (father) had given me the strength

and courage during those difficult times and to whom I am most grateful.

All names mentioned, I would like to add one more inspirational figure, my

late beloved mother, Tom, who happened to have passed away during the course of

my study.

iv

TABLE OF CONTENTS

Page

ACKNOWLEDGEMENTS ii

TABLE OF CONTENTS iv

LIST OF TABLES ix

LIST OF FIGURES xiii

LIST OF APPENDICES xix

ABBREVIATIONS xxii

ABSTRAK xxiv

ABSTRACT xxv

CHAPTER 1 INTRODUCTION 1

1.1 Brief History of Weedy Rice Infestation in Rice Cultivation 1

1.2 The Malaysian Scenario 3

1.3 Current Issues 5

1.4 Problem Statement 5

1.5 The Need to Conduct the Study 6

1.6 Aim and Objectives 6

1.7 Hypotheses 7

CHAPTER 2 LITERATURE REVIEW 9

2.1 Basic Introduction to Rice Crop Science 9

2.2 General Background 10

2.2.1 Origins of Rice Culture 10

2.2.2 Classification, Species and Varieties 11

2.2.2.1 Classification of Oryza 11

2.2.2.2 Species and Varieties of Rice 12

2.2.2.3 Phylogentic Relationship 14

2.2.2.4 The International Rice Genebank 14

2.2.2.5 WR in General 14

2.2.2.6 WR in Peninsular Malaysia 17

2.2.2.7 Oryza rufipogon Griff. – A Wild Species of Rice 18

v

2.2.2.8 CR Varieties 20

2.2.2.9 Yield of Malaysian (MARDI) Rice Cultivar 22

2.2.2.10 General Statistics on Rice Industry in Malaysia 22

2.3 WR Phenomenon in Peninsular Malaysia 23

2.3.1 Characteristics of WR 24

2.3.1.1 Morphological and Anatomical Characters 24

2.3.1.2 Life-Cycle, Growth, Dominance and Dormancy 25

2.3.1.3 WR Accessions 26

2.3.1.4 Reduced Yield of CR due to WR 27

2.4 Previous Studies in Other Countries 29

2.4.1 General 29

2.4.2 Growth Studies 30

2.4.3 Yield Studies 33

2.4.4 Competition Between WR and CR 35

CHAPTER 3 METHODOLOGY 37

3.1 Introduction 37

3.2 Study Site 37

3.3 Germination Test 38

3.4 Selection of CR and WR Varieties 39

3.4.1 WR 39

3.4.2 Greenhouse Experiment – Competition Study 39

3.4.3 Field Experiment 41

3.5 Preparation for Planting Materials 41

3.5.1 Greenhouse Experiment 41

3.5.2 Field Experiment 43

3.6 Experimental Design 44

3.6.1 Overall Experiment Design 45

3.6.2 Additive Series and Replacement Series 46

3.6.3 Detailed Experiment Designs 47

3.6.3.1 Greenhouse Experiment 47

3.6.3.2 Field Experiment 50

3.7 Detailed Methodology 54

3.7.1 Methodology for Objectives 1 (Greenhouse) 55

vi

3.7.1.1 Planting Method 55

3.7.1.2 Agronomic Practice 58

3.7.1.3 Collection of Data 59

3.7.2 Methodology for Objectives 2 60




3.7.3 Methodology for Objectives 3 62




3.8 Analysis of Data 63

3.8.1 Analysis of Data for Objectives 1 63



CHAPTER 4 RESULTS 68

4.1 Introduction 68

4.2 Secondary Data (Meteorological Data) 68

4.3 Germination Test 69

4.4 Results for Objective 1 71

4.4.1 Relative Growth Rate for Greenhouse 71

4.4.2 Relative Growth Rate for Field 77


4.5.1 Culm Height for Greenhouse 82

4.5.1.1 Additive Series 82

4.5.1.2 Replacement Series 83

4.5.2 Number of Tiller for Greenhouse 85



4.5.3 Number of Filled Grain for Greenhouse 89



4.5.4 Straw Weight (g) for Greenhouse 93

vii



4.5.5 The Value of 1000 Grain Weight (g) for Greenhouse 96



4.5.6 Yield per Hectare (tonnes/hectare) for Greenhouse 99



4.5.6.3 Overall Results for Yield 106

4.5.7 Culm Height for Field 106

4.5.7.1 Additive Series: Season 1 106


4.5.7.3 Replacement Series: Season 1 109


4.5.8 Number of Tiller for Field 112





4.5.9 Number of Filled Grain for Field 117





4.5.10 Straw Weight (g) for Field 123





4.5.11 The Value of 1000 Grain Weight (g) for Field 128





viii

4.5.12 Yield per Hectare (tonnes/hectare) for Field 134






4.6.1 Prediction for CR Yield Model in Greenhouse 144

4.6.2 Prediction Model for CR Yields in Field 145

CHAPTER 5 DISCUSSIONS 147

CHAPTER 6 CONCLUSION 160

REFERENCES 163

APPENDICES 173

ix

LIST OF TABLES

Table 2.1: Species of rice (Oryza) in the world.

13

Table 2.2: List of rice cultivars in Peninsular Malaysia.

21

Table 2.3: Malaysia rice cultivars.

22

Table 2.4: Yield loss, density of CR plants and levels of infestation.

28

Table 2.5: Reduction of yield according to variety.

28

Table 3.1: Agronomic traits and origin of the selected cultivars.

40

Table 3.2: Planting pots used in the study (Ratio CR: WR [% WR

infested]).

48

Table 3.3: Additive series for CR-WR arrangement and seed rate

(density) used in Season 1.

53

Table 3.4: Replacement series for CR-WR arrangement and seed rate


53

Table 3.5: Additive series for CR-WR arrangement and seed rate


54

Table 3.6: Replacement series for CR-WR arrangement and seed rate


54

Table 3.7: Fertiliser rate used on pots and plots. This rate was derived

from MARDI (2008).

59

Table 3.8: Summary of measurement characteristics.

61

Table 4.1: Culm height reduction (%) in competition by comparing

monoculture and mixture.

80

Table 4.1: (continue).

81

Table 4.2: Relative culm height (RYch) of CR and WR in the additive

series.

83

Table 4.3: Relative culm height (RYch) of CR and WR in the

replacement series.

84

Table 4.4: Relative number of tiller (RYt) of CR and WR in the

additive series.

87

Table 4.5: Relative number of tiller (RYt) of CR and WR in the 88

x

replacement series.

Table 4.6: Relative number of filled grain (RYfg) of CR and WR in

the additive series.

90


the replacement series.

92

Table 4.8: Relative straw weight (RYsw) of CR and WR in the additive

series.

93

Table 4.9: Relative straw weight (RYsw) of CR and WR in the

replacement series.

96

Table 4.10: Relative 1000 grain weight (RY1000gw) of CR and WR in

the additive series.

97


the replacement series.

98

Table 4.12: Parameter estimates for the prediction of yield per hectare

(tonne) as a result of interferences of CR and WR in the

additive series.

101

Table 4.13: Relative yield (RYyph) of CR and WR in the additive series.

102



replacement series.

104

Table 4.15: Relative yield (RYyph) of CR and WR in the replacement

series.

105

Table 4.16: Relative culm height (RYch) of CR and WR in the additive

series for Season 1.

107

Table 4.17: Relative culm height (RYch) of CR in the additive series for

Season 2.

109

Table 4.18: Relative culm height (RYch) of CR and WR in the

replacement series for Season 1.

110

Table 4.19: Relative culm height (RYch) of CR in the replacement


112


additive series for Season 1.

113

Table 4.21: Relative number of tiller (RYt) of CR in the additive series

for Season 2.

115

xi



115

Table 4.23: Relative number of tiller (RYt) of CR in the replacement


117


the additive series for Season 1.

119

Table 4.25: Relative number of filled grain (RYfg) of CR in the additive


119


the replacement series for Season 1.

121

Table 4.27: Relative number of filled grain (RYfg) of CR in the


123

Table 4.28: Relative straw weight (RYsw) of CR and WR in the additive


124

Table 4.29: Relative straw weight (RYsw) of CR in the additive series

for Season 2.

126

Table 4.30: Relative straw weight (RYsw) of CR and WR in the


126

Table 4.31: Relative straw weight (RYsw) of CR in the replacement


128



130

Table 4.33: Relative 1000 grain weight (RY1000gw) of CR in the additive


130



132



134




136

Table 4.37: Relative yield (RYyph) of CR and WR in the additive series

for Season 1.

136

xii




139

Table 4.39: Relative yield (RYyph) of CR in the additive series for

Season 2.

139




141

Table 4.41: Relative yield (RYyph) of CR and WR in the replacement


141




143

Table 4.43: Relative yield (RYyph) of CR in the replacement series for

Season 2.

144

xiii

LIST OF FIGURES

Figure 2.1: Life-history of CR (from Yoshida 1981).

9

Figure 2.2 Phylogenetic tree showing the AA genome in rice (after

Song Ge 1999).

15

Figure 2.3: Pattern in percentage reduction in yield for Malaysian CR

varieties with increased WR infestation (constructed from

Table 2.5)

29

Figure 3.1: Seed germination test.

38

Figure 3.2: WR were planted for seed multiplication and to obtain

homogenous seed.

40

Figure 3.3: Planting pots - soil filled to 20 cm up the pot from bottom.

41

Figure 3.4: Tagging WR seedling.

43

Figure 3.5: Land preparation.

44

Figure 3.6: Overall diagram used to determine the influence of WR on

CR in term of RGR, yield components and yield per

hectare.

45

Figure 3.6a: Chart used to determine RGR.

45

Figure 3.6b: Chart used to determine the yield components and yield per

hectare.

46

Figure 3.6c: Chart used to determine the influence of yield components

on yield per hectare (CR only).

46

Figure 3.7: Experimental design for greenhouse.

49

Figure 3.8: Pots arrangement in greenhouse.

50

Figure 3.9: Additive series and replacement series was employed to

elucidate findings on the effects of invasive WR on the

RGR, yield components and yield per hectare of CR in

field.

51

xiv

Figure 3.10: Plot numbers arrangement in a RCBD with three blocks

(Block 1, Block 2, Block 3) in a field layout for Season 1.

52

Figure 3.11: Plot numbers arrangement in a RCBD with three replicates

(Block 1, Block 2, Block 3) in a field layout for Season 2.

52

Figure 3.12: Planting Method - blue circles represent CR, green circles

represent WR.

56

Figure 3.13: Planting lined for field experiment. Blue lines represent

CR, green lines represent WR.

57

Figure 3.14: Subplot used in the field study.

60

Figure 4.1: The bar chart and line graph for temperature and rainfall

respectively in 2011 (Malaysian Meteorological

Department Pulau Pinang).

69

Figure 4.2: The bar chart and line graph for temperature and rainfall

respectively in 2012 (Malaysian Meteorological

Department Pulau Pinang).

69

Figure 4.3: The germination rate for different types of CR and WR.

70

Figure 4.4: RGR value (cm cm−1

d−1

) growth phase for culm height in

the additive series in CR and WR.

72


d−1


the replacement series in CR and WR.

73


d−1

) is growth phase for culm height

in the additive series for Season 1.

78


d−1



79


d−1



79


d−1



80

Figure 4.10: Culm height in the additive series measured at maturity. 83

xv

The vertical bars indicate standard deviation of the means.

Figure 4.11: Culm height in the replacement series measured at

maturity. The vertical bars indicate standard deviation of

the means.

85

Figure 4.12: Number of tiller in the additive series measured at


the means.

86

Figure 4.13: Number of tiller in the replacement series measured at


the means.

88

Figure 4.14: Number of filled grain in the additive series measured at


the means.

90

Figure 4.15: Number of filled grain in the replacement series measured

at maturity. The vertical bars indicate standard deviation of

the means.

92

Figure 4.16: Straw weight in the additive series measured at maturity.

The vertical bars indicate standard deviation of the means.

94

Figure 4.17: Straw weight in the replacement series measured at


the means.

95

Figure 4.18: The value of 1000 grain weight in the additive series

measured at maturity. The vertical bars indicate standard

deviation of the means.

97

Figure 4.19: The value of 1000 grain weight in the replacement series



99

Figure 4.20: Yield per hectare (tonne) in the additive series measured at


the means.

102

Figure 4.21: Yield per hectare (tonne) in the replacement series



105

xvi

Figure 4.22: Culm height in the additive series for Season 1 measured at


the means.

107

Figure 4.23: Culm height in the additive series for Season 2 measured at


the means.

108

Figure 4.24: Culm height in the replacement series for Season 1



110

Figure 4.25: Culm height in the replacement series for Season 2



111

Figure 4.26: Number of tiller in the additive series for Season 1



113

Figure 4.27: Number of tiller in the additive series in Season 2



114

Figure 4.28: Number of tiller in the replacement series for Season 1



116

Figure 4.29: Number of tiller in the replacement series for Season 2



117

Figure 4.30: Number of filled grain in the additive series for Season 1



118

Figure 4.31: Number of filled grain in the additive series for Season 2



120

Figure 4.32: Number of filled grain in the replacement series for Season

1 measured at maturity. The vertical bars indicate standard


121

xvii

Figure 4.33: Number of filled grain in the replacement series for Season

2 measured at maturity. The vertical bars indicate standard


122

Figure 4.34: Straw weight in the additive series for Season 1 measured


the means.

124

Figure 4.35: Straw weight in the additive series for Season 2 measured


the means.

125

Figure 4.36: Straw weight in the replacement series for Season 1



127

Figure 4.37: Straw weight in the replacement series for Season 2



128

Figure 4.38: The value of 1000 grain weight in the additive series for

Season 1 measured at maturity. The vertical bars indicate

standard deviation of the means.

129

Figure 4.39: The value of 1000 grain weight in the additive series for



131


for Season 1 measured at maturity. The vertical bars

indicate standard deviation of the means.

132


for Season 2 measured at maturity. The vertical bars

indicate standard deviation of the means.

133

Figure 4.42: Yield per hectare (tonne) in the additive series for Season 1



136

Figure 4.43: Yield per hectare (tonne) in the additive series for Season 2



138

xviii

Figure 4.44: Yield per hectare (tonne) in the replacement series for



141

Figure 4.45: Yield per hectare (tonne) in the replacement series for



143

xix

LIST OF APPENDICES

Appendix 2.1: Trends in the number of tiller in five WR variants

(source: Chauhan and Johnson 2010).

173

Appendix 2.2: Plant height after days of transplanting (after Munene et

al. 2008).

174

Appendix 2.3: Relative height growth rate (RGR) for the grass species

Piptocheatium napostaense and Poa ligularis (after

Palaez et al. 2009).

175

Appendix 2.4: RGR (g g-1

d-1

) for CR (after Hassanuzzaman et al.

2010).

176

Appendix 2.5: Relative yield for CR (IR64) and five type of WR

variaties from five Asian countries (after Chauhan and

Johnson 2010).

177

Appendix 2.6: Reduction of white rice yield due to red rice infestation

(after Ottis et al. 2005).

178

Appendix 3.1: Rice Seed Standard by MARDI. 178

Appendix 4.1: Mean of culm height result in greenhouse. 179

Appendix 4.1: (continue). 180


Appendix 4.2: Summary of analysis of covariance (ANCOVA) results

for relative growth rates (RGR) of culm height in

greenhouse.

182

Appendix 4.3: Summary of analysis of variance (ANOVA) results for

culm height in greenhouse.

183


Appendix 4.4: Summary of analysis of covariance (ANCOVA) results

for relative growth rates (RGR) of culm height in field.

185


Appendix 4.5: Mean of culm height result in field. 187



culm height in greenhouse on maturity.

189

xx


number of tiller in greenhouse.

189


number of filled grain in greenhouse.

190


straw weight in greenhouse.

190


1000 grain weight in greenhouse

191


yield per hectare in greenhouse.

191


culm height in field.

192


number of tiller in field.

193


number of filled grain in field.

194


straw weight in field.

195


1000 grain weight in field.

196


yield per hectare in field.

197

Appendix 4.18: Eigenvalues and proportions of variance for the two

components for CR in greenhouse.

198

Appendix 4.19: Results from the Principal Component Analysis variable

loadings for CR in greenhouse.

198

Appendix 4.20: Summary of analysis of linear regression analysis for

CR in greenhouse.

198

Appendix 4.21: Regressive model coefficients for CR in greenhouse. 198


PCA (CR) in greenhouse.

199

Appendix 4.23: Eigenvalues and proportions of variance for the two

components for CR in field.

199

Appendix 4.24: Results from the Principal Component Analysis variable

loadings for CR in field.

199

xxi

Appendix 4.25: Summary of analysis of linear regression analysis for

CR in field.

200

Appendix 4.26: Regressive model coefficients for CR in field. 200

Appendix 4.27 Summary of analysis of variance (ANOVA) results for

PCA (CR) in field.

200

Appendix 5.1: Field observation on 40 DAS. 201

Appendix 5.2: Field observation on 60 DAS WR overlapping the CR.

WR had overlay whole surface CR.

201

Appendix 5.3: Tall WR overshade short CR and CR type CL2 mature

earlier while WR in heading stage.

202

Appendix 5.4: Seed of WR shattered. 202

Appendix 5.5: WR growing higher than CR (CL2) on maturity stage in

field study.

203

Appendix 5.6: Comparison of WR and CR. 203

Appendix 5.7: Lodging WR at density ≥ 75kg/hectare WR infestation. 204

xxii

ABBREVIATIONS

211 MR 211

220 MR 220

ANCOVA Analysis Covariate

ANOVA Analysis of Variance

B Regression coefficient

CL1 MR 220 CL1

CL2 MR 220 CL2

cm Centimeter

CR Cultivated rice/ rice/ cultivar

d Day

DAS Day of sowing

et al. Et alii/ et aliae/ et alia/ and others

e.g. For example

f. Forma

g Gram

GRIN Germplasm Resources Information Network

h Hour

Ha Hectare

i.e In other words or that is

IRRI International Rice Research Centre

IUCN International Union for Conservation of Nature

Kg Kilogram

LC Least Concern

m Meter

m2 Meter square

m-2

Per meter square

MARDI Malaysian Agricultural Research and Development Institute

mm Milimeter

MVSP Multivariate Statistical Package

No. Number

NPK Nitrogen Phospate Potassium fertilizer

O. Oryza

PC’s Principal Component

xxiii

PCA Principal Component Analysis

R2 Sum of squares due to regression

RGR Realtive Growth Rate

RY Relative Yield

RYch Relative Yield Culm Height

RYt Relative Yield Number of Tiller

RYfg Relative Yield Number of Filled Grain

RY1000g Relative Yield 1000 Grain Weight

RYyph Relative Yield per Hectare

S Setanjung

Sect. Section

Ser. Series

Sig. Significant

Sp. Species

SPSS Statistical Package for the Social Sciences

WR Weedy rice

% Percentage

> Larger than

∑ Sum

% Percentage

xxiv

KESAN PADI ANGIN (Oryza sativa L.) TERHADAP HASIL PADI SAWAH

(Oryza sativa L.) DI PERSEKITARAN RUMAH HIJAU DAN LAPANGAN

ABSTRAK

Kajian ini bertujuan untuk mengkaji keupayaan persaingan padi sawah (CR)

terhadap padi angin (WR). Kajian ini yang telah dijalankan selama dua belas bulan

dari Januari 2012 hingga Disember 2012 di persekitaran rumah hijau dan lapangan.

MR220, MR220 CL1, MR220 CL2, MR211, dan Setanjung adalah varieti yang telah

dipilih bagi kajian rumah hijau. Kajian di lapangan dijalankan pada masa yang sama

dengan menggunakan jenis variati CR yang sama dengan kajian rumah hijau.

Walaubagaimanapun, hanya satu jenis variati CR yang ditanam dikawasan lapangan

kerana kekurangan masa, tempat dan tenaga pekerja. MR220 CL2 dipilih kerana

keupayaan hasil tuaian yang lebih baik dan tempoh kematangan lebih pendek

berbanding varieti CR yang lain. WR dan CR telah ditanam mengikut nisbah tertentu

di dalam pasu untuk kajian rumah hijau dan plot di lapangan dengan mengunakan

kaedah rekabentuk tambah siri dan penggantian siri. Keupayaan persaingan varieti

CR diukur berdasarkan Kadar Pertumbuhan Relatif (RGR), Hasil Relatif (RY) dan

analisis regresi linear pada kepadatan serangan WR yang berlainan. Keputusan

kaedah tambah siri dan penggantian siri telah menunjukkan bahawa varieti CR

kurang kompetitif berbanding WR. Varieti CR yang berbeza menunjukkan

kebolehan kompetitif yang berbeza. Kehadiran WR di CR menunjukkan penurunan

hasil secara keseluruhan RGR, komponen hasil dan hasil tuaian. WR memberi kesan

signifikan (P<0.05) kepada RGR, ketinggian batang, bilangan anak pokok, bilangan

benih berisi, berat jerami, berat 1000 biji benih dan juga hasil tuaian varieti-varieti

CR. Variati CR baru (MR220 CL2) memberikan hasil tuaian lebih tinggi, tetapi ia

kurang kompetitif kepada WR berbanding dengan variati CR lain.

xxv

EFFECT OF WEEDY RICE (Oryza sativa L.) ON THE YIELD OF

CULTIVATED RICE (Oryza sativa L.) IN GREENHOUSE AND FIELD

ENVIRONMENT

ABSTRACT

This study aimed to investigate the competitive abilities of cultivated rice (CR)

and weedy rice (WR). This study was performed over a period of twelve months

from January 2012 to December 2012 in greenhouse and field environments.

MR220, MR220 CL1, MR220 CL2, MR211, and Setanjung were the selected CR

varieties used in the greenhouse study. The field study was simultaneously conducted

using the same selected CR varieties as in the greenhouse study. However, only one

type of CR variety was planted in the field study because of time, space and labour

constraints. MR220 CL2 was selected because of its high yields and short maturity

period among all the CR varieties. Specific proportions of WR and CR were planted

in pots for the greenhouse study and plots for the field study based on additive series

and replacement series designs. The competitive abilities of CR varieties were

measured based on the Relative Growth Rate (RGR), Relative Yield, and linear

regression analysis under different infestation densities of WR. Results of additive

series and replacement series designs indicate that CR varieties were less competitive

than WR. Different CR varieties demonstrated various competitive abilities. The

presence of WR in CR decreased overall RGR, yield components, and yield. WR

significantly (P < 0.05) affected RGR, culm height, number of tiller, number of filled

grain, straw weight, 1000 grain weight, and yield of CR varieties. The new CR

variety (MR220 CL2) demonstrated high yield, but it was less competitive than WR

and other old rice varieties.

1

CHAPTER 1

INTRODUCTION

1.1 Brief History of Weedy Rice Infestation in Rice Cultivation

Weedy rice (WR) infestations were first reported from the Americas when

red rice infestations were known to have occurred as early as 1846 (Allston, 1846).

Delouche et al. (2007) stated that it is generally believed that the red rice was

introduced into the United States of America at a much earlier date as contaminants

in imported seed rice.

Problems related to WR infestations in rice fields were said to have been

reported from European countries since the 1970s (Tarditi and Verseci, 1993). The

WR phenomenon started when European farmers were cultivating the weak and

semi-dwarf types of Oryza sativa var. indica (Tarditi and Verseci, 1993). In South-

East Asian countries, Azmi et al. (1998) reported that WR infestation started after the

adoption of direct seeding practices in rice cultivation. This is in contrast to the

traditional practice of transplanting seedlings from seedbeds to the paddy fields

where WR infestation was relatively unknown. In Malaysia, the phenomenon is said

to have started in the 1980s (Vaughan et al., 1993; Azmi and Karim, 2008).

Several theories have explained on the possible emergence or evolution of

WR. One theory states that WR was produced as a result of outcrossing between

cultivated rice (CR) species and their relatives in the wild or between different

cultivars while other theories consider weedy species to be derived from natural

mutations (Catling, 1992; Abdullah et al., 1996; Gressel, 1999; Federici et al., 2001).

One phenomenon related to WR is what is known as “volunteer seeding”. It

is generally defined as seeds (usually of inferior quality) that are already present in

2

the field that would germinate and grow into a crop, as opposed to those selected

superior seeds of a crop which are sown to produce a good harvestable crop.

In terms of chromosome numbers, most of the different types of WR have

the same genome as CR genome AA, 2n=24 (Azmi and Karim, 2008). Apparently,

according to Azmi and Karim (2008) there are ten different genomic groups for

Oryza species, denoted as AA, BB, CC, BBCC, CCDD, EE, FF, GG, JJHH and

JJKK. Oka (1990), Gressel (1999), Lu et al. (2003) and Lu (2004) stated that species

with different genomes are not compatible for intercrossing. The number of rice

species from the various reports vary 22 to 26 (see Section 2.2.2).

In Malaysia, WR is of the same species as CR, Oryza sativa L., but the

former is derived from inferior seed sources produced by CR as a result of

unfavourable (drought) growing season as suggested by Watanabe et al. (2000). One

of its main characteristics is its early shattering of mature seeds which accumulate at

the ground level in the paddy fields while CR retain its seeds much longer and

harvestable. Thus the seeds of WR would germinate and grow in the paddy fields

after harvest season. Germination and growth of WR is much vigorous in the next

rice planting season since growth conditions for the WR are made more favourable.

The WR will thus compete with the CR in terms of space and nutrients.

In general, rice species including WR are characterized by their capability to

self-propagate and to produce seeds (Azmi and Karim, 2008). Apart from this, WR is

also known to have the adaptability to withstand different weather conditions and

thus it has an added advantage when competing with CR (Baki et al., 2000). On the

other hand, Begum et al. (2005a, 2005b) had confirmed that WR populations could

successfully colonize a CR field to such an extent that they would thus become the

dominant weed species.

3

1.2 The Malaysian Scenario

Baki et al. (2000) first reported on the occurrence of WR in paddy fields in

the Projek Barat Laut Selangor (PBLS) since 1988 and its subsequent occurrence in

the Muda rice scheme in Kedah in the 1990s. The report also stated that the

emergence of WR in paddy fields might be attributed to severe droughts which

occurred in Peninsular Malaysia in the 1980s. Subsequently, this had led to

significant rice crop yield losses in the Malaysian rice production due to growth

competition between the CR and the WR. It was also noted that WR had spread to

other rice cultivation areas in all parts of Peninsular Malaysia.

Rice cultivation has undergone revolutionary advances especially with the

introduction of machineries such as tractors and combine harvesters. These machines

are often transported from place to place and they thus become carriers of WR seeds

which are physically stuck to their body parts. This phenomenon has been observed

and reported by Baki and Shakirin (2010) who specifically mentioned that the

movement of farm machinery between granaries in different areas was a contributing

factor to the WR infestation problems. On the other hand, Azmi et al. (2000)

observed that the wide spread of WR in paddy fields throughout Peninsular Malaysia

was also due to the shift of rice planting practice from the traditional method of

transplanting rice seedlings (from seedbeds to the paddy fields) and to that of the

modern practice of direct seeding.

Several factors are thought to cause the appearance of WR in rice fields.

Initially the wild rice retains its genetic makeup and grows as separate genepools

apart from CR or “cultivars”. Gradually, the initial genetic materials of the WR

become mixed with the genetic materials of the CR as a result of natural

hybridization including backcrossing. The mingling of genetic resources between

4

WR and the CR eventually produced new genetic strains of WR which are

commonly referred to as the “new unwanted varieties” as mentioned by Azmi and

Karim (2008). These new unwanted varieties are also known as “padi angin” in

Malay (or “wind rice” in English) because of the early shattering characteristics and

the lighter grains which are easily detached from the panicles when blown in the

wind and thus these grains drop on the ground before rice harvesting.

Baki et al. (2000) and Azmi and Karim (2008) explained that the new

unwanted varieties or “variants” (new strains of WR) could be triggered to grow

competitively with CR as a result of external factors such as unpredictable weather

conditions and lack of control in agricultural management. The unpredictability of

weather conditions at times in Malaysia has increased the quantity of WR seeds

embedded in natural seed bank sat the ground level as mentioned by Azmi and

Karim (2008). In addition, the absence of proper control of WR has allowed quick

dispersal of WR seeds which is normally unknown to farmers in the field and thus

would cause a possible major upsetting of the yield of the whole rice crop Azmi and

Karim (2008).

From available data gathered, it is known that at 35% level of WR

infestation, the lost yield of CR is about 50-60% or 3.20-3.84 tonnes per hectare per

season (Baki, 2004). In extreme cases, up to 75-100% lost yields have been recorded

due to WR infestation (Azmi et al. unpublished data, in Baki 2004). These estimates

are general information gathered by relevant authorities such MARDI based random

surveys on rice production in certain rice paddy areas. However, detailed surveys on

the effect of WR at different levels of infestation are seldom undertaken or very little

known.

5

1.3 Current Issues

At present Malaysia is only 72 percent self-sufficient in rice production

(Gomez, 2011; Zhi, 2011). Despite Malaysian Government’s efforts to boost its rice

industry, rice production has not increased as expected. So much so Malaysia is still

heavily dependent on rice imports. There was even a rice crisis in 2008 when rice

exporting countries stopped exporting rice to Malaysia (Childs and Kiawu, 2009;

Vengedasalam, 2013), thus rice production is an important security issue in the

country.

1.4 Problem Statement

Despite efforts to overcome problems caused by WR in the rice fields in

Peninsular Malaysia, the problems have persisted to the present day. Among the

major issues faced by the rice industry is the indifferent attitude of rice farmers

toward these problems. Some farmers prefer to use CR for seed stock, and do not

consider WR as a weed. The lack of interaction and communication among

agricultural agencies and insufficiency of integrated technologies to control WR have

resulted in minimal attention being given to WR management in Peninsular

Malaysia. A group of farmers reportedly secured uncontaminated seed sources from

the Pertubuhan Peladang Kawasan (“Regional Farmers Organization”), but seed

contamination still occurs. During field inspection for certified seeds, off-type

varieties cannot always be differentiated from WR. When differences can be

distinguished, the maximum mixture of other varieties permitted is approximately

0.10%, which is equivalent to 0.15 kg per 150 kg CR rate. Little is known about seed

contamination resulting from contaminated seed sources in actual rice fields, and

information on actual levels of WR infestations in paddy fields throughout

6

Peninsular Malaysia is lacking. Given that this subject is becoming increasingly

critical, more studies are necessary to supplement data.

1.5 The Need to Conduct the Study

Based on ISI Web of Knowledge Journal Citation Reports, there were about

146 studies on WR, which focused on various topics. Most of the studies were done

on specifications of WR, while few were done on competition of WR. Only five

studies recorded on WR competition by Burgos et al. (2006), Chauhan and Johnson

(2010), Lawton-Rauh and Burgos (2010) and Ziska et al. (2010). Based on the

current state of knowledge on the effects of WR on CR production in Peninsular

Malaysia as mentioned above, a study of this nature is much needed in order to have

better knowledge on the subject. This study is hoped to gather the much needed

information especially on the effects of WR at different levels of infestation on the

CR.

1.6 Aim and Objectives

The aim of the study is to compare CR yields that are produced by CR at

differing conditions, without and with the infestations at different levels of WR

(ratio) in cultivation. Three objectives have been identified in this study as follows:-

1. To determine the influence of WR on the Relative Growth Rate (RGR) of CR

by comparing CR monoculture with those of mixed culture at different ratios.

2. To determine the influence of WR on the yield components and yield of CR

by comparing CR monoculture with those of mixed culture at different ratios.

7

3. To determine the influence of yield components on yields of CR by

comparing CR monoculture with those of mixed culture at different ratios.

1.7 Hypotheses

Based on the three objectives above, the following three hypotheses are

formulated to test the statements of these objectives. The objectives and the

hypotheses are the basis for the methodology adopted in this study as shown in

Chapter 3.

a) Hypothesis for Objective 1 (HA)

Null hypothesis: HA(0): WR does not affect RGR of CR even with increased levels of

infestation.

Alternative hypotheses: HA(1): WR does affect RGR of CR increasingly with

increased levels of infestation.

b) Hypothesis for Objective 2 (HB)

Null hypothesis: HB(0): WR does not affect the yield components and yield of CR

even with increased levels of infestation.

Alternative hypothesis: HB(1): WR does affect the yield components and yield of CR

increasingly with increased levels of infestation.

c) Hypothesis for Objective 3 (HC)

Null hypothesis: HC(0): Yield components does not affect yield of CR even with

increased levels of infestation.

8

Alternative hypothesis: HC(1): Yield components does affect yield of CR increasingly

with increased levels of infestation.

9

CHAPTER 2

LITERATURE REVIEW

2.1 Basic Introduction to Rice Crop Science

Yoshida (1981) provided vital information pertaining to the fundamentals of

rice crops science. Figure 2.1 shows the growth behaviour of the rice plant.

Figure 2.1: Life-history of CR (from Yoshida 1981).

The growth behaviour of the CR plant observed in this study would much

refer to the established growth pattern such as the one shown above. Basically the

annual CR takes about 3 to 4 months to complete its life-cycle. Based on a 120-day

(4-month) growth cycle, the vegetative growth lasts to about 90 days after which

vegetative growth will be reduced significantly. Tillering usually starts at about 20

10

days after sowing and reaches maximum growth at about 60 days after sowing and

after which tillering would remain constant or reduced (as shown in Figure 2.1).

Panicle initiation starts at about 80 plus days at the booting stage followed by grain

filling at about 90 days after sowing. The rice plant should reach maturity in 120

days and after which growth will cease and the plant starts to undergo senescence.

2.2 General Background

A brief background information on rice is provided in this section. The

subtopics under this section are those dealing with the origins of rice, taxonomic

classification, and information on the species and cultivated varieties of rice in

general.

2.2.1 Origins of Rice Culture

According to Zhimin (1999), the Asian-centered rice-planting culture has a

wide distribution and a long history, with different hypotheses concerning its origin

pointing to several regions including Assam, Yunnan, East Asian Crescent and

middle and lower Yangtze River. Zhimin (1999) has also stated that,

archaeologically, China has the earliest rice site with a rich culture, tracing both to

the middle and lower Yangtze River, and thus subsequently its powerful influence on

surrounding areas is well evidenced by Korean and Japanese findings.

The Chang-Watanabe hypothesis (Sato, 2000; History of Rice Cultivation),

however, proposed that the Asian CR (O. sativa L.) emerged in an area stretching

across Assam District of India, upper Myanmar, northen Thailand, northern Lao

(PDR), and the southwestern provinces of China.

11

In the African continent, the species used for CR is Oryza glaberrima, and

the species has been long in cultivation in Africa before the arrival of the Europeans

in the continent (Linares, 2002). However this species was gradually replaced by the

Asian Oryza sativa and according to Linares (2002) the Asian CR has replaced most

of the native CR except in certain traditional areas. In the American continent, rice

was introduced by the European settlers in the 17th

century. Rice is not known to be

native to the Americas.

2.2.2 Classification, Species and Varieties

2.2.2.1 Classification of Oryza

Oryza is a genus in the Graminae or Poaceae family, or commonly known

as the grass family. The grass family is the fourth largest flowering plant family and

contains about 11 000 species in 800 genera worldwide (Peterson 2001). Twenty-

three genera contain 100 or more species or about half of all grass species, and

almost half of the 800 genera are monotypic or diatypic, i.e. with only one or two

species (Peterson, 2001).

APG 3 (Angiosperm Phylogenetic Group III) 2009 classifies rice or Oryza

sativa L. as follows (also based on Gramene Oryza website; note the rank of

Subfamily is used based on GRIN and the rank of Tribe is used used after Tang et

al,. 2010):-

Kingdom: Plantae - Plants

Subkingdom: Tracheobionta - Vascular plants

Superdivision: Spermatophyta - Seed plants

Division: Magnoliophyta - Flowering plants

Class: Liliopsida - Monocotyledons

Subclass: Commelinidae

Gramene

http://www.ars-grin.gov/

12

Order: Cyperales

Family: Poaceae - Grass family

[Subfamily: Ehrhartoideae]

[Tribe: Oryzeae]

Genus: Oryza L. – CR

2.2.2.2 Species and Varieties of Rice

Scientists are still divided on the taxonomy of Oryza and the number of

species quoted ranges from 21 to 26 species; 21 species (Delouche et al. 2007), 22

species (Brondani et al,. 2003; Jaiswal et al,. 2005; Mabilangan et al,. 2008), 23

species (American group – according to Gramene Oryza), 24 species (Jena, 2010;

Rice Bank Knowledge), 25 (GRIN database – see the list of species below) and 26

species listed by Gramene Oryza (based on survey of species names list). The list of

species in Gramene Oryza is shown in Table 2.1.

A list of rice species based on GRIN database is given below (note: 67 taxa are

listed in GRIN but only 25 have been extracted and regarded as valid species and

listed here):-

1. Oryza alta Swallen (sect. Oryza ser. Latifoliae)

2. Oryza australiensis Domin (sect. Australiensis)

3. Oryza barthii A. Chev. (sect. Oryza ser. Oryza)

4. Oryza brachyantha A. Chev. & Roehr. (sect. Brachyantha)

5. Oryza eichingeri Peter (sect. Oryza ser. Latifoliae)

6. Oryza glaberrima Steud. (sect. Oryza ser. Oryza)

7. Oryza glumipatula Steud. (sect. Oryza ser. Oryza)

8. Oryza grandiglumis (Döll) Prodoehl (sect. Oryza ser. Latifoliae)

9. Oryza latifolia Desv. (sect. Oryza ser. Latifoliae)

10. Oryza longiglumis Jansen (sect. Padia ser. Ridleyanae)

11. Oryza longistaminata A. Chev. & Roehr. (sect. Oryza ser. Oryza)

12. Oryza malampuzhaensis Krishnasw. &

13. Oryza meridionalis Ng (sect. Oryza ser. Oryza)

14. Oryza meyeriana (Zoll. & Moritzi) Baill.

15. Oryza minuta J. Presl (sect. Oryza ser. Latifoliae)

16. Oryza neocaledonica Morat (sect. Padia ser. Meyerianae)

17. Oryza nivara S. D. Sharma & Shastry (sect. Oryza ser. Oryza)

http://www.knowledgebank.irri.org/

http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?310120

















13

18. Oryza officinalis Wall. ex G. Watt (sect. Oryza ser. Latifoliae)

19. Oryza punctata Kotschy ex Steud. (sect. Oryza ser. Latifoliae)

20. Oryza rhizomatis D. A. Vaughan (sect. Oryza ser. Latifoliae)

21. Oryza ridleyi Hook. f. (sect. Padia ser. Ridleyanae)

22. Oryza rufipogon Griff. (sect. Oryza ser. Oryza)

23. Oryza sativa L. (sect. Oryza ser. Oryza)

24. Oryza schlechteri Pilg. (sect. Padia ser. Schlechterianae)

25. Oryza schweinfurthiana Prodoehl (sect. Oryza ser. Latifoliae)

Table 2.1: Species of rice (Oryza) in the world.

Oryza alta Oryza australiensis Oryza barthii Oryza brachyantha Oryza coarctata Oryza eichingeri Oryza glaberrima Oryza glumipatula (Oryza glumaepatula) Oryza grandiglumis

Oryza granulata Oryza latifolia Oryza longiglumis Oryza longistaminata (Oryza glumaepatula) Oryza malampuzhaensis Oryza meridionalis Oryza meyeriana Oryza minuta Oryza nivara (Oryza sativa f. spontanea)

Oryza officinalis Oryza perennis Oryza punctata Oryza rhizomatis Oryza ridleyi Oryza rufipogon Oryza sativa Oryza schlecteri Data retrieved October 17, 2006

(Note: Adapted from Gramene Oryza).

Up until now, the taxonomy of Oryza has not been fully resolved, but as for

the cultivated species, most scientists accept two species; Oryza sativa and Oryza

glaberrima as the world’s widely CR species. The rest of the species are considered

wild although a few species of these so-called wild species might be in cultivation

e.g. Oryza longistaminata or Red Rice which is cultivated in parts of traditional

Africa. The non-cultivated species may sometimes be referred to as “WR” (see

subsection [e] below).

In Peninsular Malaysia, two species or rice are know to exist; Oryza

rufipogon (the wild rice species) and Oryza sativa (cultivated species). Although

Oryza rufipogon is considered a wild species, it is however listed in IUCN Red Data

Book (or Red List) 2012 release under “Least Concern” (LC) or “Lowest risk”. In the

IUCN category of threatened species, this category denotes that a species does not









http://www.gramene.org/

14

qualify for a more “at risk” category. Widespread and abundant taxa are included in

this category.

2.2.2.3 Phylogentic Relationship

Recently, there have been many studies on the phylogenetic relationships of

Oryza species by Song Ge et al. (1999), Sacks et al. (2006), Duan et al. (2007),

Zuccolo et al. (2007), Ammiraju et al. (2010), Tang et al. (2010) and Lawton-Rauh

and Burgos (2010). The general concensus by scientists agrees that the two CR

species Oryza sativa and Oryza glaberrima are both of genome AA together in the

same clade (within the phylogenetic tree) with the non-cultivated species Oryza

rufipogon, Oryza glumipatula, Oryza longistaminata, Oryza barthii, Oryza

meridionalis and Oryza nivara as shown by Song Ge et al. (1999). It is generally

believed that Oryza sativa is derived from Oryza rugifogon and that Oryza

glaberrima is derived from Oryza nivara (Zuccolo et al. 2007).

2.2.2.4 The International Rice Genebank

IRRI (International Rice Research Institute) which is based in Los Banos,

Philippines holds more than 117,000 “types” of rice - the biggest collection of rice

genetic diversity in the world. The genetic diversity of rice is used to breed new rice

varieties (IRRI).

2.2.2.5 WR in General

This subject has been introduced earlier in Chapter 1 (Sections 1.2). As can

be seen above, there are more than twenty species of rice, two of which are

http://www.irri.org/

15

cultivated, and all of which belong to the AA genome (Figure 2.2). There is the

tendency for outcrossing, backcrossing and hybridization between populations of

different species and varieties. As a result there would exist hybrids and outcrossed

rice species and varieties that resemble closely with cultivated. These hybrids or

varieties may infest rice fields though volunteer seeding or contaminated seeds.

Figure 2.2: Phylogenetic tree showing the AA genome in rice (after Song Ge 1999).

Begum et al. (2005a, 2005b) stated that existing weed vegetation could be

drastically replaced by the WR of the Oryza sativa complex. WR, however, had not

been listed as a dominant weed species before the emergence of the WR

phenomenon in rice fields, but once it began to emerge in the rice fields, it then

started to seriously infest the rice cultivars (Zainal, 2008). Baki et al. (2000)

16

postulated that the emergence of WR in rice fields was probably caused by severe

droughts in Peninsular Malaysia in the 1980s.

Baki (2004) reported that WR had began to colonise the MADA rice

cultivated areas in the early 1990s, followed by the Besut area (Terengganu) in 1995,

Sg. Manik and Kerian areas (Perak) in 1996, Seberang Perai (Pulau Pinang) in 1997,

and Seberang Perak (Perak) and Kemubu (Kelantan) areas in 2001. It was also noted

that about half of the 700 hectares of rice farm blocks in Selangor areas (Sekinchan,

Sungai Leman, Sungai Burong and Sungai Nipah) were infested by WR for Season 2

in 1993 (Baki, 2004).

According to Baki et al. (2000), owing to the sympatric occurrence of WR

and commercial rice, the WR had the tendency to compete for space and the common

pools of nutrients which were necessary for growth and survival. Baki et al. (2000)

also reported that WR populations in the various rice cultivated areas in Selangor did

not show distinct morphological variation.

Methods of WR control have been developed in Peninsular Malaysia to

address the WR menace in rice fields such as better water management, application

of suitable herbicides, and improved tilling method (Azmi and Karim, 2008). Despite

efforts to reduce WR infestations in rice fields, the phenomenon had continued to

persist. Baki et al. (2000) were of the opinion that the persistence or continued

prevalence of WR over CR was an indication of better ecological adaptations by WR

compared to the commercial rice varieties.

The use of herbicide-resistant rice cultivars has the potential to improve the

efficiency of weed management in rice fields and to increase rice yields (MARDI,

2008). However, any new herbicide that is applied to the rice fields to protect a rice

http://www.mardi.gov.my/

17

cultivar would consequently induce similar resistence in the WR found in the same

area. This would happen through outcrossing (Busconi et al., 2012).

WR normally takes about 90-120 days to mature compared to the

commercial variety which takes about 115 days to 120 days (Zainal, 2008). In

addition, WR exhibits other advantageous characters over the commercial varieties

such as taller plant height, faster growth rate, and earlier seed shattering. Some WR

variants are known to have a life-cycle of less than 3 months, thus the seeds mature

earlier and dropped into the natural seed banks and remain dormant until the next

growing season. At the sametime, the dropped seeds of WR can also germinate and

colonise abandoned rice fields after the harvest season.

WR can also originate from the natural hybrids between CR and WR

through cross-pollination (Azmi and Karim, 2008; Grillo et al., 2009) as well

through introgression (Baki et al., 2000). Introgression or introgressive hybridization

is generally defined as the movement of a gene from one species into the gene pool

of another by the repeated backcrossing of an interspecific hybrid with one of its

parent species. The level of introgression can be determined by outcrossing (Baki et

al., 2000). The rate of outcrossing affects the heterozygosity of populations which

might also to contribute to the evolutionary potential of WR (Baki et al., 2000). For a

non-specific crop, introgression is said to able to influence the genetic variation and

possibly also the evolution of its co-existing WR populations (Baki, et al., 2000).

2.2.2.6 WR in Peninsular Malaysia

From personal study and observation, in Peninsular Malaysia, WR can be

attributed to four factors were (i) volunteer seedling, (ii) seed contamination, (iii)

outcrossing between Oryza rufipogon and Oryza sativa, (iv) outcrossing between

18

WR (which is a low quality variety of Oryza sativa) and CR (the high quality

commercial variety) of the same species Oryza sativa. Azmi and Karim (2008)

however regarded three factors that help to initiate the population growth of WR i.e.

(i) the existence of dormant seeds retained in the soil over crop seasons, (ii) the

distribution of the WR seeds through contaminated seeds, and (iii) the return seeds

from plants of the previous crop.

2.2.2.7 Oryza rufipogon Griff. – A Wild Species of Rice

Most of the following information was retrieved from the IUCN Red Data

List website (http://www.iucnredlist.org) on 29th

August 2013. The plant description

part (botanical description) was retrieved from the Rice Bank Knowledge website

(http://www.knowledgebank.irri.org) on 29th

August 2013, and Ngu et al. (2010).

Oryza rufipogon is the wild species from which the CR, Oryza sativa, has

been domesticated. It is wide spread in most of the world, being invasive in parts of

America. It is considered a weed in rice fields, as it easily crosses with the CR,

reducing its market value. No serious threats have been reported for the species and

hence it is included in the category Least Concern. It is important for the germplasm

which has many resistant genes, and hence is collected and conserved in-situ and ex-

situ in China.

Oryza rufipogon is a widely distributed tropical plant. It has been recorded

in Asia (Afghanistan, Bangladesh, Cambodia, China, India, Indonesia, Iran, Iraq,

Korea, DPR, Republic of Korea, Laos, Malaysia, Myanmar, Nepal, Pakistan,

Philippines, Sri Lanka, Thailand, Vietnam), Africa (Egypt, Senegal, Swaziland,

Tanzania), North America (USA), Central America, South America (Brazil,

http://www.iucnredlist.org/

http://www.knowledgebank.irri.org/

19

Colombia, Ecuador, Guyana, Peru, Venezuela, Oceania), Australia (Australia,

Queensland, Papua New Guinea).

Native countries for Oryza rufipogon is native to these following countries:

Afghanistan; Australia; Bangladesh; Brazil; Cambodia; China (Guangdong, Guangxi,

Hunan, Jiangxi, Yunnan); Colombia; Ecuador; Egypt; Guyana; Hong Kong; India

(Andhra Pradesh, Assam, Bihar, Goa, Karnataka, Kerala, Madhya Pradesh,

Maharashtra, Orissa, Tamil Nadu, Uttar Pradesh, West Bengal); Indonesia (Irian

Jaya, Jawa, Kalimantan, Sulawesi); Iran, Islamic Republic of Iraq; Korea,

Democratic People's Republic of Korea, Republic of Lao People's Democratic

Republic; Malaysia; Myanmar; Nepal; Pakistan; Papua New Guinea; Peru;

Philippines; Senegal; Sri Lanka; Swaziland; Taiwan, Province of China; Tanzania,

United Republic of; Thailand; United States; Venezuela; Viet Nam.

The species is widely distributed and has invasive tendencies. The

population trend is reported to be increasing. Oryza rufipogon grows in shallow

water, irrigated fields, pools, ditches and sites with stagnant or slow, running water.

It occurs at altitudes from 0 to 1000 m and is suited to sites that support populations

of CR. It is naturally found in terrestrial and freshwater swamp ecosystems.

Oryza rufipogon is perennial, tufted, and scrambling grass with nodal

tillering; plant height variable (1-5 m) depending on the depth of water; panicles

open; spikelets usually 4.5-10.6 mm long and 1.6-3.5 mm wide with awns usually 4-

10 cm long; anthers >3 mm reaching 7.4 mm long.

Oryza rufipogon were found growing in swamps, along river banks,

irrigation canals and in or at margins of rice fields (Abdullah et al., 1991; Ngu et al.,

2010). However, this natural population Oryza rufipogon still can be found in

Peninsular Malaysia such as Seberang Perai of Pulau Pinang, Kedah, Kelantan and

20

Terengganu. For Malaysia, this species can be found only in the northern part of

Peninsular Malaysia (Seberang Perai of Pulau Pinang, Kedah, Kelantan and

Terengganu), growing in swamps, along river banks, irrigation canals and in or at the

margins of rice fields (Abdullah et al., 1991; Ngu et al., 2010). Oryza rufipogon is a

perennial that lives in relatively a seasonal habitats and relies primarily on vegetative

production; it is a short day plant that flowers near the end of the monsoon season

(October to March). It outcrosses at a much higher rate (7–56%) compared to Oryza

sativa (1–2%) (Cao et al., 2007; Ngu et al., 2010) and has large, indehiscent and

pendant anthers (Grillo et al., 2009; Ngu et al., 2010).

Since Oryza rufipogon is one of the most important gene pools for rice

breeding, there is an urgent need for its conservation. The results of the present study

on population structure of Oryza rufipogon can be helpful in designing methods for

developing collection and conservation strategies for different populations of Oryza

rufipogon in Malaysia (Ngu et al., 2010).

2.2.2.8 CR Varieties

Rice has been cultivated in China since ancient times and was introduced to

India before the time of the Greeks, and Chinese records of rice cultivation go back

4,000 years (IRRI website; Pearson Education website). Thus, the history of selective

breeding for rice a rather long one. To date, more than 117,000 types of rice

(cultivars) are kept in the International Rice Genebank at IRRI in the Philippines (see

subsection [2.2.2.4] above).

In Peninsular Malaysia, at least forty cultivars have been recorded thus far

by MARDI (MARDI 2011) as listed in Table 2.2 below.

21

Table 2.2: List of rice cultivars in Peninsular Malaysia.

CR YEAR

RELEASED

CR YEAR

RELEASED Malinja 1964

MR 81 1988

Mahsuri 1965

Pulut Hitam 9 PH9 1990 Ria (IR8) 1966

MR 103 1990

Bahagia 1968

MR 106 1990 Murni 1972

MR 123 1991

Masria Pulut 1972

MR 127 1991 Jaya (C4-63) 1973

MR 159 1995

Sri Malaysia I 1974

MR 167 1995

Pulut Malaysia I 1974

MR 185 1997 Sri Malaysia II 1974

MRQ 50 1999

Sekencang 1979

MR 211 1999 Setanjung 1979

MR 219 2001

Sekembang 1979

MR 220 2003

Kadaria 1981

Maswangi MRQ 74 2005 Pulut Siding 1981

MR 232 2006

Seberang 1984

MRM 16 2010 Manik 1984

MR220 CL1 2010

Muda 1984

MR220 CL2 2010 Makmur 1985

MR 253 2010

MR 84 1986

MR 263 2010

(Note: This table was constructed based on MARDI, 2011)

At present, majority of Peninsular Malaysia rice farmers are encouraged to

use seeds of rice cultivars recommended by MARDI. However Chinese rice farmers

in the Sekinchan area in Selangor prefer to use their own seed sources including

those cultivars developed by selection and breeding conducted by these farmers.

Production from the Sekinchan paddy areas is usually higher compared to those areas

using MARDI seeds. One such variety is the “Siraj” which is said to contribute about

200-300 % increase in rice yield.

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2.2.2.9 Yield of Malaysian (MARDI) Rice Cultivars

Table 2.3: Malaysia rice cultivars.

CR YIELD (kg/hectare) YEAR RELEASED

JAYA 3500-5000 1973

MR1 (Setanjung) 4100-6000 1979

Kadaria 2900-5000 1981

MR 52 (Manik) 4000-5000 1984

MR 71 (Muda) 5000-5500 1984

MR 77 (Seberang) 5000-5500 1984

MR 73 (Makmur) 5500-6500 1985

MR 84 4057-6235 1986

MR 81 4200-6000 1989

MR 106 4500-7100 1990

PH 9 (Pulut hitam) 3800-4700 1990

MR 127 4831-7245 1991

MR 159 3500-5400 1995

MR 167 4000-6000 1995

MR 211 6000-9000 1999

MRQ 50 3500-4500 1999

MR 219 7000-10000 2001

MR 220 7000-10000 2003

MRQ 74 (Maswangi) 4500-5500 2005

MR 232 7000-10000 2006

MR 220 CL1 5740-9140 2009

MR 220 CL2 5840-9740 2009

MR253 5600-7000 2010

MR263 5500-7000 2010

(Note: Cultivars in bold are used in this study, compiled from information gathered

from MARDI website).

2.2.2.10 General Statistics on Rice Industry in Malaysia

At present, nearly 690,000 hectare are currently under rice cultivation in

2011 in Malaysia (Department of Agriculture; Department of Statistics Malaysia).

Nearly 520,000 hectare are in Peninsular Malaysia which contribute to about 2.2

million tonnes of rice in 2001 (Department of Agriculture).

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For rice production in rice scheme areas with granaries, a total of nearly

390,000 hectare are under rice cultivation in 2011 with rice production is in the range

of about 1.6 million tonnes to nearly 1.9 million tonnes from 2007 to 2011

(Department of Agriculture).

In terms of acreages, the area under rice cultivation for Malaysia does not

show marked increase over the years. In 1970 rice cultivation covered about 533,400

hectare and in 2011 it covers about 690,000 hectare (Department of Statistics

Malaysia) showing about 30 % increase in over 40 years.

2.3 WR Phenomenon in Peninsular Malaysia

According to Azmi and Karim (2008) WR has been known to become a

menace to the rice crop in Peninsular Malaysia since 1988. According to Azmi and

Baki (2007), on average about 10 % of the Muda rice scheme area was infected by

WR. Based on personal observation, about 5 to 50 % (in terms of area) of the rice

field in the Muda rice scheme are infected by WR.

Outcrossing between WR and CR is said to have occurred in various rice

cultivated areas in the granary schemes all over Malaysia (Abdullah et al., 1996;

Vaughan et al., 1995; Chin, 2001; Shakirin, 2009; Baki and Shakirin, 2010;

Zainuddin et al., 2010). This has led to the emergence of various new types of WR in

rice field in Peninsular Malaysia. According to Watanabe et al. (2000), the WR has

different genetic makeups for different areas meaning that they are part of the rice

gene-pools of those specific areas and thus confined within such areas. At present,

the in-depth study on WR is lacking in Peninsular Malaysia.

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2.3.1 Characteristics of WR

2.3.1.1 Morphological and Anatomical Characters

WR (weedy variety of Oryza sativa) some what resembles CR but with

some minor observable differences. WR tends to be slightly more hardy and

sometimes relatively taller than CR, and its internodes are relatively (slightly) longer.

A characteristic of WR is the presence of anthocyanin pigment in various parts of the

plant including collar, ligule, grain apiculus, stigma and awns as mentioned by Azmi

and Karim (2008). Awned WR has longer epidermal hairs (Zainal, 2008). The

abaxial epidermis contains a higher number of stomata than the adaxial epidermis

(Arrieta-Espinoza et al., 2005; Zainal, 2008)

Baki et al. (2000) construed that the differences among the variants of WR

could be determined based on the shape of fruit stalks (either compact or otherwise),

the presence of reddish purple pigmentation, and the hairy characteristics of the

seeds. In addition, differences in the length of rice stalks, the number of spikelets and

empty seeds were also noted to occur from variant to variant. The name “Red Rice”

as for some species and varieties is due to the pigmentation.

There are four important characters for WR in general; plant height,

pigmented grain, easy shattering, and long awn. WR can occur as ecotypes

depending on its environment and its morphological features are somewhat

comparable to that of CR varieties from the seedling to the reproductive stage

(Zainal, 2008). According to Baki et al. (2000), most farmers in Peninsular Malaysia

are able to differentiate WR from CR based on morphological characteristics.

In general, WR can be distinguished from rice cultivars in terms of height

(Zainal, 2008). Azmi and Baki (1995) studied several variants of WR from 18

different locations and it was discovered that some of the characteristic differences

EFFECT OF WEEDY RICE (Oryza sativa L.) ON THE YIELD OF ...

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