Assessment of global warming impacts on paddy rice growth and yield using a process based numerical crop growth model matcro rice in thai binh province, vietnam

VIETNAM NATONAL UNIVERSITY, HANOIVIETNAM JAPAN UNIVERSITY DAO THI THU HANG ASSESSMENT OF GLOBAL WARMING IMPACTS ON PADDY RICE GROWTH AND YIELD USING A PROCESS-BASED NUMERICAL CROP GROWTH

VIETNAM NATONAL UNIVERSITY, HANOI

VIETNAM JAPAN UNIVERSITY

DAO THI THU HANG

ASSESSMENT OF GLOBAL WARMING IMPACTS ON PADDY RICE GROWTH AND YIELD USING A PROCESS-BASED NUMERICAL CROP GROWTH MODEL

MATCRO-RICE IN THAI BINH

PROVINCE, VIETNAM

MASTER’S THESIS

VIETNAM NATONAL UNIVERSITY, HANOI

VIETNAM JAPAN UNIVERSITY

DAO THI THU HANG

ASSESSMENT OF GLOBAL WARMING IMPACTS ON PADDY RICE GROWTH AND YIELD USING A PROCESS-BASED NUMERICAL CROP GROWTH MODEL

MATCRO-RICE IN THAI BINH

I assure that this thesis is the result of my own research and has not beenpublished The use of other research’s result and other documents must comply withregulations The citations and references to documents, books, research papers, andwebsites must be in the list of references of the thesis

AUTHOR OF THE THESIS

DAO THI THU HANG

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TABLE OF CONTENTS

PLEDGE i

LIST OF TABLES iv

LIST OF FIGURES v

LIST OF ABBREVIATIONS vi

ACKNOWLEDGEMENT vii

ABSTRACT viii

CHAPTER 1 INTRODUCTION 1

1.1 Overview 1

1.2 Research objectives 4

1.3 Structure of the Thesis 5

1.4 Learning Outcomes 7

CHAPTER 2 METHODOLOGY 10

2.1 Framework of the study 10

2.2 Study area 12

2.2.1 Location 12

2.2.2 Climate 13

2.2.3.Rice variety (Bac Thom No 7 cultivar_BT7) 17

2.3 MATCRO-Rice model 17

2.4 Data sources 20

2.4.1 Meteorological data 20

2.4.2 Crop management 21

2.5 Model parameterization 23

2.5.1 Phenology 23

2.5.2 Dry matter Partitioning 25

2.6 Nitrogen response 25

2.7 Model validation 27

2.8 Global warming impact assessment 27

CHAPTER 3 RESULTS 29

3.1 MATCRO-Rice parameterization and validation 29

3.1.1.The effect of parameterization to phenology 29

3.1.2.The effect of parameterization to Carbon partitioning 31

3.2 Yield and nitrogen response 34

3.3 Impact of temperature increase on rice yield 36

CHAPTER 4 DISCUSSION AND LIMITATION 38

4.1 Discussion 38

4.2 Limitations 41

ii

4.2.1 Data gaps 41

4.2.2 Limitation of the parameterization 41

CHAPTER 5 CONCLUSION 42

REFERENCES 43

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LIST OF TABLES

Table 2.1 Thai Binh province weather by month and weather averages 15

Table 2.2 Site information and input 18

Table 2.3 Meteorological variables 20

Table 2.4 Information of Site 1 and Site 2 21

Table 2.5 Crop calendar and field measurements 22

Table 3.1 Comparison of development stage index between simulation and global 29 Table 3.2 Timing of growth date (mm/dd/yr) 29

Table 3.3 Partitioning parameters 33

Table 3.4 The difference between before and after calibrated nitrogen response index 34

Table 3.5 Percentage different between observed and simulated yield 35

Table 3.6 The statistical analysis of rice yield 35

Table 3.7 Influence of temperature increase on rice yield 37

Table 4.1 Yield reduction 40

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LIST OF FIGURES

Figure 2.1 Framework MATCRO-Rice model simulation 11

Figure 2.2 Map of Thai Binh administrative regions 13

Figure 2.3 Monthly average temperature (oC, line and left vertical axis) and monthly rainfall (mm, column and right axis) 14

Figure 2.4 MATCRO-Rice model structure 18

Figure 2.5 The relationship between specific leaf nitrogen and DVS 27

Figure 3.1 Heading date of simulation and global data 30

Figure 3.2 Heading date of simulation and global data 31

Figure 3.3 Partitioning ratio of glucose to organs including leaves (a), panicles (b) within shoots and root (c) 33

Figure 3.4 Correlation between the observed and simulated yields The orange line is the 1:1 line 36

Figure 3.5 Comparison between simulated yield, yield at 4 warming scenarios applied for 3 nitrogen cases (high, medium and low) 37

Figure 4.1 Menu for adaptation options on agriculture 39

Figure 4.2 Influence of N fertilizer levels on rice yield at different temperature increase scenarios 40

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LIST OF ABBREVIATIONS

DVS: Development stages index

GSO: General statistic office

hGDH: Growing degree hour from seedling to heading

mGDH: Growing degree hour from seedling to harvest

MONRE: Ministry of Natural Resources and Environment

SLN: Specific leaf nitrogen

UNFCCC: United Nations Framework Convention on Climate Change

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I would like to express my sincere gratitude to my supervisors Dr YujiMasutomi - Ibaraki University and Dr Mai Van Trinh - Director of Institute forAgricultural Environment for providing the invaluable guidance, comments andsuggestions throughout my thesis

I would special thank Dr Akihiko Kotera for scientific consulting andconstantly motivating me to work harder I am also grateful to all the lectures in theVietnam Japan University and Ibaraki University for their support towards thesuccessful completion of my studies in Vietnam and Japan

Without the financial support of the Vietnamese and Japanese Governmentwhich offered me a scholarship for graduate studies, this work would not have beenpossible Special thanks go to all the lecturers and staffs at the Institute for GlobalClimate Adaptation Science (ICAS) and department of Agriculture in IbarakiUniversity for providing me an internship in Japan in two months which I had anopportunity to research with professionals and enjoy culture exchange I am reallygrateful to them

In addition, I would also like to thank my friends and colleagues at theInstitute for Agricultural Environment for supporting me during the entire datacollection period and creating best conditions for me to balance my work and study

Finally, I want to dedicate my success to my family for the encouragementand support throughout my research process I give special thanks to my parents forhelping me take care of my children, providing logistical support andencouragement that no one to help me cannot complete my work

I submit this thesis of mine with great humility and regards

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Rice is directly feeding more people than any other crops Vietnam is one ofthe largest exporters of rice with the main supply from Red River Delta Riceproduction in Red River Delta is susceptible to yield reduction from risingtemperature Thus, understanding the impacts of global warming on rice production

is essential to food security in Vietnam in the near future This research used areliable data of crop management in Thai Binh, located province in Red RiverDelta To simulate the rice production, I used the crop growth model, MATCRO-Rice, first the model needs to be parameterized the phenology and dry matterpartitioning, then I validated by comparing the simulated yield to observe yield.Next, the model was used to predict the changes of rice production under 4 warmingscenarios (1.5 oC, 2 oC, 3 oC and 4 oC) Results show that the yield reductionhappened in all of warming scenarios and decline up to 39% compare with observeyields The yield will be improved by adding more fertilizer, but this applicationcannot offset the losses due to rising temperature This research got some limitationfrom both data and model, but it can contribute to the development of a nationaladaptation plan with a scientific basis

Keywords: global warming scenarios, rice production, crop growth model

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CHAPTER 1 INTRODUCTION

According to the IPCC in 2014, climate change that was caused by globalwarming, has recorded high impacts on human and natural systems during the pastfew decades (IPCC, 2014) At the end of the twentieth century, the temperature wasrecorded 0.7 oC higher than the nineteenth century According to the conclusion ofthe Paris Agreement in 2015, all countries under the United Nations FrameworkConvention on Climate Change (UNFCCC) seek the long term temperature target toprotect the climate (UNFCCC, 2015) to limit future global warming to less than 2.0o

C above the pre-industrial levels (1861 – 1880) Ideally, global temperature risingwill be kept under 1.5 oC (UNFCCC, 2015) due to the adverse effects of climatechange that have been observed worldwide It is necessary to evaluate climatechange impacts, especially global warming to implement adaptation plans atnational scale

Fossil fuel and biomass burning are the main causes to increase carbondioxide (CO2) in atmosphere as the main greenhouse gas So far, the CO2concentration has increased from 280 ppm to around 400 ppm and mainly causedclimate change On the other hand, rising CO2 concentration also roots of risingtemperature and changing in precipitation and this still continues in the future(IPCC, 2014)

There have been many researches on assessing the range of global warmingbased on the 2015 Paris Agreement on many fields across the globe (Mitchell et al.,2017) and agriculture is strongly influenced by it across the world (Faye et al.,2018; Liu et al., 2018; Schleussner et al., 2018) The scientists have made efforts onmitigation of global warming to ensure the food stability in context of thepopulation continues to rise in the next decades (Gaupp et al., 2019)

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Rice (Oryza sativa L.) is the most important food crop in the world in general

and in Asia in particular (Clauss et al., 2018), directly feeding more people than anyother crop There have been a number of past studies to examine the effects ofglobal warming on rice growth and yield in global or regional scales (Zhai andZhuang, 2009; Chen, McCarl, & Chang, 2011; Rosenzweig et al., 2014; Zhao et al.,2016; Lobell and Asseng, 2017) The exceeding temperature during the rice growthwill impact on photosynthesis capacity (Cai et al., 2018), root length (Sanchez et al.,2014), increasing the rate of unfilled grain and others (Prasad et al., 2006) Whenthe temperature is higher, it will promote the reproductive development, thusshortening the rice growth time (Lu et al., 2008) and leading to decrease the riceyield (Prasad et al., 2006) According to Peng et al., 2004, with 1 oC increase innighttime, rice yield will reduce by about 10% and the reasons come from thedecrease of solar radiation Other researches have shown that the future reduction inrice yields will be more evident at low latitudes than medium or high latitudes, sincewarmer temperatures at low latitude result in higher thermal stress for rice(Rosenzweig and Parry, 1994) Almost previous studies have shown that rice yieldhas been reduced due to climate change, but the extent of the reduction and thespatial variability of impacts have been controversial so far (Yang et al., 2014).Therefore, in the future global warming could seriously threaten rice yield to feedfuture generation in global scale, especially in Asia

Vietnam is a developing country in which agriculture is a traditionaleconomic sector Currently, Vietnam is one of the world’s richest agriculturalregions and is the second largest exporter worldwide and the world’s seventh largestconsumer of rice Rice cultivation accounts for more than three-quarters of thecountry’s total annual harvested agricultural area and employs about two-thirds ofthe rural labor force which has been making a significant contribution to rurallivelihood (Vu and Glewwe, 2009; Nguyen, 2006) Agricultural production could beeasily affected on climate variability and according to the Ministry of NaturalResources and Environment (MONRE), an average annual temperature has tended

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to increase by about 0.62 oC since 1958 (MONRE, 2016) It is estimated that by theend of the 21st century, compared with the average of the period 1980-1999, theaverage temperature in Vietnam may increase by 2.3 oC, annual rainfall increases

by 5% and the sea level may rise 75cm (MONRE, 2016) As a result, globalwarming has caused the instability in rice production in the country (Yu et al.,2010) Therefore, it is essential to quantify the projected impact of risingtemperature on rice yield to contribute the literature on food stability and security.Vietnam needs to proactively assess, forecast and adapt to the impacts of climatechange, in order to have timely appropriate solution and agricultural economicdevelopment

Vietnam has two large rice production delta regions including Mekong delta

to the south and Red River delta (RRD) to the north, which are vital to the domesticfood supply Although, each delta has different geographical characteristics, both ofthem are suffering from rice yield reduction because of changing climate Climatechange impacts on rice growth and yield in the Mekong delta and central part ofVietnam (Kontgis et al., 2019; Deb et al., 2015; Yu et al., 2010), however, littleattention has been paid on rice production in RRD, especially in Thai Binh provincewhich has provided largest rice in the North of Vietnam Moreover, with apopulation of 1.7 million (GSO, 2012) and more than 70% of the income sharecomes from farming activities, rising temperature could have detrimental effect onrice production in this province, and this has led to a decline in the quality oflivelihoods of people living here who rely on rice cultivation Therefore, it isimportant to predict and create adaptation plans due to climate change andtemperature is the key factor of climate issues

Prediction and assessment of climate change impacts on rice production can

be implemented by process-based numerical crop growth models which have beenincreasingly developed in the recent years (Xiong et al., 2014) Some crop growthmodels are used as much by researchers such as ORYZA2000 (Sheehy et al., 2006),CERES-Rice (Kim et al., 2013), DSSAT (Hoogenboom et al., 2010) which have

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judged rice growth and yield changes under different climate change scenarios Inrecent years, they have tended to apply model to large areas to figure out theimpacts of climate change (IPCC, 2014; Ruane et al., 2014), productivity gapsbetween the region and food security (Bezner et al., 2019), carbon sequestration(Arunrat et al., 2018), however, there is a few of studies providing enoughinformation or data to assess the performance of the models There are many kinds

of crop growth model (CGM) but it is difficult to compare the accuracy betweenmodels across larger scale because each model used different plant model and inputdata In this study, we used the process-based numerical crop growth modelMATCRO – Rice model which was developed by Professor Yuji Masutomi(Masutomi et al., 2016) to measure the effects of global warming on rice growthand yield

With all of these above reasons, I chose the topic: “Assessment of globalwarming impacts on paddy rice growth and yield using a process-based numericalcrop growth model MATCRO-Rice in Thai Binh province, Vietnam” to aim forevaluation of rising temperature impacts on the main crop in one of the highest riceproduction area in Vietnam My research results provide policymakers withvaluable information in making the global warming adaptation strategies for riceproduction in Thai Binh province

The research is necessary to choose a suitable model for climate changeimpact evaluation on rice production in Thai Binh province – one of the largest riceproduction provinces in the Red River Delta My thesis aims to solve three researchquestions:

How to develop an appropriate and efficient parameterization of crop growthmodel (CGM) performance for improvement of crop simulation?

How much rice yield will increase or decrease with global warmingscenarios?

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Which adaptation measures are preferred to address global warming in riceproduction in Vietnam?

To answer these questions, this research used the crop growth Rice model First, the model was parameterized using the crop management data forlocal cultivar named Bac Thom number 7 (BT7) which is one of the most majorlocal varieties in the Northern of Vietnam in general and in Thai Binh province inparticular Next, the temperature increase scenarios were used to identify the impact

MATCRO-on rice productiMATCRO-on The specific activities of this thesis were:

(1) to collect the data of rice crop management in Thai Binh province and climate data in this region;

(2) to parameterize and validate the model to figure out the parameters whichcould simulate model closely to the observation data;

(3) to simulate rice growth and yield by MATCRO-Rice;

(4) to predict the future rice by rising temperature scenarios;

(5) to suggest some adaptations strategies for climate change in Vietnam in general and in Red River Delta in particular

1.3 Structure of the Thesis

My thesis is organized in 5 chapters as below:

Chapter 1: Introduction

Overview the climate change has affected the rice yield in global and in Vietnam

Overview some researches regarding to rice growth duration and production

Overview some crop growth models

Give the main and specific thesis’s objectives

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Chapter 2: Material and Method

Framework of the study

Overview of study area

Introduction the crop growth model MATCRO-Rice

Data source to study

Method to parameterize and validate the model

Method to assess the impact of global warming on rice growth and

1.4 Learning Outcomes

The thesis gave the measure strategies to adapt with thereduction of rice yield due to climate change such asPLO1: Mastering the fundamental, interdisciplinary knowledge

changing in agricultural management (example: plantingand methodologies to assess and address actual problems (fate

date, fertilizer, etc ), changing in planting crop, do the earlyand features) related to CC mitigation, adaptation for

warning system, seasonal forecasting system, changing thesustainable development at global, national and local levels

variety (breeding new variety), developing the irrigationsystem…

PLO2: Understanding and developing systematic thinking;

necessary knowledge on science, technology, innovation and The thesis used the crop growth modeling which has beengovernance related to CC response for development; simulated for global scale I calibrated the parameters to fitidentifying, analyzing, assessing and forecasting the issues with small regional scale and to predict the trend of ricerelated to CC and CCR; predicting the developing trend of CC production under global warming scenario

science

PLO3: Applying knowledge to solve the problems in CC and

CCR: planning and approaching the works in field of CC;

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proposing the initiatives as well as the researches on CC;

implementing the solutions on science, technology, mechanism,

policy and finance for CCR and development

PLO4: Having skills of cooperation with personal, agencies,

To calibrate the model, I need to collect the rice yield dataorganizations domestically and internationally to solve the CC

and crop management data, hence I need to cooperate withissues, communication in works, projects on CC; and

Institute of Agricultural Environment to use the data of oneorganizing, managing and administrating advanced career

projectdevelopment

The crop growth model is written by R programing and the

PLO5: Accumulating soft skills to self-directed and adapt to user need to understand and practice some commands fromcompetitive working environment such as English proficiency easy to difficult Besides other computer skills are improved(at level 4/6 according to English competencies Framework for after the thesis course

Vietnam), Japanese communication skills; having skills on time Working with Japanese professors requires studentmanagement; using the basic computer skills proficiently; complete deadline in time, time management and self-working and researching independently; having skills of discipline in research

research and development; and using technologies creatively in Besides using English in communicate and writing reports,academic and professional fields thesis; knowing a little Japanese will make the friendly

environment between student and other Japanese professors

8PLO6: Having social/community’s responsibility and

professional morality, especially for the scientific research

results; being able to adapt to multicultural environment, ensure

the harmony between the stakeholders, CCR and development;

having good social morality, assist the vulnerable people to

climate change; compliance with the law; discipline at work and

positive lifestyle; having good attitude to their career in climate

change response for sustainable development

The thesis results show the effect of climate change to foodsecurity and sustainable agriculture and especially stronglyimpact to the vulnerable people such as farmers and thepoor Therefore, giving measure adaptation strategies is one

of the social responsibilities

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CHAPTER 2 METHODOLOGY

Figure 2.1 illustrates the framework to assess global warming impacts on riceproduction in local area using crop growth model MATCRO-Rice This researchused the phenological and biomass data of two sites in Dong Co commune, TienHai district, Thai Binh province and both sites applied three different amount offertilizer application with low, medium and high nitrogen To simulate the riceyield, we used the process-based crop growth model MATCRO-Rice Based onthese data, we made the parameterization for BT7 cultivar phenological andpartitioning parameters After the parameterization, we run the model and the modeloutput is the simulated yield and then we validated by compared with the simulatedyield with the observed yield This process will be repeated if the simulated riceyields do not match the observation data Finally, we simulated four global warmingscenarios (rising 1.5 oC, 2 oC, 3 oC and 4.0 oC) impacts on rice yield which cansupport the policy makers in conducting the adaptation strategies for rice production

in Vietnam

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Study area information

heading, harvest

Nitrogen response

Running MATCRO-Rice model

Simulation the Rice growth and yield in Thai Binh Province

Global warming scenarios

Figure 2.1 Framework MATCRO-Rice model simulation

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2.2 Study area

2.2.1 Location

Red River Delta (RRD) is the second largest in Vietnam which is located inthe northern part formed by the Red river and its distributaries merging with theThai Binh River RRD is a rich agriculture area in which the agriculture land iscultivated paddy rice RRD covers eight provinces and the capital Hanoi and HaiPhong city with a population of approximately 23 million (GSO, 2012) and denselypopulated 80% of the population are employed in agriculture, but the agriculturallands of the delta amount to only about 0.3 - 0.5 hectares per household, making thelimited supply of arable lands a significant constraint to improve living standards.RRD is the second most important rice-producing area in Vietnam, accounting for20% of the national crop Production of rice is close to optimal with very little yieldgap to exploit and employ double cropping techniques to achieve close to maximumyields

This research focused on Thai Binh province belonging to the RRD (Figure2.2) Thai Binh is the main paddy rice production area in the RRD with more than80% of land in the province under the rice farming The agriculture in this area ischaracterized by small land size (0.04 ha per rural capita or 0.2 ha per household onaverage) and complex farming like VAC system (FAO, 2001) which is anabbreviation of Vietnamese phrase meaning horticulture – aquaculture – animalhusbandry

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Figure 2.2 Map of Thai Binh administrative regions

Thai Binh is the only province in the country with three sides of the river andone side to the sea which is located in the direct influence area of the economicgrowth triangle Hanoi - Hai Phong - Quang Ninh The area of agricultural land isover 105,700 ha, mainly alluvial by two main river systems Red River and ThaiBinh River system, which is favorable for transplanting rice and other annual crops

- especially in the direction of intensive cultivation and developing high-techagriculture Like other provinces in Northern Vietnam, rice is grown in two seasons:spring (January to late May) and summer (mid-June to early October) This study focuses

on the summer growing season in 2012

2.2.2 Climate

Thai Binh belongs to typical monsoon area with one rainy season whichstarts in May and ends in October The total rainfall in the rainy season is up to1,445 millimeter (mm), accounting for approximately 85% of the total annual

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rainfall of 1,704 mm The yearly average temperature across the year is from 19 oC

to 32 oC

Figure 2.3 Monthly average temperature (oC, line and left vertical axis) and

monthly rainfall (mm, column and right axis)The driest month is December, with 24 mm of rain With an average of 355

mm, the most precipitation falls in September

July is the hottest month of the year with the average temperature is 29.8 °Cand January has the lowest average temperature of the year which is around 17.8

°C

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Table 2.1 Thai Binh province weather by month and weather averages

in Thai Binh, extremely cold event directly affecting agriculture - forestry - fishery production Pests and diseases have spread on a largescale losed investment in production development, slow-growing plants and seasonal effects The prolonged hot weather due to the impact

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of climate change in recent years, has led to the seawater intrusion into the land causing saline land for cultivation If the sea level rises by

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of flooding in the province is 11.8%; if raised to 100 cm, there will be about 31.4%

of the area at risk of flood In which, 2 districts: Thai Thuy and Tien Hai are hardesthit, with flooded areas of 31.86 km2 and 35.91 km2 respectively, followed by KienXuong, Dong Hung, Quynh Phu, Vu Thu, Hung Ha districts and Thai Binh City

2.2.3 Rice variety

The cultivar Bac thom No 7 (BT7) is a common rice variety grown in theNorthern Vietnam in general and in Thai Binh province in particular BT7 is highlyeconomical compared to conventional rice varieties and due to high Amylose 13%this variety has high quality

BT7 can grow in two seasons: Spring crop (125 – 135 days) and Summercrop (105 – 110 days) It has 100 – 105 cm plant height but it is easy to fall, goodtillering and the mass of 1000 seeds is 18.5 – 19.5 grams The average yield is 50 –

55 quintals/ha, but good intensive farming reaches to 60 – 65 quintals/ha

2.3 MATCRO-Rice model

To simulate global warming on rice yield, the process-based crop growthmodel MATCRO-Rice was used This model is combined by two models: landsurface model (LSM) and crop growth model (CGM) This model can simulatelatent heat flux, sensible heat flux, net carbon uptake by crop and crop yield byexchange variables between the LSM and CGM (Masutomi et al., 2016) However,

in the thesis framework, this research used only crop growth model (CGM) insimulation of rice yield This model has simulated rice growth and yield in globaland regional scale In addition, the model’s author has also studied the impact ofglobal warming on rice yield in Indonesia by using meteorological data in this areawhich effects on phenology and physiological rice Here is the structure of CGM inMATCRO-Rice:

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Figure 2.4 MATCRO-Rice model structure (Masutomi et al., 2016)

The CGM of MATCRO-Rice model mainly calculate rice production andbiomass for each organ during the growing period It has four modules: net carbonassimilation, crop development, crop growth and LAI, crop height, root depth.These modules combines to calculate the rice yield by simulating thephotosynthesis rate, respiration rate, allocation of photosynthesis products to eachplant organ and phenology (the timing of planting, heading and harvesting date),which are dependent on meteorological conditions although the photosynthetic rate

is influenced by the air temperature, solar radiation, humidity and other weatherconditions Table 2.2 summarized the data of simulation setting, required data

Table 2.2 Site information and input

Spatial resolution 0.50 x 0.50 grid

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Parameter Value

Site 2: Alternated wet dry

High nitrogen (HN): 110.4 kg N/haMedium nitrogen (MN): 78.2 kg N/haLow nitrogen (LN): 55.2 kg N/haModule 1: Net carbon assimilation

The main role of this module is to calculate net carbon assimilation (An) incanopy for simulating crop growth In addition, the stomatal conductance per unitleaf area for both sides of the leave (gs) is calculated for simulating roughnesslength Although this module is based on the big-leaf model, we refined two points

in the calculation according to the approach described by de Pury and Farquhar(1997) and Dai et al (2004) The first refinement is that leaves in a canopy aredivided into sunlit and shade leaves Subsequently, An per unit leaf area for each thesunlit and shade leaves are calculated The second refinement is that An for theentire canopy is calculated considering vertical distribution of nitrogen within thecanopy

Module 2: Crop development

The crop development module calculates Dvs, which is an index used toquantify developmental stage of crops Dvs is mainly used for determining thetiming of transplanting, heading, and harvesting In addition, Dvs is used for parti-tioning of carbon assimilation into each organ and for esti- mating LAI and height.This module is based on the formu- lation by Bouman et al (2001)

Module 3: Crop growth

This module calculates the growth of organs and reserves The organsconsidered in MATCRO-Rice include the leaf, stem, panicle, and root In addition,the model considers glucose reserves in leaves and starch reserves in stems Allcarbon assimilated in leaves through photosynthesis is first stored in the leaf in theform of glucose Then, the stored glu- cose is partitioned to each organ and stored inthe stem when the amount of the stored glucose exceeds the critical rate to dryweight of the leaf

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MATCRO-Rice model was calculated for the global scale or continent,therefore, to apply this model to small area we made some simplifications to theoriginal model In the study, CO2 concentration is fixed value by 400 ppm and theair temperature was generally used for all kind of temperature in the model.

2.4 Data sources

2.4.1 Meteorological data

In this thesis, I relied on widely used global climate datasets of WFDEI(WATCH-Forcing-Data-ERA-Interim) which has belonged to the WATCH project.This project has produced a large number of datasets which could be used inregional studies of climate and water In these datasets are the meteorological dataused by global hydrological and land surface models and model output for the 20thand 21st centuries Format file of the dataset is NetCDF which is popular as inputformat These datasets could be free downloaded in the website: http://www.eu-watch.org/data_availability Table 2.3 lists the meteorological variables and units asbelow:

Table 2.3 Meteorological variables

radiation flux

radiation flux

In this research, we used the weather data in 2012 for MATCRO-Ricerequirements including air temperature, wind speed, precipitation, air pressure,radiation and humidity Six meteorological variables at 3-hourly time steps anddaily averages for the global land surface at 0.5o x 0.5o resolution

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2.4.2 Crop management

Phenological and physiological data are required for MATCRO-Rice whichwere collected in the project: “Research on the impact of climate change on somemajor crops (rice, maize, soybean, sugarcane) in the Mekong River Delta and theRed River Delta” This project was implemented by Institute of AgriculturalEnvironment under Ministry of Natural Resource Environment (MONRE) in 2012.This project had the experiment fields of rice in Thai Binh, Soc Trang province,however this study focused on rice fields in Dong Co commune, Tien Hai district,Thai Binh province There are two sites where they managed different irrigation forcultivation Site 1 was implemented continuously flooded cultivation during thegrowing season while site 2 was cultivated under alternative wetting and drying(AWD) which is a water saving technology Each site has three fields which appliedthree fertilizer amounts (high nitrogen, medium nitrogen and low nitrogen) Thedetail information of two sites were shown in the table 2.4

Table 2.4 Information of Site 1 and Site 2

rice cultivation drying (AWD)

54.4 (kg P2O5/ha) 54.4 (kg P2O5/ha)

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Items Site 1 Site 2

32 (kg P2O5/ha) 32 (kg P2O5/ha)

Table 2.5 showed the information of phenological and physiological at twosites and each fertilizer application such as the date of transplanting, heading andharvest and the biomass for each organ leaf, panicle, root and stem

Table 2.5 Crop calendar and field measurements

8/16/12 0.93 1.25 2.52 1.19 1.13 0.39

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