VIETNAM NATIONAL UNIVERSITY OF AGRICULTURE FACULTY OF AGRONOMY UNDERGRADUATE THESIS TITLE OF RESEARCH: “COMBINING ABILITY FOR TRAITS ASSOCIATED WITH YIELD AND QUALITY OF SWEET CORN (ZEA MAYS L SACCHARATA)” Student : Ngo Thi Nhung Student code : 611712 Class : K61KHCTT Instructor : Prof PhD Vu Van Liet Department : Plant Genetics and Breeding Ha Noi - 2021 ACKNOWLEDGEMENTS I would like to express my respect and deep gratitude to Prof PhD Vu Van Liet, for giving me the opportunity to carry out this work, and his huge efforts, enthusiasm, and support throughout the duration of the undergraduate thesis I would like to express sincere gratitude to MSc Tran Thi Thanh Ha and all the members of Research and Technology Development Plant – Crop Research Institute and Plant Development were enthusiastic to help me through the project I would also like to thank the Directors, Management Training, Department of Genetics - Plant Breeding, Faculty of Agronomy – Vietnam National University of Agriculture (VNUA was dedicated to help me during earning process, to complete the thesis Finally, I would like to thank my family, those with us and those sadly departed You provided fantastic support and inspiration throughout the duration of this undergraduate thesis, and without you all, this would never have been possible Hanoi, 1st March 2021 Student Ngo Thi Nhung i CONTENTS ACKNOWLEDGEMENTS i CONTENTS ii LIST OF ABBREVIATIONS iv LIST OF TABLE .v LIST OF FIGURES vii ABSTRACT viii I INTRODUCTION 1.1 Introduction .1 1.2 Objectives and requirements 1.2.1 Objectives 1.2.2 Requirements II LITERATURE REVIEW 2.1 Sweet corn production in the world and in Vietnam 2.1.1 Sweet corn production in the world 2.1.2 Sweet maize production in Vietnam .7 2.2 Origin and classification of sweet maize 2.3 Genetics of sweet maize 12 2.5 Combining ability 17 2.5.1 General combining ability 19 2.5.2 Specific combining ability 19 III MATERIALS AND METHODS 21 3.1 Materials 21 3.2 Location and time of research 21 3.3 Research content 21 3.4 Experiment design: 22 3.5 Field experiments: 22 3.6 Data collection 25 ii IV RESULT AND DISCUSSION 36 4.1 Growth duration of sweet maize hybrids tested in the Autumn- Winter season of 2020 in Gia Lam, Ha Noi 36 4.2 Some morphological characteristics of sweet maize hybrids in Autumn-Winter season of 2020 at Gia Lam, Ha Noi 41 4.3 Leaf area and leaf area index of the sweet maize hybrids in the experiment in Autumn Winter 2020 in Gia Lam, Hanoi 44 4.4 The pest and disease resistance in the field of the sweet corn hybrids in the experiment in Autumn Winter season 2020 at Gia Lam, Hanoi 45 4.5 Ear morphological characteristics of sweet maize hybrids in the Autumn Winter 2020 experiment at Gia Lam, Hanoi 49 4.6 The yield and yield components of the sweet maize hybrids in the Autumn Winter 2020 experiment at Gia Lam, Hanoi 52 4.7 Some sensory quality traits of sweet maize hybrids in Autumn Winter 2020 experiment at Gia Lam, Hanoi 56 4.8 Combining ability of sweet maize parent lines in Autumn-Winter 2020 experiment at Gia Lam, Ha Noi 59 4.8.1 Combing ability of sweet maize parent lines associated for yield in AutumnWinter 2020 experiment at Gia Lam, Ha Noi 59 4.8.2 Combing ability of sweet maize parent lines associated for brix degree in Autumn-Winter 2020 experiment at Gia Lam, Ha Noi 64 V CONCLUSION AND RECOMMENDATION 69 5.1 Conclusion 69 5.2 Recommendation 70 VI REFERENCES 71 APPENDIX I 73 APPENDIX II 79 iii LIST OF ABBREVIATIONS ASI Anthesis-silking interval CV Coefficient of Variance GCA General combining ability LSD Least significant difference SCA Specific combining ability iv LIST OF TABLES Table 2.1 Corn production in the world from 2014 to 2018 Table 2.2 Distribution of area, yield and corn production by region in 2018 Table 2.3 Top 10 countries leading corn production and corn yield in the world 2018 Table 2.4 Area, yield and corn production in Vietnam from 2014 to 2018 Table Endosperm genes used in commercial sweet corn cultivars 12 Table Carbohydrate composition of various endosperm genotypes at 21 days after pollination (DAP) or mature seed 14 Table 3.1 Score range for some eating indicators of sweet maize 33 Table 4.1 The growth stages of sweet corn hybrids in Autumn Winter season of 2020 in Gia Lam, Ha Noi 36 Table Some indicators of plant morphology and number of leaves of sweet corn hybrids in the Autumn Winter season 2020 experiment in Gia Lam, Hanoi 41 Table 4.3 Leaf area and leaf area index of sweet corn hybrids in the experiment in Autumn-Winter season 2020 at Gia Lam, Ha Noi 45 Table 4.4.The level of pest and disease resistance and anti-pour ability of the sweet corn hybrids in the experiment in Autumn Winter season 2020 at Gia Lam, Hanoi 46 Table 4.5 Ear morphological characteristics of sweet maize hybrids in the Autumn Winter 2020 experiment at Gia Lam, Hanoi 50 Table 4.6 The yield and yield components of the sweet maize hybrids in the Autumn Winter 2020 experiment at Gia Lam, Hanoi 53 Table 4.7 Some sensory quality indicators of sweet maize hybrids in Autumn Winter 2020 experiment at Gia Lam, Hanoi 56 Table 4.8 Mean of fresh yield of sweet maize follows Griffing model-IV in Autumn-Winter 2020 experiment at Gia Lam, Ha Noi 59 Table 4.9 General combination ability associated for yield of sweet maize lines 60 v Table 4.10 Variation of general combination associated for yield 60 Table 4.11 Special combination ability for yield of sweet maize lines 61 Table 12 Variation of special combination associated for yield of sweet maize lines 62 Table 4.13 Verifying combining ability associated for yield of sweet maize lines 62 Table 4.14 Mean of Brix degree of sweet maize follows Griffing model-IV in Autumn-Winter 2020 experiment at Gia Lam, Ha Noi 64 Table 4.15 General combining ability associated for Brix degree of sweet maize lines 65 Table 4.16 Variation of general combining ability associated for Brix degree of sweet maize lines 65 Table 4.17 Specific combining ability associated for Brix degree of sweet maize lines 66 Table 4.18 Variation of specific combining ability associated for Brix degree of sweet maize lines 66 Table 4.19 Verifying combining ability associated for Brix degree of sweet maize lines 67 vi LIST OF FIGURES Figure Sweet corn production of the world from 1990 to 2003 (source: USDA 2004) Figure Diagram of pericarp and tip cap indicating peeling procedure 35 Figure Fresh yield of sweet maize hybrids in the Autumn-Winter experiment 2020 at Gia Lam, Ha Noi 55 Figure General combination ability associated for yield of sweet maize lines in autumn-winter 2020 experiment at Gia Lam, Ha Noi 61 Figure General combining ability associated for Brix degree of sweet maize lines 65 vii ABSTRACT This experiment was conducted to evaluate the combining ability for traits associated for fresh yield and quality of the inbred sweet maize lines In AutumnWinter season 2020, we grew and evaluated 15 sweet corn hybrids of S6 inbred lines (sh2) generation that obtained from the breeding program of Crop Research and Development Institute, Vietnam National University of Agriculture (VNUA) and a control variety ( Viet Thai variety) layout in a randomized complete block design with replications After harvesting, we measured yield and quality indicators of each hybrid and evaluated the combining ability of parent lines based on fresh yield and Brix degree The results showed that, all hybrids have short growth duration (