I wish to thank and express my appreciation of the MEKARN project, financed by Sida/SAREC, for supporting my research.
I also express my sincere gratitude to my supervisors, Professor Brian Ogle, MEKARN International Coordinator, Dr. Thomas Preston, Director of UTAF, Colombia and Adviser to MEKARN and Dr. Khieu Borin, Director of CelAgrid, for their patient and valuable guidance and advice during my experiments and for their help in correcting my thesis.
Acknowledgements are also expressed to all lecturers during the MSc courses. I also thank my assistants, Sam Tatanakitya, Pech Sopheak and Sok Chanthoeun, for their technical help.