Science in Agriculture (Agronomy)

With the blessing of ever-present God, I offer my sincerest gratitude to Him. This thesis would certainly not have existed without His presence. First and foremost I would like to pay my entire gratitude to my family especially, my beloved parents (Mr. B.T. Mthiyane and Mrs. N.C Mthiyane); this task would not have been accomplished. I bow my head with respect to them for their continuous source of inspiration and motivation to me. My supervisor, Mr. Sydney Mavengahama for his expert guidance, ready assistance, valuable suggestions, immense patience and support in the completion of this study. Professor A.R. Opoku who was not just the supervisor, but willing to go an extra mile during the study. His willingness to share the scientific knowledge with me will never go unnoticed. I would like to devote my sincerest gratitude to Professor F.B. Lewu for recognising me as his research student from 2010. I am very much thankful to him for his approachability, support, enthusiasm and encouragement for me to pursue this study. I would also like to acknowledge Professor A.M Zobolo, I had a privilege of working with throughout the study. His technical, logistic and scientific support is highly appreciated. His sense of humour, playfulness and ability to work as a team during the study lifted the entire work burden in my mind. His willingness to do more than what he ought to do is deeply appreciated. The staff and fellow postgraduate students of the Department of Biochemistry an