assistance of his fellow graduate students and friends in Vegetacle 

 Crops Department are also appreciated. 



The author is grateful to the Rockefeller Foundation for 

 providing a graduate fellowship and to the persons who recommended 

 him for this fellowship, namely, Dr. N. C. Brady, Director General, 

 International Rice Research Institute (iRRi) , Los Bancs, Philippines, 

 and Dr. Richard R. Harwood, Director, Organic Gardening and Farming 

 Research Center, Kutztown, Pennsylvania, 



Finally, the author wishes to express his sincere thanks to 

 his wife, Elie; daughter, Daffodil; and son, Ted Peter, for their 

 love, constant inspiration, encoioragement, and understanding. 



iv 



