Rice Genetics Newsletter 13 (1996)
Dedication This volume of the Rice Genetics Newsletter is dedicated to the late Dr. H.I. Oka.
The late Dr. H.I. Oka (1916-1996) Dr. H.I. Oka was born in 1916 in Wakayama, Japan. In 1940, he Finished his undergraduate study at Faculty of Agriculture, Hokkaido Imperial University. After a short service as assistant researcher at the Ohara Institute for Agricultural Research in Kurashiki, he moved to Taiwan. This was the beginning of his long and intimate association with Taiwan. He briefly worked as assistant at the Taihoku Imperial University in Taipei and then taught as professor at the Taichu Agricultural College in Taichung from 1943-45. After World War II ended, he was asked by the Taiwan Provincial College of Agriculture (the successor of the Taichu Agricultural College) to stay on as professor. In 1954 he was invited by the National Institute of Genetics in Mishima (Japan) to join the new Institute as researcher and laboratory head, a position he held until 1970. During 1970-72, he took leave from the National Institute of Genetics and served as a UNESCO Expert at the Central Luzon State University in the Philippines. He then became head of the Applied Genetics Department at the National Institute of Genetics until his retirement in 1980. In 1983 and 1986, he returned to Taichung as visiting professor at the National Chung-Hsing University. He spent his last 15 years in Mishima.

The Taiwan years: Dr. Oka initiated his research on phylogenetic differentiation of cultivated rice in 1942. Using a large collection of Asian primitive cultivars, a collection later called Oka's tester, he made an extensive variation survey of various characters and intervarietal hybrid sterility. He defined Indica and Japonica as the two major varietal groups characterized by a particular association of multiple traits. A series of his genetic studies on hybrid sterility is one of the pioneering works in the Field

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of genetics of reproductive isolation in plants. These works were carried out under the hard conditions during and after the World War II. The Doctor of Agriculture Degree was awarded to him by the Hokkaido University in 1951. After leaving his position in Taichung, he frequently visited Taiwan to help his former colleagues and students.

The NIG years: A little after Dr. Oka joined National Institute of Genetics, Japan (NIG), a big research project on the "Origin of Cultivated Rice" was launched at NIG under a grant from the Rockefeller Foundation. He took charge of the project and this subject became the main theme of the later half of his career. Since it was clear that rice domestication proceeded within a single biological species, his basic strategy of research was to elucidate the mechanism of micro-evolution. Together with his colleagues, he carried out a wide range of researches on evolutionary genetics in Oryza species; evolutionary pathways of two cultivated rice species from their respective progenitors, reproductive isolating barriers between and within species, differentiation of adaptive strategies within wild-rice species, genetic structure and dynamics of natural populations, ecological genetics of wild rice and weed community, etc. Later, his interest shifted towards interface between genetics and ecology.

For collecting materials and information for the study of rice evolution. Dr. Oka travelled far and wide in almost all wild-rice growing countries to explore a broad spectrum of Oryza species. In particular, he furnished us with a number of population samples collected on an individual basis. In 1963, he and the late Dr. W.T. Chang met a car accident while collecting wild rice in Cameroon. Dr. Oka was seriously injured and Dr. Chang was killed. Thus, he established a basis of rice genetic stocks center at NIG, and generously shared these materials with others.

Dr. Oka wrote a number of leading articles on the genetics and evolution of rice totalling some 160 papers. His indepth research is summarized in his book "Origin of Cultivated Rice", published by the JSSP/Elsevier in 1988.

RGC & SABRAO: Dr. Oka played an important role in establishing Rice Genetics Cooperative, and served as the first co-editor of RGN together with Dr. G.S. Khush (Vol. 1 - Vol. 12). We owe very much to his dedicated service for improvement of every issue of RGN. Further, we are grateful for his consistent efforts about coordination of chromosome numbering system as well as gene symbols. He was also a founding member of SABRAO, and elected Vice President (1981-1985) and President (1985-1989).

As a scientist. Dr. Oka contributed a number of findings on evolutionary dynamics in rice species and proposed several speculative hypotheses. His interest was not confined to rice but extended over the broad subjects on plant genetics, breeding and evolution in general. Everyone who had ever had contact with him was impressed by his memorable personality. He was strongly individual and did not hesitate to say what he believed right. At the same time, he had flexible and unprejudiced way of thinking, and was kind and willing to help others. Dr. Oka was a born naturalist. Sine 1980's he was actively involved in the

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environmental conservation movement in Mishima. For the last few years, his health was declining. His death came on January 4th, 1996, after spending New Year's days with his family.

For his outstanding contributions, the following honors were conferred: Japan Agricultural Science Prize, 1963; Indian Genetics and Plant Breeding Society Prize, 1964; Honorary Fellow of the National Institute of Genetics, 1980; Honorary Fellow, SABRAO, 1993; The Order of the Sacred Treasure, Gold and Silver Star (Kun 2-to Zuihou-sho), 1996.

(H. Morishima)