This report reviews the distribution, origin, evolution, dissemination, and diversification of wild rice in and around tropical Asia. Some characteristics of wild rice species are described from the viewpoint of their morphological and ecological characters.
 The genus Oryza is constituted by about 20 valid species, including two cultivated and many wild species. As in other cereals, the evolutionary pathway of cultivated rice may be conceptualized as: wild perennial species→wild annual species→cultivars. Wild relatives of O. sativa are widely distributing in tropical and subtropical Asia and Oceanea. Record of them has been found in Thailand, India, and South China dating back as far as 3,500 B. C. They are rich in genetic diversity, much of which remains to be tapped, and which stems largely from their wide geographical dispersal and eco-genetic diversification. From the 1960s, abundant research into and collection of wild rice in Asia has been reported.
 The characteristics of wild rice species in tropical Asia have been discussed in comparison with the wild rice distributed in other regions in terms of grain morphology, anatomical and histological characters of glumes and leaves, germination behaviour, seed longevity, affinity between embryo and endosperm, flowering order and time of grains in a panicle, panicle structure, floating habit, and specificity of O. officinalis.
 Several factors account for the different photoperiodic sensitivities in the genus Oryza. It can be concluded that the adaptation to natural photoperiod has played an essential role in the existence of cultivated and wild species. Some characteristics become clear from the physiological and evolutionary relationships and phylogenetic differentiation of the genus Oryza.

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From the viewpoint of ecological classifiaction, Linne's species consists of ecospecies, ecotypes and ecophenes. Rice plants are mainly classified into three ecospecies, i. e., indica, japonica and javanica. Indica rice, which is mainly grown in South and Southeast Asia, can be classified into several ecotypes, such as aus, aman, boro, and tjereh, based on its morphological, physiological and ecological traits. Although ecotypic differentiation in japonica is less obvious than in indica, where the progressive improvement of rice cultivars has advanced further, it can be classified into two types, i.e., the northern and southern groups. The characteristics of javanica, which may consist of several ecotypes like Italian, Brazilian, bulu and so on, are also obscure to us.
 Bulu, an ecotype of the javanica rice grown in the Southeast Asian archipelago, shows intermediate types between indica and japonica ecospecies in terms of physiological and ecological traits. Further analysis of the characteristics of the bulu ecotype is considered to be indispensable in order to establish a conceptual framework of the ecospecies and ecotypes of rice plants.

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This paper first compares the general plant properties of rainfed upland rice varieties with those of lowland rice varieties. Then the Asian ricegrowing region is divided into three subregions, the tropical monsoon forest region (moist deciduous), the tropical rainforest region, and the temperate region (hard leaf evergreen or broad-leaf frostdeciduous forest), and the rainfed upland rice varieties established in each region are discussed. Close phylogenetic relations are noted between Japanese and Korean upland varieties; but it is also clear that some Japanese upland varieties belong to the rainfed aus ecotype of the indica ecospecies that were established in the monsoon forest region, and were introduced into Japan via China; and others belong primarily to Japanese lowland rice varieties. In addition some of the late Japanese upland varieties appear to have been introduced directly from the tropical rainforest region of Southeast Asia.

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In Southeast Asia, floating rice is grown in lowlying areas of Thailand, Vietnam, Cambodia and Burma. The floating rice plant is characterized by its ability to elongate at the internode in lag phases during the rise in water level. The lowest elongated internode (LEI) of the plant varied from one variety to another and from one country to another. The mean value of the LEI position was at internode 10.7 for Vietnam, 10.8 for Thailand, 11.1 for Cambodia and 12.3 for Burma. These values are larger than the mean value of Bangladesh floating rice varieties. Considering the presence of awns, the length/width ratio of grains, the acid phosphatase isozyme genotype, and other factors besides the elongation ability of the plants, floating rice in Southeast Asia seems to belong to a different ecotype group from Bangladesh floating rice. The former may be more evolved than the latter.

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A physiology-oriented dynamic model incorporating crop physiological data on IR36 rice was proposed for the evaluation of climatic productivity and water balance of irrigated rice. The model explained well the location-to-location variations of actual rice yield in Japan and the U. S. A.
 The climatic productivity per crop at Bangkok (Thailand) and Los Banos (Philippines) was evaluated to be approximately 9.0 and 11.0 ton/ha for the wet- and dry-season crops, respectively. These values were significantly lower than the 19.3, 15.6 and 13.9 ton/ha evaluated for California, Milano and Niigata, respectively. The lower productivity in tropical Southeast Asia is mainly attributable to the too rapid development of the crop due to the higher temperature. Since three to four crops per year are possible in tropical monsoon regions, the annual climatic productivity in tropical monsoon Asia was estimated to be at least twice as high as in the most temperate regions. The climatic water balance at Bangkok and Los Banos was evaluated to be about -460mm per dry-season crop, implying that at least this amount of irrigation water is necessary for the dry-season rice crop there.

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Don Daeng village is located near Khon Kaen in Northeast Thailand. Rice production in the village depends on rain-fed paddy fields, and is extremely unstable. This paper discusses its yield variation.
 At harvest time in 1981 and 1983, paddy yields were estimated by cutting and by standing crop survey. The latter was also done in 1985.
 For analysis, a computer-compatible data base including field size, landform unit, and cropping calendar was used.
 Frequency distributions of paddy yield grades differed greatly from year to year, being skewed toward the lower range in 1981 and 1985, when the production was poor, and toward the higher range in 1983, when there was a bumper crop. The maximum yields, however, did not differ from one year to another.
 In the years of poor harvest, plots at lower elevations gave higher yields than those on higher ground, while there was no difference between them in the year of good harvest. In all years, yields were nearly equal in the lower land; but in the higher land yields increased drastically in the good year.
 The bumper harvest of 1983 was thus primarily due to a bottom-up effect, the increased yield in normally poor-yielding plots, rather than to a yield increase across all plots.
 The lower land produced a large amount of paddy not only in the good harvest year but also in the poor harvest years. But in the bumper year the production share of this land was decreased by the increase of production in the higher and middle land.

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The annual cultivation cycle in rainfed upland fields in a Sundanese hamlet in Priangan, a hilly region in West Java, is described at some length. This report focuses on how Sundanese peasants reckon the timing of agricultural operations. In upland fields (or gardens), which are generally referred to as kĕbon and are usually located on steep hillsides, tobacco, maize, hill-rice, Phaseolus beans, cassava, etc., are simultaneously or sequentially raised for cash income and home consumption. The agricultural operations for these garden crops are seasonal, in contrast to wet-rice cultivation, which is not seasonal because sufficient water is available throughout the year. The timing of upland agricultural operations is not calendrically fixed, but reckoned by continuous and careful observation of such indicators as seasonal fluctuations in rainfall frequency, moisture and wind direction, phenological changes in wild flora, the seasonal appearance or specific behavior of certain insects and birds, and, in particular, such marked stellar events as heliacal risings and culminations of the Pleiades (béntang kĕrĕti), Orion's belt (béntang wuluku), and the Southern Cross (béntang langlayangan). These indicators allow the reckoning of time with varying accuracy throughout the year. Peasants believe that these allow them to identify the “best” timing for crucial agricultural operations such as sowing, planting, etc., and that delay in operations will result in reduction of yields. Interestingly, precipitation data suggest that some of these “best” times for crucial agricultural operations accord with the agroclimatologically determined times of onset and termination of the wet season. The peasants' reckoning of the timing of agricultural operations reflects the persistence of the pranåtåmångså, the traditional Javanese agricultural calendar.

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Lampung Province lies at the southern end of Sumatra, nearest to Java. Its inhabitants are said to originate from the Belalau area, about 30km southeast of Lake Ranau in Lampung Province. They originally cultivated upland rice mixed with other crops in swiddens for subsistence.
 Lampung can be classified topographically into four areas: mountain slopes, hills, peneplain, and coastal swamp.
 Rice cultivation in the mountain slopes and hills consisted of upland rice in swiddens and lowland rice in small swamps called rawa in Indonesian. These cultural systems were practiced by Lampung people. Irrigated lowland rice, on the other hand, was introduced in immigrants mainly from Java and was cultivated in the hill and peneplain areas. It has been the object of technical improvement by the BIMAS (mass guidance), using the improved IR varieties. In the upland rice culture, traditional local varieties are still popular. These possess such characteristics as tall stature, few tillers, long ears, long-necked spikes and sometimes long awns. Grain shapes include slender, large and round, although most varieties have slender grains.
 The problems involved in the introduction of new improved upland rice varieties into traditional upland areas are discussed with special reference to cultivation conditions and cropping systems.

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The low-lying areas of the Bengal Delta have unique methods for growing and processing rice. These are the mixed cultivation of aus and broadcast aman and parboiling of rice. These methods are not commonly found in the rice-growing countries in Southeast Asia.
 The cultivation of aus and its expansion in the Bengal Delta since the late 19th century are discussed based on my field observations in several Districts and a preliminary survey at Chiladi village, Noakhali District from November 1984 to February 1986.
 The results obtained are as follows:
 (1) The cultivation of aus varieties has expanded into the deltaic lowland despite their low potentiality in terms of ecological traits. Although this expansion was simply a result of population increase in the delta, it seems to have been made possible by the traditional and sophisticated technologies adopted by the farmers. The methods of harvesting of mixed aus and inter-tillage after the aus harvest in the mixed aman stand show a wide variation from location to location. This wide variation in the mixed cultivation seems to have supported the expansion of aus in the Bengal Delta.
 (2) Although Bangladesh has a wide variety of rice-cooking methods, most dishes except boiled rice employ non-parboiled aman rice. Aus rice was believed to be the food for poor people and it was not used for ceremonial purposes because of its low degree of sanctity. From these facts it is considered that aus varieties were adopted later than aman varieties in the Bengal Delta.
 (3) As aus is harvested in the middle of the rainy season, high humidity and wet conditions make processing difficult. Parboiling is indispensable to counter the deterioration of harvested aus rice. The farmers' traditional parboiling method is, therefore, considered to have been effective in expanding aus cultivation in the Bengal Delta.

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The surveying of ancient paddy fields by plant opal analysis has recently found practical application in archaeological excavation.
 This paper discusses problems encountered in the remains of ancient paddy fields of the Yayoi period excavated at the Megumi site in Tottori prefecture and the Tareyanagi site in Aomori prefecture.
 1. The distribution of paddy fields surveyed by plant opal analysis agrees with the results of archaeological excavation in both sites.
 2. The mean size of ancient paddy fields is 33.7m² at the Megumi site and 7.8m² at the Tareyanagi site. This difference seems to have arisen from the circumstances of water supply.
 3. The lateral lengths of plant opals originating from rice plants (Oryza sativa) of the Yayoi period have larger mean values than those from the middle ages.

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Rice in Malaya aims to relate the historical changes and regional diversity of rice cultivation in the Malay Peninsula to the geographical and socioeconomic situation there from prehistoric times to the beginning of the twentieth century. Rice in the prehistoric and early historic cultures of Southeast Asia is described in the first two chapters, which cite archaeological and historical evidence for the age and area of origination of rice cultivation and its spread to the Malay Peninsula. Rice cultivation had become widespread throughout the peninsula by the beginning of the nineteenth century, and chapter 3 illustrates the cycle of operations involved in shifting, semipermanent and permanent cultivation at that time. It also describes land tenure and the gradual changes in the concept of land as real property in Malayan society.
 As a means to understand the diversity of development of rice cultivation, the author proposes that four major regions of rice cultivation emerged between the nineteenth and the early twentieth century. The first is the northern region centered upon Kedah, the colonized lands of Penang and Province Wellesley, and Kelantan, Trengganu. Perak, apart from the tin-mining areas in the south, is also included and offers a fine example of development under British rule. Second, the southern region includes the plain of Malacca, which is largely non-Minangkabau in its techniques, tradition and law, together with the contrasting Minangkabau lands of Negri Sembilan. The third region, which includes southern Perak, the whole of Selangor and Pahang, comprised the ‘marches’ areas, where rice-growing was of little importance. The fourth region, that of the hill peoples, was only partly known during the nineteenth century.
 The remaining chapters focus mainly on the northern and southern centers of rice cultivation, dealing with the traditional or common cultivation methods and their distribution; acreages of paddy fields, with many statistical data on land-ownership and the races engaged in rice-growing; the socioeconomic background; and schemes for expansion of rice cultivation, the motives behind them and the fates they met. The discussion on the expansion of cultivated area in relation to the regional pattern of economic development in a colonized area indicates that large-scale development succeeded more often under Malay initiative than British.
 Finally, the author proposes a typological scheme which comprehends all the spatial patterns of rice-growing in the Malay Peninsula. The scheme could be used to classify the ecotypically varied pattern of rice-growing, but difficulty remains in its application to evolutional development, because multi-ancestral and different types of rice-growing were introduced into the peninsula in different ages and in different areas. On the origin and dispersion of cultivated rice in the Malay Peninsula and adjacent areas, a more detailed and precise theory should be provided by recent studies in this field.
 Throughout this volume, the author has successfully combined geographical and historical approaches in depicting rice in Malaya.

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