The carbonized grains of rice, Oryza sativa L., excavated at Non Yang Site, Thailand, were used for investigations on morphological characters. The values of grain length, width, thickness, ratios of length to width, length to thickness, width to thickness, area, volume and weight were found to be 4.81mm, 2.44mm, 1.79mm, 1.98, 2.71, 1.38, 11.75mm², 20.95mm³ and 8.23mg on the average, respectively. Based on the data obtained here, the materials corresponded to the round, A type, japonica variety. Among 15 character-combinations, the correlation coefficients of 6, 1, 1 and 7 items were significant at the 0.1%, 1% and 5% levels and not significant even at the 5% level, respectively.
In the case of unhusked grains, based on the converted values, the average values of length, width and ratio of length to width were found to be 6.69mm, 2.88mm and 2.34, respectively. The materials also corresponded to the A type. The materials consisted of one or a few varieties, based on the small intra-population variations in the respective characters measured.
In comparison with the present and the past data, the present materials were remarkably short length with a low value for width and ratio of length to width. Historically, grain length and width increased with time in East Thailand.

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The objective of this study was to analyse the effect of seven kinds of plant growth regulators on the growth and enlargement of microtubers in yams (Dioscorea alata L.) . Microtubers from nodal stem segments were used in this investigation.
Among the growth regulators examined, 3-indoleacetic acid (IAA), kinetin, zeatin riboside (ZR), brassinosteroids (BRs) and methyl jasmonate (JA-Me) promoted growth and enlargement of microtubers. While gibberellic acid (GA₃) and abscisic acid (ABA) exerted an inhibitory effect.
Closer examination revealed differences in the modes of actions. Growth was promoted with the increase in the concentration of ZR (0.1/1M-100μM), but it did not respond to an increase in IAA concentration from 1μM to 100μM. Both BRs and JA-Me exerted a beneficial effect on growth at lower concentrations.unlike at higher concentrations.
Both IAA and BRs stimulated root development whereas cytokinins promoted shoot growth, giving rise to shoots with long internodes. JA-Me did not significantly induce root and shoot growth.
These results indicate that microtubers of yam can be used in vitro bioassays of plant growth regulators. In other words, the new method applied in this study, “microtuber test”, is considered to be reliable enough to enable to detect the action of the endogenous growth substances, though the experiment can be performed in vitro.

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Using Asian deepwater rice (Oryza sativa L.) varieties from different countries, the elongation ability of the internodes was examined by increasing the water depth. When the seedlings reached the 10-11th or the 13-14th leaf stage, submergence treatment was initiated at the rate of 2 cm/day or 4 cm/day. In 25 varieties in which the LEI position corresponded to the 9th-10th Internode, plants of all varieties used could grow until the end of the treatments (ca. 190 cm water depth or 85 days in the2cm/day-and 280 cm or 65 days in the 4cm/day-submerged lots) . Differences in plant growth were not appreciable not only among varieties of the same country but also among varieties from different countries. In 17 varieties in which the LEI position corresponded to the 12th-13th internode, three varieties in the 2 cm/day-and 13 varieties in the 4 cm/day-submerged lots could not continue to grow until the end of the treatment. In those varieties, the elongation ability of the internodes especially in the lower position was lower than that of the varieties which could grow until the end of the treatment. In Asian deepwater rice, it appears that the earlier the growth stage at which internode elongation occurs, the higher the elongation ability of internodes is. Furthermore, in the deepwater rice varieties used, increase of the water depth by 4 cm per day may be the limit for the elongation ability of internodes.

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Okinoerabu Island is a typical Island located in the subtropics and covered with coral limestone which is characterized by a high water permeability. Intensive floriculture has been actively promoted in recent years on this island. In this report the concentrations of nitrate and some other chemical components in the groundwater mainly from the area with intensive cultivation on this island were determined. The relations between the nitrate concentration and the geographical characteristics or land use was reviewed. Furthermore, the nitrate concentration in the water of several wells for municipal water supply that had been recorded over a long period of time was examined in relation to land use in the surrounding areas.
1. The distribution of the nitrate concentration of groundwater in this area was not related to the geographical characteristics of the land. Instead, it showed an apparent increase from the central area of the village toward the cultivated fields.
2. In the study area, the proportion of cultivated land was very high and a relatively large part of the farms was used for intensive floriculture. The nitrate concentration of groundwater in this area was generally high. The concentration of Seven out of 17 samples exceeded 10 ppm.
3. Among the wells for municipal water supply in Wadomaritown on this island, the water of some wells which were surrounded by farms showed a continuous increase in nitrate concentration over a long period of time. On the other hand, the concentration of the water of the wells located near a preserved forest was low.
4. These results indicate that agricultural activity on the ground exerts a significant influence on the underground water environment in this island. The strategy for land use or agricultural development must be planned in considering the need for the preservation of the quality of drinking groundwater.

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The role of international agriculture research institutions could be limited to the collection, maintenance and distribution of basic germplasm materials if the research capacity of national programs were satisfactory. However, the research capacity in many tropical countries was far from this and it was necessary that international institutions such as CIAT upgraded the immediate usefulness of germplasm materials to be offered to national programas. In cassava, there was no major complication with the breeding method per se and following the orthodox breeding scheme promised steady progress in yield improvement. The CIAT/Colombia breeding program started with the enhancement of basic physiological yied capacity of the breeding population in a low stress environment and accomplished a 100% increase in the yied capacity of the breeding population compared with that of the original unselected population thanks largely to improved harvest index. A simultaneous selection in a high stress environment added tolerance to numerous diseases and pests as well as adaptation to infertile and acid soils. The selection and population improvement by the CIAT/Thai collaborative program in a semi-arid environment further upgraded the total biomass production, root dry matter content and tolerance to drought of the breeding population. Thus, I consider that the current CIAT cassava breeding materials provide national program breeders with immediate selection opportunities for higher yielding capacity and adaptation to high stress growing environments.

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Suckers are the most popularly used planting materials in establishing sago palms in small-holder gardens and plantations in Sarawak. This is because suckers are true-to-type and are faster in their subsequent estabishment as compared to seedlings raised from open pollinated seeds.
In the world's first sago palm plantation in Mukah, Sarawak, large numbers of suckers were nursed for three to five months in nurseries before field planting. The nurseries were usually sited in open fields and frequently, a substantial proportion of the suckers failed to survive. The mortality rate was extremely high especially in the dry season and most of the death occurred during the first month of planting in the nursery, causing substantial financial losses in the nursery.
In the current study, factors suspected to affect the subsequent survival rate of sago palm suckers were investigated. It was found that survival was significantly enhanced if suckers were planted promptly, notably within three days after removal from the parental palm. Suckers stored for more than two weeks before planting generally showed a marked decrease in their subsequent survival in the nursery. When the cut-ends as well as part or whole rhizome were completely buried in the soil, an increased rate of survival was also obtained. Rhizomes planted 8cm below or just placed on top of the soil surface were shown to have lower survival rate. Trimming of roots to as short as 1cm did not affect the subsequent survival of the suckers but excessive trimming of the rhizomes was deleterious. Shading of suckers during the dry season appeared to contribute positively to their successful establishment.
When planting of suckers was delayed, treatment with a wide spectrum fungicide together with keeping the suckers in cool and moist places were shown to reduce their mortality rate.
Based on the above findings and experience gained in the field, a recommendation on some of the important aspects in sago palm nursery practices is made.

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