Recently in Okinawa, Casuarina equisetifolia has been mainly used as windbreak tree as it grows fast. However, in terms of other characteristics for windbreak trees, such as wind resistance, salt breeze tolerance, usefulness for wood production etc., Garainia subelliptica or Calophyllum inophyllum seem to be more suitable, but they grow slowly. This study was focussed on the effects of gibberellin on seedling growth in four kinds of windbreak trees. Using one-year-old seedlings of Casuarina equisetifolia which grows faster and of Podocarpus macrophyllus, Garainia subelliptica and Calophyllum inophyllum which grow more slowly, studies were carried out in Miyako Is., Okinawa, from Aug. 1, 1990 to Jan. 2, 1991. Forty seedlings of each tree species were used for this study and half of them were treated with a gibberellin tape placed at about 3 cm below their growing points. Throughout this period, the height of seedlings was measured at intervals of two weeks. It was shown that the difference in growth between the control and the treated seedlings was remarkable in Calophyllum inophyllum. The growth ratio, represented by the percentage of the length increment divided by the height at the beginning of the study, was 61.8% for the treated seedlings, or seven times as much as that for the control. Also in Garainia subelliptica, the difference was significant and the growth ratio of the control was 32.2%, which was twofold the value of the control. The results showed that the treatment by gibberellin tape exerted a significant effect on the acceleration of seedling growth in two kinds of trees which are suitable for windbreak but naturally grow slowly.

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After-effect of water stress at the pre-anthesis stage on physiological characteristics in chilli pepper (Capsicum annuum L.) was studied using four cultivars, “Deshi Morich” (DM), “Huay Siithon” (HS), “Khonkaen University Cluster” (KC) and“Yatsubusa” (YB) . The plants were subjected to water stress prior to anthesis by withholding the water supply completely, and then rewatered for the remainder of their growth. Recovery of the photosynthetic ability was faster than that of the leaf water potential after the removal of stress, presumably due to the partial stomatal closure in chilli pepper. In the absence of water stress, KC and YB, which belong to the red cluster pepper type, were considered to have the genotype of high leaf water potential, whereas DM and HS, which belong to the cone pepper type, the genotype of low leaf water potential. Late recovery of the photosynthetic ability combined with the marked decrease in the harvest index in KC and YB was considered to be a characteristic of drought sensitivity, whereas the earlier recovery of the photosynthetic ability upon rehydration combined with limited after-effect on the mature fruit yield and the other physiological responses in HS was considered to be a characteristic of drought tolerance. In addition, the early recovery of the physiological characteristics is considered to be a reliable indicator of drought tolerance, since it showed a high correlation with the harvest index for the mature fruit yield.

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Grain yield and dry matter production of rice in hydromorphic lands were intermediate between those in a freely drained upland and those in a valley bottom lowland in a V-shaped valley. The hydromorphic lands were located on the slope without bunding and leveling, and were classified, based on groundwater depth, into lower and upper hydromorphic lands. The lower hydromorphic land was located on the lower slope, having seeps or shallower groundwater table than the upper land. Despite the high moisture availability in the lower hydromorphic land, the dry matter production there was less than those in the upper hydromorphic land, presumably due to nutrient imbalances. Applying potassium chloride to the soil in pot increased the dry matter production.

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The size and number of useful plant species in 11 homegardens in various locations of Java Island were surveyed during the rainy season to gain a better understanding of the actual conditions of utilization of plants and the function of homegardens.
The structure of the homegardens varied widely among the gardens, i.e. the area and number of plant species in each homegarden ranged from 500 to 3, 200m² and from 24 to 76, respectively. However, the differences among the locations were not significant. The larger the area of a homegarden, the larger the number of total plant species. The ratio of fruit trees and ornamental plants to the total number of plant species in each homegarden was remarkably high, though various kinds of useful plants, such as fruit trees, vegetables, starchy crops, ornamental plants, etc., were cultivated. The total number of plant species observed in 11 homegardens was 218, and the number of species classifiedby the purpose of utilization was as follows; 36 in the case of fruit trees, 25 for vegetables, 12 for starchy crops, 13 for speice crops, 14 for medicinal plants, 8 for industrial plants, 79 for ornamental plants, and 31 for miscellaneous uses, including trees for building, firewood, etc. Fifty percent or more of the industrial, medicinal, ornamental, and miscellaneous plant species were observed only in one garden among the 11 samples, whereas in the case of fruit trees, vegetables and starchy crops many species were cultivated in some gardens.
These results show that the structure of the homegarden in Java Island varied widely among the gardens mainly in the area and number of plant species. However, no significant differences among the locations were detected, since the number of sample gardens surveyed was too small.

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To evaluate the indirect effects of waterlogging on the growth and yield of yard long bean, the response to waterlogging was compared between plants cultivated in non-sterilized and sterilized soils. The waterlogging treatment was applied at 28 days after sowing and continued until harvest. In both non-sterilized and sterilized soils, the non-waterlogged plants grew well. Some of the waterlogged plants cultivated in non-sterilized soils did not survive, while all the waterlogged plants cultivated in sterilized soils survived. The waterlogged plants formed white and spongy tissues and developed adventitious roots, although such tissue and root formation was retarded in several plants cultivated in non-sterilized soils. The growth of the above-ground portions was retarded by the waterlogging treatment, but the degree of retardation was more pronounced in the plants cultivated in non-sterilized soils. In the waterlogged plants cultivated in sterilized soils the growth of the above-ground portions recovered rapidly in contrast to that in most of the waterlogged plants cultivated in non-sterilized soils. The seed yield was reduced by waterlogging in the plants cultivated in non-sterilized soils, while not reduced significantly in those cultivated in sterilized soils. The present results indicated that yard long bean was able to adapt to root oxygen deficiency, but that it was susceptible to some of the indirect effects of waterlogging.

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This paper attempts to the analyse conditions and problems of the national agricultural extension system immediately after the establishment of the agricultural technology transfer system in developing countries.
The study carried out in P.D.R.L. covered the following items.
1. Conditions of technology (including government) and problems of the organizations in charge of the transfer.
2. Conditions and problems pertaining to the reaction of the farmers to the transfer of technology.
3. Technologies to be transferred, method and results of transfer.
By examining the condtions of the technology transfer system in P.D.R.L., the following problems and characteristics were identified.
Lack of manpower, equipment and poor organization of the transfer system (including research and experimental work) are problems faced by the organizations in charge (government, etc.) . Reluctance to adopt new technologies, lack of economic, intellectual and technical capacity are problems faced by the farmers. The technologies to be transferred aim at the increase of quantity (not at quality improvement), of the staple crop (rice) as well as at low cost, and simple use. The transfer on an individual basis is direct and the method applied consists of demonstrations to farmers.
The following conclusion can be drawn. To address those problems, it may be useful to apply some of the methods used at the early stage of establishment of the extension system in Japan including the organization of mobile classes/training courses for farmers, exhibitions of farm products, and exchange of seeds, seedlings, tools and livestock which may lead to the development of new crop varieties, machines, animal breeds, etc.
It is considered that thses findings may be useful for the promotion of international cooperation by Japan in future.

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The utilization of cultivated plants in five homegardens each with and without a fish pond in Selajambe Village, located at about 70km west of Bandung in Java Island, was surveyed in the dry season.
The area of the homegardens with and without a fish pond was in the range of 98-1000m² and 78-1500m², respectively. The area of the fish pond ranged from 20 to 40m². The area of the fields including lowland and upland fields belonging to the farmers who owned a homegarden with a fish pond was larger than that in the absence of a fish pond. The total number of plant species cultivated in the homegardens with and without a fish pond was in the range of 13-33 and 19-60, respectively, indicating that the utilization of plants was wider in the gardens without a fish pond compared with that in the presence of a fish pond. When all the plants were classified according to the purpose of utilization, the number of vegetable, starchy, spice and medicinal plants as well as that of plants for miscellaneous uses was larger in the homegardens without a fish pond than in those with a fish pond, while in the case of the industrial and ornamental plants there were no differences between the two types of homegardens. Regardless of the presence of a fish pond, fruit trees were the most important crops grown in the homegardens, in terms of species.
Based on these observations, it was considered that the degree of dependence of the farmers on homegardens without a fish pond was higher compared with the homegardens with a pond.

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A soil ameliorant of hydroxy aluminium polymers (Hydral) was tested to improve some of the physical properties of a heavy clay soil belonging to Gray Upland soil group.
The addition of Hydral (0 to 5% on the weight basis) to the soil resulted in significant decrease in hardness and adhesion. The increase of water permeability was observed significant, although the effect of Hydral treatment on porosity was rather slight.
The pH values of the soil was lowered by the Hydral application. The followed leaching alleviated this pH drop in the soil to some extent. Electric conductivity of the soil tended to rise by the Hydral treatment but controlled to fovorable levels by the leaching.
The leaching treatment after the Hydral application did not weaken the effect of Hydral in improving hardness, adhesion, porosity, and water permeability of the soil. Consequently, this soil ameliorant was regarded very useful for the tested soil to improve its physical properties mentioned above, although further studies were necessary for alleviating unfavorable effects on pH and EC of the soil in relation to crop cultivation.

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A survey was conducted to determine the couse of the losses of imported papaya fruits (Carica papaya L.) produced in Hawaii upon their arrival in Japan, from September 1986 to May 1987. The incidence of losses caused by physiolosical disorders, mechanical injury and pests and diseases was 0.9%, 1.8% and 0.9%. Analysis of the seasonal pattern indicated that the loss of fruits increased in December, and decreased in April and May.

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In the case study of the field research conducted by authors in Ghana, 1991, it was presumed that the very short fallow period due to socio-economic situations of large population and tenant problem would cause fast circulation of shifting lands and this fact means severe decreasing forest and fertile fields. Therefore, sustainable agriculture with flexibility should exist to support their increased population in those difficult regions instead of extending arable lands by burning.
In the tropical region where the farmers manage the fields of small size of area intensively, the multiple cropping system would be useful and effective to insure the safety of yields.
Intercropping or mixed cropping method requires usually much labour to grow plants due to more than two crop species at the same field, nevertheless, so far, these techniques have been adopted among many farmers because of those rational advantages in farm management.
Some of these attractive merits come from the characteristics of the complicated planting patterns with decreasing damage of crops by insects or fungi attack and preventing soil erosion of the fields from heavy rain, strong wind and drought.
One of the newly noticeable intercropping might be the combination of cereals and perennial leguminous plants from the view of low input energy, which could be regarded as the category of agro-forest system.
By certain strip type of planting there is a possibility of realization of mechanical management, if the crop combination is proper and acceptable in an easy way, and this mechanization management will be valid in developed countries, too.

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