Effects of the application rate of basic slag (BS₁₀ and BS₂₀: basic slag 10 and 20 t ha^-1), aggregate size (A₂₀ and A₃₀: aggregate sizes of soils, less than 20 and 20-30 mm) and groundwater level (GW₀: no influence of groundwater and GW₅₀: groundwater beneath 50 cm of the soil surface) treatments on the growth and yield of rice (Oryza sativa L.; BR-3 Mukta) cultivated in two pre-leached (leached for a week through tap water to remove excessive acidity and salinity from the soils before seedling transplantation) acid sulfate soils of Badarkhali (Salidic Sulfaquept) and Cheringa (Typic Sulfic Halaquept) series were evaluated in a simulation study. Optimum growth and yield of rice were recorded by the treatment combining A₃₀GW₅₀BS₂₀ in both the Cheringa (grain: 6.70 t ha^-1) and Badarkhali (5.78 t ha^-1) soils. The application of basic slag (BS₂₀) was found to be the most effective among the individual treatments, followed by the BS₁₀>GW₅₀>A₃₀ treatments. The application of BS₂₀ increased the grain yield in combination with the GW₀ treatment by 100% for A₂₀, while by 122% for A₃₀ in the Badarkhali soil. On the other hand, in the case of GW₅₀, these increments were 138 and 246% for A₂₀ and A₃₀, respectively, in the soils. However, the application of BS at the highest rate (BS₂₀) to the Cheringa soil was not as effective as the A₂₀ and A₃₀ treatments in the Badarkhali soil. On the other hand, the same rate (BS₂₀) of basic slag in combination with the GW₅₀ treatment increased the grain yield by 152 to 382% in the Cheringa soil compared with 138 to 246% in the Badarkhali soil. Almost similar and significant (p≤0.05) effects were observed for the other yield components of rice grown in both soil series. The effect of a larger soil aggregate size (20-30 mm) was more significant on the increase of the growth and yield of rice during the 4-month growing period of rice, regardless of treatments.

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The effect of different seed corm regions used as planting materials on the growth of elephant foot yam [Amorphophallus paeoniifolius (Dennst.) Nicolson] plants was studied. Corms were prepared as follows: whole corms, upper corm halves with intact apical buds, lower corm halves without apical buds, vertical 1/2, 1/4, and 1/8 sections of corms, and corm sections around apical buds. The fresh mass of each corm or corm section was adjusted to 100 g. Seed corms with intact apical buds sprouted earlier and produced larger plants than either corms with dissected buds or corms without apical buds. Dissection of the apical bud promoted the development of lateral buds, which resulted in sprouting delay. Whole corms and upper corm halves with intact apical buds produced larger daughter corms than corms with damaged buds. Corm sections around the apical bud produced only one leaf, while whole corms and other corm sections produced two leaves. The low yield obtained from the use of corm sections with dissected apical buds might be ascribed to the fact that corm sectioning reduced the size of the leaves developed during the growth season.

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The morphology of the pollen grains obtained from dried specimens of one spiny and one spineless folk varieties grown at distant sites, West Papua (Irian Jaya) and West Sumatra, in Indonesia was examined to investigate intra-specific differences in sago palm (Metroxylon sagu Rottb.) . The two folk varieties displayed both perfect (hermaphrodite) and male (staminate) flowers on a single palm. The two flower types did not differ in size in either folk varieties and the gynoecium was reduced to a pistillode in the male flower. Pollen grains were produced from hermaphrodite and staminate flowers in both folk varieties, and were examined by SEM. The pollen grains were equatorially disulcate, i.e. they exhibited two germination apertures on the short equatorial axis of the pollen grains. In vitro, the general shape of the pollen grains was ellipsoid. There were variations in the pollen grain shape from the hermaphrodite and staminate flowers in both folk varieties, presumably due to the level of contraction or expansion of the pollen grain wall (exine) . However, there were no distinct differences in the shape between the pollen grains produced from hermaphrodite or staminate flowers in either folk varieties. In the hermaphrodite and staminate flowers of both folk varieties, the tectum of the pollen grains was psilate (smooth), and often sparsely perforated. We did not record any significant differences in the exine characteristics or, in the pollen grain shape, in the two folk varieties examined.

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The optimum rate of fertilizer application and harvest date for the production of three leafy vegetables were investigated in a nylon net house (16 meshes) from October to December at the Tropical Vegetable Research Center (TVRC), Kasetsart University, Kampaengsaen Campus, Nakhonpathom, Thailand. Three kinds of leafy vegetables were used: 1) Kale (Brassica oleracea var. alboglabra), 2) Pakchoi (Brassica papa var. chinensis) and 3) Green petiole (Brassica chinensis var. chinensis) . The experiment enabled to determine the effects of nitrogen application on the growth and nitrogen use efficiency of leafy vegetables. The three leafy vegetables were grown at 4 levels of nitrogen fertilizer (156, 312, 468 and 625 kg ha^-1) . For Kale, pakchoi and green petiole, the fertilizer efficiency was best at the nitrogen fertilizer rate of 156 kg ha^-1. The optimum harvest time was 35 DAS for kale and pakchoi, and 28 DAS for green petiole.

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Recently, the conditions prevailing in mountainous areas in mainland Southeast Asia have undergone drastic changes. In order to determine how local people adapted themselves to the new conditions, the changes in land use and agricultural systems in the survey village, Sam Sop Bon, in the mountainous area of North Thailand, were analyzed based on land use maps and interviews of the villagers. In the survey village, upland rice production based on shifting cultivation with a long fallow period had been carried out until the middle of the 20th century. In the 1960s, the fallow lands were replaced with poppy fields mainly by lowlanders, resulting in the shortening of fallow period. In the later 1970s, the whole village area became a part of a National Park, and although the confiscation and reforestation of opium fields increased the forest area, it accelerated the shortening of the fallow period and exacerbated land shortage for cultivation. Shifting cultivation disappeared and slope lands formerly used for shifting cultivation were converted to permanent cultivation fields or to reforested areas. On the other hand, technologies to produce paddy rice, whose productivity is more stable than that of upland rice produced by shifting cultivation, were introduced, and the paddy field areas gradually increased. Presently, the villagers cultivate both rice for subsistence and cash crops. Due to the reduction of upland rice productivity caused by continuous cropping, the villagers have started to use fertilizers, which in turn induced the use of herbicides because of the increase of weed problems. The present study revealed that people in the survey village intensified subsistence crop cultivation by introducing cash crops, namely diversifying agricultural activities, in response to the new conditions.

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The seed germination characteristics of Capsicum frutescens from the Ryukyu Islands were studied. Constant temperatures and darkness conditions inhibited seed germination in Ryukyu Islands' C. frutescens, whereas fluctuating temperatures and light irradiation accelerated germination, suggesting the presence of dormancy in these seeds. This dormancy was considered to be weak because the seeds could germinate at constant temperatures and under continuous darkness. Therefore, C. frutescens from the Ryukyu Islands could be at an intermediate stage between wild and domesticated forms. Since it was revealed that the seeds of C. frutescens from the Ryukyu Islands displayed dormancy, seed dormancy of C. frutescens obtained from Southeast Asia was studied. Among 72 accessions, 47 failed to show dormancy and germinated very rapidly; in these accessions, plant organs were larger than those in other Southeast Asian accessions. On the other hand, the seeds of the other 25 accessions from Southeast Asia showed a weedier character, including some dormancy and smaller plant organs. Accessions of C. frutescens from Southeast Asia thus appeared to be at various stages of domestication, suggesting that the domestication process had already stabilized under low selection pressure and the tropical climatic conditions of Southeast Asia. The various accessions of C. frutescens in Southeast Asia ranging from fully domesticated to weedier forms are very useful for breeding and horticulture as genetic resources.

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Angelica acutiloba Kitagawa (Touki) is a perennial medicinal plant used as a natural drug, in Japan and in many other Asian countries. Seed germination and seedling growth are critical for species survival, plant quality and productivity. However, the seed characteristics (e.g. seed weight and specific gravity) and the optimal temperature, which affect the germination of Touki seeds and seedling growth, have not been reported. In the present study, a suitable method for classifying seeds based on the specific gravity and seed weight was applied. Experiments were conducted to examine the effect of seed weight and specific gravity on the germination of Touki seeds in the laboratory, and seedling emergence and growth in a closed system. Also the effect of the temperature on seed germination was examined. The results showed that the optimal temperature for germination was 20.0°C. Selecting seeds based on the seed weight showed that by increasing the seed weight, the germination percentage increased and seedling growth was promoted. The root diameter and the values of the total plant dry weight were higher in the seedlings obtained from heavier seeds than in those obtained from lighter seeds. Root/shoot ratio was relatively higher in the seedlings obtained from heavier seeds than in those obtained from lighter seeds. Water uptake was affected by the seed weight. Lighter seeds absorbed water faster than heavier seeds. Selecting seeds based on the specific gravity enabled to increase the seed germination percentage, and seedling emergence and quality. The root/shoot ratio tended to be higher in the seedlings obtained from seeds with a higher specific gravity. Heavy seeds with a high specific gravity produced highly vigorous seedlings.

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During these 50 years, in the mountainous regions in Tanzania, new settlements and cultivated fields have been expanding to surrounding plains around the mountains due to population increase. In the present paper, we picked up a case of the northern slopes of the Uluguru Mountains and discussed about the role of the newly commenced cultivation on the plains by the farmers who were still staying on the mountains, based on surveys on the distribution of fields, crop cultivations, farm managements, etc. The farmers' fields were located both on the slopes and in the plains. Most of the farmer's staple foods supply depended on production in smaller fields in the plains. The cultivation in the plains required a large amount of cash expenses for transportation, land rent, tractor fee, etc. In spite of the expenses, the farmers mostly consumed the products with few sales. The cash was derived from activities in the neighboring large city. The objective of the production of staple food crops in the plains for consumption was to avoid the purchase of food products the markets at a higher cost. Due to various risks associated with cultivation in the plains, such as flooding, damages by wild animals, etc., it was difficult to rely only on the plains from the viewpoint of food security. The fields on the mountain slopes contributed to the stability of the food supply. It was considered that cultivation in the plains could be performed due to the reliability of mountain agriculture and to the geographical conditions that facilitated the acquisition of cash income.

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