Rice paddy art（Tambo art in Japanese） is a huge artwork of fi gures or letters in the rice paddy as a canvas, drawn with planting rice varieties with diff erent leaf or panicle colors. It is an eff ective use of rice paddies to create a tourism resource and to revitalize the local community. It has been spread throughout Japan and now attracts great interest from overseas as well. The rice varieties used, collectively called ornamental or landscape varieties, have purple, red, yellow, or white leaves or panicles, unlike ordinary rice, and have been known to exist since ancient times and have been preserved in universities and agricultural research institutions. Recently, new varieties have been bred based on these native varieties and mutant lines. This review introduces a century-old Wakayama Prefectural Agricultural Experiment Station report on local rice varieties and summarizes some examples and methods of creating rice paddy art throughout Japan and the issues related to ornamental rice varieties.

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When using a harvesting and shelling machine that can remove the shelling directly in the field of the edamame (green soybean), labor savings are great, but harvest losses occur near the ground edge. Therefore, we investigated the adaptability of black soybean ‘Tambaguro’ edamame (green soybean) cultivars bred in Kyoto Prefecture seedlings to the harvesting machine by transplanting seedlings with extended lower internodes by extending the number of days of seedling growth. The results showed that the use of seedlings with elongated internodes reduced the number of pods left in the standing plants and the number of pods falling into the fi eld, suggesting that the use of these seedlings can reduce harvest loss. However, there were some inter-variety diff erences and annual variations in the degree of harvest loss. Therefore, further research is needed to elucidate the seedlings that are more adaptable to mechanical harvesting.

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The antibacterial activity of the ethanol extracts from hulled rice was evaluated in black, red, and white (ordinary) rice cultivars against Escherichia coli and Bacillus subtilis. In the agar diff usion method, the ethanol extract from the hulled rice of black and red rice cultivars apparently formed blocking circles in a dosedependent manner against both bacterial species, whereas those from white rice cultivars did not. The ethanol extracts from black and red rice cultivars also showed antibacterial activity against both species observed from the minimum inhibitory concentrations in agar plate dilution method. In this method, the overall activity might be slightly stronger against E. coli than B. subtilis. Asamurasaki (black rice) with higher anthocyanin content showed stronger antibacterial activity. The extracts from the bran layer of a black rice cultivar and a red rice cultivar showed strong antibacterial activity assayed by the turbidimetric method by measuring the OD (660nm). On the other hand, the polished rice extracts of the same cultivars showed considerably weak activity, suggesting that effective substances may exist more abundantly in the bran layer of black and red rice cultivars. The possibility of using extracts of black and red rice cultivars as an antibacterial agent in the food processing industry was suggested.

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Cluster analysis using RAPD-PCR was conducted on the kaya （Torreya nucifera（L.） Siebold et Zucc.） population, particularly focusing on one of its varieties, ‘Hidarimakigaya’（T. nucifera f. macrosperma（Miyoshi） Kusaka）, collected from two districts in the Kimino Town, Wakayama Prefecture, located at the foot of the World Heritage Site Koyasan （Mt. Koya）. The results showed that clades were primarily branched by geographical factors （districts）, and then subclades of varieties were formed within each clade. This suggests that after geographical differentiation was well established, ‘Hidarimakigaya’ was introduced by seed from outside and integrated into the gene pool in each region. The timing of this introduction corresponds in both areas, suggesting that the introduction may have been aggressive at a certain time. Additionally, genetic differences were observed between the rootstock and the main trunk branches of a 400-year-old ‘Hidarimakigaya’ tree, indicating that the tree was grafted.

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Using a stinking lagoon（ 3,100 m2 in area and 4,000 m3 of water storage） where sludge had accumulated close to the water surface, some of which was fl oating around in the form of black and brown masses like wooden ears, and foamy masses, we investigated whether the application of Takeo-Tanisaka Solution （TT Solution）, a soil microbial activator, would be eff ective in improving water quality of reservoirs and lakes for agricultural water supply. In 2010, when the experiment started, 32,000 ml of TT solution was applied from May 10 to 12, followed by 12,000 ml on May 26 and 4,000 ml on June 9. A total of 48,000 ml in 2010 was 12 ppm of the stored water volume. In addition, on May 9, 2011, 24,000 ml, half of the amount in 2010, was applied. In June, 2010, the sludge in the lagoon was decomposed and the transparency of the water visibly improved, and by May in 2012, the sludge vanished and the bottom of the lagoon could be seen. The values of suspended solids（SS）, biochemical oxygen demand（BOD）, chemical oxygen demand（COD）, soluble COD, total phosphorus, and total nitrogen, all of which represent water quality, rapidly decreased within one month after the treatment on June 9, 2010, and then showed a downward trend with repeated upward and downward fl uctuations. Furthermore, the values for 2011 and 2012 were noticeably lower than those for the same dates in 2010, and transparency improved. From these results, it was concluded that TT solution is an eff ective material for diversifying and activating the microfl ora and improving the water quality of reservoirs and other polluted lakes and marshes.

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In rice, cool weather at the booting stage sometimes causes a significant yield reduction. Thus, improving cool weather tolerance in varieties grown in cold regions is an extremely important breeding challenge. In this study, effects of the deficiency in mineral nutrition on seed fertility at the cool weather sensitive booting stage in rice was investigated to elucidate the function of rice root under cool temperature. Rice cultivars and lines with different cool-weather-tolerance （CWT） were grown in a hydroponic solution that did not contain sulfur （S）, calcium （Ca） or iron （Fe） during the cool weather sensitive booting stage, the early booting stage （E stage）. As a result, the seed fertility of both Hokkai 241 （medium CWT） and Hayayuki （strong CWT） was significantly reduced. Furthermore, the decline in seed fertility of Hayayuki was smaller than that of Hokkai 241 （Experiment 1）. Therefore, it was revealed that the E stage is highly sensitive to nutrient deficiency, and that Hayayuki is tolerant to nutrient deficiency at E stage. In experiment 2, the concentrations of S, Ca and Fe in exudation sap were compared between the world rice core collection（WRC） and four strong CWT cultivars. As a result, the mineral nutrient concentrations of high CWT cultivars were lower than most of the WRC. These results suggest that the reduction in seed fertility due to cold treatment of roots during the E stage is mainly due to nutrient deficiency caused by a reduced supply of inorganic nutrients from the roots, and that CWT cultivars might be tolerant to nutrient deficiency.

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Four lines with different combinations of functional and non-functional types of photosensitive loci Ghd7 and Hd1 in the same genetic background of rice cultivar Gimbozu were tested and grown under four treatments: two sowing season treatments （Ⅰ: normal sowing （May 9） and Ⅱ: late sowing （June 20））, two seedling duration treatments （S: standard seedling duration（21 days） and L: long seedling duration（28 days））, and days to heading, yield, yield components, and the occurrence of upper nodal tiller were investigated. In terms of days to heading, the genetic effect of functional Ghd7 was suppressed in the late-sown treatments in both standard and long-term seedlings, and the difference in days to heading was mainly due to the genotype of Hd1. In terms of yield, functional Hd1 increased yield in the late sowing treatment in both standard and long-term seedlings, while functional Ghd7 locus had little effect on yield. This was considered to be due to the higher ripening of lines with the functional Hd1. There was also a trend towards lower yields in the long seedling duration compared to the standard seedling duration. The occurrence of upper nodal tiller tended to be higher in the long seedling duration, and functional Ghd7 and Hd1 suppressed the occurrence of upper nodal tiller. These results suggest that strong photosensitive lines with functional Hd1 are suitable for late-season paddy rice cultivation in field-oriented cropping systems in the warm south-west Japan. In the case of lines with non-function Hd1, lines with functional Ghd7 were considered desirable from the viewpoint of suppressing the occurrence of upper nodal tiller and improving ear alignment.

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In Taiwan, indica rice varieties had been cultivated since ancient times, but around 1900, the demand for mass production of japonica rice for export to Japan had become stronger, and many native japonica varieties were introduced from Japan and cultivated on a trial basis. However, these varieties could not show their potential yields, resulting in low yields. In this study, we first analyzed the reasons for this, and concluded that the short day length during the rice cultivation season in Taiwan located at low latitude, compared to that in Japan, greatly shortened the photoperiod sensitive phase of introduced Japanese varieties well adapting to the day lengths of mid-latitudes, which implies that the plant vegetative organs such as stems and leaves of Japanese varieties were not able to grow as large as they could, leading to lower yields. Subsequently, we examined the reason why “Taichung 65”, which was bred and released in 1929 at the Taichung Agricultural Experiment Station by cross breeding using the cross between Japanese native japonica varieties, “Kameji” x “Shinriki”, showed stable high yield and had been cultivated in a large scale over a period of many years as a main variety in Taiwan and has been used as an excellent breeding material for cross breeding in Taiwan. We concluded that this variety has an “extremely long basic vegetative growth phase （BVP） and low photosensitivity” which confers a long vegetative growth period sufficient for the normal growth of vegetative organs even in Taiwan located in low latitude, and that the extremely long BVP of “ Taichung 65” is due to the synergistic effect of a nonfunctional allele ef1 at the Ef1 locus and a nonfunctional allele Se1-e at the Se1 locus. Finally we showed that ef1 was most likely induced by spontaneous mutation from Ef1 in the process of breeding “Taichung 65”.

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