Since 1979, the collective production team system has been replaced by the farm household responsibility system in China. Farmers were able to improve agricultural intensification to obtain greater annual output and higher profits in the new farm system, which has led to unsustainable agriculture and environmental problem. We assessed the annual nutrient input-output balance in the heavy intensive agricultural systems in the coastal area of Dianchi Lake, one of the most eutrophic lakes in China. The annual nutrient inputs into agricultural systems have drastically increased by the heavy use of chemical fertilizers and manure in multiple cropping fields of vegetables, and concentrate feeds in intensified livestock production systems. However, parts of the nutrient inputs were not used effectively in the agricultural systems and thus the excessive nutrient surplus were emitted into the environment, causing significant environmental problems, such as nitrate contamination of the groundwater and river water. We carried out fi eld experiment based on the result mentioned above and suggested the effective methods showing next that could improve the input–output balance of nutrients without yield loss in the intensive agricultural system. The first method was improvement of input-output balance in multiple cropping fi elds by reducing chemical fertilizer input for leaf vegetables depending on nitrate concentration of the soil without yield loss. The second was improvement of absorption ratio of chemical nitrogen in continuous cropping fields by controlling club root disease （Plasmodiophora brassicae） of cruciferous vegetables by soil solarization. The third was enhancement of the nitrogen cycle in the agricultural system by harvesting common reed planted in constructed wetlands for wastewater treatments, and using harvested common reed as roughage for ruminants.

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Japanese knotweed （Fallopia japonica） is a local wild plant eaten mainly in mountainous areas in Wakayama prefecture. However, the yield in the mountains has been decreasing due to damage caused by deer feeding etc. Instead of harvesting wild knotweed, cultivation is undertaken by farmers in several areas. It is needed to supply excellent strain with desirable properties such as large yields and easy peeling for efficient cultivation. In order to accommodate the needs of farmers, we conducted a characteristic survey of Japanese knotweed sampled in Wakayama Prefecture, selected excellent strains, and worked on the propagation by tissue culture. The seedlings are purchasable at Biocenter Nakatsu （1052-1, Takatsuo, Hidakagawa town, Wakayama, Japan）. In addition, in order to lead to new utilization of Japanese knotweed, functional analysis and product development was conducted through joint research with ʻItadori-bukaiʼ, a local producer group in Hidakagawa town. Functional analysis revealed that the tips of young buds, fl owers, and skins of Japanese knotweed, which were unused so far, contained a large amount of polyphenols. Jam paste, salad dressing, and health tea have been developed using the unused parts. These products are on sale at farmerʼs market in Hidakagawa town.

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In the middle of the 18th century, with the rise of the Japanese wax industry, cultivation of the Japanese wax tree, ʻHazenokiʼ, originally brought from Kyushu, developed on a large scale in the Kanto region and westward. In the Kimino area, Wakayama Prefecture, where large-scale cultivation of ʻHazenokiʼ was conducted, genetic infiltration from cultivated ʻHazenokiʼ into a closely related wild species, ʻYama-hazeʼ, may have occurred. In this work, RAPD-PCR and cluster analysis of ʻHazenokiʼ and ʻYama-hazeʼ collected in this area were conducted to investigate the impact of the new industry on the genetic diversity of the closely related wild species. The results suggested that interbreeding between ʻHazenokiʼ and ʻYama-hazeʼ was progressing in this area and that typical ʻYama-hazeʼ had already disappeared. The study also showed that the rate of genetic infiltration is increasing as the Japanese wax industry declines and ʻHazenokiʼ orchards are no longer managed, and that economic coniferous forests may act as a barrier to genetic infiltration in ʻHazenokiʼ and ʻYama-hazeʼ whose pollen and seeds are transported by small birds.

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A japonica rice Isehikari, which is believed as a natural mutant of Koshihikari, is known to yield various mutants under natural conditions though at low frequency. In this study, we investigated the mobilization of transposable elements, mPing and nDart, in Isehikari. Transposon display analyses revealed that the insertion polymorphisms and copy number variations of both mPing and nDart were found between Isehikari and Koshihikari, indicating that mPing and nDart might have mobilized at the timing when Isehikari was derived from Koshihikari. However, transposon display analyses using 100 progenies derived from two single selfed plants of Isehikari showed no evidence that mPing and nDart are still actively transposing in Isehikari. These results indicate that mPing and nDart might be inactive or less active in intact plants of Isehikari grown under natural conditions.

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We performed a 2-year cultivation demonstration and management evaluation in a field with a 3-year, 4-crop paddy-upland rotation system of a large individual agricultural management entity at Kora, Inukami, Shiga prefecture, Japan to verify effects of the introduction of a high-speed ridge forming seeder for soybean （4-row prototype） cultivation, developed cooperatively by the National Agriculture and Food Research Organization and Agritechno Search Co., Ltd. for paddy-upland rotation systems. Then we compared those results with those obtained using a rotary seeder conventionally used in the area （hereinafter designated as the conventional machine）. Compared to results obtained with the conventional machine, the seeding efficiency and work efficiency in intertillage ridging of the 4-row prototype were as high as 2 and 1.4 times, respectively. In 2020, when heavy rains occurred in July, in the fi eld where the 4-row prototype was used where ridging was conducted during seeding, resulting in better initial growth than in the fi eld sown using the conventional machine. For both years, the grain weight in the 4-row prototype fi eld was at least equivalent to that achieved using the conventional machine. The numbers of nodes and pods were significantly greater in 2020. Management was evaluated based on the results presented above, indicating increased profits by 1,277 – 3,673 yen per 1000 m² because the 4-row prototype exhibited better work efficiency for seeding and intertillage ridging than the conventional machine, thereby reducing the labor cost by approximately 50% and ensuring at least equivalent yield. Based on those points explained above, introduction of the 4-row prototype to large agricultural management entities is estimated to have strong effects because it can seed large areas during the rainy season if the soil is in good condition. Therefore, stable yields and better profits can be expected.

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In Mindanao, Republic of the Philippines of which rice grain yield per unit area is particularly low among those of Asian countries, we tried to identify the problems of tropical rice cultivation through growing the fixed-type indica rice variety RC240 in 24 hectares (hereafter, ha) of farmersʼ paddy fi elds and investigated the effects of the soil-microbial flora activator Takeo-Tanisaka Solution (hereafter, TT Solution) on tropical rice cultivation (Experiment 1). Experimental results showed that the low grain yield of rice cultivation in Mindanao was caused chiefly by severe damages from diseases, insect pests and rodents, natural disasters such as floods and droughts, and inadequate fi eld facilities such as irrigation systems, and the application of TT Solution and the reduced use of chemical fertilizers not only increased grain yield markedly but also lessened damages from diseases, insect pests and drought. It was also indicated that fungicides should not be used, though the use of minimal insecticide was allowed. Subsequently, to validate the results in Experiment 1, we participated in a rice cultivation contest competing only in grain yield, which was organized by Agusan Branch of the Philippine Rice Research Institute, for three consecutive cropping seasons (Experiment 2). In the contest, we did not use chemical fertilizers and fungicides, but used TT Solution and the minimum necessary insecticide. Also, grass and bushes that were spreading around the experimental paddy fi eld (1,995 m²) were constantly and thoroughly mowed, because they were considered convenient breeding places for insect pests, rodents, and pathogenic fungi. In addition, water management in the experimental fi eld was meticulously performed. As a result, despite using the fixed-type rice variety RC240 not having as high yield potential as hybrid varieties, we achieved higher grain yields than any other participating teams (major bio-chemical companies), all of which used their self-developed hybrid varieties, fertilizers, and agricultural chemicals, in all three seasons. The average grain yield 7.22 t/ha over the three seasons we achieved were 2.4 to 2.9 and 1.9 to 2.0 times higher than the average of RC240 in Agusan region and that of all varieties in Republic of the Philippines, respectively. Further, the application of TT Solution and our field water management completely suppressed the occurrences of soil cracking, surface soil separation, and diseases. It was therefore concluded that the application of TT Solution and the fi eld management adopted in the contest would be an effective way to increase grain yield and to realize and promote ʻlow input sustainable agricultureʼ in the tropics.

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In order to develop a weed control technology for the narrow-row dense cultivation of adzuki beans widely practiced in Kyoto Prefecture, we investigated the effects of mechanical weeding against weeds and adzuki beans using a weeding cultivator widely used for young wheat and barley leaf cultivation. In the weed survey conducted after weeding by the weed cultivator in this study, residual weeds were mostly observed between the plants, mainly in the seeding rows. Weeds in the plots with two or three times of mechanical weeding tended to be suppressed compared with those in the plots with single mechanical weeding, suggesting that mechanical weeding should be conducted several times during the adzuki bean cultivation period. However, the number of pods per plant decreased with the frequency of mechanical weeding treatments, suggesting that mechanical weeding by the cultivator negatively affected adzuki bean yield-related traits.

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Codominant markers insertion/deletion (InDel) were developed for the Enokitake mushroom Flammulina velutipes cv. “Hatsuyuki” (HY). To detect heterozygous loci, two types of monokaryons derived from oidia (asexual spore) produced by dikaryotic mycelia HY were used. We detected heterozygous loci on a gel in 145 sets of PCR primers out of 314 sets tested. On 18 developed InDel markers randomly picked up, there was a 1:1 segregation ratio of alleles among 70 monokaryotic strains derived from basidiospores of HY, suggesting the InDel marker is available as a neutral marker under selection during spore generation and germination.

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