Recently, the Japanese government policy has recommended the cultivation of multipurpose high-yield paddy rice cultivars for animal feed (not only in the form of brown rice but also of whole crop silage (WCS) and others) in response to the decrease in demand on palatable rice for human consumption in Japan. However, when palatable cultivars are cropped in the following year of cultivations of high-yield cultivars for animal feed, the seeds of the high-yield cultivars are often left in the paddy field and grow as volunteer rice in the next crop season over winter, resulting in decrease in grain yield and lowering the quality of the palatable rice. Up to date, many ecological studies on overwintering ability of rice seeds have been carried out, and several key techniques on how to reduce volunteer rice were developed. This review summarizes ecological characteristics of volunteer rice, and describes effective countermeasures with cultural method, herbicides, lime nitrogen, and premature harvest (for only WCS).

This paper presented a literature review of the actual situation and efforts in securing temporary and seasonal agricultural labor forces in Japan. Until the 1990s, farmers can secure temporary agricultural labor forces from within their communities in most parts of Japan. However, with the decrease in the number of farmers, labor shortages in the horticultural sector became apparent in the 2000s. In Hokkaido, the temporary agricultural labor forces were provided by a group of female laborers; however, from the late 1990s, the aging of these women began to raise the issue of labor shortages. Therefore, job offers were spread to more regions, but securing laborers in the domestic labor market became difficult in recent years. Under these circumstances, the foreign technical training system played a role in the acceptance of foreign agricultural laborers, but there were many restrictions on accepting foreign workers as temporary or seasonal labor forces. Alternatively, from 2019, the “Specified Skilled Worker Systems” was started, making it possible to accept foreign agricultural laborers more flexibly. This means that the target regions for job offers are expanding beyond national borders.

Onion is one of the most productive vegetables in Japan, and onion growth models have been developed to predict its yield. However, onion growth is complex, and the selection of simple parameters is required to estimate bulb weight. This study utilized a 2-year dataset from a sequential growth study of spring-sown onions in the northeastern region of Japan to evaluate the correlation among growth parameters and to determine suitable parameters for estimating the dry weight of bulbs via multiple regression analysis. The results indicated that when bulb dry weight was the objective variable, the coefficients of determination of the single regression equation with plant height and leaf area as explanatory variables were 0.553 and 0.508, respectively, and the leaf parameter explained more than 50% of variance in bulb dry weight. Furthermore, the coefficient of determination was 0.912 when the leaf sheath basal diameter (ball width of the bulb) was used as an explanatory variable to explain the bulb dry weight. This indicates that there is a gap between the top and bulb growth. This study revealed the important parameters for predicting onion yield and demonstrated the switch in onion development from tops to bulbs.

Cambodia has a wealth of rice landraces (traditional varieties) adapted to different ecosystems. These are expected to include diverse genetic resources that could be utilized in the genetic improvement of yield. A detailed investigation of panicle architecture and grain size in 173 Cambodian accessions revealed a wide diversity in these traits. The diversity in improved cultivars (grown mostly in irrigated fields) was clearly reduced in most traits. Although diversity was reduced in the improved cultivars, the superior traits had contributed increasing productivity. On the other hand, the landraces conserved wide diversities. More than 80% of rice cultivation in Cambodia is still rainfed, with uncontrolled and limited access to water and nutrients. Therefore, it is difficult for uniform improved cultivars to adapt to such heterogeneous growing conditions. Although landraces may be inferior to improved cultivars in overall yield performance under favorable conditions, many are superior to improved cultivars in various characteristics. This indicates their value as resources for breeding for an increased yield. To efficiently identify and evaluate them, we developed a mini-core collection of 53 accessions that maintain the diversity of all accessions. The mini-core collection will be valuable for further detail genetic analysis and genetic yield improvement.

Greenhouse floor management is essential for effectively utilizing solar energy in horticultural production. Covering soil floors with concrete is one method of greenhouse floor management. This paper assesses the effects of this method on greenhouse microclimate and floor surface heat balance by comparing two adjacent single-span greenhouses, namely, an “interlocking concrete block floor” greenhouse (ICFG) and an “uncovered soil floor” greenhouse (SFG). During days with high solar radiation in 2019 winter, the maximum air temperature was 10.0°C lower, and the average vapor pressure was 0.5 kPa lower in the ICFG than in the SFG. On clear nights, the average air temperature was 1.6°C higher in the ICFG than in the SFG. The concrete floor had a higher albedo than the soil floor. This contributed to the lower daytime temperatures in the ICFG. The lower heat absorption by the concrete during the day was more than compensated for by a larger total transmission of heat from the ground to the greenhouse air at night due to the greater thermal conductivity of concrete. These results indicate that replacing soil floors with concrete floors could help farmers avoid temperature extremes and high daytime humidity without requiring external energy derived from fossil fuels or other sources.

Tulipa gesneriana L. ‘Sanne’, a tulip cut flower cultivar, has a fruity scent derived from monoterpenes based on linalool. Treatment with a commercial preservative containing plant growth regulators, such as ethephon, before transportation or with a preservative containing glucose after transportation extends the vase life of various tulip cut flowers. However, the effects of preservatives on floral scents are unknown. In this study, pre-transport ethephon treatment did not affect the scent emission and increased the vase life of Sanne. However, post-transport glucose treatment increased terpenoid emissions and caused stalk softening. The combination of pre- and post-transport treatments increased terpenoid emissions but did not cause stalk softening. Comparative analysis with previous sensory evaluation of the Sanne scent revealed that the duration of the noticeable scent under the combination treatment was estimated to be twice than that under the control treatment. In Sanne, the vase life and scents are expected to be improved by the pre- and post-transport treatment combination.

This study investigated the variations in ¹³⁷Cs concentrations in the fruits and leaves of persimmon trees, which had been affected by radioactive cesium for several years. The trees were divided into lateral or main branches, and ¹³⁷Cs concentrations of fruits and leaves in the branches were measured. The ¹³⁷Cs concentration differed among the fruits of the branches of the same tree, and the difference in ¹³⁷Cs concentration in the fruits of each branch was confirmed for multiple years. A difference in ¹³⁷Cs concentration of approximately ten times was found between the fruits of each branch on the same tree. In addition, a correlation was found between ¹³⁷Cs concentrations in fruits and leaves. These results suggest that a difference might exist in the ¹³⁷Cs concentration of each branch of the tree at the time of fallout in 2011, and it was considered that the difference might persist.

Genetic engineering of the domesticated silkworm Bombyx mori is a useful tool for developing sericulture. New races that produce recombinant silk with fluorescent color and spider silk protein have been constructed. Strains resistant to B. mori nuclear polyhedrosis virus have also been constructed and started to rear in the field. In this genetic engineering method, the use of nondiapause eggs that do not arrest embryonic development is indispensable as it includes the injection process of vector DNA into the eggs. However, most silkworm strains are bivoltine or univoltine and lay diapause eggs that arrest their embryonic development. Thus, applying this method to these silkworm strains is impossible. To enable the application, whether dimethyl sulfoxide (DMSO), which can prevent the diapause of eggs, can be used to develop an injection method for the genetic engineering of diapause strains was investigated. The DMSO treatment worked well for this purpose, and an injection method for the genetic engineering of diapause eggs was successfully developed. This method gave high hatchability in the injection of diapause eggs. Genetically modified silkworms were efficiently created in three different diapause silkworms: hybrid race and Japanese and Chinese strains. Thus, DMSO treatment is useful for creating genetically modified silkworms.

We examined a female Kiso horse (a native Japanese horse breed) aged 2 years and 9 months with persisting nasal discharge that died due to lymphoma. Necropsy revealed masses in the left nasal cavity, left periorbital cavity, and left maxillary and mandibular areas. Histologically, the neoplastic tissues were composed of lymphoid and plasmacytoid cells, with immunoglobulin A (α and λ chains) production in the latter. The foci of large lymphoid cells were detected at some sites. All neoplastic cell types were positively stained in immunohistochemical staining for CD20. Extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) was suspected on the basis of the presence of lymphoepithelial lesions, plasmacytic differentiation, and large-cell transformation. A history of chronic rhinitis may be linked to the development of this disorder.

In Japan, subsistence feed production has gained momentum in recent years. There has been an increase in the establishment of feed production contractors and efforts by cultivating farmers to grow feed crops, which are then harvested and purchased by contractors and others. These efforts serve a large production scale where the target fields are dispersed over a wide area. Thus, it is challenging to manage the work progress, which is a significant issue in the production field. Multipurpose process management methods and software are available for general manufacturing industries. However, applications for agricultural production, especially those that allow process management while displaying field information on a map, are expensive and lack sufficient functionality. To address these issues, this study developed a free, map-based agricultural production process management system, QAgriSupport, and a mobile application, Foregis, which can be coupled with QAgriSupport for agricultural enterprises that are large-scale and have widely dispersed fields. These applications have been introduced at a farm-type TMR (total mixed ration) center engaged in large-scale double-cropping of corn and a large-scale rice production corporation engaged in rice WCS (whole crop silage) and forage rice production. In addition, these applications have made a significant contribution to agricultural production process management by improving the efficiency of field-to-field movement and reducing the time required for work orders.