In recent years, extensive damage to rice and soybeans frequently occurs by salty wind. However, in many cases, disaster studies on salty wind damage are mainly fact-finding surveys, due to lack of time for detailed studies. Compared to other weather-related disasters such as cold damage and high temperature damage, there are few studies on the reproduction method, mechanism, estimation of yield loss, simple damage estimation, and reduction measures for salty wind damage. In this review, the actual situation, the occurrence mechanism, assessment methods, reproduction methods, and techniques to reduce salty wind damage in rice and soybean are explained, with a discussion on future research prospects.

The effect of brown rice grain thickness on the appearance quality and physical properties of cooked rice were investigated using rice variety ‘Hitomebore’, brown rice with a thickness of more than 1.9 mm, the conventional sieve and with four different thicknesses (1.9-2.0, 2.0-2.1, 2.1-2.2, and more than 2.2 mm). In addition, the effects of ripening temperature on the appearance quality and physical property of cooked were analyzed. In addition, the physical properties of cooked rice with a thickness of 1.9-2.2 mm tended to be hard, but the overall balance was higher than that of ‘Hitomebore’ on the conventional sieve. Brown rice with a thickness of 2.1-2.2 mm showed the highest ratio of lowered appearance quality due to the high temperature in the early ripening stage; and, the amylose content and the stickiness and balance of cooked rice of 2.1-2.2 mm grains decreased due to the rise in temperature in the late stage of rice ripening. ‘Hitomebore’ with a thickness of more than 1.9 mm used in this study had good appearance quality and physical properties of cooked rice, However, the quality of ‘Hitomebore’ on the conventional sieve might be susceptible to the effect of high temperature during the ripening period, affected by the susceptibility of grains with a thickness of 2.1-2.2 mm.

Field experiments using five rice varieties in a cold region, and those combining two rice varieties, three fertilization methods and two transplanting times in a warm region were conducted. Grains were classified into superior grain, medium grain and inferior grain according to the position within the panicle. Husk size, grain weight at 20 days after heading (early grain weight), and grain weight at maturity (grain weight) and their differences (late grain weight) were measured. Husk size clearly differed depending on variety and slightly differed depending on fertilization method, year and transplanting time. In most cases, the husk size was larger in the order of superior grain, medium grain and inferior grain. Grain growth differed depending on variety, fertilization method, year and transplanting time. In all cases, the early grain weight was larger in the order of superior grain, medium grain and inferior grain, and the late grain weight tended to be larger in medium and inferior grains than in superior grain. Grain weight was inferred to be determined by husk size in the superior and medium grains, although it seemed suppressed by insufficient grain growth in the inferior grain. The early grain weight of superior grain tended to be large in the extra-large grain variety ‘Bekoaoba’. On the contrary, the late grain weight of every grain was large in the slightly large grain variety ‘Niji-no-kirameki’.

In recent years, the yield of Tanba black soybeans has declined notably in Tanba-sasayama city. To address this issue, we explored the multifaceted effects of climate change on seed yield. We utilized historical data in plots where yields are investigated annually in Tanba-sasayama city, employing the FAO56 model with the Agro-Meteorological Grid Square Data, NARO for soil moisture estimates, alongside trend analysis, variable selection with Least Absolute Shrinkage and Selection Operator (LASSO), and Structural Equation Modeling (SEM) to uncover the causal relationships impacting yield. The estimations based on measured soil physical properties, crop calendars, and the Agro-Meteorological Grid Square Data, demonstrated the efficacy of the FAO56 model in predicting soil moisture for the studied plots. Trend analysis showed significant decline in seed yield and the ratio of whole seeds. Conversely, we observed an increase in the ratio of off-grade seeds. An intriguing finding was the role of increased solar radiation in late October, which significantly contributed to the negative trends in seed yield and the rise in the ratio of off-grade seeds. Further insights from LASSO and SEM analyses highlighted early October soil moisture as a critical factor for seed yield variability. This suggests that seed yield may be effectively enhanced by optimizing the irrigation schedule. These findings will be useful for improving the cultivation techniques and developing a climate-resilient production system to counteract the reduction of yield in Tanba black soybeans, thereby contributing to the future sustainability of Tanba black soybean production.

Abstract: The soybean cultivar ‘Yukipirika’ was grown and compared under two different conditions: twin-row cultivation (TR), with 75 cm between rows and 20 cm between subrows for 2 years using a special sowing machine, and the conventional cultivation (CR) with 75 cm between rows.Seed yields in 2021 and 2022 were higher under TR than under CR, by 24% and 22%, respectively. The higher seed yield under TR was attributed to an increase in the number of pods associated with an increased number of branch nodes. The latter increase was due to two factors: 1) high total intercepted radiation from vegetative to beginning pod (R3) stages and 2) good community structure, with a low light extinction coefficient and easy penetration of solar radiation into the community in the late reproductive stage, after R3. The increase in intercepted radiation may have affected total dry matter weight by accelerating crop growth, whereas the light-intercepting characteristics of the community during the late reproductive stage may have increased total dry matter weight by improving the net assimilation rate. The same trends were observed both in 2021, a high-yielding year with high solar radiation and spindle-shaped leaf structure, and in 2022, a low-yielding year characterized by high temperatures, low solar radiation, and inverted triangle leaf structure.

Organic rice cultivation in Japan commonly involves the transplantation of middle or mature seedlings. However, transplanting these seedlings requires more labor than transplanting young seedlings. To reduce labor in organic rice cultivation, we investigated the suitability of young seedlings for cultivation without pesticides or chemical fertilizers under shallow water conditions. We compared weed growth and rice yield between young and older seedling transplants in paddy fields, where weed incidence varied with the flooding period and mechanical weeding. There were no significant differences in weed growth or rice yield between the plots in which young and older seedlings were transplanted. Rice yield decreased linearly with increasing weed abundance in both young and older seedling transplants, but no significant differences were observed in the slopes and intercepts of their regression lines. These results suggest that rice yields are similar in young and older seedling transplants and that young seedlings can be used for rice cultivation without pesticides or chemical fertilizers under shallow water conditions.