Root-elongated rice seeds that have roots emerged during the pre-germination period are used in the direct seeding of rice using a puddling seeder for improved seedling establishment and seedling vigor. We investigated the factors responsible for these improvements, in field experiments conducted in 2017, 2018 and 2019. Root-elongated seeds (RS), coleoptile-elongated seeds (CS), and pre-germinated seeds (GS) were sown in paddy fields with a puddling seeder. While more than half of CS were damaged, RS were not damaged during machine seeding. The percentage of seedling establishment using RS was 74–90%, which was higher than that using CS and GS. There was no difference in the sowing depth of RS, CS and GS. The percentage of seedling establishment using RS was higher than that using GS regardless of the sowing depth. Furthermore, the seedlings of RS emerged earlier than those of GS, and leaf number and shoot weight were greater than those of GS. These results suggest that root-elongated seeds are not significantly damaged by machine seeding and that their seedlings emerge quickly from a relatively deep sowing depth, which contributes to the high seedling establishment percentage. The quick seedling emergence also promotes early growth of root-elongated seeds.

The high temperature from the heading period to the ripening period caused by global warming hinders rice grain ripening in rice cultivation sites in Japan. In this study, we aimed to predict during the heading period, the degree of high-temperature damage in rice grain ripening at harvest, and examined whether the rates of perfect grain and immature grain at harvest could be estimated by the proximity remote sensing during the heading period. Two varieties, Akitakomachi and Fusaotome, which have different degrees of resistance to the high-temperature during rice grain ripening, were cultivated in pots and subjected to different temperature treatments from the heading period to the ripening period. The data obtained by proximity remote sensing during the heading period were compared with the rates of perfect grain and immature grain at harvest. By using the spectral reflectances of two wavelengths, 462.4 nm and 469 nm, at the heading stage, a significant correlation was obtained with the rate of perfect grain at harvest by multiple regression analysis. The relationship between the normalized sufferance spectral index （NDSI）and the rate of perfect grain was also the most significant in the NDSI_{462.4 nm, 495.4 nm} calculated using the spectral reflectances of 488.8 nm and 532.8 nm. A significant correlation with the rate of immature grain at harvest was obtained by multiple regression analysis using the spectral reflectances of the five wavelengths of 462.4 nm, 464.6 nm, 730.8 nm, 735.2 nm, and 737.4 nm during the heading period. Regarding the relationship between NDSI and immature grain ratio, the most significant correlation was obtained at NDSI_{462.4 nm, 495.4 nm} calculated using the spectral reflectances of 462.4 nm and 495.4 nm. These results showed that it is possible to predict the degree of the high-temperature damage to rice grain ripening at harvest from the spectral reflectance data obtained by proximity remote sensing at the heading stage.

Phytophthora root and stem rot (PRSR) in soybean tends to occur on poorly drained fields; however, the contribution of soil moisture on its spread is not clear. A field survey was conducted to analyze the relationship between the soil moisture condition and other soil attributes with field-to-field and intra field variation and PRSR occurrence. The field surveys were conducted in 2019 and 2020 on a drained paddy field in Sasayama and an upland field in Ayabe, where the cultivar Tanbaguro was grown. PRSR was observed in both fields and disease occurrence on soybean was tested by collecting soils under identical moisture conditions using a pot experiment. Results showed that PRSR occurred more in the Sasayama field than in the Ayabe field. Spatial variation was analyzed for the Sasayama field (10 m×100 m) by dividing it into 75 blocks. The occurrence rate was higher in the blocks with lower moisture content than the other blocks. The other factors examined were infection potential and soil properties such as soil pH, total nitrogen, total carbon, exchangeable cations, available phosphate, and stone content. The Sasayama field showed higher content of most cations and stones and greater infection potential than the Ayabe field. The spatial variation analysis for the Sasayama field showed weak positive correlations with soil magnesium and stone contents. The infection potential correlated with the total carbon and nitrogen contents. These results suggested that excess soil moisture is not necessarily the dominant factor causing the spread of PRSR in soybean and that soil fertility may be related to the infection potential.

The percentage of first grade Koshihikari rice （a paddy rice variety） produced in Niigata Prefecture was over 70％ from 2013 to 2018. However, the ratio in 2019 （25％） was the second lowest ever. In 2019, the temperature from late-July to mid-August was 1.4-4.0°C higher than usual, reaching a record high temperature due to the foehn winds that occurred from August 14 to 15. The reason for the downgrading was mostly milky white grains. Despite this observation, it was speculated that excess spikelet number was not the main factor. The pattern and proportion of cross-sectional chalkiness in brown rice grains was investigated in Koshihikari samples with different heading times. A combination of chalkiness in center, dorsal and ventral sides was confirmed in samples exposed to the foehn winds 11 to 17 days after heading time. In these samples, the ratio of dorsal chalkiness was also increased, and the ratio of perfect grains was low. Peak heading time for Koshihikari in Niigata Prefecture was August 3, suggesting that the quality deteriorated due to exposure to the foehn winds in the first half of ripening, when the rice is highly sensitive to the increase in temperatures in most areas.

The grain ash content is problematically high in the wheat variety ‘Yukichikara’ for bread cultivated in the sand dune in Niigata city. We examined the farmer’s fields of ‘Yukichikara’ for four cropping seasons in the sand dune to clarify the actual state of grain ash content and the conditions leading to the increase in grain ash content. The grain ash content was not affected by the available phosphoric acid in the sand dune soil. The grain protein content was correlated to the grain ash content in the 2016, 2017 and 2019 cropping seasons, but not in the 2018 cropping season. The thousand grain weight was increased by nitrogen topdressing at flowering in the 2018 cropping season, and the increase of grain ash was relatively smaller than the increase of grain ash in the other three cropping seasons. The soil matric potential in the ripening period decreased to about -100 kPa in the 2018 cropping season, but it was about –1000 kPa in the other three cropping seasons. Soil water deficiency occurred during the ripening period except in the 2018 cropping season. These results suggested that soil water deficiency during the ripening period suppressed the increase in thousand grain weight in response to nitrogen topdressing at flowering, and resulted in an increase in the grain ash content.