A technique has been developed for transplanting densely-seeded seedlings. The range of leaf age suitable for transplanting is narrow in these seedlings. This limits the acceptable range of the nursery period. In addition to heating nursery boxes till emergence, a conventional method, keeping those unheated under outdoor or greenhouse conditions may produce various periods to emergence which could be utilized to adjust the nursery period. Clarification of the thermal time required for emergence could help us estimate the period from seeding to emergence. The objective of this study was to clarify the effective cumulative temperature required for emergence and to clarify the climate factor affecting nursery box temperature under a covering material. We investigated the period from seeding to emergence in nursery boxes kept unheated under outdoor and greenhouse conditions from the beginning of April to the beginning of May. We also measured the hourly temperature of each nursery box under a covering material. The period from seeding to emergence was 7-18 days and 5-8 days under outdoor and greenhouse conditions, respectively. The smallest coefficient of variance, 63°C, was obtained, when calculated with the base temperature at 8.7°C. Heat shielding material kept the temperature under the covering material <40°C.The daily mean temperature under the covering material significantly and positively correlated with that of the surrounding atmosphere suggesting that day of emergence can be estimated from the surrounding air temperature.

High temperatures lead to higher concentrations of inorganic arsenic in the rice grain; thus, locations with high levels of inorganic arsenic concentrations in rice grains will likely increase with global warming. Therefore, it is important to develop rice cultivars with lower inorganic arsenic concentrations in grains. Here, we investigated inorganic arsenic concentrations in whole rice grains and ratios of perfect grains using reciprocal chromosome segment substitution lines (CSSLs) and near-isogenic lines (NILs) derived from the crossing between a japonica cultivar ‘Koshihikari’ and an indica cultivar ‘Takanari’ which has a lower concentration of inorganic arsenic in grain than that in ‘Koshihikari’. A NIL showing a lower inorganic arsenic concentration in grain than that in ‘Koshihikari’ was identified as that carrying a ‘Takanari’ chromosome 10 segment in a ‘Koshihikari’ genetic background. There was no significant difference in the ratio of perfect grain between the NIL and ‘Koshihikari’.

For barley pearling in Japan, glassy grain rate is an important quality factor. However, the relationship between glassy grain rate and temperature has not been clarified. We investigated the effects of moderately high daytime and nighttime temperatures during the ripening period on the glassy grain rate of barley using phytotrons. The barley variety ‘Shunrai’ was tested under three conditions: high daytime temperature (HD: 25°C / 9°C), high nighttime temperature (HN: 20°C / 14°C), and control (CT: 20°C / 9°C) in 2016/2017 and 2017/2018. The HD group showed an increase in the glassy grain rate. This was possibly due to the decrease in grain weight and increase in grain protein content. The HN group did not show any decrease in grain weight or increase in grain protein content, and the glassy grain rate was similar to that in the CT group. Based on these results, we investigated the trends of starch, soluble sugars, N, and C content in the seed during the ripening process in the HD and CT groups in 2019/2020. Accumulation of starch and N was accelerated during the first half of ripening in the HD group, but the final starch synthesis per individual plant was reduced because the ripening period was shortened. The ratio of change in N content to C content (ΔN/ΔC) from flowering to physiological maturity increased. Protein content per grain increased in the HD group. Furthermore, electron microscopic observation of the endosperm in the HD group revealed that large starch granules became larger while small starch granules became smaller. These results suggest that the increase in glassy grain rate due to high daytime temperatures is mainly due to changes in the accumulation pattern of starch and cytoplasmic proteins in the endosperm and the accumulation of more cytoplasmic proteins. This study may serve as a stepping stone to understanding the factors that increase the glassy grain rate in barley production sites.

Phenological models from sowing to flowering time were constructed for 50 cultivars and lines using historical data of soybean breeding over the past 55 years. Three methods for optimizing the parameters: Nelder-Mead (NM), swarm particle optimization (PSO), and genetic algorithm. In cross-validation, PSO was significantly more accurate than the other two methods, although the difference was small. NM was more dependent on initial values than the other two methods, and the optimization had to be repeated multiple times from different initial values to reach the global optimal solution. Although the number of records included in the historical data varied greatly among the cultivars and lines, when more than 300 records were used, the accuracy for predicting days to flowering did not deteriorate drastically. Specifically, the correlation coefficient (r) and root mean squared error (RMSE) between the predicted and observed values were ≥0.92 and ≤4.52 days, respectively. As a result of the prediction of the extra data that was not included in the historical data, the accuracy of PSO was 0.98–0.99 (r) and 3.20–4.34 days (RMSE), suggesting the usefulness of the historical data for flowering time prediction. Comparison of the optimized parameter values among the breeding centers revealed certain trends such as prolonged critical daylength at higher latitudes. The results of this study will be useful for the construction of phenological models from historical data.

According to the analysis of yield data from 2016 to 2021, the economic yield of soybean cultivar 'Satonohohoemi' grown in Saitama prefecture was mainly determined by biological yield, and the effect of harvest index was very small. Therefore, the evaluation of soybean cultivation should be conducted by total weight measurement and growth analysis, not by decomposition into yield components. It was considered that the low biological yield of soybean in Saitama was caused by the insufficient leaf area index of the soybean canopy. As a countermeasure, sowing earlier or dense planting in late sowing was considered to be effective. However, the area where early sowing can be introduced is limited due to work conflicts with rice and wheat, and the amount of seed supply is insufficient for late dense sowing. Therefore, it was considered that a cultivation system in which the amount of seed left over from early sparse sowing was used for late dense sowing would be more realistic.

Reduced basal fertilizer and increased additional fertilizer application have been reported to increase barley yield in some regions, but not in the Kanto region. We conducted a two-year trial to clarify the effects of this fertilization system in the Kanto region. Fertilizer was added at different growth stages to the six-row barley cultivars ‘Shunrai’ (a pearling and barley tea variety) and ‘Kashimagoal’ (a barley tea variety) and the amount of N (g m^-2) was 6 (as basal fertilizer) –0 (at tillering stage) –3 (at jointing stage), 3–0–6, 6–0–6, and 3–3–6 in ‘Shunrai’, 6–0–6 and 3–3–6 in ‘Kashimagoal’. Compared to the 6–0–3, the 3–3–6 tended to be higher number of ears and yield in ‘Shunrai’. Furthermore, the protein content and glassy grain rate of the grain were higher in the plot with more N in the jointing fertilization, indicating the possibility of quality problems for pearling. The number of grains and yield of ‘Kashimagoal’ tended to be higher in the 3–3–6 system, than in the 6–0–6 system, and there was no difference in the protein content of grains. This study indicated that the 3–3–6 fertilizer system with a high ratio of additional fertilizer to basal fertilizer in the Kanto region increases the yield of six-row barley cultivars and is particularly suitable for barley tea.