The aim of this study was to reveal the effect of gibberellin application to the apical part of current-year saplings on shoot growth and flower bud formation in the following year in columnar apple Morioka No. 74. The application schemes were 5-times-application of 100 mg 2.7% gibberellin or 10-times-spray of 300–500 ppm gibberellin solution during the growing season. When saplings were not transplanted, the paste application reduced elongation of the main shoot but increased flower bud formation of the other lateral shoots in the following year. Continued paste application in the following year canceled the reduction of shoot elongation, but sapling heights were not different between both-year-application and second-year application. This result indicated that second-year application is efficient for shoot growth promotion in two-year raising. If saplings were transplanted, similar following-year-reduction of main shoot elongation was observed irrespective of application schemes. However, sapling heights and numbers of lateral shoots and flower buds of applied saplings were larger than in non-applied controls after following-year-growth. Since the application of pastes or 500-ppm solution significantly reduced root biomass accumulation in the current year, non-applied controls with larger root systems may be severely damaged even by regular transplanting, which can also decrease shoot elongation in the following year. Considering these results, even in one-year raising, it is suggested that growth promotion by the application schemes contributes to early increases in tree crowns and fruiting parts in columnar apple.

The fruit set ratio in a greenhouse sweet pepper (Capsicum annuum) fluctuates with peaks and troughs during cultivation, and fresh fruit yields also fluctuate. The main causes of this phenomenon may be the amount of dry matter production and fruit sink strength: source-to-sink relationship. However, this theory has not been sufficiently investigated in a wide range of cultivars with different fruit sizes. Therefore, we examined the relationship between the fruit set ratio and source-to-sink ratio of four sweet pepper cultivars (‘Artega’, ‘Nagano’, ‘Nesbitt’, and ‘Trirosso’) under a rockwool system for 250 days. Medium to large fruit cultivars showed marked fluctuations in fruit set ratio and source-to-sink ratio, compared with small ones. Regression curves between the source-to-sink ratio and fruit set ratio in each cultivar were significant (P < 0.001), and they showed different tendencies among cultivars. In conclusion, stabilizing the source-to-sink ratio of each cultivar based on the fruit size might mitigate fluctuations in fresh fruit yields.

A new cultivar of green soybean, ‘Niigata Kei 14 Gou’, was developed in Niigata Prefecture to meet the demand of earlier supply of “Chamame”, a special group of soybean cultivars that has a pleasant aroma. In order to evaluate a wider range of cropping types for this cultivar, we conducted experiments from sowing in late April to late July to determine the range of possible sowing periods that can ensure a stable yield. The results showed that the yield was only 40% when sown in late July, while yields equivalent to those of the standard cropping type were achieved when sown up to late June. There were no significant differences in plant growth in any of the tested cropping types, indicating that the same cultivation management could be applied through the practical cropping period. It was found that the thickness of pods, which is widely recognized as a reliable indicator in predicting the harvesting time, could be accurately estimated using the cumulative average temperature after flowering for all cropping types. It was also possible to estimate the thickness of pods of the whole plant by measuring only those attached to the uppermost node of the main stem, allowing for quick and efficient measurements in fields. In response to an increasing demand for stable seed production of this cultivar, we showed that the optimal sowing period for obtaining high-quality seeds was from early to mid-August.

We experimentally cultivated the garlic variety ‘Fukuchi White’ on transparent mulch in Aomori Prefecture, Japan, from 2011 to 2021. The dates of snow disappearance, scale differentiation stage, and harvesting stage when the yield of high-quality product was at its maximal were March 7th, April 19th, and June 30th, respectively. The cumulative daily mean air temperature from the snow disappearance date to the scale differentiation stage was approximately 220°C. The cumulative air temperature from the scale differentiation stage to harvesting stage was approximately 1010°C. To predict the harvesting stage, the actual-measured air temperature was used in the summation to determine the cumulative air temperature, with the smallest error level falling between the estimated and actual-measured values at the harvesting stage. The root mean square error (RMSE) between the estimated harvesting stage (date when the cumulative air temperature became 1240°C after the disappearance of snow) and measured harvesting stage was 4.15 days. RMSE between the estimated harvesting stage (date when the cumulative air temperature became 1010°C after the scale differentiation stage) and measured harvesting stage was 4.00 days. To predict the current year harvesting stage, RMSE between the predicted and measured harvesting stage was determined from the actual-measured air temperature and annual average value. RMSE was approximately 4 days when the annual average temperature from 90 days after the snow disappearance date to harvesting stage was used. RMSE was approximately 3 days when the annual average temperature from 50 days after the scale differentiation stage to harvesting stage was used.

Conditions under which the ‘Avalanche’ variety of white roses turns orange during high temperatures were investigated, to determine methods by which the color change can be prevented. The pigment responsible was identified as β-Carotene, it was measured in rose petals harvested under various conditions. Results indicated that the petals did not turn orange when cut flowers absorbed water at 25°C for 24 hours. However, the β-Carotene content increased afterwards when the flowers absorbed water at 3°C during the same time period. When cut flowers were pretreated at 20°C for at least 4 hours immediately after harvest and then refrigerated, the β-Carotene content decreased to 0.1 mg･100 gFW^–1, and at this level no discoloration could be visually detected. The β-Carotene content of the petals was highest when harvested 2 and 4 hours after sunrise. Furthermore, when the time of harvest and length of time cut flowers were kept in the refrigerator were varied, assuming harvesting and shipping, the β-Carotene content was lower when the flowers were harvested around 4:00 p.m., supporting the above results. β-Carotene was detected when the temperature exceeded 23°C during the growing period, and the higher the temperature, the higher the content. Results indicate that it is not practical to improve the growing environment, and that adjustment of harvest times, as well as pre-treatment after harvest and before refrigeration, can help prevent color change in white roses.