The aims of this study are to 1) examine the relationships between various indices of rice quality and agro-climatological elements, and to 2) contribute to the evaluation of projecting climate change impact on rice quality in Japan. We used a large collection of rice quality dataset from the Crop Survey database provided ad hoc by the Ministry of Agriculture, Forestry and Fisheries of Japan. Firstly, we conducted statistical analysis to determine the interrelationships among the various indices of rice quality such as the percentages of the first-grade rice, undamaged rice and chalky grain, then also analyzed their relationships with surface meteorological elements and their composite indices. The results showed that the indices of rice qualities were well correlated with a heat stress index HD_m26, that is a cumulative deviation of daily averaged surface air temperature from a base of 26 °C during the 20days after heading. Especially, the percentage of chalky grain was better explained in relation with the HD_m26 than that of simple 20 days-averaged air temperature during the corresponding period. In addition, the Quantile Regression analysis was applied to regress the percentage of chalky grain based on the HD_m26. Although the result showed the significant linear, quadratic and cubic curves regression in each percentile values of the chalky grain with the zone of HD_m26 values, varietal differences were perceived in these statistical relationships.

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　We developed models for predicting fruit ripening of loquat cultivars (‘Mogi’, ‘BN21 gou’ and ‘Biwa Nagasaki No.24’) grown in orchards at four major loquat production regions of Japan (Chiba, Kagawa, Nagasaki and Kagoshima prefecture). The models were constructed based on temperature-dependent properties of fruit developmental rate (DVR), which were investigated by conducting temperature control experiments of potted loquat trees and by analyzing fruit growth records of loquats and daily temperature of the orchards collected over the past 12 years. Our experimental results suggested that there was a liner relationship between fruit growth rate and temperature in each cultivar regardless of growing stages. The most accurate predictions were made when we started DVR calculations with our models from the next day of the end of flowering date (about 22 to 27 days from full bloom). The models enable to estimate the period of fruit ripening for ‘Mogi’, ‘BN21 gou’ and ‘Biwa Nagasaki No.24’ tree with mean errors of 3.9 days, 4.2 days and 2.9 days, respectively, although flowering time and fruit developing period varies at each region. For practical use of our models in agricultural field, precise information of flowering date and temperature in growing area is expected to be needed for minimizing the prediction errors.

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　We aimed to determine the timing of weed control in direct sowing of rice on well-drained paddy fields in Hokkaido region. To this end, we developed calculation models to estimate the date of beginning of seedling emergence from the sowing date, based on an effective accumulated temperature model. The model had different base temperatures set for the earlier and later periods, from sowing to emergence, to calculate daily effective temperature. As non-selective herbicides to remove weeds must be applied before the emergence of rice, new methods to ensure their appropriate application prior to the seedling emergence date are required. These methods must be accurate, as an estimated seedling emergence date that occurs after seedling emergence will be detrimental to the crop. Our results indicate that the use of daily mean soil temperature is more appropriate to estimate the emergence date, and that it is possible to use the daily mean soil temperature which is estimated from daily mean air temperature. The root mean square error of the estimated seedling emergence date is 2.0 days, with only one case of the estimated date occurring after the actual date.

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　To improve reliability in predicting times and volumes of market arrival of major open-field vegetables, we used all available data to identify the Japanese production situation of such vegetables. First, based on market statistics, we investigated the assumption that the production allocation of major open-field vegetables is climatically optimized. Then, we prepared prediction models for cultivation periods, based on cultivation samples. We also elucidated the characteristics of cultivation methods, by region and season; and the ranges of preferred cultivation temperatures, by vegetable type and growing stage. In addition, by optimizing the allocation of major open-field vegetables for climate conditions (using deviations from the ranges of preferred cultivation temperatures as indicators), we identified the production situations for in-season major open-field vegetables, for 10-day periods, by former municipality (based on the Agriculture and Forestry Census), based on production and market statistics. The deviations were calculated by subtracting the limits of preferred cultivation temperature ranges from the meteorological environments of given cultivation periods (back-calculated from the arrival date based on market statistics and cultivation period prediction models). Based on a static optimization algorithm, optimized production situations were identified by repeatedly selecting, as optimal solutions, the allocations with the smallest margins, from all possible land resource allocations. Although there are still issues to be resolved, the identified production situations were consistent with the available data, and can be considered sufficiently valid.

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　We assessed the impact of global warming on the production of major open-field vegetables, based on the daily mean temperature on average over 20-year periods, using the results of Ohara et al. (2020), which identified the production situation of major open-field vegetables (in season), by former municipality (based on the Agriculture and Forestry Census), over a roughly 10-day period. Compared to the period from 1981 to 2000, the yearly mean temperature in Japan will be 0.5 to 1.5°C higher from 2026 to 2045, and 0.8 to 2.7°C higher from 2046 to 2065, based on the Model for Interdisciplinary Research on Climate Version Five (MIROC5) RCP 8.5. As temperatures rise, cultivation and harvest periods are typically shortened. Therefore, if the beginning of planting season remains unchanged, times and quantities of market arrival of the vegetables will be significantly altered. Winter harvesting periods will begin earlier, and become more concentrated. Total harvest area will increase between November and December, decrease between February and March, and experience decreases during the transitions between hot and cool season production periods. Planting frequency during cultivation periods can dramatically impact the total harvested area, with planting frequency being inversely correlated with impact. Thus far, cooperation has enabled production areas to successfully adapt to seasonal climate changes; however, these efforts are unlikely to remain successful in the face of future temperature increases due to global warming. In the near future, it is improbable that the daily mean temperature on average over 20-year periods in Japan will significantly exceed the preferred range for cultivation. However, annual temperature fluctuation is already significant (in Japan, the annual fluctuation of monthly mean temperatures from 1981 and 2000 was 1.0 to 1.4°C [RMS value]), and its impact may exceed that of global warming; therefore, careful attention must be paid to such fluctuation.

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　The Sanriku coastal region of Tohoku, Japan, is characterized by large interannual weather fluctuations, which is an important consideration when scheduling crop cultivation. Therefore, we developed a temperature summation model to predict harvesting time for mini cauliflower (Brassica oleracea var. botrytis). The model parameters were determined from the data obtained during field experiments, and the model was designed using 30-year air temperature records from the AMEDAS observatories. The results indicated that interannual variation at the time of harvest was less when the cauliflower seedlings were transplanted from mid-April through August, but it increased when seedlings were transplanted after September, with the time of harvest often being delayed to mid-winter or later, resulting in severe cold damage to the crop. Based on these results, we concluded that outdoor-cultivated mini cauliflower seedlings should be transplanted before early September in the northern coast and mid-September in the southern coast to ensure harvesting before winter. The effects of greenhouse cover were also evaluated, assuming that the air temperature inside the greenhouse was 2°C-4°C higher than that of outdoors, which showed that greenhouse cultivation decreased the variation in the time of harvest, allowing the time of transplanting to be extended by 2-3 weeks.

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　Freezing tolerance of plants is lowered by high temperatures in which plants are grown before exposure to subzero freezing temperatures. As a measure of freezing tolerance, we used the daily mean and/or the daily maximum air temperature, averaged over 10 days, before the daily minimum air temperature dropped below freezing point during early winter. For the vegetable crop, we assumed a freezing temperature of -3°C or -5°C. The 30-year temperature records from 15 AMeDAS observatories of the Japan Meteorological Agency were used. Of these, 13 are located in the Sanriku coastal region and two in the inland area of Iwate Prefecture. The calculated 10-day averages across the coastal sites were comparable to or larger than those of the inland sites. They showed a specific increase in the coastal zone ranging from Kuji to Yamada. The larger values resulted from relatively low minimum and high maximum temperatures, which are specific to that region. It is generally thought that coastal areas are suitable for the production of winter vegetable crops due to their moderate temperature regime. However, our results indicate that unlike the other typical coastal areas, the temperature regime of the Sanriku region is not moderate; therefore, it possibly increases the risk of crop freezing injury.

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　In this study, the differences in plant growth and canopy surface temperature (T_c) among three different cultivars of sugar beet : “Monohikari”, “Amahomare” and “Hokkaimitsuboshi” were investigated and the relationship between them was analyzed.
　The result showed that leaf number differed significantly among cultivars and “Hokkaimitsuboshi” showed the highest leaf number and increase rate. Plant length also differed among cultivars, with “Monohikari” showing the highest. It was speculated that the highest plant length of “Monohikari” might have caused the highest leaf area index values among cultivars. SPAD also had varietal differences and all cultivars had been changing over 40 by 101 DAT, after which all the cultivars decreased to below 35.
　Diurnal variation of T_c was maximal around noon and the maximum difference among cultivars was about 2°C. These differences of T_c among the cultivars increased with increasing vapor pressure deficit. Comparing the 6 hours mean T_c value from 10 to 16 o’clock, “Monohikari” had the highest while “Amahomare” had the lowest, and the maximum difference was about 1.7°C.

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　Due to the enrichment of atmospheric CO₂ concentration, the air temperature will rise by 3-6℃ and the amount of snowfall will change by the end of the 21st century in northern Tohoku district of Japan. The effect of these changes to the apple cultivation at present and in the future is reviewed. Due to the temperature increase, the date of flowering will advance at the rate 0.2 days year^-1 until 2040, as is observed already at present. The advancement will continue until 2100 under RCP8.5 scenario, while it will slow down after 2040 and stop around 2080 under RCP4.5 scenario. Because the varietal difference in the flowering date will gradually increase, the insect pollination may become difficult at the end of this century. Harvesting date will advance and delay in early- and late-maturing varieties, respectively. Thus in late-maturing varieties, fruit weight may increase depending on the extension of fruit growth period. On the contrary, fruit storability will very likely reduce, and pigmentation will get worse especially in red-skin early-maturing varieties. Moreover, the risk of sunburn damage will increase, and the risk of late frost injury is also indicated to increase by several researchers. On the other hand, we can expect the reduction of snow damage because the amount of snowfall is generally predicted to decrease in the future, although such decreasing tendency is not detected in the past 50-100 years. Considering the conspicuous midday depression of photosynthesis observed in apple trees, they are now in serious sink-limited condition possibly due to the severe fruit thinning. Therefore, the fruit yield cultivated under high CO₂ concentration will hardly increase, unless we alter the strength of thinning to improve the sink capacity of the tree.

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2018年4月発行の生物と気象18巻2号に掲載された， 「農業気象分野で応用可能な広域気象データセットの現状と課題」の56ページ右段41から54行および57ページ左段1から11行に誤りがございました。謹んでお詫び申し上げ，訂正いたします。

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