Pub Date : 2021-10-10DOI: 10.2480/agrmet.d-21-00022
Masako KAJIURA, Takeshi TOKIDA
Methane (CH4) produced in rice-paddy soil is transported to the atmosphere either via the rice plants or by bubbling events (ebullition); however, little is known about the frequency and intensity of bubbling CH4 emissions and the factors that affect them. We developed a method to quantify ebullition using high-time-resolution (~1 Hz) CH4 concentration data obtained by closed-chamber measurements. Field measurements were conducted in a Japanese rice paddy at different rice growth stages: panicle formation (PF), booting (BT), and heading (HD). A dataset of 132 chamber measurements was used to develop and evaluate the method. A scripting file written in R programing language was used to automatically determine CH4 emissions via the two pathways. Plant-mediated CH4 emission intensity was constant during chamber deployment and was reflected as a steady linear increase in chamber [CH4] with time or as a constant baseline in a flux time series. We found that the plant-mediated emission could be determined as the peak with the lowest flux intensity in the flux frequency distribution even if bubbling events occurred during the chamber deployment. The field measurement results in combination with established data processing protocols showed that at PF, ebullition contributed only 4% of the total emission, whereas it accounted for 32% and 60% of the total emission at BT and HD, respectively. In contrast, the plant-mediated flux variation among growth stages was smaller. Both ebullition and plant-mediated emissions correlated significantly with air temperature at HD, but the magnitude of the dependency was much higher for ebullition than for rice-mediated emission. These results demonstrate that ebullition occurs more frequently than has previously been thought, and the different transport pathways show varying degrees of dependency on plant phenological and environmental factors, thus underscoring the need to separately determine CH4 emissions via each transport pathway.
{"title":"Quantifying bubbling emission (ebullition) of methane from a rice paddy using high-time-resolution concentration data obtained during a closed-chamber measurement","authors":"Masako KAJIURA, Takeshi TOKIDA","doi":"10.2480/agrmet.d-21-00022","DOIUrl":"https://doi.org/10.2480/agrmet.d-21-00022","url":null,"abstract":"Methane (CH<sub>4</sub>) produced in rice-paddy soil is transported to the atmosphere either via the rice plants or by bubbling events (ebullition); however, little is known about the frequency and intensity of bubbling CH<sub>4</sub> emissions and the factors that affect them. We developed a method to quantify ebullition using high-time-resolution (~1 Hz) CH<sub>4</sub> concentration data obtained by closed-chamber measurements. Field measurements were conducted in a Japanese rice paddy at different rice growth stages: panicle formation (PF), booting (BT), and heading (HD). A dataset of 132 chamber measurements was used to develop and evaluate the method. A scripting file written in R programing language was used to automatically determine CH<sub>4</sub> emissions via the two pathways. Plant-mediated CH<sub>4</sub> emission intensity was constant during chamber deployment and was reflected as a steady linear increase in chamber [CH<sub>4</sub>] with time or as a constant baseline in a flux time series. We found that the plant-mediated emission could be determined as the peak with the lowest flux intensity in the flux frequency distribution even if bubbling events occurred during the chamber deployment. The field measurement results in combination with established data processing protocols showed that at PF, ebullition contributed only 4% of the total emission, whereas it accounted for 32% and 60% of the total emission at BT and HD, respectively. In contrast, the plant-mediated flux variation among growth stages was smaller. Both ebullition and plant-mediated emissions correlated significantly with air temperature at HD, but the magnitude of the dependency was much higher for ebullition than for rice-mediated emission. These results demonstrate that ebullition occurs more frequently than has previously been thought, and the different transport pathways show varying degrees of dependency on plant phenological and environmental factors, thus underscoring the need to separately determine CH<sub>4</sub> emissions via each transport pathway.\u0000</p>","PeriodicalId":56074,"journal":{"name":"Journal of Agricultural Meteorology","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2021-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138542025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-06-18DOI: 10.21203/rs.3.rs-632766/v1
M. Kajiura, T. Tokida
A modified closed-chamber method for estimating total, plant-mediated, and bubbling (ebullition) emissions of CH4 from rice paddies has been developed to use high-time-resolution CH4 concentration data (~ 1 Hz) obtained by a spectroscopic mobile gas analyzer. Here we aimed at determining an appropriate minimum time length of chamber closure for accurate flux measurement by investigating 3255 datasets obtained from a 2-year field survey. To investigate the minimum time length for each chamber measurement, we generated a series of datasets from each measurement: by setting the hypothetical termination time of the chamber closure ahead in 1-min intervals, we obtained various chamber CH4 concentration time series with different durations of chamber closure, and separately estimated CH4 emissions via rice plants and bubbling from each. The estimated flux was sensitive to time length with short closure times, but became less sensitive with longer closure. We defined the minimum time length at which the difference in estimated flux between adjacent time windows was small enough (< 10% of plant-mediated emission). The estimated minimum time length differed from one measurement to another, but 10 min was sufficient for > 99% of cases. Detailed analysis showed a positive correlation between minimum time length and frequency of bubbling events; the time length needed to be longer as bubbling events became more frequent. From this relationship, we computed the appropriate chamber-duration time as a function of bubbling frequency. In the absence of ebullition, 4–5 min was sufficient, but as the bubbling frequency increased to 2.5 times per minute 15–20 min was necessary for accurate pathway-dependent flux measurements.
{"title":"Appropriate chamber deployment time for separate quantification of CH4 emissions via plant and ebullition from rice paddies using a modified closed-chamber method","authors":"M. Kajiura, T. Tokida","doi":"10.21203/rs.3.rs-632766/v1","DOIUrl":"https://doi.org/10.21203/rs.3.rs-632766/v1","url":null,"abstract":"\u0000 A modified closed-chamber method for estimating total, plant-mediated, and bubbling (ebullition) emissions of CH4 from rice paddies has been developed to use high-time-resolution CH4 concentration data (~ 1 Hz) obtained by a spectroscopic mobile gas analyzer. Here we aimed at determining an appropriate minimum time length of chamber closure for accurate flux measurement by investigating 3255 datasets obtained from a 2-year field survey. To investigate the minimum time length for each chamber measurement, we generated a series of datasets from each measurement: by setting the hypothetical termination time of the chamber closure ahead in 1-min intervals, we obtained various chamber CH4 concentration time series with different durations of chamber closure, and separately estimated CH4 emissions via rice plants and bubbling from each. The estimated flux was sensitive to time length with short closure times, but became less sensitive with longer closure. We defined the minimum time length at which the difference in estimated flux between adjacent time windows was small enough (< 10% of plant-mediated emission). The estimated minimum time length differed from one measurement to another, but 10 min was sufficient for > 99% of cases. Detailed analysis showed a positive correlation between minimum time length and frequency of bubbling events; the time length needed to be longer as bubbling events became more frequent. From this relationship, we computed the appropriate chamber-duration time as a function of bubbling frequency. In the absence of ebullition, 4–5 min was sufficient, but as the bubbling frequency increased to 2.5 times per minute 15–20 min was necessary for accurate pathway-dependent flux measurements.","PeriodicalId":56074,"journal":{"name":"Journal of Agricultural Meteorology","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2021-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42049238","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-05-01DOI: 10.2480/AGRMET.D-21-00003
Shihori Kawashima, M. Ueyama, Mikita Okamura, Y. Harazono, H. Iwata, Hideki Kobayashi
Spring phenology is essential in modeling the carbon balance of high‑latitude ecosystems and is possibly sensitive to climate change. In the present study, we evaluated the onset of the growing season for three species ( paper birch, bog blueberry, and bog Labrador tea ) in interior Alaska from 2012 to 2019 using photos taken using time‑lapse cameras. We also evaluated the onset of the growing season at the ecosystem scale from 2010 to 2019 on the basis of the CO 2 flux by the eddy covariance method at the site. On the basis of the growing degree‑day ( GDD ) model with the parameters estimated using the Bayesian approach, we found that the interannual variations in the spring onsets were explained by the model, and the thermal forcing requirement differed among the species. At the ecosystem scale, the spring onset was closely linked to the snow disappearance date. Under the possible future climate scenarios indicated by the representative concentration pathway 8.5 scenario, the spring onsets were predicted to be one to three weeks earlier than the present dates for the three species. The ecosystem‑scale onsets were also predicted to be five days to a little over a month earlier at the end of this century. The future spring onset is highly sensitive to the snow disappearance date for high‑latitude vegetation; thus, further understanding of climate change before snowmelting is required.
{"title":"Spring onsets of a young forest in interior Alaska determined based on time‑lapse camera and eddy covariance measurements","authors":"Shihori Kawashima, M. Ueyama, Mikita Okamura, Y. Harazono, H. Iwata, Hideki Kobayashi","doi":"10.2480/AGRMET.D-21-00003","DOIUrl":"https://doi.org/10.2480/AGRMET.D-21-00003","url":null,"abstract":"Spring phenology is essential in modeling the carbon balance of high‑latitude ecosystems and is possibly sensitive to climate change. In the present study, we evaluated the onset of the growing season for three species ( paper birch, bog blueberry, and bog Labrador tea ) in interior Alaska from 2012 to 2019 using photos taken using time‑lapse cameras. We also evaluated the onset of the growing season at the ecosystem scale from 2010 to 2019 on the basis of the CO 2 flux by the eddy covariance method at the site. On the basis of the growing degree‑day ( GDD ) model with the parameters estimated using the Bayesian approach, we found that the interannual variations in the spring onsets were explained by the model, and the thermal forcing requirement differed among the species. At the ecosystem scale, the spring onset was closely linked to the snow disappearance date. Under the possible future climate scenarios indicated by the representative concentration pathway 8.5 scenario, the spring onsets were predicted to be one to three weeks earlier than the present dates for the three species. The ecosystem‑scale onsets were also predicted to be five days to a little over a month earlier at the end of this century. The future spring onset is highly sensitive to the snow disappearance date for high‑latitude vegetation; thus, further understanding of climate change before snowmelting is required.","PeriodicalId":56074,"journal":{"name":"Journal of Agricultural Meteorology","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2021-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48741533","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-04-06DOI: 10.21203/RS.3.RS-396475/V1
M. Kajiura, T. Tokida
Methane (CH4) produced in rice-paddy soil is transported to the atmosphere either via the rice plants or by bubbling events (ebullition); however, little is known about the frequency and intensity of bubbling CH4 emissions and the factors that affect them. We developed a method to quantify ebullition using high-time-resolution (~1 Hz) CH4 concentration data obtained by closed-chamber measurements. Field measurements were conducted in a Japanese rice paddy at different rice growth stages: panicle formation (PF), booting (BT), and heading (HD). A dataset of 132 chamber measurements was used to develop and evaluate the method. A scripting file written in R programing language was used to automatically determine CH4 emissions via the two pathways. Plant-mediated CH4 emission intensity was constant during chamber deployment and was reflected as a steady linear increase in chamber [CH4] with time or as a constant baseline in a flux time series. We found that the plant-mediated emission could be determined as the peak with the lowest flux intensity in the flux frequency distribution even if bubbling events occurred during the chamber deployment. The field measurement results in combination with established data processing protocols showed that at PF, ebullition contributed only 4% of the total emission, whereas it accounted for 32% and 60% of the total emission at BT and HD, respectively. In contrast, the plant-mediated flux variation among growth stages was smaller. Both ebullition and plant-mediated emissions correlated significantly with air temperature at HD, but the magnitude of the dependency was much higher for ebullition than for rice-mediated emission. These results demonstrate that ebullition occurs more frequently than has previously been thought, and the different transport pathways show varying degrees of dependency on plant phenological and environmental factors, thus underscoring the need to separately determine CH4 emissions via each transport pathway.
{"title":"Quantifying bubbling emission (ebullition) of methane from a rice paddy using high-time-resolution concentration data obtained during a closed-chamber measurement","authors":"M. Kajiura, T. Tokida","doi":"10.21203/RS.3.RS-396475/V1","DOIUrl":"https://doi.org/10.21203/RS.3.RS-396475/V1","url":null,"abstract":"\u0000 Methane (CH4) produced in rice-paddy soil is transported to the atmosphere either via the rice plants or by bubbling events (ebullition); however, little is known about the frequency and intensity of bubbling CH4 emissions and the factors that affect them. We developed a method to quantify ebullition using high-time-resolution (~1 Hz) CH4 concentration data obtained by closed-chamber measurements. Field measurements were conducted in a Japanese rice paddy at different rice growth stages: panicle formation (PF), booting (BT), and heading (HD). A dataset of 132 chamber measurements was used to develop and evaluate the method. A scripting file written in R programing language was used to automatically determine CH4 emissions via the two pathways. Plant-mediated CH4 emission intensity was constant during chamber deployment and was reflected as a steady linear increase in chamber [CH4] with time or as a constant baseline in a flux time series. We found that the plant-mediated emission could be determined as the peak with the lowest flux intensity in the flux frequency distribution even if bubbling events occurred during the chamber deployment. The field measurement results in combination with established data processing protocols showed that at PF, ebullition contributed only 4% of the total emission, whereas it accounted for 32% and 60% of the total emission at BT and HD, respectively. In contrast, the plant-mediated flux variation among growth stages was smaller. Both ebullition and plant-mediated emissions correlated significantly with air temperature at HD, but the magnitude of the dependency was much higher for ebullition than for rice-mediated emission. These results demonstrate that ebullition occurs more frequently than has previously been thought, and the different transport pathways show varying degrees of dependency on plant phenological and environmental factors, thus underscoring the need to separately determine CH4 emissions via each transport pathway.","PeriodicalId":56074,"journal":{"name":"Journal of Agricultural Meteorology","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2021-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41349511","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.2480/AGRMET.D-20-00049
Rui Cui, T. Hirano, Lifei Sun, Munemasa Teramoto, N. Liang
Root respiration ( R r ) plays a crucial role in the global carbon balance, because R r accounts for about a half of soil respiration in typical forest ecosystems. Plant roots are different in metabolism and functions according to size. Fine roots, which are typically defined as roots < 2 mm in diameter, perform important ecosystem functions and consequently govern belowground carbon cycles mainly because of their high turnover rates. However, the phenological variation of fine root functions is not well understood yet. To quantitatively examine the fine root functions, we adopted an approach to partition R r into growth respiration ( R g ) and maintenance respiration ( R m ) using a modified traditional model, in which R g was proportional to root production, and R m was proportional to root biomass and exponentially related to soil temperature. We conducted a field experiment on soil respiration and fine root biomass and production over a year in a larch-dominated young forest developing on the bare ground after removing surface organic soil to parameterize the model. The model was significantly parameterized using the field data measured in such simplified field conditions, because we could control spatial variation in heterotrophic respiration and contamination from roots other than fine roots. The annual R r of all roots was 94 g C m - 2 yr - 1 and accounted for 25 % of total soil respiration on average. The annual R r was partitioned into fine root R g , fine root R m and coarse root R m by 30, 44 and 26 % , respectively; coarse root R g was presumed to be negligible. Fine root R g and R m varied according to the seasonal variations of fine root production and soil temperature, respectively; the contribution of fine root biomass was minor because of its small seasonality. The contribution of R g to total fine root respiration was lower in the cold season with low production.
根系呼吸(R R)在全球碳平衡中起着至关重要的作用，因为R R约占典型森林生态系统土壤呼吸的一半。植物根的大小不同，其代谢和功能也不同。细根，通常被定义为直径小于2毫米的根，具有重要的生态系统功能，因此主要由于其高周转率而控制地下碳循环。然而，细根功能的物候变化尚不清楚。为了定量研究细根功能，我们采用了一种改进的传统模型，将R R划分为生长呼吸(R g)和维持呼吸(R m)，其中R g与根系产量成正比，R m与根系生物量成正比，与土壤温度呈指数相关。为了对模型进行参数化，我们在一个以落叶松为主的裸地幼林中进行了1年的土壤呼吸、细根生物量和产量的野外试验。由于可以控制异养呼吸的空间变化和细根以外的根系污染，因此在简化的田间条件下测量的野外数据对模型进行了显著的参数化。所有根系的年R值为94 g C m - 2 yr - 1，平均占土壤呼吸总量的25%。年R R分别为细根R g、细根R m和粗根R m的30%、44%和26%;粗根rg可以忽略不计。细根R g和R m分别随细根产量和土壤温度的季节变化而变化;细根生物量的贡献较小，因为其季节性较小。在产量低的寒冷季节，R g对总细根呼吸的贡献较低。
{"title":"Variations in biomass, production and respiration of fine roots in a young larch forest","authors":"Rui Cui, T. Hirano, Lifei Sun, Munemasa Teramoto, N. Liang","doi":"10.2480/AGRMET.D-20-00049","DOIUrl":"https://doi.org/10.2480/AGRMET.D-20-00049","url":null,"abstract":"Root respiration ( R r ) plays a crucial role in the global carbon balance, because R r accounts for about a half of soil respiration in typical forest ecosystems. Plant roots are different in metabolism and functions according to size. Fine roots, which are typically defined as roots < 2 mm in diameter, perform important ecosystem functions and consequently govern belowground carbon cycles mainly because of their high turnover rates. However, the phenological variation of fine root functions is not well understood yet. To quantitatively examine the fine root functions, we adopted an approach to partition R r into growth respiration ( R g ) and maintenance respiration ( R m ) using a modified traditional model, in which R g was proportional to root production, and R m was proportional to root biomass and exponentially related to soil temperature. We conducted a field experiment on soil respiration and fine root biomass and production over a year in a larch-dominated young forest developing on the bare ground after removing surface organic soil to parameterize the model. The model was significantly parameterized using the field data measured in such simplified field conditions, because we could control spatial variation in heterotrophic respiration and contamination from roots other than fine roots. The annual R r of all roots was 94 g C m - 2 yr - 1 and accounted for 25 % of total soil respiration on average. The annual R r was partitioned into fine root R g , fine root R m and coarse root R m by 30, 44 and 26 % , respectively; coarse root R g was presumed to be negligible. Fine root R g and R m varied according to the seasonal variations of fine root production and soil temperature, respectively; the contribution of fine root biomass was minor because of its small seasonality. The contribution of R g to total fine root respiration was lower in the cold season with low production.","PeriodicalId":56074,"journal":{"name":"Journal of Agricultural Meteorology","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69170349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.2480/agrmet.d-21-00011
Kensuke Kimura, K. Kudo, A. Maruyama
Climate change may induce severe frost damage to crops, and thus a reasonable assessment of frost risk, considering both crop phenology and meteorology, is required. Here, we introduced a new index of potential frost risk ( F risk ) using thermal time ( minimum air temperature below the threshold value ) weighted by the percentage of budburst ( P bud ) . Moreover, we evaluated the spatiotemporal distributions of F risk in tea fields within a 60 km × 60 km area in east Japan from 1981 - 2020, using 1 km 2 -gridded meteorological data and a newly developed model of P bud . The P bud model considered three phenological phases ( endodormancy, ecodormancy, and progress of budburst ) and successfully represented changes in the P bud of the tea buds for 15 years, with root mean square errors of 8.5 percentage points. The spatiotemporal distributions of F risk over the past 40 years showed that potential frost risk significantly increased at elevations ranging from 50 m to 300 m because the budburst advanced at a faster rate than the temperature warming. These elevations corresponded to areas where tea plants were mainly cultivated, which indicates that tea cultivation is becoming vulnerable to frost, and the risk of economic losses due to the frost is increasing. The proposed assessment of frost risk could contribute to predicting frost damage and developing more reliable strategies for the operation of frost protection under the effects of future climate change.
气候变化可能对农作物造成严重的霜冻危害，因此需要在考虑作物物候和气象学的基础上对霜冻风险进行合理的评估。在此，我们引入了一个新的霜冻风险指数(F风险)，该指数使用热时间(低于阈值的最低气温)加权发芽百分比(P芽)。利用1 km 2格点气象数据和新开发的P芽模型，对1981 - 2020年日本东部60 km × 60 km区域内茶田F风险的时空分布进行了评价。P芽模型考虑了3个物候阶段(内胚期、生态期和出芽期)，成功地反映了15年茶芽P芽的变化，均方根误差为8.5个百分点。近40 a F风险的时空分布表明，在海拔50 ~ 300 m范围内，潜在霜冻风险显著增加，因为霜冻的推进速度快于气温的升温速度。这些海拔高度与茶树主要种植的地区相对应，这表明茶叶种植越来越容易受到霜冻的影响，霜冻造成经济损失的风险正在增加。提出的霜冻风险评估有助于预测未来气候变化影响下的霜冻灾害，制定更可靠的霜冻防护策略。
{"title":"Spatiotemporal distribution of the potential risk of frost damage in tea fields from 1981-2020: A modeling approach considering phenology and meteorology","authors":"Kensuke Kimura, K. Kudo, A. Maruyama","doi":"10.2480/agrmet.d-21-00011","DOIUrl":"https://doi.org/10.2480/agrmet.d-21-00011","url":null,"abstract":"Climate change may induce severe frost damage to crops, and thus a reasonable assessment of frost risk, considering both crop phenology and meteorology, is required. Here, we introduced a new index of potential frost risk ( F risk ) using thermal time ( minimum air temperature below the threshold value ) weighted by the percentage of budburst ( P bud ) . Moreover, we evaluated the spatiotemporal distributions of F risk in tea fields within a 60 km × 60 km area in east Japan from 1981 - 2020, using 1 km 2 -gridded meteorological data and a newly developed model of P bud . The P bud model considered three phenological phases ( endodormancy, ecodormancy, and progress of budburst ) and successfully represented changes in the P bud of the tea buds for 15 years, with root mean square errors of 8.5 percentage points. The spatiotemporal distributions of F risk over the past 40 years showed that potential frost risk significantly increased at elevations ranging from 50 m to 300 m because the budburst advanced at a faster rate than the temperature warming. These elevations corresponded to areas where tea plants were mainly cultivated, which indicates that tea cultivation is becoming vulnerable to frost, and the risk of economic losses due to the frost is increasing. The proposed assessment of frost risk could contribute to predicting frost damage and developing more reliable strategies for the operation of frost protection under the effects of future climate change.","PeriodicalId":56074,"journal":{"name":"Journal of Agricultural Meteorology","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69170386","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.2480/agrmet.d-21-00024
M. Yoshimoto, H. Sakai, Y. Ishigooka, T. Kuwagata, T. Ishimaru, H. Nakagawa, A. Maruyama, H. Ogiwara, K. Nagata
In rice (Oryza sativa L.), heat-induced spikelet sterility (HISS) has long been recognized a major threat in the production, and currently the potential risk of yield reduction is likely to be increasing under global warming. However, there have been few studies on HISS conducted under field conditions. In recent years in Japan, extremely high temperatures have frequently recorded in the daytime during the summer. In 2018, heat wave lasted from mid-July to late August, which overlapped the typical rice heading period from eastern to western Honshu and raised a concern about HISS during flowering. To examine this possibility, we surveyed rice sterility in eight prefectures in the Kanto, Tokai, and Kinki regions. During surveys in 2018 and 2019, we collected field data on the sterility of ‘Koshihikari’, the most popular rice variety in Japan, and the sterility ranged from 3.7 to 15.4% in paddy fields. The sterility tended to be higher in the paddy fields where heading occurred during the heat wave. We modeled the sterility rate using the heat dose based on daytime mean panicle temperature, with a threshold for HISS at 33°C. The model estimates based on meteorological data showed that HISS can be induced even under current climatic conditions, depending on the timing of heading. Considering the projected global warming, this study raises an issue that rice plants would face a risk of HISS under the temperate climate in Japan.
{"title":"Field survey on rice spikelet sterility in an extremely hot summer of 2018 in Japan","authors":"M. Yoshimoto, H. Sakai, Y. Ishigooka, T. Kuwagata, T. Ishimaru, H. Nakagawa, A. Maruyama, H. Ogiwara, K. Nagata","doi":"10.2480/agrmet.d-21-00024","DOIUrl":"https://doi.org/10.2480/agrmet.d-21-00024","url":null,"abstract":"In rice (Oryza sativa L.), heat-induced spikelet sterility (HISS) has long been recognized a major threat in the production, and currently the potential risk of yield reduction is likely to be increasing under global warming. However, there have been few studies on HISS conducted under field conditions. In recent years in Japan, extremely high temperatures have frequently recorded in the daytime during the summer. In 2018, heat wave lasted from mid-July to late August, which overlapped the typical rice heading period from eastern to western Honshu and raised a concern about HISS during flowering. To examine this possibility, we surveyed rice sterility in eight prefectures in the Kanto, Tokai, and Kinki regions. During surveys in 2018 and 2019, we collected field data on the sterility of ‘Koshihikari’, the most popular rice variety in Japan, and the sterility ranged from 3.7 to 15.4% in paddy fields. The sterility tended to be higher in the paddy fields where heading occurred during the heat wave. We modeled the sterility rate using the heat dose based on daytime mean panicle temperature, with a threshold for HISS at 33°C. The model estimates based on meteorological data showed that HISS can be induced even under current climatic conditions, depending on the timing of heading. Considering the projected global warming, this study raises an issue that rice plants would face a risk of HISS under the temperate climate in Japan.","PeriodicalId":56074,"journal":{"name":"Journal of Agricultural Meteorology","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69170453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.2480/AGRMET.D-20-00033
K. Murakami, T. Hamasaki, M. Nemoto, S. Inoue, T. Hirota
Leafy vegetables cultivated in greenhouses during the winter are sometimes exposed to cold air from outside the greenhouse to enhance sugar and nutrient content. To analyze the possible involvement of photosynthetic and respiratory activities in this process, we evaluated the gas-exchange activity of spinach ( Spinacia oleracea L. ) plants cultivated in an unheated greenhouse in mid-winter in Sapporo, where the daily mean air and soil temperatures are approximately - 5 and 0 ° C, respectively. Shoot fresh weight showed little increase, whereas the net leaf photosynthetic rate ( P n ) attained 20 µmol m -2 s -1 and the CO 2 concentration in the greenhouse ( [CO 2 ] ) was sometimes lower than 200 µmol mol -1 , which was suggestive of active photosynthetic CO 2 uptake. After its peak in the morning, P n decreased in the afternoon, presumably owing to ‘midday depression’ caused by suppressed water uptake in the root zone. Observed diurnal [CO 2 ] change was consistent with a significant CO 2 uptake during the daytime. The change also suggested that respiration was active immediately after sunset and suppressed at night. In addition, we calculated the whole-greenhouse CO 2 emission rate ( R ) as a measure of night respiration in the plants, taking into account the air ventilation of the greenhouse. The R value was positive under sub-zero air temperatures in the greenhouse and was positively correlated with the nighttime air and soil temperatures. These experimental data suggest active photosynthesis and respiration of winter-sweetened spinach in the greenhouse, despite the low air and soil temperatures and growth retardation, and implies their involvement in the
冬季在温室种植的叶菜有时会暴露在温室外的冷空气中，以提高糖和营养含量。为了分析光合和呼吸活动可能参与了这一过程，我们对菠菜(Spinacia oleracea L.)的气体交换活性进行了评估。在札幌的冬季中期，在没有加热的温室中种植的植物，那里的日平均空气和土壤温度分别约为- 5°C和0°C。茎部鲜重增幅不大，叶片净光合速率(pn)达到20µmol m -2 s -1，温室内co2浓度([co2])有时低于200µmol mol mol -1，表明光合co2吸收活跃。磷在上午达到峰值后，下午开始下降，这可能是由于根区水分吸收受到抑制而导致的“午间抑制”。观测到的日[co2]变化与白天显著的co2吸收一致。这一变化还表明，呼吸在日落之后立即活跃，而在夜间受到抑制。此外，考虑到温室的空气流通情况，我们计算了整个温室的co2排放率(R)，作为植物夜间呼吸的度量。温室气温低于零度时R值为正，与夜间空气温度和土壤温度呈正相关。这些实验数据表明，尽管空气和土壤温度较低，生长迟缓，但温室中冬甜菠菜的光合作用和呼吸作用仍很活跃，并暗示它们参与了温室的光合作用
{"title":"Photosynthetic and respiratory activities of spinach in an unheated greenhouse during winter in Sapporo, Japan","authors":"K. Murakami, T. Hamasaki, M. Nemoto, S. Inoue, T. Hirota","doi":"10.2480/AGRMET.D-20-00033","DOIUrl":"https://doi.org/10.2480/AGRMET.D-20-00033","url":null,"abstract":"Leafy vegetables cultivated in greenhouses during the winter are sometimes exposed to cold air from outside the greenhouse to enhance sugar and nutrient content. To analyze the possible involvement of photosynthetic and respiratory activities in this process, we evaluated the gas-exchange activity of spinach ( Spinacia oleracea L. ) plants cultivated in an unheated greenhouse in mid-winter in Sapporo, where the daily mean air and soil temperatures are approximately - 5 and 0 ° C, respectively. Shoot fresh weight showed little increase, whereas the net leaf photosynthetic rate ( P n ) attained 20 µmol m -2 s -1 and the CO 2 concentration in the greenhouse ( [CO 2 ] ) was sometimes lower than 200 µmol mol -1 , which was suggestive of active photosynthetic CO 2 uptake. After its peak in the morning, P n decreased in the afternoon, presumably owing to ‘midday depression’ caused by suppressed water uptake in the root zone. Observed diurnal [CO 2 ] change was consistent with a significant CO 2 uptake during the daytime. The change also suggested that respiration was active immediately after sunset and suppressed at night. In addition, we calculated the whole-greenhouse CO 2 emission rate ( R ) as a measure of night respiration in the plants, taking into account the air ventilation of the greenhouse. The R value was positive under sub-zero air temperatures in the greenhouse and was positively correlated with the nighttime air and soil temperatures. These experimental data suggest active photosynthesis and respiration of winter-sweetened spinach in the greenhouse, despite the low air and soil temperatures and growth retardation, and implies their involvement in the","PeriodicalId":56074,"journal":{"name":"Journal of Agricultural Meteorology","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69170285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.2480/agrmet.d-21-00029
Kota Shimomoto, N. Fujiuchi, N. Takahashi, H. Nishina, K. Inaba, Yayu Romdhonah, K. Takayama
A real-time monitoring system was developed and applied to monitor the time course of photosynthesis and transpiration in fully-grown tomato plants in a semi-commercial greenhouse. The system was based on an open chamber method in which the ventilator airflow rate is an important parameter affecting the environmental factors in the chamber and physiological response of plants enclosed inside the chamber. So, we assumed that the effects of this parameter on these responses should be evaluated for an agricultural production site. In this study, we investigated differences in the environmental factors in the chamber and physiological response of whole-tomato plants obtained from two chambers ( 0.5 m [W] × 1.0 m [D] × 2.2 m [H] ) implemented with a single ventilator ( SV, 0.36 m 3 min - 1 ) or double ventilators ( DV, 0.72 m 3 min - 1 ) . The relative humidity and vapor pressure deficit inside the SV chamber were about 10 % higher and 0.5 kPa lower than those inside the DV chamber because of the difference in air exchange rates. However, we found no significant effect of airflow rate on net photosynthetic rate, transpiration rate and total conductance of the plants in the SV and DV chambers by analyzing with weighted Deming regression. This simultaneous monitoring method, undertaken in multiple chambers, and weighted Deming regression analysis can be used to check whether measurement conditions are appropriate for on-site monitoring.
开发了一种实时监测系统，并应用于半商业化温室番茄植株光合和蒸腾作用的实时监测。该系统采用开室法，通风机的风量是影响室内环境因素和室内植物生理反应的重要参数。因此，我们假设该参数对这些响应的影响应该对农业生产场地进行评估。在本研究中，我们研究了在单通气机(SV, 0.36 m 3 min - 1)和双通气机(DV, 0.72 m 3 min - 1)的两个通气机(0.5 m [W] × 1.0 m [D] × 2.2 m [H])中获得的番茄植株在室内环境因子和生理反应上的差异。由于空气交换速率的差异，SV室内的相对湿度和蒸汽压差比DV室内高约10%，低约0.5 kPa。然而，通过加权Deming回归分析，我们发现气流速率对SV和DV室内植物的净光合速率、蒸腾速率和总导度没有显著影响。这种多室同时监测的方法，通过加权Deming回归分析，可以检验测量条件是否适合现场监测。
{"title":"Comparison of photosynthetic rates, transpiration rates, and total conductance of greenhouse-grown tomato plants measured with two open chambers with different ventilation rates","authors":"Kota Shimomoto, N. Fujiuchi, N. Takahashi, H. Nishina, K. Inaba, Yayu Romdhonah, K. Takayama","doi":"10.2480/agrmet.d-21-00029","DOIUrl":"https://doi.org/10.2480/agrmet.d-21-00029","url":null,"abstract":"A real-time monitoring system was developed and applied to monitor the time course of photosynthesis and transpiration in fully-grown tomato plants in a semi-commercial greenhouse. The system was based on an open chamber method in which the ventilator airflow rate is an important parameter affecting the environmental factors in the chamber and physiological response of plants enclosed inside the chamber. So, we assumed that the effects of this parameter on these responses should be evaluated for an agricultural production site. In this study, we investigated differences in the environmental factors in the chamber and physiological response of whole-tomato plants obtained from two chambers ( 0.5 m [W] × 1.0 m [D] × 2.2 m [H] ) implemented with a single ventilator ( SV, 0.36 m 3 min - 1 ) or double ventilators ( DV, 0.72 m 3 min - 1 ) . The relative humidity and vapor pressure deficit inside the SV chamber were about 10 % higher and 0.5 kPa lower than those inside the DV chamber because of the difference in air exchange rates. However, we found no significant effect of airflow rate on net photosynthetic rate, transpiration rate and total conductance of the plants in the SV and DV chambers by analyzing with weighted Deming regression. This simultaneous monitoring method, undertaken in multiple chambers, and weighted Deming regression analysis can be used to check whether measurement conditions are appropriate for on-site monitoring.","PeriodicalId":56074,"journal":{"name":"Journal of Agricultural Meteorology","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69170463","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-01-01DOI: 10.2480/AGRMET.D-20-00013
L. Sha, Munemasa Teramoto, N. Noh, S. Hashimoto, Meng Yang, Montri Sanwangsri, N. Liang
Soil respiration (Rs) is the largest flux of carbon dioxide (CO2) next to photosynthesis in terrestrial ecosystems. With the absorption of atmospheric methane (CH4), upland soils become a large CO2 source and CH4 sink. These soil carbon (C) fluxes are key factors in the mitigation and adaption of future climate change. The Asian region spans an extensive area from the northern boreal to tropical regions in Southeast Asia. As this region is characterised by highly diverse ecosystems, it is expected to experience the strong impact of ecosystem responses to global climate change. For the past two decades, researchers in the AsiaFlux community have meaningfully contributed to improve the current understanding of soil C dynamics, response of soil C fluxes to disturbances and climate change, and regional and global estimation based on model analysis. This review focuses on five important aspects: 1) the historical methodology for soil C flux measurement; 2) responses of soil C flux components to environmental factors; 3) soil C fluxes in typical ecosystems in Asia; 4) the influence of disturbance and climate change on soil C fluxes; and 5) model analysis and the estimation of soil C fluxes in research largely focused in Asia.
{"title":"Soil carbon flux research in the Asian region: Review and future perspectives","authors":"L. Sha, Munemasa Teramoto, N. Noh, S. Hashimoto, Meng Yang, Montri Sanwangsri, N. Liang","doi":"10.2480/AGRMET.D-20-00013","DOIUrl":"https://doi.org/10.2480/AGRMET.D-20-00013","url":null,"abstract":"Soil respiration (Rs) is the largest flux of carbon dioxide (CO2) next to photosynthesis in terrestrial ecosystems. With the absorption of atmospheric methane (CH4), upland soils become a large CO2 source and CH4 sink. These soil carbon (C) fluxes are key factors in the mitigation and adaption of future climate change. The Asian region spans an extensive area from the northern boreal to tropical regions in Southeast Asia. As this region is characterised by highly diverse ecosystems, it is expected to experience the strong impact of ecosystem responses to global climate change. For the past two decades, researchers in the AsiaFlux community have meaningfully contributed to improve the current understanding of soil C dynamics, response of soil C fluxes to disturbances and climate change, and regional and global estimation based on model analysis. This review focuses on five important aspects: 1) the historical methodology for soil C flux measurement; 2) responses of soil C flux components to environmental factors; 3) soil C fluxes in typical ecosystems in Asia; 4) the influence of disturbance and climate change on soil C fluxes; and 5) model analysis and the estimation of soil C fluxes in research largely focused in Asia.","PeriodicalId":56074,"journal":{"name":"Journal of Agricultural Meteorology","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69170118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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