巻号一覧
70 巻 (2014)
- 4 号 p. 171-
- 3 号 p. 133-
- 2 号 p. 73-
- 1 号 p. 1-
70 巻, 2 号
選択された号の論文の5件中1～5を表示しています
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Full Paper
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Toshichika IIZUMI, Gen SAKURAI, Masayuki YOKOZAWA2014 年 70 巻 2 号 p. 73-90
発行日: 2014年
公開日: 2014/06/10
[早期公開] 公開日: 2014/04/03ジャーナル フリーThe consequences of changes observed in climate and management to yield trends in major crop-producing regions have implications for future food availability. We present an assessment of the impacts of historical changes in sowing date and climate to the maize yield trend in the U.S. Corn Belt from 1980 to 2006 by using large-area crop modeling and a data assimilation technique (i.e., the model optimization based on the Markov chain Monte Carlo method). Calibrated at a regional scale, the model captured the major characteristics of the changes reported in yield as well as the timing and length of maize growth periods across the Corn Belt. The simulation results using the calibrated model indicate that while the climate change observed for the period likely contributed to a decreasing yield trend, the positive contribution from the reported shift to an earlier sowing date offset the negative impacts. With the given spread in the assessment results across previous studies and in this study, the conclusion that the negative impacts of climate change on U.S. maize yield trend more likely derive from a decreasing trend in growing-season precipitation than to an increasing trend in temperature.抄録全体を表示PDF形式でダウンロード (2536K) -
O. Modesto OLANYA, Robert P. LARKIN, John M. HALLORAN, Zhongqi HE2014 年 70 巻 2 号 p. 91-104
発行日: 2014年
公開日: 2014/06/10
ジャーナル フリーCrop, soil and water management systems may alter microclimatic conditions of agronomic crops and substantially affect plant growth and pest dynamics. However, the extent to which this may impact meteorological variables of potato canopy in a humid temperate region has not been substantially determined. Field plots of Russet Burbank potato were established to assess the potential impacts of different management systems on meteorological variables and subsequent effects on disease dynamics during the cropping cycle. The effects of five cropping systems (i.e Status Quo -SQ, Continuous Potato -PP, Soil Conserving -SC, Disease Suppressive -DS, and Soil Improving -SI) and irrigation application on meteorological variables of potato canopy were investigated from 2006 to 2009. Air and soil temperatures, relative humidity, leaf wetness, and soil water potential were assessed during the potato cropping cycle (May to September). The cropping systems had diverse, but limited significant effects on the meteorological variables of a Russet Burbank potato canopy, implying that treatment effects were similar. It appears that climate induced effects from the environment surrounding field plots substantially negated any cropping system or water treatment effects in field plots. In contrast, data for potato disease development, including early blight, stem canker, black scurf, and common scab, demonstrated consistent significant effects due to management system, indicating that disease parameters were affected by cropping system factors not related to potato canopy microclimate. These results suggest that in a humid environment, selective use of systems management may optimize potato growth and productivity and simultaneously minimize adverse microclimate.抄録全体を表示PDF形式でダウンロード (4121K) -
Tomoko NAKANO, Masato SHINODA2014 年 70 巻 2 号 p. 105-116
発行日: 2014年
公開日: 2014/06/10
[早期公開] 公開日: 2014/04/17ジャーナル フリーGrassland ecosystems cover a large area of the land surface and play an important role in the global carbon cycle. The objectives of this study were to examine the spatial variability of gross primary production (GPP) and ecosystem respiration (Reco) within a semiarid grassland ecosystem and to evaluate the environmental factors that control the spatial patterns of carbon exchanges. We determined GPP and Reco using transparent and opaque closed chambers at nine grassland sites in central Mongolia during the summers from 2009 through 2011. To remove effects of temporal changes in radiation and temperature, GPP and Reco were fitted to light- and temperature-response curves. The fitting parameters (light-saturated GPP [Pmax], apparent quantum yield [α], standardized Reco at 20 °C [R20], and the temperature sensitivity [Q10] of Reco) were compared among the sites. The GPP and Reco parameters differed significantly among the sites. Spatial patterns of Pmax and R20 were highly correlated with plant aboveground green biomass (AGB) and number of plant species. The Q10 of Reco was significantly related to soil moisture. The light-saturated GPP normalized to the amount of AGB did not differ significantly among the sites, whereas the R20 residuals of the linear biomass model were correlated with soil water content and carbon/nitrogen ratios. The results suggest that, within this semiarid grassland, spatial variations of GPP are strongly controlled by AGB and that variations in Reco are associated mainly with AGB and secondarily with soil water content and soil nutrient condition.抄録全体を表示PDF形式でダウンロード (1330K)
Short Paper
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Seiichi NISHIMURA, Michio KOMADA, Masako TAKEBE, Shigeru TAKAHASHI, Se ...2014 年 70 巻 2 号 p. 117-125
発行日: 2014年
公開日: 2014/06/10
ジャーナル フリーThe effects of soil mulching on the emission of nitrous oxide (N2O), a major greenhouse gas, from arable fields have rarely been investigated to date. In a previous study, we showed that a significant amount of N2O is emitted to the atmosphere from an arable field in which soil is covered with plastic mulch films; N2O is emitted both by permeation through the mulch films and by horizontal diffusion to the adjacent furrow soil surface. We continued measuring the N2O flux from a field grown to lettuce and carrots for two years. With the results of our previous study, we also estimated the contribution of N2O emitted during soil mulching to the cumulative emission. In winter, the contribution of N2O emission during soil mulching was low, ranging from 4 to 12 %. In contrast, in summer, the contribution of N2O emission during soil mulching after fertilization was high, ranging from 41 to 66 % of the cumulative emission. Among these, the contribution of N2O emission by permeation through the mulch film was found to be particularly important, which ranged from 33 to 53 % of the cumulative emission. These results indicate that N2O emission during soil mulching largely contributes to cumulative emission.抄録全体を表示PDF形式でダウンロード (1101K) -
Yasuhiro ISHIGAMI, Tatsuya TETSUKA, Eiji GOTO2014 年 70 巻 2 号 p. 127-131
発行日: 2014年
公開日: 2014/06/10
ジャーナル フリーFog cooling systems with natural ventilation are a type of evaporative cooling technique that is widely used in Japan. One drawback of these systems is that it is difficult to maintain the greenhouse air temperature at its optimum range in summer using the conventional single-fluid nozzle system because it has a low cooling efficiency and produces a high risk of pathogen invasion due to excessive wetting of the plant foliage. Therefore, we introduced a twin-fluid nozzle system as an alternative fogging system. This system affords a higher evaporation ratio and a lower degree of plant foliage wetting because it generates fog droplets with diameters smaller than those generated by single-fluid nozzles. We installed these two types of fogging systems in tomato greenhouses and investigated the different aerial environments that they produced. We observed that the twin-fluid nozzle system maintained the air temperature at the same level as that maintained by the single-fluid nozzle system. We also observed that the single-fluid nozzle system significantly inhibited the evapotranspiration in the tomato plants due to wetting of the plant foliage, whereas the evapotranspiration rate when using the twin-fluid nozzle system was 70-100 % higher.抄録全体を表示PDF形式でダウンロード (1411K)
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