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Itoh M.,Japan National Institute for Agro - Environmental Sciences | Itoh M.,Kyoto University | Sudo S.,Japan National Institute for Agro - Environmental Sciences | Mori S.,Yamagata Integrated Agricultural Research Center | And 10 more authors.
Agriculture, Ecosystems and Environment

In order to analyze the mitigation of methane (CH4) emissions and the global warming potentials (GWPs) of CH4 and nitrous oxide (N2O) emissions from paddy fields by modifying the adopted water-management technique, we conducted field experiments to measure the CH4 and N2O fluxes at nine sites across Japan. Over 2 years, we tested different water-management strategies such as prolonged midseason drainage (MD) in each site. The CH4 emission rates at each site varied considerably; the rates were dependent on the ratio of reductive and oxidative capacities of the fields. Seasonal CH4 emission was effectively reduced at most sites by prolonging MD beyond its conventional duration, especially at sites where organic matter was added to the soil before the cultivation. We attribute this result to the effective suppression of the CH4 emission peak that occurs early in the cultivation period. Despite the large variation in seasonal CH4 emissions among the sites, the rate of CH4 emission resulting from alternative water-management strategies relative to that resulting from conventional water-management strategies is highly dependent on the degree of drainage during the MD period. N2O emission at most sites, in terms of GWP-based CO2-equivalent, was much smaller than that of CH4 emission. Compared to conventional water-management strategies, the seasonal CH4 emissions and the net 100-year GWPs (CH4+N2O) can be suppressed to 69.5±3.4 (SE)% and 72.0±3.1% while maintaining grain yields as high as 96.2±2.0% by prolonging MD on average by employing the selected alternative water-management strategies that satisfied the following conditions: the percent of CH4 emission of alternative water-management strategies was less than 90% and the grain yield was greater than 85% relative to conventional water-management strategies. © 2011 Elsevier B.V. Source

Hayama H.,Japan National Agriculture and Food Research Organization | Iwatani A.,Kumamoto Prefectural Agricultural Research Center | Nishimoto T.,Kochi Prefectural Agricultural Research Center | Oya Y.,Tochigi Prefectural Agricultural Experimental Station | Nakamura Y.,Japan National Agriculture and Food Research Organization
Scientia Horticulturae

We investigated the effects of fruit temperature on the incidence of watercore in Japanese pear 'Niitaka'. To increase the temperatures in the environments of maturing fruit, we fixed electric heating cables around the fruit during the maturation period (6-3 weeks before estimated harvest date). This treatment increased the average temperatures, the daily minimum temperatures, and the daily maximum temperatures by 1.4-2.5. °C, 1.5-2.8. °C, and 0.8-1.7. °C, respectively. The incidences of watercore were statistically increased by heat treatment (P< 0.01). In particular, the incidences of watercore in heated fruit were almost twice those of untreated fruit in Ibaraki in 2008 and Kumamoto in 2009. Furthermore, the fruit treated with higher temperatures showed increased flesh firmness, soluble solids contents, and pH at harvest, although the interactions (treatment × place/year) were also significant. These results imply that parameters of fruit quality, including the occurrence of watercore, are affected by the temperature of fruit during maturation, and that high temperatures give rise to watercore. Accordingly, we attempted to reduce the maximum daily fruit temperatures by putting shade hats over the fruit to see if this would reduce the incidence of watercore. Shade hat treatment decreased the daily maximum temperature by 0.5-2.2. °C during maturation without significantly altering the mean and daily minimum temperatures. Watercore incidence was reduced by shade hats in all experiments, however, the effects were not statistically significant. The temperatures in the tested years were very high, with mean and daily maximum temperatures around control fruit of over 28. °C and 34. °C, respectively. The results of this study suggest that shade hat treatment may not be enough to decrease temperatures around fruit and reduce the incidence of watercore. © 2014 Elsevier B.V. Source

Ishikawa S.,Japan National Institute for Agro - Environmental Sciences | Makino T.,Japan National Institute for Agro - Environmental Sciences | Ito M.,Akita | Harada K.,Chiba Prefectural Agriculture and Forestry Research Center | And 9 more authors.
Soil Science and Plant Nutrition

In previous research, we produced a japonica rice (Oryza sativa L.) cultivar (‘Koshihikari Kan No. 1’) with nearly undetectable levels of cadmium (Cd) in the grains. In this study, we hypothesized that growing this cultivar aerobically would simultaneously reduce arsenic (As) and Cd concentrations in the grains. We grew this cultivar and ‘Koshihikari’, its parent, in paddy fields with different soil properties under three water regimes: flooded conditions (FLD), alternate wetting and drying conditions (AWD) and water-saving conditions (WAS). FLD for several weeks before and after heading significantly increased the grain As concentration in both cultivars. AWD, with the soil re-flooded just after disappearance of the ponded water, reduced grain As concentrations by an average of 27% relative to FLD for both cultivars. WAS, with irrigation after drying of the soil surface, decreased grain As concentrations by an average of 43.1% for ‘Koshihikari Kan No. 1’ and 48.2% for ‘Koshihikari’ compared to FLD. Although AWD and WAS remarkably increased grain Cd concentrations in ‘Koshihikari’, ‘Koshihikari Kan No. 1’ had nearly undetectable levels of grain Cd in all treatments. Compared with ‘Koshihikari’ in FLD, grain yield of ‘Koshihikari Kan No. 1’ and ‘Koshihikari’ decreased by averages of 2% for AWD and 4 to 6% for WAS. In addition, WAS tended to decrease grain quality slightly for both cultivars. Although aerobic conditions such as WAS have somewhat adverse effects on grain yield and quality, growing the low-Cd cultivar aerobically is the most practical way to simultaneously reduce Cd and As contents in the rice grains. © 2016 Japanese Society of Soil Science and Plant Nutrition Source

Matsumura M.,Japan National Agriculture and Food Research Organization | Sanada-Morimura S.,Japan National Agriculture and Food Research Organization | Otuka A.,Japan National Agriculture and Food Research Organization | Ohtsu R.,Nagasaki Plant Protection Station | And 3 more authors.
Pest Management Science

BACKGROUND: The brown planthopper Nilaparvata lugens and the whitebacked planthopper Sogatella furcifera are both important pests on rice throughout Asia. The major cause of recent outbreaks is thought to be the development of insecticide resistance. Thus, the authors monitored insecticide susceptibilities in populations of these two insects immigrating into Japan in the period 2005-2012. Ten insecticides were tested, including members of the organophosphate, carbamate, pyrethroid, neonicotinoid and phenylpyrazole groups. RESULTS: The LD50 values of N. lugens against imidacloprid increased from 2005 (0.7 μg g-1) to 2012 (98.5 μg g-1). The resistance ratio (LD50 value in 2012/baseline LD50 value in 1992) was 615.5. In contrast, LD50 values of N. lugens against fipronil were <1.0 μg g-1 up to 2012, suggesting that N. lugens had developed no insecticide resistance to this insecticide. However, S. furcifera exhibited resistance against fipronil up to 2012. Except for the case of malathion, the resistances of N. lugens against members of the organophosphate and carbamate groups were closely similar in the period 2005-2012 to earlier determinations in 1984 and 1985. CONCLUSION: Species-specific insecticide resistance (imidacloprid resistance in N. lugens and fipronil resistance in S. furcifera) is ongoing in populations of the two planthoppers immigrating into Japan. © 2013 Society of Chemical Industry. Source

Nishina K.,Japan National Institute for Agro - Environmental Sciences | Nishina K.,Japan National Institute of Environmental Studies | Sudo S.,Japan National Institute for Agro - Environmental Sciences | Yagi K.,Japan National Institute for Agro - Environmental Sciences | And 16 more authors.
Nutrient Cycling in Agroecosystems

The use of N fertilizers for agricultural production acts as a sources of atmospheric N2O. Fertilizer induced N2O emission considerably varies in accordance with environmental factors. We conducted a N2O flux measurement campaign across 10 different experimental sites with various soil types throughout Japan and investigated the fertilizer induced N2O emission factors (FIEFs) of synthetic fertilizers (mainly urea) in multiple growing periods at each experimental site. FIEFs considerably varied among the 10 sites, and measurement periods ranged from 0.00 to 7.13 % in 40 total observations. Soil profile information divided the experimental sites into two major groups through cluster analysis, which are volcanic or non-volcanic soils. According to this classification, FIEFs were clearly differentiated into high and low FIEF groups (mean values: 2.67 and 0.59 %, respectively). Regression trees selected total soil carbon, the depth to the Fe mottling horizon, and mean air temperature as the key parameters to determine the strength of FIEFs out of 10 explanatory variables (e.g., N fertilizer application rates, fertilizer application times, clay content, total precipitation during measurement periods, pH, total soil carbon, and total soil nitrogen). The existence of shallow Fe mottling layer (up to 42.5 cm) induced high FIEFs in this model, suggesting that upward N2O emissions derived from the intermediate Fe mottling layers presumably contributed high N2O emissions in such soils. Our results suggest that the soil profile information associated with the water regime is an important index for synthetic fertilizer inducedN2O emissions. © 2015, Springer Science+Business Media Dordrecht. Source

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