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AbstractThe effect of different rice-based crop rotation sequences on the population densities of Meloidogyne graminicola and on the yield of rice was evaluated in a microplot experiment under lowland rice field conditions. Ten treatments of cropping sequences were grown in four successive growing seasons: continuous growing of the susceptible rice cultivar Thihtatyin (rice-rice-rice-rice), four treatments of 1- season crop rotation sequences (rice-rice-chickpea-rice, rice-rice-black gram-rice, rice-rice-soybean-rice, rice-rice-cowpea-rice), and five treatments of 2-season crop rotation sequences (groundnut-rice-chickpea-rice, green gram-rice-black gram-rice, cowpea-rice-soybean-rice, sesame-rice-cowpea-rice, sunflower-rice-sesame-rice). Population densities of M. graminicola recovered from the rice plants and the nematode multiplication factors (Mf) in the soil in the continuous rice cropping sequence (rice-rice-rice-rice) was the highest among the ten cropping sequences. Lowest nematode Mf in the soil was observed in the 2-season crop rotation sequence sunflower-rice-sesame-rice and the highest was observed in the 1-season crop rotation sequence rice-rice-cowpea-rice among the nine crop rotation sequences. Highest rice yield was obtained in the 2-season crop rotation sequences green gram-rice-black gram-rice, sesame-rice-cowpea-rice and sunflower-rice-sesame-rice, which were about 2 times higher compared with the 1-season crop rotation sequences and about 3 times higher compared with the continuous rice cropping sequence. 相似文献
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In 19 wheat-milling fractions total pentosan content, calculated as 0.88 x (% L-arabinose + % D-xylose), varied between 1.44 and 30.66% on dry matter (dm). It increased with ash content once the latter exceeded 0.6% (dm basis). Water-extractable arabinoxylans were recovered by saturating water extracts to 65% ethanol. Their contents in the milling fractions varied between 0.35 and 1.38%, and above 0.6% ash content also increased with this parameter. Their L-arabinose-to-D-xylose ratios ranged between 0.65 and 0.39, with the lowest values found for the fractions with highest ash content, indicating that the ash-rich tissues contain more arabinoxylans that are less branched. (1)H NMR spectroscopy revealed that the decrease in L-arabinose-to-D-xylose ratio was accompanied by an increase in unsubstituted xylose residues and a decrease in disubstituted xylose residues, while the contents of monosubstituted xyloses were virtually constant. 相似文献
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Selection logging is a principal management scheme in natural teak-bearing forests in Myanmar. Monitoring the spatial extent
and intensity of selection logging is important for sustainable forest management. This study applied the normalized difference
vegetation index (NDVI) image differencing method using two SPOT-5 pan-sharpened images (2.5 m spatial resolution) taken in
October 2007 and January 2009 to analyze canopy changes associated with damage from forest harvesting. According to the pixel-based
analysis, NDVI changes were larger in most logging road/log landing points whereas smaller NDVI changes were seen in most
unlogged points. NDVI changes in teak stump areas were related to distance from a logging road and the number of stumps within
the estimated crown area (a circular area with a 10 m radius from the center of each stump). A Fisher’s exact test showed that one of the main factors
causing the high NDVI change in teak stump areas was the effect of road construction. The distribution pattern of teak stumps
indicated that teak stumps with estimated crown areas that contained more than one stump had high mean change in NDVI. The spectral difference between before and after logging
revealed that logging roads had a greater effect on canopy changes than teak stumps. 相似文献
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Khin Thawda Win Ryoko Nonaka Koki Toyota Takashi Motobayashi Masaaki Hosomi 《Biology and Fertility of Soils》2010,46(6):589-595
A lysimeter experiment was carried out to evaluate the effects of the NH3 volatilization mitigation by adding anaerobically digested cattle slurry (ADCS) alone, with wood vinegar (WV) or with a higher
level of floodwater (HFW), on emissions of CH4 and N2O from a paddy soil planted with fodder rice. We have carried out the following treatments: (1) chemical fertilizer, (2) ADCS,
(3) ADCS + WV, and (4) ADCS + HFW; the height of floodwater was 10 cm in the latter treatment, and it was 3 to 4 cm in the
other treatments just before fertilizer applications. Nitrogen fertilizer rate added to soil in each treatment was 30 g NH4+–N m−2 (split in one basal and two top-dressing additions). Ammonia volatilization in the ADCS treatment was 2.7 g NH3–N m−2 throughout the growing season, and it was significantly reduced by 79% and 55% in the ADCS + WV and ADCS + HFW treatments,
respectively. The total amount of CH4 emitted in the ADCS treatment in the growing season was not significantly enhanced by the mitigation of NH3 volatilization either by adding wood vinegar or by increasing the height of the floodwater. Negligible N2O emissions were observed in all treatments during the growing period. 相似文献
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A new type of sampler for dry deposition in a forest canopy was designed and tested to confirm its usefulness. The new sampler
is made of Teflon chips packed in a nylon net, and tied on a rod like a branch in the canopy. The validity and characteristics
of the new sampler were checked by comparing it with the conventional bucket sampler and the foliar extraction method using
hinoki (Chamaecyparis obtusa) trees. The comparison between the deposited amounts on the dummy branch and those on the bucket indicates that the dummy
could trap gaseous matter more effective than the bucket. From a comparison with the foliar extracting method, it is concluded
that the trapping of particulate matter by the new dummy branch is comparable to that of natural needle leaves. However, its
efficiency for gaseous matter is relatively small. This disadvantage should be improved by applying other materials to the
dummy. Moreover, it is found that the uptake of gas especially SO2 through the stomata is an important point in the discussion about dry deposition. To evaluate the amounts of dry deposition
in the forest canopy more precisely, combination with the additional method should be useful.
This study was supported in part by a grant-in-aid for Scientific Research from the Ministry of Education, Science, Sports,
and Culture, Japan. 相似文献
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K. T. Win R. Nonaka A. T. Win Y. Sasada K. Toyota T. Motobayashi M. Hosomi 《Paddy and Water Environment》2012,10(4):281-289
Methane oxidation activity (MOA), methanotrophic bacteria (MOB), and CH4 emission in a paddy field fertilized with anaerobically digested slurry were compared between two varieties: a fodder rice variety Leaf star (LS) and a normal rice variety Kinuhikari (KN). Average MOA and MOB per unit dry root were significantly higher in KN (7.1?μmol?g?1 CH4?g?1 dry root h?1 and 3.7?×?107 MPN?g?1 dry root, respectively) than in LS (4.3?μmol?g?1 CH4?g?1 dry root h?1, 2.1?×?107 MPN?g?1 dry root), although MOA in the rice root per whole plant was not significantly different since root biomass of LS (1.5?g dry root plant?1) was significantly higher than that of KN (1.2?g dry root plant?1). MOA in the soil ranged from 0.031 to 0.087?μmol?g?1 CH4?g?1 dry soil h?1, but there were no significant differences in both depths (0–5 and 5–15?cm) between the two rice varieties. MOA in the rhizosphere soil was significantly different between the rice varieties at flowering, but not at tillering. Methane emission in the field was lower and MOA and MOB in the rice root were higher in LS than in KN at tillering, but the reverse results were found at flowering and maturity stages. Total CH4 emission during a growing period was not significantly different between LS (27.4?±?16.9?g CH4?m?2) and KN (24.0?±?19.5?g CH4?m?2). There was a significant negative relationship between CH4 emission and rice root MOB (P?<?0.01) or MOA (P?<?0.05) and significant positive relationship was observed between root MOA and MOB (P?<?0.01). This study revealed that choice of rice variety might be an important environmental issue in paddy cultivation since it can influence MOA and MOB in rice root and rhizosphere soil which relate with CH4 emission. 相似文献
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G. Darrel Jenerette Sharon L. Harlan Alexander Buyantuev William L. Stefanov Juan Declet-Barreto Benjamin L. Ruddell Soe Win Myint Shai Kaplan Xiaoxiao Li 《Landscape Ecology》2016,31(4):745-760
Context
With rapidly expanding urban regions, the effects of land cover changes on urban surface temperatures and the consequences of these changes for human health are becoming progressively larger problems.Objectives
We investigated residential parcel and neighborhood scale variations in urban land surface temperature, land cover, and residents’ perceptions of landscapes and heat illnesses in the subtropical desert city of Phoenix, AZ USA.Methods
We conducted an airborne imaging campaign that acquired high resolution urban land surface temperature data (7 m/pixel) during the day and night. We performed a geographic overlay of these data with high resolution land cover maps, parcel boundaries, neighborhood boundaries, and a household survey.Results
Land cover composition, including percentages of vegetated, building, and road areas, and values for NDVI, and albedo, was correlated with residential parcel surface temperatures and the effects differed between day and night. Vegetation was more effective at cooling hotter neighborhoods. We found consistencies between heat risk factors in neighborhood environments and residents’ perceptions of these factors. Symptoms of heat-related illness were correlated with parcel scale surface temperature patterns during the daytime but no corresponding relationship was observed with nighttime surface temperatures.Conclusions
Residents’ experiences of heat vulnerability were related to the daytime land surface thermal environment, which is influenced by micro-scale variation in land cover composition. These results provide a first look at parcel-scale causes and consequences of urban surface temperature variation and provide a critically needed perspective on heat vulnerability assessment studies conducted at much coarser scales.10.
1—甲基环丙烯延缓青花菜衰老的效应及机理 总被引:23,自引:0,他引:23
研究了1—甲基环丙烯(1-MCP)对青花菜衰老的影响。结果表明,0~20 µL/L的1-MCP在20℃下处理青花菜花球6 h,能延长2O 藏条件下苛仡菜的货架寿命,延缓花蕾中营养成分叶绿素、类胡萝卜素和维生素c等的降解,其中以2.5 µL/L处 的效果最佳。进一步研究还表明2.5 µL/L 1-MCP处理抑制花蕾的呼吸速率和乙烯释放速率,行使 藏期 花蕾的蛋白质含量升高;丙二醛(MDA)含量下降,使超氧化物歧化酶(SOD)和过氧化氧酶(CAT)的活性升高,过氧化物酶(POD)的活性下降,同时,SDS-PAGE分析表明,这一处理使花球中醇溶性蛋白和水溶性蛋白的组分和含量发生明显变化 相似文献