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1.
采用UPLC-MS/MS法对番石榴多酚中部分酚类物质进行了定性分析。以抑菌圈直径为评价指标,测定了番石榴多酚的抑菌活性,并以金黄色葡萄球菌为指示菌,对其抑菌稳定性进行了研究。结果表明：番石榴多酚中含有没食子酸、儿茶素、槲皮素、原儿茶酸、山奈素和绿原酸等酚类物质。番石榴多酚对金黄色葡萄球菌、大肠埃希氏杆菌、单增李斯特菌、铜绿假单胞菌、腐败希瓦氏菌和枯草芽孢杆菌具有较好的抑制效果,除了单增李斯特菌和腐败希瓦氏菌的MIC低于5 mg/mL外,其余均低于2.5 mg/mL。番石榴多酚在pH4~5范围内处理后抑菌活性最强,其抑菌活性对温度、紫外照射具有稳定性,低盐度会促进其抑菌活性。 相似文献
2.
Seong-Joon Kim Hyung-Joong Kwon In-Kyun Jung Geun-Ae Park 《Paddy and Water Environment》2003,1(3):149-155
The simulated streamflow from Thiessen average rainfall (T) and spatially distributed rainfall (R) may be significantly different from each other. To identify the hydrologic effects quantitatively, the grid-based kinematic wave storm runoff model was adopted. The model predicts temporal and spatial variations of surface and subsurface flow at each cell by calculating the water balance, and routes the streamflow to the outlet. The model was tested at the Yeoncheondam watershed (1,875 km2), one third of which belongs to North Korea. The watershed is elongated to north and south directions crossing the border. Four rain gauges cover the watershed within the territory of South Korea, while no records from North Korea are given. The simulated results showed the large differences in runoff volume and peak flow rates between T and R when rain moves in a north to south direction. The simulated results of east-to-west-direction storms showed little difference in the hydrographs. The hydrograph was strongly affected by the spatial variations of the rainfall moving along the stream of the watershed. 相似文献
3.
4.
益智是我国四大南药之一,其间作在橡胶林下成为胶园最重要的农林复合模式。项目组前期研究发现,旱季降雨不足是橡胶林下益智生长和光合的主要限制因子。然而,目前对益智如何应对旱季降雨格局变化的认识非常有限。为研究旱季降雨格局变化对益智生长和碳氮代谢的影响,在实验中模拟3个降雨量梯度：减雨量（W-）10 mm/月、自然雨量（W）25 mm/月、增雨量（W+）40 mm/月,并设置5 d和10 d的降雨间隔期,通过双因素实验分析益智植株的生长参数、碳水化合物和氮化合物水平以及与碳和氮代谢相关的关键酶活性。结果表明：（1）益智的地上生物量和地下生物量随着降雨量的减少而下降。在所有降水水平下,5 d处理下的生物量均显著高于10 d（P<0.05）,降雨量减少和降雨间隔期延长均抑制植株生物量的增加。在W-处理下,10 d的叶片含水率比5 d显著增加3.63%;（2）降雨减少改变了碳代谢酶的活性,抑制了AMY和INV活性,促进了SPS活性,但这种促进作用随着降雨间隔期延长变得不显著。降雨量减少促进了非结构碳水化合物（可溶性糖和淀粉）积累;（3）降雨减少降低了益智叶片全N含量,5 d处理组中W+和W-的全氮含量比10 d显著增加8.33%和9.81%,降雨量变化改变了N代谢组分;（4）同时GS/GOGAT循环活性以及NR和NiR酶活性增加,这加速了硝态氮还原和铵态氮同化。在W处理下,5 d处理组中的硝态氮和铵态氮比10 d显著降低了57.54%和152.98%。因此,在旱季降雨格局变化会影响益智的生物量、碳氮化合物及代谢酶变化,但益智通过生物量分配和叶片C、N代谢调节来适应不同的干旱胁迫,以保证益智植株的正常生长。 相似文献
5.
Yumi Yoshioka Kimihito Nakamura Haruhiko Horino Shigeto Kawashima 《Paddy and Water Environment》2016,14(1):93-103
Quantitative assessment of the impacts of climate change on groundwater levels is important for sustainable groundwater use. This study examined the Tedori River alluvial fan in Ishikawa Prefecture, Japan, where paddy fields occupy 45 % of the total area. A regional groundwater flow model simulated future groundwater levels in response to 38 climate change projections generated for each of three GCMs, using three GHG emission scenarios with the ELPIS-JP datasets. The numerical groundwater flow model consisted of a 1-D unsaturated water flow model (HYDRUS-1D) for estimating groundwater recharge and a 3-D groundwater flow model (MODFLOW). Variable parameters consisted of daily air temperature, precipitation, humidity, solar radiation, and wind speed, which influence groundwater through infiltration, evapotranspiration, snowfall, and snowmelt. Groundwater levels had both decreasing and increasing trends, depending on climate change. There were more decreasing than increasing trends, and the maximum groundwater drawdown during 2010–2090 was ~1 m. Groundwater level was most sensitive to change in rate of precipitation during the non-irrigation period. Variations of relatively low-intensity precipitation days, when daily precipitation was <10 mm, had an effect on groundwater level. These results contribute to development of adaptive and sustainable groundwater managements (e.g. land use management and pumping strategies) in the future. 相似文献
6.
A water balance model for characterization of length of growing period and water stress development for rainfed lowland rice 总被引：1，自引：0，他引：1
There is large year-to-year variation in rice production across the Mekong region (Laos, Cambodia and Thailand) due to uncertainty in the timing of the onset of the wet season and drought stress that may develop at any time during the growth of rainfed lowland rice. Unique to the nature of lowland water balance is a large component of deep percolation water loss, which depends on soil texture. The objectives of this study were to develop a soil water balance model for calculating the amount of water held in field storage (i.e. in soil and, if there is standing water, above the soil surface) and to apply it to determine the length of growing period (LGP) and water stress development in relation to soil type and rainfall pattern for the rice ecosystem. The water balance is computed separately for above-ground plus topsoil layer and subsoil layer. Components of the water balance are the existing amount of stored water, rainfall, evapotranspiration, deep percolation, and runoff. The deep percolation rate was determined from clay content in each soil layer. The model runs with daily or weekly weather data to estimate the soil water level for the growing period in the wet season. The model was validated with data collected from top, middle and bottom of rainfed lowland fields in Savannakhet province, Laos. The best correlation between the observed and simulated water level was obtained (r2 = 0.41) for middle fields. The simulation results showed that LGP varied greatly from year to year, particularly in locations with sandy soils, due mostly to variation in monthly rainfall occurring at the early part of the growing season (April), but also to some extent by variation at the end of growing season (October). Soil texture on the other hand is shown to have a large influence on the end of the rice growing period and hence LGP, and also water stress development during growth. Sandy soils with clay content less than 7% that are prevalent in the province are shown to cause frequent water stress and early finish in rainfed lowland rice. The model accordingly provides reasonable outputs that can provide a geographical dimension of soil hydrological patterns for various rice growing environments, and also identify the spatial pattern of drought stress that is likely to occur. Model outputs can be used to provide guidelines for practical advice to the rice farmers and researchers for determination of appropriate crop management strategies (e.g. time of planting, varieties), and policy makers for investment decisions on inputs (e.g. fertilizer price) aimed at increasing rice productivity in this Mekong region. 相似文献
7.
气象条件对广西春大豆生长发育及产量的影响 总被引：4，自引：0，他引：4
本文用1983—1985年广西春大豆区试播种资料与气象资料进行了相关统计分析。结果表明,影响广西春大豆各生育阶段生育日数的关键气象因子:播种至出苗期为土壤温度;出苗至始花期为日平均气温和降水日数;始花至成熟期为日照时数;出苗至成熟期为降水日数。影响产量的关键气象因子为始花至成熟期的温度日较差、平均相对湿度和降水量。温度日较差和降水量对广西春大豆各生育阶段生育日数的影响不显著。 相似文献
8.
为了解降水变化对黄土旱塬区冬小麦生长及产量的影响,通过遮雨棚模拟冬小麦生长季减少30%降水(R-30%)、正常降水(CK)和增加30%降水(R+30%)情景,于2016-2018年研究了黄土旱塬区两季冬小麦土壤相对有效含水量、LAI、NDVI、生物量、产量及其构成的动态变化特征。结果表明,在降水正常的2016-2017年(降水距平百分率位于±15%以内),与CK相比,R-30%处理的土壤相对有效含水量在返青至抽穗期显著下降,冬小麦冠层NDVI显著降低,LAI和干物质增长速率明显变缓,冬小麦的穗数和千粒重显著降低,而R+30%处理下冬小麦LAI和干物质保持稳定增长优势。R+30%、CK和R-30%三种降水条件下冬小麦产量分别为4.66、3.12和2.43 t·hm~(-2),处理间差异显著。在降水偏多的2017-2018年(降水距平百分率超过30%),不同降水处理间土壤相对有效含水量、冬小麦LAI、冠层NDVI、生物量、产量及其构成等指标均未表现出显著差异。R+30%、CK和R-30%三个处理下冬小麦的产量分别为3.70、3.39和3.14t·hm~(-2),处理间差异亦不显著。因此,在正常降水年份,生长季增加30%降水可使冬小麦显著增产44.2%,减少30%降水可使冬小麦显著减产28.4%;在降水偏多年份,生长季降水增加30%或减少30%对冬小麦的生长及产量没有显著影响。 相似文献
9.
选取3种熟期类型杂交组合(早熟×晚熟、相近熟期×相近熟期、晚熟×早熟)各10个,对杂交期间的日平均温度、日平均湿度、日降雨量及不同类型杂交组合成活率进行统计,并进行了通径分析。结果表明:气象因子对杂交成活率影响较大,不同气象因子对不同杂交类型影响效应不同,早熟×晚熟组合在较低温度、较小湿度、无降雨的天气下成活率较高;类似熟期亲本组合对天气要求宽泛,在常温、低湿天气下杂交成活率更高;晚熟×早熟组合在温度较高、空气湿度小、无降雨的天气具有较高的杂交成活率。 相似文献
10.
Martin Köchy 《BMC ecology》2008,8(1):1-23
Background
To improve the understanding of consequences of climate change for annual plant communities, I used a detailed, grid-based model that simulates the effect of daily rainfall variability on individual plants in five climatic regions on a gradient from 100 to 800 mm mean annual precipitation (MAP). The model explicitly considers moisture storage in the soil. I manipulated daily rainfall variability by changing the daily mean rain (DMR, rain volume on rainy days averaged across years for each day of the year) by ± 20%. At the same time I adjusted intervals appropriately between rainy days for keeping the mean annual volume constant. In factorial combination with changing DMR I also changed MAP by ± 20%.Results
Increasing MAP generally increased water availability, establishment, and peak shoot biomass. Increasing DMR increased the time that water was continuously available to plants in the upper 15 to 30 cm of the soil (longest wet period, LWP). The effect of DMR diminished with increasing humidity of the climate. An interaction between water availability and density-dependent germination increased the establishment of seedlings in the arid region, but in the more humid regions the establishment of seedlings decreased with increasing DMR. As plants matured, competition among individuals and their productivity increased, but the size of these effects decreased with the humidity of the regions. Therefore, peak shoot biomass generally increased with increasing DMR but the effect size diminished from the semiarid to the mesic Mediterranean region. Increasing DMR reduced via LWP the annual variability of biomass in the semiarid and dry Mediterranean regions.Conclusion
More rainstorms (greater DMR) increased the recharge of soil water reservoirs in more arid sites with consequences for germination, establishment, productivity, and population persistence. The order of magnitudes of DMR and MAP overlapped partially so that their combined effect is important for projections of climate change effects on annual vegetation. 相似文献11.
H. Yasuda S. N. Panda Mohamed A. M. Abd Elbasit T. Kawai T. Elgamri A. A. Fenta H. Nawata 《Paddy and Water Environment》2018,16(4):805-821
We investigated teleconnections of rainfall time series in the central Nile Basin (Sudan and South Sudan) with localities in the global sea surface temperature (SST) field, using monthly rainfall data from 11 gauging stations from 1960 to 1999. Annual rainfall ranged from 100 mm in the north to more than 700 mm in the south, and all stations had a strong contrast between rainy and dry seasons with rainless dry periods of several months. Rainfall time series at the stations were categorized as strongly seasonal, with precipitation concentration index exceeding 16 and seasonality index exceeding 0.9. The rainfall stations were classified into four zones on the basis of annual rainfall, seasonality, and cross-correlations among the stations. We calculated cross-correlations of interannual rainfall time series in summer (July and August) with the global SST field. For short lag times (0 or 1 month), summer rainfall in Zones I and II (northern arid regions) had significant correlations with SST over the eastern Mediterranean Sea and southern Indian Ocean, summer rainfall in Zone III (semiarid region) had significant negative correlations with SST over the Indian Ocean, and summer rainfall in Zone IV (southern wet region) had significant correlations with SST over tropical areas and the southwestern Pacific Ocean. For long lag times (3–6 months), Nile Basin summer rainfall time series had significant correlations with SST in various regions of the Atlantic and Indian Oceans but not the Pacific Ocean. Rainfall in Zones I and II had positive correlations (significance level?<?0.01) with SST south of Greenland and around the Azores Islands and negative correlations with SST south of Madagascar; rainfall in Zone III had negative correlations with SST in parts of the Indian Ocean; and rainfall in Zone IV had significant positive correlations with SST southwest of South Africa and negative correlations with SST in the southwestern Indian Ocean. In sum, rainfall in three of the zones (I, II, and IV) had significant positive and negative correlations with SST in parts of the Indian and Atlantic Oceans. For each of these zones, one positive correlation and one negative correlation were selected and correlations with the time series of the difference between the two SST records were calculated. Correlations of Nile Basin rainfall with the SST differences were stronger than the original positive and negative correlations. The resulting time series of SST difference were applied to an artificial neural network to predict summer rainfall, yielding satisfactory correlation coefficients between the observed and predicted summer rainfall (r?>?0.70). 相似文献
12.
利用2007～2011年海南热带气旋过程的地面站雨量资料，对国家卫星气象中心和中国气象局上海台风所基于FY2D和GMS-5红外亮温资料研发的卫星降水估计产品进行定量评估。结果表明：无论是6 h还是24 h降水，FY2D降水估计产品对海南热带气旋降水的反演精度要比GMS-5降水估计产品高；FY2D和GMS-5卫星估计降水具有估测大暴雨以上强降水的优势，对热带气旋强降水预报业务具有参考性；对6h强降水估计能力的空间分布而言，FY2D降水估计产品估测能力为岛西高，岛东低。GMS-5降水估计产品的估测能力为岛北高，岛南低；登陆海南岛北部地区的热带气旋降水估计技巧比登陆海南岛南部地区的热带气旋高；两种卫星降水估计产品对中小尺度强降水极值估计偏弱。 相似文献
13.
Kei Ishida Macarius Yangyuoru Koichi Unami Toshihiko Kawachi 《Paddy and Water Environment》2011,9(4):393-401
Analysis of runoff processes in farmlands during storm events in particular is an important engineering topic. The shallow
water equations describing the physical conservation laws are attractive tools for understanding motion of surface water.
A numerical model is developed to reproduce surface water flows during storm events, using the finite element method and the
finite volume method applied to the one-dimensional shallow water equations. The numerical model has the advantage of dealing
with transcritical flows, wet, and dry processes, irregular channel bed slopes, and channel junctions involving multiply connected
networks. Standard numerical tests demonstrated some of these features. Runoff processes from farmlands in a Japanese hilly
area is analyzed with the numerical model coupled with another runoff model of black-box type. Parameters of the models are
calibrated and validated using observed series of rainfall and runoff discharge data. Simulated results included submergence
of hydraulic jumps and flood storage in farming plots, which are very informative in terms of assessing diverse functions
of the farmlands. 相似文献
14.
为了探明影响广西甘蔗种茎出苗及苗期生长的气象因子,本研究选用2个广西当家甘蔗品种‘新台糖22号’（T22）和‘桂糖42号’（G42）为研究对象,从2—5月开展甘蔗分期播种试验,每半个月播种1期。通过观测每期甘蔗的出苗率、苗期生长状况以及同期的气象因子（降雨量、平均气温）,并对数据进行相关统计分析。结果表明,T22、G42蔗种的出苗率与播种后20 d的累积降雨量呈显著正相关,而与播种后10 d的累积降雨量呈正相关,差异未达显著水平。由播种后20 d的累积降雨量与甘蔗出苗率的对数函数方程进一步显示,为了使甘蔗种茎出苗率达80%以上,甘蔗播种后20 d的累积降雨量要达到75 mm以上;播种后的平均气温、降水量和日照时数与甘蔗苗茎伸长期株高/茎粗相关性达到5%显著性水平以上,进一步逐步回归分析显示,降水量是影响甘蔗茎伸长期株高/茎粗的显著性自变量。推断甘蔗播种后10~20 d的累积降雨量是决定甘蔗出苗的关键气象因子,在甘蔗苗期生长过程中,降雨量对甘蔗生长至关重要,可以通过降雨量预测甘蔗苗期株高/茎粗。鉴于以上研究结果,在广西甘蔗生产过程中,为了提高甘蔗出苗率,要加强甘蔗种植后20 d内的水分管理,在这期间累积降雨量需达到75 mm以上才能达到甘蔗齐苗的目的,甘蔗出苗后也需加强水分管理,利于苗期快速生长,从而提高蔗苗质量。 相似文献
15.
Chad Shouquan Cheng Pao-Shan Yu Qian Li Guilong Li Jung-Lien Chu 《Paddy and Water Environment》2009,7(4):293-300
In this study, an automated synoptic weather typing was employed to identity the weather types most likely associated with
daily typhoon/typhoon-related heavy rainfall events for Chiayi, Taiwan. The synoptic weather typing was developed using principal
components analysis, an average linkage clustering procedure, and discriminant function analysis. The classification results
showed that the synoptic weather typing was successful at identifying typhoon-related weather types. Five synoptic weather
types (Weather Types 1–5) were identified over the past 11-year period as the primary typhoon-related weather types. These
five typhoon-related weather types can capture 34 out of 36 total typhoon-related heavy rainfall days (>50 mm/d) and all nine
cases with typhoon-related daily rainfall >200 mm during the period March 1998–December 2008. This result suggests that synoptic
weather typing can be useful to identify historical typhoon/typhoon-related heavy rainfall events. Moreover, the method has
potential to assess climate change impacts on the frequency/intensity of future typhoon/typhoon-related heavy rainfall events
using future downscaled GCM climate data. 相似文献
16.
Efficacy of foliar applied fungicides following simulated rainfall for the control of dollar spot (caused by Sclerotinia homoeocarpa F.T. Bennett) was assessed in a two-year field study on creeping bentgrass (Agrostis stolonifera L.) turf maintained as a golf course fairway. The study was conducted as a randomized complete block design with a factorial arrangement. Fluazinam (0.8 kg a.i. ha−1), chlorothalonil (3.79 kg a.i. ha−1) or iprodione (1.5 kg a.i. ha−1) were applied, then subjected to simulated rainfall (2.54-mm) at intervals of 15-, 30-, 60-min post-application, or no simulated rain. In most cases, simulated rainfall occurring ≤60 min post-application had greater disease than no rain plots; however, few differences occurred among rainfall intervals ≤60 min. Fluazinam provided the greatest dollar spot reduction regardless of simulated rainfall interval throughout the study. Chlorothalonil was most susceptible to losses in efficacy due to simulated rainfall, resulting in the greatest disease incidence of those fungicides evaluated. Iprodione was comparable to chlorothalonil during high disease pressure, although during moderate disease pressure it controlled dollar spot for approximately 7 days before disease increased in plots receiving simulated rain compared to those without simulated rain. These data demonstrate that efficacy of fungicides applied for dollar spot control are affected by rain, and differ in their ability to control disease following post-application rain events. Fluazinam, a recently introduced contact fungicide for use on turfgrass, can provide improved control compared to chlorothalonil or iprodione when rain is eminent. 相似文献
17.
South Africa has three wheat production regions, the winter rainfall region where spring wheat is planted; the summer rainfall where winter and intermediate wheat is cultivated; and the irrigation region where spring wheat is grown. The aim of this study was to determine dough mixing characteristics as measured by Mixsmart® software in these three regions over seasons and locations, and to relate this to important quality characteristics. In the winter rainfall area Mixsmart characteristics were very poor predictors of baking quality, especially of loaf volume, flour protein content and wet gluten content. The best predictors of loaf volume in this region were flour protein content and wet gluten content, which were highly interrelated. In the irrigation area, midline peak value and midline right value were very good predictors of flour protein content, gluten content and loaf volume. Midline peak value was highly correlated with protein content in both the irrigation and summer rainfall areas and was a better predictor than peak time of baking quality. The ideal would be to select several parameters from the mixograph and use them in a multivariate statistical analysis to obtain a more accurate prediction of loaf volume in the irrigation and summer rainfall areas. 相似文献
18.
Le Van Chinh Haruka Iseri Kazuaki Hiramatsu Masayoshi Harada Makito Mori 《Paddy and Water Environment》2013,11(1-4):97-112
In watershed management, the determination of peak and total runoff due to rainfall and prediction of pollutant load are very important. Measurement of rainfall runoff and pollutant load is always the best approach but is not always possible at the desired time and location. In practice, diffuse pollution has a complex natural dependence on various land-use activities such as agriculture, livestock breeding, and forestry. Estimation of pollutant load is therefore essential for watershed management and water pollution control. In this study, a model of rainfall runoff and pollutant load, which uses a geographical information system (GIS) database, is a convenient and powerful tool for resolving the abovementioned complexities. This technology was applied in order to simulate the runoff discharge and the pollutant load of total nitrogen (TN) and total phosphorus (TP) in the Chikugo River basin of Kyushu Island, Japan. First, a hydrologic modeling system (HEC-HMS) and GIS software extension tool were used for simulations of elevation, drainage line definition, watershed delineation, drainage feature characterization, and geometric network generation. The spatial distributions of land cover, soil classes, rainfall, and evaporation were then analyzed in order to simulate the daily runoff discharge at the Chikugo Barrage from April 2005 to December 2007. An important point in this approach is that a new development for data input processing with HEC-HMS was introduced for optimizing parameters of the model. Next, the water quality indicators TN and TP were examined, and an efficient approach was investigated for estimating monthly pollutant loads directly from unit load and ground-observed hydrological data. Both nonpoint and point sources of pollutants were considered, including different land-cover categories, sewers, factories, and livestock farms. The observed and simulated results for the runoff discharges and pollutant loads were in good agreement and totally consistent, indicating that the proposed model is applicable to simulation of rainfall runoff and pollutant load in the Chikugo River basin. Further, this model will be able to provide managers with a useful tool for optimizing the water surface management of this river basin. 相似文献
19.
Mohammadi Elham Movahedi Saeed Mohammadi Reza Golkari Sabar 《Paddy and Water Environment》2022,20(2):241-253
In this study, the effect of climate change on planting date and growth duration of rainfed wheat in the west and northwest parts of Iran has been investigated. The occurrence of climate change in the region was first evaluated for the base period (1992–2018) using two nonparametric tests of Mann–Kendall and Sen's slope estimator. Then, the climatic parameters of maximum temperature, minimum temperature and precipitation were simulated under RCP4.5 scenario for the period 2019–2039 based on downscaled output data of the Community Climate System Model (CCSM4) using LARS WG software. The growth period was obtained using a linear multiple regression model, which was selected based on R-square and accounted for 87% of its total variation. The results predicted that the average annual temperature will increase by 2 °C, while the average annual precipitation will increase by 30% by the end of 2039. Planting dates were determined based on two indices combining temperature and precipitation for the base and future periods. The results showed that climate change effects at the 2039 horizon will shorten by 18 days the wheat growth period and the appropriate planting time for rainfed wheat will be reduced by 2–19 days.
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