水稻障碍型冷害损失评估及预测动态模型研究   总被引：18，自引：2，他引：18  

马树庆  王琪  沈享文  许英子  李哲 《气象学报》2003,61(4):507-512

在分析东北水稻生殖生长关键期低温生理反应的基础上,建立了计算日冷积温(时积温)及其与空壳率关系的模式和敏感期内每日水稻敏感群体数量比率分布标准化模式,进而建立了水稻在生殖生长关键期内因低温影响而导致空壳率及减产率评估、预测模式。该模式可较精确地计算出逐日低温导致的空壳率及减产率,可比成熟期提前25 d左右进行冷害评估和损失预测。  相似文献   

The CERES‐Rice Model‐Based Estimates of Potential Monsoon Season Rainfed Rice Productivity in Bangladesh*     

Rezaul Mahmood  Mark Meo  David R. Legates  Mark L. Morrissey 《The Professional geographer》2003,55(2):259-273

Agricultural practices in Bangladesh are largely dependent on the monsoonal rainfall. Historically, Bangladesh often experiences severe droughts and floods during the monsoon months, with significant crop losses during both extreme conditions. This article provides a quantitative assessment of potential monsoon‐season aman rice for four transplanting dates: 1 June, 1 July, 15 July, and 15 August. A crop‐growth simulation model, the CERES‐Rice, is applied to sixteen locations representing major rice‐growing regions of Bangladesh to determine baseline yield estimates for four transplanting dates. The applications were conducted for 1975 through 1987. Average potential yield in Bangladesh is 6,907, 5,039, 3,637, and 1,762 kg ha^?1 for the above transplanting dates, respectively. In other words, Bangladesh would obtain 27 percent, 48 percent, and 75 percent less yield for 1 July, 15 July, and 15 August transplanting, respectively, than for 1 June transplanting. Potential yield vulnerability is the least for 1 June transplanting (up to 5 percent) and the highest (up to 66 percent) for 15 July transplanting date. The model applications show that regional variations exist for potential yield and yield vulnerability for a particular transplanting date. In addition, response of yield and vulnerability for a region changes with transplanting dates.  相似文献   

Analysing spatial–temporal changes in rice cultivation practices in the Senegal River Valley using MODIS time-series and the PhenoRice algorithm     

《International Journal of Applied Earth Observation and Geoinformation》2019

In this study we used the PhenoRice algorithm to track recent variations of rice cultivation practices along the Senegal River Valley. Time series of MODIS imagery with 250 m spatial resolution and a nominal 8-days frequency were used as input for the algorithm to map the spatial and temporal variations of rice cultivated area and of several important phenological metrics (e.g., crop establishment and harvesting dates, length of season) for the 2003–2016 period in both the dry and the wet rice cultivation seasons. Comparison between PhenoRice results and ancillary and field data available for the Senegal part of the study area showed that the algorithm is able to track the interannual variations of rice cultivated area, despite the total detected rice area being consistently underestimated. PhenoRice estimates of crop establishment and harvesting dates resulted accurate when compared with field observations available for two sub-regions for a period of 10 years, and thus allow assessing interannual variability and tracking changes in agronomic practices. An analysis of interannual trends of rice growing practices based on PhenoRice results highlighted a clear shift of rice cultivation from the wet to the dry season starting approximately from 2008. The shift was found to be particularly evident in the delta part of the SRV. Additionally, a statistically significant trend was revealed starting 2006 towards a longer dry season (r² = 0.81; Slope = 1.24 days y⁻¹) and a shorter wet season (r² = 0.65; Slope = 0.53 days y⁻¹). These findings are in agreement with expert knowledge of changes ongoing in the area. In particular the shorter wet season is attributed to shortage of labor and equipment leading to a delay in completion of harvesting operations in the dry season, which led to the adoption of short-duration rice varieties by farmers in the wet season to avoid risk of yield losses due to climatic constraints. Aforementioned results highlight the usefulness of the PhenoRice algorithm for providing insights about recent variations in rice cultivation practices over large areas in developing countries, where high-quality up to date information about changes in agricultural practices are often lacking.  相似文献   

稻田氮磷径流流失模型研究进展   总被引：1，自引：0，他引：1  

黄微尘  周丰  梁浩  陈磊 《湖泊科学》2021,33(2):336-348

水稻是全球最重要的粮食作物,但种植过程中不合理的水肥管理引起了稻田氮磷径流流失,对邻近水体造成污染风险.稻田氮磷径流流失模型是理解区域水体污染排放时空特征和评估水污染风险的有效手段.论文阐述了稻田氮磷径流流失的发生机制和关键过程,梳理了统计经验模型、物理机理模型、水文过程模型和生态系统模型的研发历程.结果表明,当前模型...  相似文献   

南方丘陵地区水稻种植面积遥感信息提取的试验   总被引：7，自引：0，他引：7       下载免费PDF全文

赖格英  杨星卫 《应用气象学报》2000,11(1):47-54

以浙江省为试验区, 针对水稻种植面积遥感信息提取的业务化运行问题, 进行了以下试验:(1) 以传统的单象元统计分类识别方法为分类器, 在地理信息系统支持下, 提取丘陵地区大范围水稻种植面积信息的可行性; (2) 在遥感资料的基础上, 结合地形数据综合提取水稻种植面积专题信息的可行性和有效性; (3) 混合象元分解方法在丘陵地区的有效性和适用性.结果表明, 用最大似然法提取大范围水稻种植面积信息的精度可满足业务化运行的要求; 模糊监督分类有较高的分类精度和较好的稳定性, 具有较强的适应性; 坡度数据作为遥感影像分类的辅助数据层, 可以有效地提高丘陵地区水稻种植面积信息的提取精度, 还可以提高分类的稳定性和空间位置精度.  相似文献   

1961-2017年江西省晚稻寒露风时空演变特征     

胡磊  田俊  卓红秀  郭瑞鸽  谢远玉 《气象与环境学报》2020,36(4):67-73

利用1961—2017年江西省23个代表站逐日气温资料和1984—2017年14个农业气象观测站晚稻发育期资料,根据晚稻不同发育阶段,采用数理统计方法分析了晚稻寒露风的时空演变特征。结果表明：江西省（简称“赣”）轻度寒露风在9月中旬前出现的频率最高,赣北地区约3 a一遇,赣中地区约10 a三遇,赣南地区约5 a一遇,且由东南向西北呈增多趋势。中度寒露风在9月中旬前出现的频率较低,赣北、赣中约10 a一遇,赣南约20 a一遇;重度寒露风在9月中旬前出现的频率极低,赣中、赣北分别为0.4%和1.2%;中、重度寒露风由南向北呈逐渐增多趋势。轻度寒露风在晚稻幼穗分化到抽穗扬花阶段出现的频率为34.1%,灌浆阶段为26.9%;中度寒露风在晚稻幼穗分化到抽穗扬花阶段出现的频率为7.5%,灌浆阶段为8.0%;重度寒露风对晚稻的影响相对较小,在各发育阶段出现的频率均不到2%。  相似文献   

2020—2021年越冬季鄱阳湖两处垦殖场农田白鹤数量动态     

底明晓  翁晓东  卢萍  陆远鸿  戴年华 《湿地科学与管理》2022,18(1):23-26

近年来鄱阳湖区农田已成为越冬白鹤的重要觅食地,白鹤在农田的数量动态研究尚不充分。本研究选择白鹤集中越冬的五星、康山垦殖场,采用样线法调查了2020—2021年越冬季两处垦殖场农田的白鹤种群动态。结果表明:7只白鹤2020年10月底到达五星垦殖场藕田觅食,11月有1523只,12月有693只,2021年1月有420只,2月1次调查记录到80只,3月白鹤北迁;康山垦殖场稻田白鹤数量在12月初开始增加,12月有1163只,1月有1536只,2月1次调查记录到543只,3月北迁。五星垦殖场农田白鹤数量高峰期在2020年11月,单次记录达2282只,康山垦殖场高峰期在2021年1月,单次记录达2000只。白鹤全球种群数量现存约3500~4000只,两个垦殖场越冬期单次调查记录均超过白鹤全球种群总数量的50%,农田对鄱阳湖白鹤越冬发挥了重要作用。  相似文献   

Rice monitoring with multi-temporal and dual-polarimetric TerraSAR-X data     

《International Journal of Applied Earth Observation and Geoinformation》2013

This study assesses the use of TerraSAR-X data for monitoring rice cultivation in the Sanjiang Plain in Heilongjiang Province, Northeast China. The main objective is the understanding of the coherent co-polarized X-band backscattering signature of rice at different phenological stages in order to retrieve growth status.For this, multi-temporal dual polarimetric TerraSAR-X High Resolution SpotLight data (HH/VV) as well as single polarized StripMap (VV) data were acquired over the test site. In conjunction with the satellite data acquisition, a ground truth field campaign was carried out.The backscattering coefficients at HH and VV of the observed fields were extracted on the different dates and analysed as a function of rice phenology to provide a physical interpretation for the co-polarized backscatter response in a temporal and spatial manner. Then, a correlation analysis was carried out between TerraSAR-X backscattering signal and rice biomass of stem, leaf and head to evaluate the relationship with different vertical layers within the rice vegetation.HH and VV signatures show two phases of backscatter increase, one at the beginning up to 46 days after transplanting and a second one from 80 days after transplanting onwards. The first increase is related to increasing double bounce reflection from the surface–stem interaction. Then, a decreasing trend of both polarizations can be observed due to signal attenuation by increasing leaf density. A second slight increase is observed during senescence. Correlation analysis showed a significant relationship with different vertical layers at different phenological stages which prove the physical interpretation of X-band backscatter of rice. The seasonal backscatter coefficient showed that X-band is highly sensitive to changes in size, orientation and density of the dominant elements in the upper canopy.  相似文献   

Metal Impregnated Silica‐Carbon Materials from Rice Husk: A Versatile Sorbent for Toxic Organics and Inorganics in Water and Air     

Sanhita Majumdar  Pijush Kanti Mandal  Sudip Kumar Das  Rabindranath Majumdar 《洁净——土壤、空气、水》2013,41(3):291-297

Carbon bearing materials derived from rice husk (RH) have long been recognized as sorbents for diverse chemicals – both organic and inorganic. This work presents an overview of studies demonstrating a single step process of carbonization of chemically pretreated RH to produce metal impregnated silica‐carbon char designated as silicarbon materials that can be utilized in sorbing out water‐borne organic and inorganic hazardous substances (such as phenol, hexavalent chromium, fluoride, and arsenic) and air‐borne volatile organic chemicals (such as acetone, chloroform, benzene, and pyridine). The metal‐impregnated silicarbon solids derived from RH appear to constitute renewable, low‐cost, user‐friendly, and efficient materials for control systems for indoor air contamination and for industrial as well as non‐industrial hazardous aqueous pollution.  相似文献   

A review of low-cost scanners†     

JANE DRUMMOND  MARIJN BOSMA 《International journal of geographical information science》2013,27(1):83-95

Abstract

This paper summarizes the characteristics of 19 scanners costing less than Dfl20000 (US$10000). It also describes the completeness of scanning performed by three of these low-cost scanners (from Agfa, Cannon and Houston Instruments) and the accuracy of one (SCAN-CAD of Houston Instruments). It was found that complete scanning occurs with resolutions of half the minimum map line width and that maximum errors of 0-5 mm were achieved.  相似文献