共查询到20条相似文献，搜索用时 46 毫秒
1.
Akihiko Kotera Khang Duy Nguyen Toshihiro Sakamoto Toshichika Iizumi Masayuki Yokozawa 《Paddy and Water Environment》2014,12(3):343-354
We developed a crop scheduling model for rice cultivation in the Vietnam Mekong Delta (VMD), focusing on the adaptive behavior of crop planning to various water resource constraints. In addition, we also examined the effects of environmental change on rice cultivation in the last decade. In the VMD, multiple rice cropping is practiced under a variety of adverse water conditions, including flooding, salinity intrusion, and irregular monsoon rains. These environmental changes influence the durations of growing seasons and the number of crops per year, resulting in changes in productivity. To validate the performance of the model, we compared model estimates for the heading date and changes in leaf area index at nine sites with estimates of these parameters derived from MODIS satellite time series data for the period 2002–2006. The root mean square errors of heading date between the modeled and satellite data in the upper, middle, and coastal regions of the delta were 17.6, 11.2, and 13.0 days, respectively. Based on the model, we examined case studies to assess the changes in cropping cycles and crop failures in the VMD due to extreme flooding in 2000 and salinity intrusion in 2004 by applying evaluation indices defined by available period for cultivation (APC) and safe margin for cropping (SMC) which is defined as the marginal time between APC and the period required for cultivation. Findings of case studies suggested that a small difference in the SMC of the cropping pattern is critical to the stability and productive capacity of the rice crop. 相似文献
2.
This study focused on the variability of rice yield under water and soil salinity risks in farmers’ fields in northeast Thailand. A rice plot was monitored in 24, 16 and 11 farmers’ fields during the rice seasons 2005, 2006 and 2007, respectively. The results emphasized that few plots were continuously submerged during the 2005 season, when rainfall was low. Drought significantly affected the rice yield, yield components and the internal efficiency (IE) of the absorbed nutrients, while slight soil salinity had the only significant effect of increasing the IE of potassium (IEK). In the very rainy 2006 and 2007 seasons, most fields were continuously submerged, and in contrast to 2005, the slight soil salinity that was recorded had significant effects not only on IEK, but also on rice yield, spikelet sterility and 1000-grain weight. The yield decrease due to drought was about 87% and that due to salinity was 20%. When neither salinity nor water were limiting, the soil nutrient supply was high enough to achieve about 80% of the maximum yield reported in the literature for the rice cultivar in this area. As both drought and salinity risks are hardly avoided by the current farmers’ management they should be taken into account in the way technical recommendations to farmers are formulated. 相似文献
3.
Yen Thi Bich Nguyen Akihiko Kamoshita Van Thi Hai Dinh Hirotaka Matsuda Hisashi Kurokura 《Paddy and Water Environment》2017,15(1):37-48
This study was carried out to identify the vulnerability of rice production to salinity intrusion arising from climate change in Giao Thuy, a coastal district of Nam Dinh Province, located in Red River Delta in Vietnam. From the analysis of historical climate data at Nam Dinh city, both mean maximum and minimum temperatures increased by about 0.3 and 0.1 °C per decade, respectively, during the period of 1961–2010. Salt concentration of the river water was higher at the irrigation gate closer to river mouth (Con Nhat) than at the upstream gate (Ha Mieu), which generally increased from 2003 to 2012, with the average maximum concentration up to 2.13 % at Con Nhat gate in 2010. The salt water concentration in the riverside field outside the dyke reached 3.6 %, while among the fields within dyke the salinity was only 0.7 % at maximum in January 2013, and the values were higher in paddy fields close to the dyke than far from the dyke. Average yield among the selected 27 fields from 2011 summer to 2013 spring rice was higher in spring rice (748 g m?2) but lower in summer rice (417 g m?2) mainly due to unfavorable weather such as cold spell at flowering and flood at harvesting time. Rice yield was lowest in general in the most downstream commune Giao Thien, and was significantly lower in field located close to the dyke than those far from the dyke. This spatial variability of rice yield may not be directly attributable to salinity, but to the other factors such as shift of irrigation intake gate to further upstream and/or different management such as less input of N fertilizer and use of traditional local variety. 相似文献
4.
Egypt faces great challenges due to its limited water resources by enforcement policies to improve the performance of the existing delivery system and its development. The improvement of irrigation systems in the Nile Delta is one of the most important attempts in Egypt to implement more effective irrigation technologies. This study was carried out to evaluate improved tertiary canal level and farmers’ practices by comparing with other unimproved systems to understand the farmers’ practices in their farms after modifying the existing irrigation system. This study area applied to the Wasat command area’s most commonly used to the cultivation of a paddy field in Egypt, which contributes 40 % of production. The overall results indicate that the water-use application at the improved system level improved. This was due to the role of water user association in the successful management and operation of the water-supply system on the private level of water distribution network. So, water users’ association has the positive effect on managing of the improved tertiary canal. Although, there are main problems of water delivery in the irrigation networks that was a water shortage in the main canal owing to its location at the tail of the feeder canal system in the Nile Delta, and other reasons include the absence of crop production planning by farmers, especially rice farmers in summer, and the greater demand of some fields than supply. 相似文献
5.
Sakai Toru Omori Keisuke Oo Aung Naing Ma Swe Swe Zaw Yan Naung 《Paddy and Water Environment》2021,19(2):295-306
In the last 40 years, the rice-cropping system has considerably changed in the Ayeyarwady Delta. The large archive of satellite imagery provides a history of how land and water resource managements have changed in the face of growing populations, resource demand, and climate change. This study aimed to assess the decadal changes in the rice-cropping system in the Ayeyarwady Delta by using the large archive of satellite imagery for the last 40 years (1981???2020). The long-term NDVI dataset provided various information on rice cultivation. Signal processing techniques were used to detect on the historical changes in the rice-cropping system, and the impact of climate change was assessed by using trend analysis. Until the 1980s, single-cropping of summer rice was dominant in the Delta. To enhance the grain yield of rice, the irrigation facilities were introduced in 1992 under an initiative of the Myanmar government. As a result, the annual cropping intensities increased from 1.087?±?0.390 in the 1980s to 1.422?±?0.499 in the 2010s. The information on historical change in the rice-cropping system would be useful to consider the practical and cost-effective utilization of remaining land and water resources. Moreover, the trend analysis of NDVI time-series showed negative trends in coastal areas. This indicates that the rice production in coastal areas has been constrained by the saline intrusion. The salt-affected areas are expected to expand under future climate change scenarios. Government support is highly required for sustainable rice production in the Delta.
相似文献6.
Alexander M. Stuart Colin V. PrescottGrant R. Singleton Ravindra C. Joshi 《Crop Protection》2011,30(2):147-154
A survey of the knowledge, attitudes and practices (KAP) of 100 rice farmers and 50 coconut farmers was conducted in the coastal lowland agro-ecosystems of the Sierra Madre Biodiversity Corridor, Luzon, Philippines to identify current rodent management practices and to understand the extent of rat damage and the attitudes of farmers to community actions for rodent management. Pests were most commonly listed as one of the three most important rice and coconut production constraints. Other major crop production constraints were typhoons and insufficient water. Farmers consider rats to be the major pest of coconut and of rice during the wet season rice crop, with average yield losses of 3.0% and 13.2%, respectively. Rice and coconut farmers practised a wide range of rodent management techniques. These included scrub clearance, hunting and trapping. Of the 42 rice farmers and 3 coconut farmers that applied rodenticides to control rodents, all used the acute rodenticide, zinc phosphide. However, only ten rice farmers (23.8%) applied rodenticides prior to the booting stage and only seven farmers (15.6%) conducted pre-baiting before applying zinc phosphide. The majority of farmers belonged to farmer organisations and believed that rat control can only be done by farmers working together. However, during the last cropping season, less than a third of rice farmers (31.2%) applied rodent management as a group. In order to reduce the impact of rodents on the farmers of the coastal lowlands of the Sierra Madre Biodiversity Corridor, integrated management strategies need to be developed that specifically target the pest rodents in a sustainable manner, and community actions for rodent management should be promoted. 相似文献
7.
8.
盐逆境对水稻产量、光合特性及品质的影响 总被引：5，自引：0，他引：5
【目的】江苏沿海滩涂种植水稻是促进盐土脱盐改良和开发利用滩涂的主要技术之一,研究盐逆境对水稻产量、光合特性和稻米品质的影响,可为发展滩涂种稻提供参考和理论依据。【方法】以耐盐性较好的通粳981、盐稻12、盐稻10号和南粳5055等4个粳稻品种为材料,设置非盐逆境(S0,电导率0.207 d S/m)和逆境(S1,电导率1.112 d S/m)2个处理,分别测定产量及其构成因素、光合参数、稻米品质和淀粉黏滞特性。【结果】与非盐逆境相比,盐逆境下水稻产量显著下降,仅为非逆境的40.5%,单位面积穗数差异不显著,每穗粒数和千粒重显著减少;光合速率、胞间CO2浓度显著下降,而气孔导度和蒸腾速率差异不显著;稻米加工品质显著下降,外观品质变化不大,直链淀粉含量显著下降,蛋白质含量显著增加;峰值黏度、热浆黏度、最终黏度、崩解值和回复值均未发生显著的变化,消减值和起始糊化温度显著增高。【结论】盐逆境对水稻产量、光合参数、稻米品质等均有不利的影响,可在盐逆境对产量、品质影响的关键时期孕穗期和灌浆结实期采取措施缓解盐逆境的危害。 相似文献
9.
Rice production is affected by climate change, while climate change is simultaneously accelerated by methane gas (CH4) emissions from paddy fields. The rice sector must take suitable mitigation measures, such as prolonging mid-summer drainage (MSD) before the rice flowering period. To propose a mitigation policy, this study aims to demonstrate the environmental and economic effects of MSD in Japanese paddy fields by using a dynamic, spatial computable general equilibrium (CGE) model and crop model; the study also considers environmental subsidies with a carbon tax scheme to promote MSD measures. The results demonstrate that climate change under the 8.5 representative concentration pathway (RCP) scenario will reduce rice prices and rice farmers’ nominal income due to bumper harvests until the 2050s. Promoting MSD in paddy fields can prevent a decrease in farmers’ nominal income and effectively reduce CH4 emissions if all farmers adopt this measure. However, some farmers can potentially increase their own yield by avoiding MSD under high rice prices, which would be maintained through other farmers’ participation. A strong motivation exists for some farmers to gain a “free ride,” and an environmental subsidy with a carbon tax can help motivate farmers to adopt MSD. Therefore, the policy mix of prolonging MSD and environmental subsidies can increase all farmers’ incomes by preventing “free rides” and decrease greenhouse gas emissions with a slight decrease in Japan’s GDP.
相似文献10.
The case study is aimed at assessing impacts of on-farm level irrigation development and management on dry season rice production in the main irrigated rice production area of Myanmar. The study was carried out from 2003 to 2009 in the middle reaches of the Ngameoeyeik irrigation area of 28,000 ha. In addition to collecting information on water management and institutional arrangement of the study area, hydrologic and agronomic parameters were monitored during the study period. Results showed the effectiveness of on-farm level infrastructural development for increasing rice productivity owing to increased amount of water delivery, increased flexibility of water distribution, and improved drainage conditions. Besides, encouraging the involvement of farmers in design and implementation of the development led to improved farmer participation in the operation and maintenance of the irrigation system. The outcomes of this study demonstrated the importance of balancing between infrastructural and institutional development in irrigation systems of Southeast Asia. Such infrastructural development should be in close association with institutional development and capacity building, and the interactions between those two aspects should be well understood. 相似文献
11.
Rice genotype and fertilizer management for improving rice productivity under saline soil conditions
Djaman Koffi Mel Valere Boye Amith Diop Lamine Manneh Baboucarr El-Namaky Raafat Koudahe Komlan Futakuchi Koichi 《Paddy and Water Environment》2020,18(1):43-57
Paddy and Water Environment - Soil salinity is a threat to crop production in the Senegal River Delta where salt intrusion increases soil electrical conductivity and most of farmers had abandoned... 相似文献
12.
Introduction of the System of Rice Intensification in Kenya: experiences from Mwea Irrigation Scheme
There are various avenues for intensifying agricultural production, the most common being increased use of fertilizers, supplemental
irrigation of crops, and adoption of high-yielding varieties. These options are rather widely known to farmers around the
world, but they have not been widely adopted by smallholders in sub-Saharan Africa. The low adoption rate is related to complex
technical and socio-economic issues, such as poor extension services, lack of capital, failure to mobilize the requisite water,
or simply, poverty. The System of Rice Intensification (SRI) is in a special category of innovation in that, farmers stand
to gain multiple benefits from its use, including the possibility of increasing rice yields substantially, saving water, and
getting better grain quality, using differently the assets that they already have. A major impediment for the adoption of
SRI in Africa has been lack of knowledge about this intervention, especially for farmers already practicing irrigated agriculture.
Farmers generally have good business sense and will adopt technologies or practices once the benefits are proven and the risks
are seen as minor. SRI should be attractive for these reasons, but there are various issues to be resolved before large numbers
of farmers can adopt the method. This article reports on the steps taken and the technical and socio-economic issues addressed
in efforts to introduce SRI and promote it in Kenya, specifically in the Mwea Irrigation Scheme. A diverse set of individuals
and institutions in Kenya together embarked on the evaluation and dissemination of SRI methods in this East African country
beginning in July 2009. If the new methods can perform in Kenya as in other countries, this will bring much benefit to rice
farmers and rice consumers in the region. SRI is coming to Kenya relatively late, as it was the thirty-ninth country from
which favorable SRI results have been reported. This means that Kenyans can learn from others’ experience and evaluations,
and there is also now more of a supportive institutional framework. The initial results from on-farm SRI trials have been
positive, although not conclusive. They have given impetus to Kenyan farmers and institutions to collaborate within a multi-sectoral,
multi-level coalition that has provided an informal, multi-faceted platform for the evaluation, adaptation and dissemination
of SRI practices. The initiative in Kenya is now gaining more formal status and more resources. This experience is presented
to show the kinds of things that have been and can be done to utilize the SRI opportunity for raising land, labor, and water
productivity in the rice sector. 相似文献
13.
Farig Mohamed Shimizu Katsuyuki El-Kassar Gamal Abou El Hassan Waleed H. Fujimaki Haruyuki Kita Ichiro Watanabe Tsugihiro 《Paddy and Water Environment》2022,20(1):51-60
In the North Nile Delta of Egypt, the impacts of overplanting paddy rice on water delivery performance have not been discussed quantitatively. Further, the amount of water that could have been saved if farmers would follow the planned area is unknown. In this study, water delivery performance was assessed by comparison of actual paddy rice planting and the government’s planned conditions. For both conditions, performance indicators relating to adequacy, equity, and dependability were analyzed across six locations in conjunction with the branch canal water level in 2013 and 2014. Based on the difference between the actual water supply and planned water demand, the amount of water that could have been saved for downstream uses was calculated. The average adequacy for the investigation period was good at one location, fair at 2 locations, and poor at 3 locations in both years. Further, adequacy under both actual and planned conditions was poor in late July at all locations. The planned adequacy and dependability downstream and equity among locations improved compared to the actual condition in both years. Under the condition that paddy rice area is the upper limit planned by the government, about 12.3% and 9.6% of water could be potentially saved in each year. The difference between actual and planned water delivery performance is caused by the branch canal’s low water level. Control of overplanting paddy rice and coordination of water distribution among water user associations would improve stable water level in the canal and, eventually, water delivery performance.
相似文献14.
Quang Huy Hoang Naritaka Kubo Ngan Giang Hoang Hajime Tanji 《Paddy and Water Environment》2009,7(2):123-133
Ba Lai Irrigation Project is located at coastal area in the Mekong Delta. In dry season when the flow rate decreases and the
strong east wind blows into the delta, the salinity intrusion increases and seriously affects agricultural and domestic water
use. Intakes of Ba Lai system have to be closed for 1–3 months depending on their locations, and no water supply during this
period often causes water pollution in the project area. In order to solve such problems, this study aims to seek gate operation
procedures for salinity control and water environment improvement. A numerical model is developed to simulate water movement,
salinity concentration and duration of remaining water (water age) within the system under three scenarios: (1) without control
structures, (2) with available control structures, (3) with the full control structures. Through the numerical simulations,
control structures are confirmed to be an effective measure for the salinity control and suitable gate operation schedules
are proposed to improve the water environment in the project. 相似文献
15.
Pangasianodon aquaculture is the fastest growing food producing sector of the world. Recent national production of Pangasianodon hypophthalmus in India accounts for 0.7 million tonnes at present. Being influenced by trade and markets, P. hypophthalmus has been introduced to many countries including India. There has been a steady increase in the production of P. hypophthalmus by small and marginal farmers of the country. However, concern has arisen about the long-term sustainability due to diseases and its negative impacts on socio-economic aspects and biodiversity. Unregulated culture of P. hypophthalmus has been causing concern to environmental safety and warranting a very cautious and regulated approach to its culture. The standards, protocols and guidelines have been developed to address the issues of sustainability of Pangasianodon catfish production. 相似文献
16.
Transgenic Nipponbare which over-expressed a Na+/H+ antiporter gene OsNHX1 was used to compare its growth performance, water status and photosynthetic efficiency with its wild type under varying salinity regimes. Chlorophyll content, quantum yield and photosynthetic rate were measured to assess the impact of salinity stress on photosynthetic efficiency for transgenic and wild-type Nipponbare. Effects of salinity on water status and gas exchange to both lines were studied by measuring water use efficiency, instantaneous transpiration rate and stomatal conductance. Dry shoot weight and leaf area were determined after three months of growth to assess the impacts of salinity on the growth of those two lines. Our study showed that both lines were affected by salinity stress, however, the transgenic line showed higher photosynthetic efficiency, better utilization of water, and better growth due to low transpiration rate and stomatal conductance. Reduction of photosynthetic efficiency exhibited by the wild-type Nipponbare was correlated to its poor growth under salinity stress. 相似文献
17.
Yoji Kunimitsu Ryoji Kudo Toshichika Iizumi Masayuki Yokozawa 《Paddy and Water Environment》2016,14(1):131-144
Rice productivity will be affected by climate conditions not only in own region but also in neighboring regions through technological spillover. Measuring such direct and indirect influence of future climate change is important for policy making. This study analyzes socio-economic and climate factors in rice total factor productivity (TFP) and evaluates technological spillover effects by using the spatial econometric model. To consider geographical situation, we use hydrological model in addition to crop-yield and crop-quality models. Results show that spatial autoregressive tendencies were observed in rice TFP, even though the influences of climate factors were removed. Such spatial dependence brings about synergistic effects among neighboring prefectures in northern Japan and depression effects, like a spatial trap, from neighbors in southern Japan. Substantial impacts of climate change were as high as socio-economic factors but different in degrees by regions. Also, future climate change estimated by the global climate model enlarged fluctuation degree in rice TFP because accumulative or cancel out effects of temperature and precipitation occurred year by year. Therefore, technological development in rice production and provision of precise climate prediction to farmers are important in order to ease and mitigate these influences. 相似文献
18.
《Journal of Crop Improvement》2013,27(1-2):299-323
SUMMARY Salinity is a major problem that negatively impacts agricultural activities in many regions in the world, and especially the Near East and North Africa region. Generally, salinity problems increase with increasing salt concentration in irrigation water. Crop growth reduction due to salinity is generally related to the osmotic potential of the root-zone soil solution. This will lead to certain phenological changes and substantial reduction in productivity. Salinity also affects the soil physical properties. Sewage treated wastewater is an alternative water source for irrigation. Using such wastewater will provide a new water resource to expand agricultural activities as well as reduce the environmental pollution. Each country in the region has a unique system of rules and regulations to protect the quality of water resources. Important aspects that should be taken into account when using wastewater for irrigation are discussed, including some information on the different irrigation systems used in the region, and the factors leading to success of using saline water for economic crop production. Information on the use of saline water or marginal saline soils for wheat production and improvement of irrigation systems, including old land irrigation systems, under Egyptian conditions is also presented. The regional experiences and the future prospects of using saline water for crop production that vary greatly among countries in the Near East and North Africa region are summarized. This article also presents information on special cultivation methods, such as protected agriculture and soilless culture that can help in alleviating the salinity effects. Finally, the article includes some examples on the inherited knowledge for saline agriculture that conveys the grower's experience in the Near East and North Africa region where several living examples for unique and sustainable cultivation system are still in operation. One of the most impressive cultivation techniques for bio-saline crop management in Egypt is the Edkawy production system. 相似文献
19.
苏打盐碱地是我国重要的后备耕地资源,但因其土壤理化性质恶劣,种植作物产量低。改良和合理利用苏打盐碱地对于区域农业发展具有重要意义,但改良周期长、难度大、成本高。本研究通过大田试验,设置5个打孔密度,分析了填充改良物条件下不同打孔密度对土壤团聚体结构、pH值、含盐量以及水稻产量的影响。结果表明,与不打孔对照相比,填充改良物条件下打孔处理增加了耕层土壤水稳定性团聚体的含量,降低了耕层土壤pH值和含盐量,增加了水稻的有效穗数和结实率,从而提高了水稻产量。随着打孔密度的增加,耕层土壤改良效果有不同程度的提高,与不打孔对照相比,当打孔密度达到15孔/m2时,耕层土壤中水稳定性团聚体含量提高26.22% ,土壤pH 值下降4.75%,含盐量降低10.16%,水稻的实际产量增加72.57%。继续增加打孔密度,水稻产量有所下降,但与15孔/m2的打孔密度处理差异不显著。综合生产实际和可操作性,打孔密度为15孔/m2或每1 m2的打孔面积为0.12 m2可作为改良中重度苏打盐碱水田水稻种植的合理打孔方案。结果为苏打盐碱水田改良技术创新提供了理论依据。 相似文献
20.
Dipanwita Haldar Rahul Nigam C. Patnaik Sujay Dutta Bimal Bhattacharya 《Paddy and Water Environment》2016,14(4):451-461
Assessing the nature and extent of damage due to natural calamities remains one of the thrust areas in monitoring resource inventory through remote sensing. The effect of the cyclone Phailin and the post-incessant rains during second fortnight of October 2013 on coastal Odisha was studied in terms of rice area flooded, submerged and damaged. Multi-temporal SAR data were analysed to obtain the rice mask, and from this rice mask, the flood affected rice area was determined. Taluka-wise and district-wise crop loss proportion was estimated, and the overall production loss has been estimated. SAR data aided in delineation of flooded regions, while AWiFS NDVI data of subsequent dates showed both continued inundation and crop vigour status post-flood time period. The ground truth indicated that a major portion of the inundated region was not rice but was typha grasses and harvested rice field which should not be accounted as damage to rice crop. The damage on crop yield was difficult to assess; however, the inundation of the crop at panicle initiation and flowering would have impact on grain filling (results in chaffiness) and was considered as completely damaged. Most of the current inundated rice regions fall in this category. It was estimated that a total of 0.167 million hectares and 0.37 million tons of rice crop was lost in the cyclone and floods. The district-level percentage area of rice flooded was communicated to State Remote Sensing Centre in four days timeframe. The overall accuracy obtained for the validation of the ground truth sites was 91.5 %. 相似文献