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1.
Breaking the yield frontier of rice 总被引：26，自引：0，他引：26
Gurdev S. Khush 《GeoJournal》1995,35(3):329-332
Major increases in rice production have occurred during the last 25 years, due to large-scale adoption of high-yielding semidwarf rice varieties. However, the rate of increase of rice production has slowed down, and the rate of population growth of rice consumers is now higher than the rate of increase of rice production. Severe food shortages are therefore likely to occur in 20–30 years if the trend is not reversed. To meet these food needs, rice varieties with higher yield potential are needed. The yield potential of the modern high-yielding varieties grown under the best tropical conditions is 10 t ha–1. A research program is under way to develop varieties with a yield potential of 15 t ha–1. One strategy aims to develop new rice plants with a harvest index of 0.6 (60% grain: 40% straw by weight) and with an increased ability for photosynthesis to increase total biological yield. The harvest index of the modern high-yielding varieties is 0.5. Such new varieties should have a yield potential of 12.5–13 tons ha–1. These new plant type varieties will be used to produce hybrid rices with a yield advantage of 25% over the best parent. Such hybrids would have a yield potential of 15 t ha–1. 相似文献
2.
Gurdev S. Khush 《GeoJournal》1995,35(3):275-284
Green revolution technology, centered on high-yielding varieties, has revolutionized rice production since the late 1960's. These varieties are characterized by higher yield potential, better grain quality, shorter growth duration, multiple resistance to diseases and insects and tolerance to problem soils. High yielding varieties are now planted to 70% of the world's rice lands. Most countries in the Asian rice belt have become self sufficient in rice and some have exportable surpluses. The real prices of rice have declined in most countries. This price decline has benefitted the urban poor and rural landless. Labor requirement has also increased from higher intensity of cropping and resulted in growth of income of the rural landless workers. Availability of rice varieties with multiple resistance reduced the need for application of agrochemicals and facilitated the adoption of integrated pest management practices. The population of rice consumers is increasing at the rate of 2% annually. However the rate of growth of rice production has slowed to 1.2%. To reverse this trend, rice plant types with higher yield potential are being developed. 相似文献
3.
J. Bennett 《GeoJournal》1995,35(3):333-335
Rice breeders are looking to basic bioscience and biotechnology for help in the solution of important problems that conventional breeding methods have not satisfactorily solved. Among these problems are durable resistance to recalcitrant pests and diseases such as yellow stem borer, gall midge, sheath blight, bacterial leaf blight, blast and tungro virus, and tolerance of abiotic stresses such as drought, salinity and submergence. Nutrient use efficiency, yield potential and efficient hybrid rice production are additional problems for which biotechnology solutions are envisioned. IRRI's biotechnology program emphasizes techniques such as molecular markers, anther culture and DNA fingerprinting that accelerate conventional breeding, and also techniques such as wide hybridization and genetic engineering that broaden the gene pool that breeders can exploit. IRRI's experience in adopting and adapting biotechnology for use in its own breeding program is shared with the national agricultural research systems of Asia through the Asian Rice Biotechnology Network. 相似文献
4.
R. P. Samui 《Journal of Earth System Science》1999,108(4):309-316
A study was conducted with four traditional photosensitive and one high yielding rice varieties grown during the kharif season
under rainfed conditions. The curvilinear technique was used to examine the influence of meteorological parameters on the
yield of rice. Rice varieties grown in different agroclimatic regions performed differently to climatic parameters. The maximum
yield was observed when rainfall ranged between 100 and 115 cm. Maximum and minimum temperature ranges of 29–32°C and 23–25°C
respectively appear ideal for optimum yield. Photoinsensitive high yielding variety performed well even at low light intensity
(250-350 hours of bright sunshine). 相似文献
5.
Improving sustainable productivity in rice-based rainfed lowland systems of South and Southeast Asia 总被引：2，自引：0，他引：2
The lowland rice-producing areas of the world may be classified first by water regime: those with a reliable and controlled external supply of water and a drainage system, theirrigated ricelands, and those depending solely on rainfall and runoff, therainfed lowlands. The latter are diverse and range from drought-prone lands to those subjected to flooding in excess of several meters during the growing season. Rice production in these areas hasn't really benefited from the technological advances that were so successful for irrigated rice, yet hundreds of millions of Asia's poorest people depend upon the rainfed lowlands for their livelihood. This paper presents a retionale for devoting resources to research for the rainfed environments of Asia, and examines the institutional context and the key constraints and opportunities for intervention. The research strategies directed towards increasing sustainable productivity in these areas are presented, including the unique challenges presented by environmental heterogeneity and variability. 相似文献
6.
Michael T. Jackson 《GeoJournal》1995,35(3):267-274
The development of improved rice varieties depends upon access to the genetic resources of rice. These are represented by the thousands of locally adapted varieties that farmers have grown for generations, and over 20 wild rice species native to Asia, Africa, and Latin America. Rice genetic resources are threatened with extinction in farming systems when farmers adopt improved varieties, and the wild species may be lost through destruction of their habitats.IRRI has been at the forefront of international efforts for three decades to collect and conserve the biodiversity of rice. More than 80,000 samples of cultivated and wild rices are conservedex situ in the genebank at IRRI.In situ conservation of rice genetic resources is likely to become an important complementary strategy in the future.Through utilization of rice germplasm, resistances to pests and diseases have been incorporated into improved varieties. These are shared worldwide through the International Network for Genetic Evaluation of Rice (INGER). The impact of biotechnology and intellectual property rights on germplasm conservation is discussed. 相似文献
7.
Factors affecting rice productivity in Central Luzon, Philippines, among four classes of level, namely Class A — fully irrigated, Class B — partially irrigated, Class C — lowland rainfed, and Class D — upland rainfed, are examined in this study. An attempt is made to identify the ajor underlying dimensions of rice productivity and to ascertain the set of postulated factors that best determines variations associated with rice productivity. While principal-axes factor analysis is applied to isolate the underlying dimensions associated with rice productivity for 200 farms, stepwise multiple regression analysis is employed to determine which among the thirty-eight hypothesized variables have the strongest influence in accounting for variations associated with rice productivity in Central Luzon.The results showed that the economic and institutional factors accounted for most of the variations in rice productivity among the four classes of farms. Whereas the economic variables were concerned with the amount and manner in which economic inputs were used and with the amount of fixed asset in rice production, the institutional factors were focused mainly on membership in the government rice production program and the amount of loan available to farmer members. 相似文献
8.
Rice research: Food for 4 billion people 总被引：1，自引：0，他引：1
K. Lampe 《GeoJournal》1995,35(3):253-261
Rice is the staple food for about 2.4 billion people and provides more than 20% of their daily calorie intake. This number will increase to 4.6 billion people by 2050. Just to meet the projected demand for rice in the 21st Century, the world's annual rough rice production must increase from 520 million tons today to at least 880 million tons by 2025, an increase of almost 70%. That requirement may rise to one billion tons by the year 2050.To produce such an increase, on decreasing arable land, with reduced water resources, with less rural labor input, and with fewer agrochemical inputs, will require major contributions from research to increase yields and reduce inputs, costs and losses. And, more important, it will require coordinated national and international scientific efforts and, above all, strong political will, determined governments and major investments in food research in the rice-consuming countries of the world. 相似文献
9.
Y. Ali G. Sarwar Z. Aslam F. Hussain T. Rafique 《International Journal of Environmental Science and Technology》2005,2(1):27-33
Thirteen genotypes of rice comprising of approved varieties and elite candidate lines were studied at three different water regimes by supplying 12, 8 and 4 numbers of irrigations at different intervals/ stages. The experiment was conducted at NIAB Farm Faisalabad, Pakistan on a clay loam soil applying normal doses of N and P fertilizers during 2002–2003 keeping varieties in the main plot while treatments in sub plot. The data for twelve morphological characters i.e. days to flower, days to mature, plant height, panicle length, number of productive tillers, number of primary and secondary branches, 1000 grain weight, sterile grains per spike, number of total grains per spike, fertility percentage, grain yield were recorded and subjected to analysis of variance and means were compared following DMR test. Effect of water stress on different morphological attributes in all treatments showed significant differences. Plant height, branches per plant, number of grains and grain yield reduced at less number of irrigations while sterility percentage was increased at less moisture conditions. Maximum grain yield (5349 Kg/ha) was achieved at T1 where 12 number of irrigations were applied at T2 (8 irrigations) and T3 (4 irrigations). The yield reduction was observed from 30.32% to 42.53%, respectively as compared to T1 (12 irrigations). Rice variety DM 64198 produced the highest seed yield (4766 Kg/ha) followed by DM-3-89 (4770 Kg/ha).This might be due to different genetic make up of the breeding lines and their behavior and interaction in water stress environment. Furthermore, high irrigation level made possible the appropriate water availability possible at proper time for performing different types of physiochemical processes of development that hindered at less number of irrigation or water stress environment. It may be concluded that for achieving maximum economic yield, at least 12 irrigations were essential otherwise the production will be reduced to a considerable extent. 相似文献
10.
《Geoforum》2014
The System of Rice Intensification (SRI) and rice genetic improvement are proposed as two approaches to improving and increasing rice production. In recent exchanges, they have been represented by their respective supporters as starkly contrasting, almost mutually incompatible alternatives. However, advocates on both sides of this argument have tended to stress the genetic and physiological characteristics of rice plants and place less emphasis on the spatially and temporally situated knowledge and management skills of farmers, which are the means by which any agricultural technology is locally adapted and integrated into livelihood strategies, and technological potential is translated into real outcomes in specific settings. Taking this proposition seriously would entail a substantial reorganisation of agricultural research and extension, bridging the historical divide between these two wings of professional agronomy. It would require agronomists of both types to work more collaboratively with farmers. It would also require scientists to produce new kinds of outputs, such as analytical frameworks, heuristics and decision-making tools to help farmers apply scientific insights to their own constrained circumstances. This argument is made with reference to the cases of SRI (a cultivation system that is said to boost farm yields without the need for genetically improved germplasm) and C4 rice (a crop-improvement project intending to ‘supercharge’ rice photosynthesis to increase rice yields). The paper uses the agronomic concepts of the ‘yield gap’ and the ‘yield ceiling’ to offer a perspective on strategic questions about the goals and organisation of agricultural research and extension. 相似文献
11.
Intensification of irrigated rice systems: Learning from the past to meet future challenges 总被引：6，自引：0，他引：6
More than 75% of all rice is produced on irrigated land. Although the green revolution was driven by both an expansion of irrigated rice area and increased yield per unit land area, the next quantum leap must come exclusively from increasing yields on existing crop land. We review the structural changes that have accompanied the intensification process, and examine the major biophysical and economic challenges that confront Asian farmers who must further intensify irrigated rice systems to achieve a yield increase of more than 60% by the year 2025. 相似文献
12.
IRRI's Training Program and Information and Knowledge Exchange Program entail collaboration and partnerships with national agricultural research systems (NARS). Both programs disseminate research results to develop collaborators and accelerate information transfer. IRRI's training program has evolved in parallel with IRRI's strategic research focus to address specialized needs of national rice scientists. Forging partnerships with NARS rice-related training programs to collaborate in national and regional in-country training activities addresses the more general training needs of national rice research systems. IRRI's information and knowledge exchange program publishes and disseminates research results to national rice scientists, maintains and makes available to rice scientists the world's largest collection of rice literature, develops and maintains rice data bases, organizes conferences and workshops to discuss research findings with NARS scientists, and is actively involved in public awareness activities. 相似文献
13.
Losses caused by pests remain an important constraint to achieving high rice yields. Potentials of protecting these losses have stimulated innovations in pesticide development. Today the rice pesticide market is valued at US $ 3.0 billion per year. With reducing land available for rice production and increasing demand for food production, attention is turning towards intensification through higher fertilizer inputs and cropping. Such intensifications may in turn increase pest intensities and demand for more pesticides.A large proportion of insecticide sprays administered by rice farmers in Asia is influenced by misperceptions and overestimations of damages. Most farmers apply their first sprays in the first 40 days after crop establishment to control leaf feeding insects. However, these pests do not occur in sufficiently high densities to cause yield loss. Instead, such early season sprays may contribute towards development of secondary pests, such as the brown planthopper. Strategies to reduce insecticide use need to focus on enhancing naturally occurring biological control and understanding farmers' decision making behavior.Most fungicides used in rice are in the sub-tropical countries, like Japan, Korea, Taiwan and Vietnam. An important strategy towards reduction in fungicide use is through host plant resistance and gene deployment strategies. With biotechnology, tools may be used to characterize population structures in order to enhance these strategies. Cultural practices, such as rotations, cultivar mixtures, crop mosaics and planting times are being investigated.As cost of labor increases, farmers are likely to resort to using herbicides. The best way to accomplish weed control is the simultanous application of a variety of practices. These will include cultural, mechanical and chemical methods. The potentials of using naturally occurring enemies, such as plant pathogens, and the use of allelopathy are also being explored. 相似文献
14.
Impact of climate change on rainfed rice and options for adaptation in the lower Mekong Basin 总被引：1，自引：0，他引：1
We assessed the potential impact of climate change on the yield of rainfed rice in the lower Mekong Basin and evaluated some adaptation options, using a crop growth simulation model. Future climate projections are based on IPCC SRES A2 and B2 scenarios as simulated by ECHAM4 global climate model downscaled for the Mekong Basin using the PRECIS system. We divided the basin into 14 agro-climatic zones and selected a sub-catchment within each zone for the model and assessed the impact for the period of 2010–2030 and 2030–2050. In general, the results suggest that yield of rainfed rice may increase significantly in the upper part of the basin in Laos and Thailand and may decrease in the lower part of the basin in Cambodia and Vietnam. The increase is higher during 2030–2050 compared to the period of 2010–2030 for A2 scenario. For B2 scenario, yield increase is higher during 2010–2030. The impact is mainly due to the change in rainfall and CO2 concentration in the atmosphere. We have tested widely used adaptation options such as changing planting date, supplementary irrigation, and reduction in fertility stress and found that negative impact on yield can be offset and net increase in yield can be achieved. 相似文献
15.
16.
中国旱灾农业承灾体脆弱性诊断与评价 总被引：9，自引：0，他引：9
旱灾是世界上影响面最广、造成农业损失最大的自然灾害类型，世界近一半的国家干旱严重。中国旱灾频繁，每年旱灾损失占各种自然灾害损失的15%以上，随着人口和农业的快速发展，农业承灾体脆弱性对灾情的放大也在增加。基于灾害系统理论，从致灾因子和耕地承灾体的区域组合角度，在旱灾频发高值区，选择雨养农业、灌溉农业和水田农业为主要承灾体类型，构建了农业旱灾脆弱性生产压力和生活压力，灾前—灾中易损性和灾中—灾后适应性等农业旱灾承灾体脆弱性诊断指标体系。提出脆弱性评价的区域模型，即：雨养农业的易损—适应模型（兴和）、灌溉农业的生产—生活压力模型（邢台）和水田农业的需水—灌水模型（鼎城）。基于农业承灾体脆弱性评价，提出制定适应降水变化的波动土地利用结构调整区域政策、建立农业生态—生产范式、建立“水银行”管理机制、建立用水效益和开源节流的评估体系以及加强“截水—抽水—控水”为一体的灌溉系统工程建设，提高灌溉应急能力等对策，以期为农业旱灾的防御和区域粮食安全决策提供科学依据。 相似文献
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18.
Nitrogen supply is critical in attaining yield potential. Achieving the 50% higher yields that will be needed by 2025 will require at least double the 10 m tons of N fertilizer that is currently used each year for rice production. But manufacturing of fertilizer N is dependent on fast depleting non-renewable energy resources. It is in this context that biological nitrogen-fixation-derived N assumes importance in the lowland soils that provide about 86% of the world's rice.Among the conventional systems, green-manure legumes have high N supply potential. But due to associated additional costs such as labour and land opportunity, they do not form an attractive option for farmers. Rice associative N2 fixation (ANF) although has low activities, any increase will be attractive to farmers as it does not require changes in existing cropping systems, and soil and water management practices. Recently, we identified quantitative trait loci underlying ANF in rice (Wu, P.; Zhang, G.; Ladha, J. K.; McCouch, S. and Huang, N.: Restriction fragment length polymorphic markers associated with rice varietal ability to stimulate nitrogen fixation in rhizosphere. Rice Genetic Newsletter 1994 — submitted). The presence of this trait in rice provides an evidence of the occurrence of genetic factors which regulate interaction of rice with diazotrophs in rhizosphere. However, the ANF trait governing the loose diazotroph-rice association appears to have limited potential for enhancing yield. To achieve higher yields, intimate association similar to sugar cane-Acetobacter/legume-rhizobia symbioses will have to be developed in rice. In this paper, we discuss the strategies for transferring nitrogen-fixing capacity to rice. 相似文献
19.
Long-term increase in diffuse groundwater recharge following expansion of rainfed cultivation in the Sahel,West Africa 总被引：1，自引：0，他引：1
Maïmouna Ibrahim Guillaume Favreau Bridget R. Scanlon Jean Luc Seidel Mathieu Le Coz Jérôme Demarty Bernard Cappelaere 《Hydrogeology Journal》2014,22(6):1293-1305
Rapid population growth in sub-Saharan West Africa and related cropland expansion were shown in some places to have increased focused recharge through ponds, raising the water table. To estimate changes in diffuse recharge, the water content and matric potential were monitored during 2009 and 2010, and modeling was performed using the Hydrus-1D code for two field sites in southwest Niger: (1) fallow land and (2) rainfed millet cropland. Monitoring results of the upper 10 m showed increased water content and matric potential to greater depth under rainfed cropland (>2.5 m) than under fallow land (≤1.0 m). Model simulations indicate that conversion from fallow land to rainfed cropland (1) increases vadose-zone water storage and (2) should increase drainage flux (～25 mm year?1) at 10-m depth after a 30–60 year lag. Therefore, observed regional increases in groundwater storage may increasingly result from diffuse recharge, which could compensate, at least in part, groundwater withdrawal due to observed expansion in irrigated surfaces; and hence, contribute to mitigate food crises in the Sahel. 相似文献
20.
《Geoforum》2013
While plant diseases have been the subject of scientific research, little is known about the perceptions of key actors towards plant disease risk within specific food sectors. Drawing on concepts of risk and uncertainty, and using in-depth interviews, this paper examines the ways in which endemic plant disease risks in the UK wheat sector are perceived and managed by key ‘upstream’ and ‘downstream’ businesses, as well as by farmers and agronomists. A majority of interviewees feel that plant disease is a controllable risk and one that rests mainly at the point of production (i.e. with farmers) within the wheat sector. This assumed ‘control’ is based mainly around the availability of plant protection products (e.g. fungicides) which reduce the sense of risk attributable to outbreaks of plant disease. As a consequence, there can be a tendency to grow higher-yielding wheat varieties that are less disease-resistant. The potential banning of certain fungicides under EU legislation and climate change are perceived future threats that could increase uncertainty and change the balance between ‘control’ and ‘resistance’, the latter through the use of more disease-resistant wheat varieties. Further research is needed on the perceived impacts of plant diseases and on how different wheat sector actors will contribute to the future control of plant diseases and the development of more integrated systems of plant disease management. 相似文献