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Manila, Philippines

The International Rice Research Institute is an international independent research and training organization with headquarters in Los Baños, Laguna in the Philippines and offices in sixteen countries. The non-governmental organization was established in 1960 to develop new rice varieties and rice crop management techniques with finding sustainable ways to improve the well-being of poor rice farmers and consumers as well as the environment in mind.The institute is one of 15 agricultural research centers on the world that form CGIAR. It is also the largest non-profit agricultural research center in Asia.IRRI received the 2010 BBVA Foundation Frontiers of Knowledge Award in the category of Development Cooperation. Wikipedia.

Chauhan B.S.,International Rice Research Institute
Weed Technology

Rice is a principal source of food for more than half of the world population, and more than 90% of rice worldwide is grown and consumed in Asia. A change in establishment method from manual transplanting of rice seedlings to dry-seeded rice (DSR) has occurred in some countries as growers respond to increased costs or decreased availability of labor or water. However, weeds are a major constraint to DSR production because of the absence of the size differential between the crop and the weeds and the suppressive effect of standing water on weed growth at crop establishment. Herbicides are used to control weeds in DSR, but because of concerns about the evolution of herbicide resistance and a scarcity of new and effective herbicides, there is a need to integrate other weed management strategies with herbicide use. In addition, because of the variability in the growth habit of weeds, any single method of weed control cannot provide effective and season-long control in DSR. Various weed management approaches need to be integrated to achieve effective, sustainable, and long-term weed control in DSR. These approaches may include tillage systems; the use of crop residue; the use of weed-competitive cultivars with high-yield potential; appropriate water depth and duration; appropriate agronomic practices, such as row spacing and seeding rates; manual or mechanical weeding; and appropriate herbicide timing, rotation, and combination. This article aims to provide a logical perspective of what can be done to improve weed management strategies in DSR. © 2012 Weed Science Society of America. Source

Chauhan B.S.,International Rice Research Institute
Crop Protection

Weedy rice, an emerging problem in Asia, increases production costs and reduces farmers' income through yield reduction and through lowered rice value at harvest. Rice farmers in many Asian countries are shifting from transplanting to direct seeding; however, due to physical and physiological similarities of weedy rice to cultivated rice and the absence of standing water at the time of crop emergence, adoption of direct-seeded rice systems makes weedy rice infestation one of the most serious problems. Selective herbicides to control weedy rice in conventional rice cultivars are not available and therefore managing weedy rice is a challenging and increasing problem for farmers in Asia. In the absence of selective herbicides, various cultural weed management strategies may help reduce the problem of weedy rice. These strategies may include the use of clean seeds and machinery, use of stale seedbed practice, thorough land preparation, rotation of different rice establishment methods, use of high seeding rate and row-seeded crop, use of purple-coloured cultivars, use of flooding, and adoption of crop rotation. © 2013 Elsevier Ltd. Source

Echinochloa species are problematic weed species in direct-seeded rice systems in Asia. Because of concern about the continuous use of single herbicides, cultural weed management strategies need to be developed to maintain the sustainability of direct-seeded rice systems. However, the design of such strategies requires an understanding of the differential responses of weeds to shade caused by crop interference. The effects of shade on growth and seed production of Echinochloa colona, Echinochloa crus-galli, and Echinochloa glabrescens were determined. Weeds of three Echinochloa species were grown continuously in full sunlight or in 50% or 25% of full sunlight, or started in full sunlight and transferred to 50% or 25% of full sunlight at 21 days after sowing. The results suggested that changes in shade regime did not affect the plant height of E. colona and E. glabrescens; however, shade reduced the height of E. crus-galli. Compared with the plants grown in full sunlight, 75% of continuous shade reduced E. crus-galli height by 22%. Shade reduced leaf, total shoot, and root biomass and seed production in all the weed species, if occurred during the early growth of the weeds. The weeds responded with increased leaf biomass ratio when grown in shade. Compared with full sunlight, continuous shade of 75% increased leaf biomass ratio by 90% in E. colona and this value was 25% in the other two species. The results of this study show that shade can reduce weed growth and seed production of Echinochloa species but it should not be considered as a stand-alone strategy to manage these weeds in rice. This highlights the need for the integration of other weed management strategies to achieve complete control of these species. © 2012 Elsevier Ltd. Source

Chauhan B.S.,International Rice Research Institute
Weed Science

Crowfootgrass, a C4 species, is one of the principal weeds of dry-seeded rice in Asia. Weed management decisions for this species can be derived from knowledge of its seed germination biology. Experiments were conducted in the laboratory and screenhouse to determine the effects of light, alternating day/night temperatures, water stress, seed burial depth, and rice residue on seed germination and seedling emergence of crowfootgrass and to evaluate the response of this weed to commonly available selective POST herbicides in the Philippines. Light stimulated seed germination, but it was not an absolute requirement for germination. Germination in the light/dark regime was greater at alternating day/night temperatures of 25/15 C (92%) than at 30/20 (70%) or 35/25 C (44%). The osmotic potential required for 50% inhibition of maximum germination was-0.23 MPa, although some seeds germinated at-0.6 MPa. Seedling emergence was greatest for the seeds placed on the soil surface (64%), and emergence declined with increased burial depth in soil. No seedlings emerged from a burial depth of 6 cm or greater. Seedling emergence of crowfootgrass was reduced by the addition of rice residue to the soil surface at rates equivalent to 4 to 6 Mg ha -1. Fenoxaprop-p-ethyl + ethoxysulfuron at 45 g ai ha -1 provided excellent control of crowfootgrass when applied at the four-(99%) and six-leaf (86%) stage. The information gained from this study could contribute to developing components of integrated weed management strategies for crowfootgrass. Soil inversion by tillage to bury weed seeds below their maximum depth of emergence, use of crop residue as mulch, and early application of an effective POST herbicide could serve as important tools for managing crowfootgrass. Nomenclature: Bispyribac-sodium; fenoxaprop-p-ethyl + ethoxysulfuron; penoxsulam + cyhalofop; crowfootgrass, Dactyloctenium aegyptium (L.) Willd. DTTAE; rice, Oryza sativa L. © Weed Science Society of America. Copyright © 2011 BioOne All rights reserved. Source

Von Caemmerer S.,Australian National University | Quick W.P.,International Rice Research Institute | Quick W.P.,University of Sheffield | Furbank R.T.,CSIRO

Another "green revolution" is needed for crop yields to meet demands for food. The international C4 Rice Consortium is working toward introducing a higher-capacity photosynthetic mechanism - the C 4 pathway - into rice to increase yield. The goal is to identify the genes necessary to install C4 photosynthesis in rice through different approaches, including genomic and transcriptional sequence comparisons and mutant screening. Source

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