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Weed Ecology and Weed Management Strategies for Dry-Seeded Rice in Asia

Published online by Cambridge University Press:  20 January 2017

Bhagirath S. Chauhan
Bhagirath S. Chauhan*
Affiliation:
International Rice Research Institute, Los Baños, Philippines
*
Corresponding author's E-mail: [email protected]
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Abstract

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.

El arroz es una de las principales fuentes de alimentación para más de la mitad de la población del mundo; a nivel global, más del 90% es cultivado y consumido en Asia. Un cambio en el método de establecimiento de trasplante manual de plántulas de arroz a siembra directa de la semilla (DSR), ha ocurrido en algunos países conforme los agricultores responden al incremento de costos o reducciones en la disponibilidad de mano de obra o agua. Sin embargo, la maleza constituye una importante limitante para la producción DSR, debido a la ausencia de tamaño diferencial entre el cultivo y la maleza, y al efecto restrictivo del agua encharcada en el crecimiento de la maleza durante el establecimiento del arroz. Herbicidas son usados para el control de la maleza en DSR, pero debido a la preocupación por la evolución de la resistencia a los mismos y a la escasez de herbicidas nuevos y eficaces, existe una necesidad de integrar otras estrategias de manejo de maleza con el uso de herbicidas. Además, debido a la variabilidad en los hábitos de crecimiento de la maleza, un solo método individual de control no puede proporcionar a lo largo de la estación un control eficaz en DSR. Varios enfoques de manejo de la maleza necesitan integrarse para lograr en DSR un control eficaz, sustentable y de larga duración. Estos enfoques podrían incluir sistemas de labranza, el uso de residuos de cultivo, el uso de cultivares competitivos con la maleza con alto potencial de rendimiento, apropiada profundidad y duración de agua, prácticas agronómicas adecuadas tales como espacio entre surcos y densidad de siembra, deshierbe manual o mecánico, tiempo apropiado de control, rotación y combinación. El objetivo de este documento es proporcionar una perspectiva lógica de lo que puede hacerse para mejorar las estrategias de manejo de maleza en DSR.

Keywords

RiceOryza sativa L.Stale seedbedseeding raterow spacingfloodingresiduetillage systemzero-tillherbicide
Type
Review
Information
Weed Technology , Volume 26 , Issue 1 , March 2012 , pp. 1 - 13
Copyright
Copyright © Weed Science Society of America 

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References

Literature Cited

Akobundu, I. O. and Ahissou, A. 1985. Effect of interrow spacing and weeding frequency on the performance of selected rice cultivars on hydromorphic soils of West Africa. Crop Prot. 4:71–76.CrossRefGoogle Scholar
Ampong-Nyarko, K. and De Datta, S. K. 1993. Effects of light and nitrogen and their interaction on the dynamics of rice ∶ weed competition. Weed Res. 33:1–8.CrossRefGoogle Scholar
Baker, B. H. and Nabi, L. N. A. 2003. Seed germination, seedling establishment and growth patterns of wrinklegrass (Ischaemum rugosum Salisb.). Weed Biol. Manag. 3:8–14.CrossRefGoogle Scholar
Banks, P. A. and Robinson, E. L. 1982. The influence of straw mulch on the soil reception and persistence of metribuzin. Weed Sci. 30:164–168.Google Scholar
Banting, J. 1966. Studies on the persistence of Avena fatua . Can. J. Plant Sci. 46:129–140.Google Scholar
Benvenuti, S. and Macchia, M. 1995. Hypoxia effect on buried weed seed germination. Weed Res. 35:343–351.CrossRefGoogle Scholar
Bolfrey-Arku, G. E.-K., Chauhan, B. S., and Johnson, D. E. 2011. Seed germination ecology of itchgrass (Rottboellia cochinchinensis). Weed Sci. 59:182–187.Google Scholar
Buhler, D. D. 1995. Influence of tillage systems on weed population dynamics and management in corn and soybean in the central USA. Crop Sci. 35:1247–1258.CrossRefGoogle Scholar
Burgos, N. R., Norman, R. J., Gealy, D. R., and Black, H. 2006. Competitive N uptake between rice and weedy rice. Field Crops Res. 99:96–105.CrossRefGoogle Scholar
Caton, B. P., Foin, T. C., and Hill, J. E. 1997. Phenotypic plasticity of Ammannia spp. in competition with rice. Weed Res. 37:33–38.CrossRefGoogle Scholar
Chauhan, B. S. 2011. Crowfootgrass (Dactyloctenium aegyptium) germination and response to herbicides in the Philippines. Weed Sci. 59:512–516.Google Scholar
Chauhan, B. S., Gill, G., and Preston, C. 2006a. Influence of tillage systems on vertical distribution, seedling recruitment and persistence of rigid ryegrass (Lolium rigidum) seed bank. Weed Sci. 54:669–676.CrossRefGoogle Scholar
Chauhan, B. S., Gill, G., and Preston, C. 2006b. Tillage systems affect trifluralin bioavailability in soil. Weed Sci. 54:941–947.CrossRefGoogle Scholar
Chauhan, B. S., Gill, G., and Preston, C. 2006c. Tillage system effects on weed ecology, herbicide activity and persistence: a review. Aust. J. Exp. Agric. 46:1557–1570.CrossRefGoogle Scholar
Chauhan, B. S. and Johnson, D. E. 2008a. Seed germination and seedling emergence of nalta jute (Corchorus olitorius) and redweed (Melochia concatenata): important broadleaf weeds of the tropics. Weed Sci. 56:814–819.CrossRefGoogle Scholar
Chauhan, B. S. and Johnson, D. E. 2008b. Seed germination and seedling emergence of giant sensitiveplant (Mimosa invisa). Weed Sci. 56:244–248.CrossRefGoogle Scholar
Chauhan, B. S. and Johnson, D. E. 2008c. Dormancy, germination and emergence of Sida rhombifolia L. Indian J. Weed Sci. 40:6–10.Google Scholar
Chauhan, B. S. and Johnson, D. E. 2008d. Germination ecology of goosegrass (Eleusine indica): an important grass weed of rainfed rice. Weed Sci. 56:699–706.Google Scholar
Chauhan, B. S. and Johnson, D. E. 2008e. Seed germination ecology of purple-leaf button weed (Borreria ocymoides) and Indian heliotrope (Heliotropium indicum): two common weeds of rain-fed rice. Weed Sci. 56:670–675.Google Scholar
Chauhan, B. S. and Johnson, D. E. 2008f. Germination ecology of two troublesome Asteraceae species of rainfed rice: Siam weed (Chromolaena odorata) and coat buttons (Tridax procumbens). Weed Sci. 56:567–573.CrossRefGoogle Scholar
Chauhan, B. S. and Johnson, D. E. 2008g. Influence of environmental factors on seed germination and seedling emergence of eclipta (Eclipta prostrata) in a tropical environment. Weed Sci. 56:383–388.CrossRefGoogle Scholar
Chauhan, B. S. and Johnson, D. E. 2008h. Germination ecology of southern crabgrass (Digitaria ciliaris) and India crabgrass (Digitaria longiflora): two important weeds of rice in tropics. Weed Sci. 56:722–728.CrossRefGoogle Scholar
Chauhan, B. S. and Johnson, D. E. 2008i. Germination ecology of Chinese sprangletop (Leptochloa chinensis) in the Philippines. Weed Sci. 56:820–825.CrossRefGoogle Scholar
Chauhan, B. S. and Johnson, D. E. 2009a. Ludwigia hyssopifolia emergence and growth as affected by light, burial depth and water management. Crop Prot. 28:887–890.Google Scholar
Chauhan, B. S. and Johnson, D. E. 2009b. Influence of tillage systems on weed seedling emergence pattern in rainfed rice. Soil Till. Res. 106:15–21.CrossRefGoogle Scholar
Chauhan, B. S. and Johnson, D. E. 2009c. Germination, emergence, and dormancy of Mimosa pudica . Weed Biol. Manag. 9:38–45.CrossRefGoogle Scholar
Chauhan, B. S. and Johnson, D. E. 2009d. Germination ecology of spiny (Amaranthus spinosus) and slender amaranth (A. viridis): troublesome weeds of direct seeded rice. Weed Sci. 57:379–385.CrossRefGoogle Scholar
Chauhan, B. S. and Johnson, D. E. 2009e. Seed germination ecology of junglerice (Echinochloa colona): a major weed of rice. Weed Sci. 57:235–240.CrossRefGoogle Scholar
Chauhan, B. S. and Johnson, D. E. 2009f. Ecological studies on Cyperus difformis, C. iria and Fimbristylis miliacea: three troublesome annual sedge weeds of rice. Ann. Appl. Biol. 155:103–112.Google Scholar
Chauhan, B. S. and Johnson, D. E. 2009g. Seed germination ecology of Portulaca oleracea: an important weed of rice and upland crops. Ann. Appl. Biol. 155:61–69.CrossRefGoogle Scholar
Chauhan, B. S. and Johnson, D. E. 2010a. Opportunities to improve cultural approaches to manage weeds in direct-seeded rice. Pages 40–43 in 17th Australasian Weeds Conference. Christchurch, New Zealand New Zealand Plant Protection Society.Google Scholar
Chauhan, B. S. and Johnson, D. E. 2010b. Effects of nitrogen on the competitiveness of Echinochloa colona and Amaranthus viridis with direct-seeded rice. J. Agric. Sci. Technol. 4:14–19.Google Scholar
Chauhan, B. S. and Johnson, D. E. 2010c. Response of rice flatsedge (Cyperus iria) and barnyardgrass (Echinochloa crus-galli) to rice interference. Weed Sci. 58:204–208.CrossRefGoogle Scholar
Chauhan, B. S. and Johnson, D. E. 2010d. The role of seed ecology in improving weed management strategies in the tropics. Adv. Agron. 105:221–262.Google Scholar
Chauhan, B. S. and Johnson, D. E. 2010e. Weedy rice (Oryza sativa L.) I. Grain characteristics and growth response to competition of weedy rice variants from five Asian countries. Weed Sci. 58:374–380.CrossRefGoogle Scholar
Chauhan, B. S. and Johnson, D. E. 2010f. Implications of narrow crop row spacing and delayed Echinochloa colona and Echinochloa crus-galli emergence for weed growth and crop yield loss in aerobic rice. Field Crops Res. 117:177–182.CrossRefGoogle Scholar
Chauhan, B. S. and Johnson, D. E. 2010g. Relative importance of shoot and root competition in dry-seeded rice growing with junglerice (Echinochloa colona) and ludwigia (Ludwigia hyssopifolia). Weed Sci. 58:295–299.Google Scholar
Chauhan, B. S. and Johnson, D. E. 2011a. Row spacing and weed control timing affect yield of aerobic rice. Field Crops Res. 121:226–231.Google Scholar
Chauhan, B. S. and Johnson, D. E. 2011b. Growth response of direct-seeded rice to oxadiazon and bispyribac-sodium in aerobic and saturated soils. Weed Sci. 59:119–122.CrossRefGoogle Scholar
Chauhan, B. S. and Johnson, D. E. 2011c. Competitive interactions between weedy rice and cultivated rice as a function of added nitrogen and levels of competition. Weed Biol. Manag. 11:202–209.CrossRefGoogle Scholar
Chauhan, B. S., Migo, T., Westerman, P. R., and Johnson, D. E. 2010. Post-dispersal predation of weed seeds in rice fields. Weed Res. 50:553–560.CrossRefGoogle Scholar
Chauhan, B. S., Pame, A. R. P., and Johnson, D. E. 2011a. Compensatory growth of ludwigia (Ludwigia hyssopifolia) in response to interference of direct-seeded rice. Weed Sci. 59:177–181.CrossRefGoogle Scholar
Chauhan, B. S., Singh, V. P., Kumar, A., and Johnson, D. E. 2011b. Relations of rice seeding rates to crop and weed growth in aerobic rice. Field Crops Res. 121:105–115.CrossRefGoogle Scholar
Cousens, R. D. and Mokhtari, S. 1998. Seasonal and site variability in the tolerance of wheat cultivars to interference from Lolium rigidum . Weed Res. 38:301–307.CrossRefGoogle Scholar
Delouche, J. C., Burgos, N. R., Gealy, D. R., de San Martin, G. Z., Labrada, R., Larinde, M., and Rosell, C. 2007. Weedy rices—origin, biology, ecology and control. Rome FAO Plant Production and Protection Paper 188. FAO. 144 p.Google Scholar
Dyer, W. E. 1995. Exploiting weed seed dormancy and germination requirements through agronomic practices. Weed Sci. 43:498–503.Google Scholar
Farooq, M., Siddique, K. H. M., Rehman, H. M. U., Aziz, T., Lee, D., and Wahid, A. 2011. Rice direct seeding: experiences, challenges and opportunities. Soil Till. Res. 111:87–98.CrossRefGoogle Scholar
Forcella, F. 1993. Prediction of weed densities from the soil seed reservoir. Pages 53–56 in Integrated Weed Management for Sustainable Agriculture. Hisar, India Indian Society of Weed Science.Google Scholar
Froud-Williams, R. J., Chancellor, R. J., and Drennan, D. S. H. 1981. Potential changes in weed floras associated with reduced-cultivation systems for cereal production in temperate regions. Weed Res. 21:99–109.Google Scholar
Gibson, K. D. and Fischer, A. J. 2001. Relative growth and photosynthetic response of water-seeded rice and Echinochloa oryzoides (Ard.) Fritsch to shade. Int. J. Pest Manag. 47:305–309.CrossRefGoogle Scholar
Gibson, K. D. and Fischer, A. J. 2004. Competitiveness of rice cultivars as a tool for crop-based weed management. Pages 517–537 in Inderjit, , ed. Weed Biology and Management. Dordrecht, The Netherlands Kluwer Academic.CrossRefGoogle Scholar
Gibson, K. D., Fischer, A. J., and Foin, T. C. 2001. Shading and the growth and photosynthetic responses of Ammannia coccinnea . Weed Res. 41:59–67.Google Scholar
Gibson, K. D., Fischer, A. J., and Foin, T. C. 2004. Compensatory responses of late watergrass (Echinochloa phyllopogon) and rice to resource limitations. Weed Sci. 52:271–280.Google Scholar
Gibson, K. D., Foin, T. C., and Hill, J. E. 1999. The relative importance of root and shoot competition between water-seeded rice and Echinochloa phyllopogon . Weed Res. 39:181–190.CrossRefGoogle Scholar
Gopal, R., Jat, R. K., Malik, R. K., Kumar, V., Alam, M. M., Jat, M. L., Mazid, M. A., Saharawat, Y. S., McDonald, A., and Gupta, R. 2010. Direct dry seeded rice production technology and weed management in rice based systems. New Delhi, India International Maize and Wheat Improvement Center Technical Bulletin. 28 p.Google Scholar
Grundy, A. C. and Mead, A. 1998. Modelling the effects of seed depth on weed seedling emergence. Pages 75–82 in Champion, G. T., Grundy, A. C., Jones, N. E., Marshall, E. J. E. and Froud-Williams, R. J., eds. Aspects of Applied Biology 51: Weed Seedbanks: Determination, Dynamics and Manipulation. Oxford, UK Association of Applied Biologists.Google Scholar
Håkansson, S. 2003. Weeds and Weed Management on Arable Land—An Ecological Approach. Wallingford, UK CABI.288 p.CrossRefGoogle Scholar
Harper, J. L. 1977. Population Biology of Plants. London Academic. 892 p.Google Scholar
Hulme, P. E. 1994. Post-dispersal seed predation in grassland: its magnitude and sources of variation. J. Ecol. 81:645–652.CrossRefGoogle Scholar
Jacques, G. L. and Harvey, R. G. 1979. Dinitroaniline herbicide phytotoxicity as influenced by soil moisture and herbicide vaporization. Weed Sci. 27:536–539.CrossRefGoogle Scholar
Jat, M. L., Gathala, M. K., Ladha, J. K., Saharawat, Y. S., Jat, A. S., Vipin, , Kumar, A. S., Sharma, S. K., Kumar, V., and Gupta, R. K. 2009. Evaluation of precision land leveling and double zero-till systems in the rice-wheat rotation: water use, productivity, profitability and soil physical properties. Soil Till. Res. 105:112–121.Google Scholar
Jat, M. L., Chandana, P., Sharma, S. K., Gill, M. A., and Gupta, R. K. 2006. Laser land leveling: a precursor technology for resource conservation. Pages 48 in Rice–Wheat Consortium. New Delhi, India Rice–Wheat Consortium Technical Bulletin Series 7.Google Scholar
Jat, M. L., Pal, S. S., Subba Rao, A. V. M., Sirohi, K., Sharma, S. K., and Gupta, R. K. 2004. Laser land leveling: the precursor technology for resource conservation in irrigated eco-system of India. Pages 9–10 in Proceedings of National Conference on Conservation Agriculture: Conserving Resources, Enhancing Productivity. New Delhi, India NASC Complex.Google Scholar
Jones, R. E., Banks, P. A., and Radcliffe, D. E. 1990. Alachlor and metribuzin movement and dissipation in a soil profile as influenced by soil surface condition. Weed Sci. 38:589–597.Google Scholar
Lampayan, R. M., Bouman, B. A. M., de Dios, J. L., Espiritu, E. J., Soriano, J. B., Lactaoen, A. T., Faronilo, J. E., and Thant, K. M. 2010. Yield of aerobic rice in rainfed lowlands of the Philippines as affected by nitrogen management and row spacing. Field Crops Res. 116:165–174.CrossRefGoogle Scholar
Lee, J., Chauhan, B. S., and Johnson, D. E. 2011. Germination of fresh horse purslane (Trianthema portulacastrum) seeds in response to different environmental factors. Weed Sci. 59:495–499.Google Scholar
Levene, B. C. and Owen, M. D. K. 1995. Effect of moisture stress and leaf age on bentazon absorption in common cocklebur (Xanthium strumarium) and velvetleaf (Abutilon theophrasti). Weed Sci. 43:7–12.CrossRefGoogle Scholar
Liebman, M., Mohler, C. L., and Staver, C. P. 2001. Ecological Management of Agricultural Weeds. Cambridge, UK Cambridge University Press. 532 p.Google Scholar
Mahajan, G. and Chauhan, B. S. 2011. Effects of planting pattern and cultivar on weed and crop growth in aerobic rice system. Weed Technol. 25:521–525.CrossRefGoogle Scholar
Malicki, L. and Berbeciowa, C. 1986. Uptake of more important mineral components by common field weeds on loess soils. Acta Agrobot. 39:129–141.CrossRefGoogle Scholar
Mills, J. A., Witt, W. W., and Barrett, M. 1989. Effects of tillage on the efficacy and persistence of clomazone in soybean (Glycine max). Weed Sci. 37:217–222.Google Scholar
Mohler, C. L. 1993. A model of the effects of tillage on emergence of weed seedlings. Ecol. Appl. 3:53–73.Google Scholar
Mohler, C. L. and Teasdale, J. R. 1993. Response of weed emergence to rate of Vicia villosa Roth and Secale cereale L. residue. Weed Res. 33:487–499.Google Scholar
Moody, K. 1991. Weed management in rice. Pages 301–328 in Pimentel, D., ed. CRC Handbook of Pest Management in Agriculture. 2nd ed., Volume 3. Boca Raton, FL CRC.Google Scholar
Moody, K. and Drost, D. C. 1983. The role of cropping systems on weeds in rice. Pages 73–86 in Proceedings of the Conference on Weed Control in Rice. Los Baños, Philippines International Rice Research Institute.Google Scholar
Namuco, O. S., Cairns, J. E., and Johnson, D. E. 2009. Investigating early vigor in upland rice (Oryza sativa L.), part I: seedling growth and grain yield in competition with weeds. Field Crops Res. 113:197–206.Google Scholar
Pandey, S. and Velasco, L. 2005. Trends in crop establishment methods in Asia and research issues. Pages 178–181 in Rice Is Life: Scientific Perspectives for the 21st Century. Los Baños, Philippines International Rice Research Institute and Tsukuba, and Tsukuba, Japan: Japan International Research Center for Agricultural Sciences.Google Scholar
Patterson, D. T. 1979. The effects of shading on the growth and photosynthetic capacity of itchgrass (Rottboellia exaltata). Weed Sci. 27:549–553.CrossRefGoogle Scholar
Patterson, D. T. 1995. Effects of environmental stress on weed/crop interactions. Weed Sci. 43:483–490.CrossRefGoogle Scholar
Piggin, C. M., Garcia, C. O., Janiya, J. D., Bell, M. A., Castro, E. C. Jr., Razote, E. B., and Hill, J. 2001. Establishment of irrigated rice under zero and conventional tillage systems in the Philippines. Pages 533–543 in Rice Research for Food Security and Poverty Alleviation. Proceedings of the International Rice Research Conference. Makati City, Philippines International Rice Research Institute.Google Scholar
Praba, M. L., Vanangamudi, M., and Thandapani, V. 2004. Effect of low light on yield and physiological attributes of rice. Int. Rice Res. Notes 29:71–73.Google Scholar
Rao, A. N., Johnson, D. E., Sivaprasad, B., Ladha, J. K., and Mortimer, A. M. 2007. Weed management in direct-seeded rice. Adv. Agron. 93:153–255.CrossRefGoogle Scholar
Renu, S., Thomas, C. G., and Abraham, C. T. 2000. Stale seedbed technique for the management of Sacciolepis interrupta in semi-dry rice. Indian J. Weed Sci. 32:140–145.Google Scholar
Schlichting, C. D. 1986. The evolution of phenotypic plasticity in plants. Annu. Rev. Ecol. Syst. 17:667–693.CrossRefGoogle Scholar
Schnieders, B. J., van der Linden, M., Lotz, L. A. P., and Rabbinge, R. 1999. A model for interspecific competition in row crops. Pages 31–56 in Schnieders, B. J., ed. A Quantitative Analysis of Inter-Specific Competition in Crops with a Row Structure. Wageningen, The Netherlands Agricultural University Wageningen.Google Scholar
Singh, G., Singh, Y., Singh, V. P., Johnson, D. E., and Mortimer, M. 2005. System level effects in weed management in rice-wheat cropping in India. Pages 545–550 in BCPC International Congress on Crop Science and Technology (Glasgow, UK). Alton, Hampshire, UK British Crop Protection Conference.Google Scholar
Singh, S., Ladha, J. K., Gupta, R. K., Bhusan, L., Rao, A. N., Sivaprasad, B., and Singh, P. P. 2007. Evaluation of mulching, intercropping with Sesbania and herbicide use for weed management in dry-seeded rice (Oryza sativa). Crop Prot. 26:518–524.CrossRefGoogle Scholar
Thompson, K. and Grime, J. 1979. Seasonal variation in the seed banks of herbaceous species in ten contrasting habitats. J. Ecol. 67:893–921.Google Scholar
Triplett, G. B. Jr. 1985. Principles of weed control for reduced -tillage corn production. Pages 26–40 in Wiese, A. F., ed. Weed Control in Limited Tillage Systems. Champaign, IL Weed Science Society of America.Google Scholar
Tuong, T. P. and Bouman, B. A. M. 2003. Rice production in water-scarce environments. Pages 53–67 in Kijne, J. W., Barker, R. and Molden, D., eds. Water Productivity in Agriculture: Limits and Opportunities for Improvements. Wallingford, UK CABI.Google Scholar
Tuong, T. P., Bouman, B. A. M., and Mortimer, M. 2005. More rice, less water: integrated approaches for increasing water productivity in irrigated rice-based systems in Asia. Plant Prod. Sci. 8:231–241.Google Scholar
Walker, S. R. and Evenson, J. P. 1985. Biology of Commelina benghalensis L. in south-eastern Queensland, 2: seed dormancy, germination and emergence. Weed Res. 25:245–250.Google Scholar
Walker, T. W., Bond, J. A., Ottis, B. V., Gerard, P. D., and Harrell, D. L. 2008. Hybrid rice response to nitrogen fertilization for midsouthern United States rice production. Agron. J. 100:381–386.CrossRefGoogle Scholar
Wilson, D. G. Jr., Burton, M. G., Spears, J. F., and York, A. C. 2006. Doveweed (Murdannia nudiflora) germination and emergence as affected by temperature and seed burial depth. Weed Sci. 54:1000–1003.CrossRefGoogle Scholar
Woolley, J. T. and Stoller, E. 1978. Light penetration and light-induced seed germination in soil. Plant Physiol. 61:597–600.Google Scholar
Young, K. R. and Cousens, R. D. 1999. Factors affecting the germination and emergence of wild radish (Raphanus raphanistrum) and their effect on management options. Pages 179–182 in Proceedings of 12th Australian Weeds Conference. Tasmania, Hobart Tasmanian Weed Society.Google Scholar
Zhao, D. 2006. Weed Competitiveness and Yielding Ability of Aerobic Rice Genotypes, . Wageningen, The Netherlands Wageningen University.Google Scholar
Zhao, D. L., Atlin, G. N., Bastiaans, L., and Spiertz, J.H.J. 2006. Developing selection protocols for weed competitiveness in aerobic rice. Field Crops Res. 97:272–285.CrossRefGoogle Scholar