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Aspects of the Design and Interpretation of Competition (Interference) Experiments

Published online by Cambridge University Press:  12 June 2017

Roger Cousens
Roger Cousens*
Affiliation:
School of Crop Sciences, University of Sydney, NSW 2006, Australia
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Abstract

The design and analysis of competition experiments should be based on an unambiguous objective. Recent criticisms of particular designs have been made without reference to objectives and may be misleading. Three common designs are discussed: additive, replacement series, and response surface. Additive designs are well suited to agronomic objectives; replacement series are useful for comparing pairs of species; response surface designs can be used for most objectives but may be unnecessarily complex. The published criticisms of additive and replacement series designs are argued to be acceptable limitations within the bounds of the objectives for which they are used. Concerns about these designs confounding density and proportion are irrelevant to the objectives for which they are most suited. The continued use of multiple comparison tests is argued to be illogical. Regression approaches to analysis are more relevant, many non-linear equations are now easy to fit to data and these can be used without the need for linearization. However, there are various pitfalls not adequately reported to date. In particular, error structures need to be checked carefully and over-elaborate equations should be avoided.

Keywords

Objectiveadditivereplacement seriesresponse surfacemultiple comparisonfitting proceduresregression

Information

Type
Symposium
Information
Weed Technology , Volume 5 , Issue 3 , September 1991 , pp. 664 - 673
Copyright
Copyright © 1991 Weed Science Society of America 

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References

Literature Cited

1. Anonymous. 1988. Guidance for the use and presentation of statistics in Weed Research. Weed Res. 28:139–144.Google Scholar
2. Baker, R. J. 1988. Multiple comparison tests. Can. J. Plant Sci. 60: 325–327.Google Scholar
3. Box, G.E.P., Hunter, W. G., and Hunter, J. S. 1978. Statistics for Experimenters: An Introduction to Design, Data Analysis and Model Building. Wiley, NY.Google Scholar
4. Brain, P., and Cousens, R. 1989. An equation to describe dose responses where there is stimulation of growth at low doses. Weed Res. 29:93–96.CrossRefGoogle Scholar
5. Bryan-Jones, J., and Finney, D. J. 1983. On an error in “Instructions to Authors”. HortScience 18:279–282.Google Scholar
6. Carlson, H. L., and Hill, J. E., 1985. Wild oat (Avena fatua) competition with spring wheat: plant density effects. Weed Sci. 33:176–181.CrossRefGoogle Scholar
7. Chew, V. 1976. Uses and abases of Duncan's Multiple Range Test, Proc. Florida State Hortic. Soc. 89:251–253.Google Scholar
8. Cobby, J. M., Chapman, P. F., and Pike, D. J. 1986. Design of experiments for estimating inverse quadratic polynomial responses. Biometrics 42:659–664.Google Scholar
9. Connolly, J. 1987. On the use of response models in mixture experiments. Oecologia 72:95–103.Google Scholar
10. Cousens, R. 1985. An empirical model relating crop yield to weed and crop density and a statistical comparison with other models. J. Agric. Sci. 105:513–521.CrossRefGoogle Scholar
11. Cousens, R. 1985. A simple model relating yield loss to weed density. Ann. Appl. Biol. 107:239–252.Google Scholar
12. Cousens, R. 1987. Theory and reality of weed control thresholds. Plant Prot. Q. 2:13–20.Google Scholar
13. Cousens, R. 1988. Misinterpretations of results in weed research through inappropriate use of statistics. Weed Res. 28:281–289.Google Scholar
14. Cousens, R., and Marshall, C. 1987. Dangers in testing statistical hypotheses. Ann. Appl. Biol. 111:469–476.CrossRefGoogle Scholar
15. Dew, D. A. 1972. An index of competition for estimating crop loss due to weeds. Can. J. Plant Sci. 52:921–927.CrossRefGoogle Scholar
16. Firbank, L. G., and Watkinson, A. R. 1985. On the analysis of competition within two-species mixtures of plants. J. Appl. Ecol. 22: 503–517.Google Scholar
17. Firbank, L. G., and Watkinson, A. R. 1990. On the effects of competition: from monocultures to mixtures. p. 165–192 in Perspectives on Plant Competition, Eds. Grace, J. B. and Tilman, D. Academic Press, San Diego.Google Scholar
18. Firbank, L. G., and Watkinson, A. R. 1986. Modelling the population dynamics of an arable weed and its effects upon crop yield. J. Appl. Ecol. 23:147–159.Google Scholar
19. Hakansson, S. 1983. Competition and production in short-lived crop-weed stands. Density effects. Sveriges Lantbruksj., Inst. for Vaxtod. Rap. 127:1–85.Google Scholar
20. Jolliffe, P. A., Minjas, A. N., and Runeckles, V. C. 1984. A reinterpretation of yield relationships in replacement series experiments. J. Appl. Ecol, 21:227–243.Google Scholar
21. Law, R., and Watkinson, A. R. 1987. Response-surface analysis of two-species competition: an experiment on Phleum arenarium and Vulpia fasciculata . J. Ecol. 75:871–886.CrossRefGoogle Scholar
22. Marshall, D. R., and Jain, S. K. 1969. Interference in pure and mixed populations of Avena fatua and A. barbata . J. Ecol. 57:251–270.CrossRefGoogle Scholar
23. Mead, R., and Curnow, R. N. 1983. Statistical Methods in Agriculture and Experimental Biology. Chapman and Hall, London.Google Scholar
24. Mortensen, D. A., and Coble, H. D. 1989. The influence of soil water content on common cocklebur (Xanthium strumarium) interference in soybeans (Glycine max). Weed Sci 37:76–83.Google Scholar
25. O'Donovan, J. T., Kirkland, K. J., and Sharma, A. K. 1989. Canola yield and profitability as influenced by volunteer wheat infestations. Can. J. Plant Sci. 69:1235–1244.CrossRefGoogle Scholar
26. Perry, J. N. 1986. Multiple-comparison procedures: a dissenting view. J. Econ. Entomol. 79:1149–1155.Google Scholar
27. Pike, D. J., and Hasted, A. M. 1987. Experimental design and response surface analysis of pesticide trials. Pestic. Sci. 19:297–307.Google Scholar
28. Poole, M. L., and Gill, G. S. 1987. Competition between crops and weeds in southern Australia. Plant Prot. Q. 2:86–96.Google Scholar
29. Radosevich, S. R., and Holt, J. S., 1984. Weed Ecology: Implications for Vegetation Management. Wiley, New York.Google Scholar
30. Ratkowsky, D. A. 1983. Nonlinear Regression Modeling: A Unified Practical Approach. Dekker, New York.Google Scholar
31. Rejmanek, M., Robinson, G. R., and Rejmankova, E. 1989. Weed-crop competition: experimental designs and models for data analysis. Weed Sci. 37:276–284.CrossRefGoogle Scholar
32. Shurtleff, J. L., and Coble, H. D. 1985. Interference of certain broadleaf weed species in soybeans (Glycine max). Weed Sci. 33:654–657.Google Scholar
33. Snaydon, R. W., and Satorre, E. H. 1989. Bivariate diagrams for plant competition data: modifications and interpretation. J. Appl. Ecol. 26: 1043–1057.Google Scholar
34. Spitters, C.J.T. 1983. An alternative approach to the analysis of mixed cropping experiments. I. Estimation of competition effects. Neth. J. Agric. Sci. 31:1–11.Google Scholar
35. Spitters, C.J.T., Kropff, M. J., and de Groot, W. 1989. Competition between maize and Echinochloa crus-galli analysed by a hyperbolic regression model. Ann. Appl. Biol. 115:541–551.CrossRefGoogle Scholar
36. Suehiro, K., and Ogawa, H. 1980. Competition between two annual herbs, Atriplex gmelini C. A. Mey and Chenopodium album L., in mixed cultures irrigated with seawater of various concentrations. Oecologia 45:167–177.Google Scholar
37. Taylor, D. R., and Aarssen, L. W. 1989. On the density dependence of replacement-series competition experiments. J. Ecol. 77:975–988.Google Scholar
38. Weaver, S. E., and Warwick, S. I. 1982. Competitive relationships between atrazine resistant and susceptible populations of Amaranthus retroflexus and A. powellii from southern Ontario. New Phytol. 92: 131–139.Google Scholar
39. Williams, C. S., and Hayes, R. M. 1984. Johnsongrass (Sorghum halepense) competition in soybeans (Glycine max). Weed Sci. 32: 498–501.CrossRefGoogle Scholar
40. Wright, A. J. 1981. The analysis of yield-density relationships in binary mixtures using inverse polynomials. J. Agric. Sci. 96:561–567.CrossRefGoogle Scholar
41. Zimdahl, R. L. 1980. Weed-Crop Competition: A Review. International Plant Protection Centre, Corvallis, OR, USA.Google Scholar