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Adjustment for competition between varieties in plant breeding trials

  • R. A. Kempton (a1)
  • DOI:
  • Published online: 01 March 2009

A method is proposed for correcting for competition effects in yield trials by joint regression of plot yields on to the yields of neighbours. Estimation of the variety effects and competition coefficient along with tests of significance are described for a sugar-beet trial with single-row plots where competition effects are assumed to extend only to plants in immediately adjacent rows. For designs which are balanced for neighbouring varieties it is feasible to estimate separate varietal competition coefficients which may be partitioned into components for sensitivity and aggressiveness. An example is given of this extended model fitted to a competition diallel of seven species. While species differed in their sensitivity to competition there was no essential difference between inter- and intra-species behaviour. The model is used to assess comparative varietal performance in monocultures from performance in small plot trials.

(Note that the general term ‘variety’ is used throughout this paper to refer to progenies at any stage in a selection programme.)

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M. G. R. Cannell , C. K. Njuguna , E. D. Ford , R. Smith & H. M. Ross-Parker (1977). Variation in yield among competing individuals within mixed genotype stands of tea: a selection problem. Journal of Applied Ecology 14, 969985.

N. R. Draper & I. Guttman (1980). Incorporating overlap effects from neighbouring units into response surface models. Applied Statistics 29, 128134.

K. W. Finlay & G. N. Wilkinson (1963). The analysis of adaption ina plant breeding programme. Australian Journal of Agricultural Research 14, 742754.

N. F. Jensen & W. T. Federer (1964). Adjacent row competition in wheat. Crop Science 4, 641645.

R. A. Kempton & C. W. Howes (1981). The use of neighbouring plot values in the analysis of variety trials. Applied Statistics 30, 5970.

J. A. Nelder (1962). New kinds of systematic designs for spacing experiments. Biometrics 18, 283307.

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H. D. Patterson & V. Silvey (1980). Statutory and recommended list trials of crop varieties in the UK (with Discussion). Journal of the Royal Statistical Society A 143, 219252.

R. M. Williams (1952). Experimental designs for serially correlated observations. Biometrika 39, 152167.

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