A comparison of different rules of partitioning of crop growth between individual plants

Abstract Three contrasting rules to quantify the partitioning of crop dry matter between individual plants were incorporated into an overlapping zone of influence model. The model assumed that light was the limiting factor for growth and simulations were compared with growth observed in carrot ( Daucus carota , L.) experiments. The simulations were compared with (i) the growth of individual plants at different positions in an imposed spatial planting pattern and (ii) the growth of plants of contrasting pre-competitive weight planted in a uniformly-spaced array. The simulation that gave a growth response closest to that in the experimental data was based upon an equation that partitioned crop dry matter between plants according to the degree of ‘crowding’ each plant experienced. This supports the view that plants alter their morphology in response to the presence of neighbours, thereby modifying the extent of growth interactions due to competition. The modification in growth was simulated by a simple modification to an overlapping zone model.

[1]  J. Weiner,et al.  Competition and Allometry in Kochia scoparia , 1994 .

[2]  G. Berntson,et al.  Competition and growth form in a woodland annual , 1990 .

[3]  L. R. Benjamin,et al.  A Model for Plant and Crop Growth, Allowing for Competition for Light by the use of Potential and Restricted Projected Crown Zone Areas , 1994 .

[4]  L. Benjamin.  Experimental Discrimination Between Contrasting Models of Neighbourhood Competition , 1993 .

[5]  Gordon B. Bonan,et al.  The size structure of theoretical plant populations: spatial patterns and neighborhood effects , 1988 .

[6]  S. Pacala,et al.  Forest models defined by field measurements: I. The design of a northeastern forest simulator , 1993 .

[7]  J. Weiner,et al.  Asymmetric competition in plant populations. , 1990, Trends in ecology & evolution.

[8]  S. Pacala,et al.  Effects of competitive asymmetry on a local density model of plant interference. , 1991, Journal of theoretical biology.

[9]  T. Miller,et al.  Local Density Variation may Mimic Effects of Asymmetric Competition on Plant Size Variability , 1989 .

[10]  J. Brewster,et al.  Bulb development in onion (Allium cepa L.). IV. Influence on yield of radiation interception, its efficiency of conversion, the duration of growth and dry-matter partitioning , 1986 .

[11]  Claudio M. Ghersa,et al.  Early detection of neighbour plants by phytochrome perception of spectral changes in reflected sunlight , 1987 .

[12]  S. Schwinning.  Decomposition Analysis of Competitive Symmetry and Size Structure Dynamics , 1996 .

[13]  A. M. Ellison,et al.  A Null Model for Neighborhood Models of Plant Competitive Interactions , 1994 .