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Simulating allelochemical production from plant residues during decomposition

A. Min, I.R. Johnson and J.V. Lovett

School of Agriculture, Charles Sturt University, Wagga Wagga NSW 2650
Department of Agronomy and Soil Science, University of New England, Armidale NSW 2351

Plant residues may have allelopathic effects on the growth and yield of subsequent plants (1). Such effects have been attributed to the phytotoxic chemicals leached from the residues and toxins produced by micro-organisms during residue decomposition (4). A model of allelochemical production during straw decomposition has been developed.

The model

The model for allelochemical production from plant residue is shown schematically in Figure 1.

Figure 1. Schematic representation of the model.

Results and discussion

The behaviour of the model is illustrated in Figure 2. The experimental data of Harper and Lynch (2) are also shown in Figure 2b. Initially, the rate of allelochemical production increases. As decomposition continues, production declines and the level of allelochemical approaches zero. This is due to leaching and microbial decay of allelochemicals, and gradual decomposi- tion of substrate available for allelochemical formation (3, 4).

Figure 2. Allelochemical concentration: (a) arbitrary units with initial residue level Ro=10, k1 = 0.08, 1(2= 0.06; (b) Ro =1, kr= 0.0109, k2 = 0.3011 with data from (2) also shown.

References

Guenzi, W.D. and McCalla, T.M. 1966. Agron. J. 58, 303-304.

Harper, S.H.T. and Lynch, J.M. 1981. J. Sci. Food Agric. 32, 1057-1062.

Harper, S.H.T. and Lynch, J.M. 1982. Plant Soil 65, 11-17.

Masun-Sedun, W. and Jessop, R. S. 1988. Plant Soil 107, 69-80.

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