Competition between Hordeum vulgare L. and Chenopodium album L. with different dates of emergence of Chenopodium album.

Abstract

Under controlled conditions, competition experiments were carried out with (a) spring barley and (b) C. album; this experiment was also simulated with a computer programme written in CSMP (Continuous System Modeling Program) on the basis of a model. When (b) was sown 7 days earlier, it could not compete with (a), but when this period was 21 and 31 days, (a) could no longer compete with (b). This result was hardly influenced by the applied densities of (b). Correspondence between the simulated and observed yields was rather poor initially, but could be considerably improved by correcting the model with the length factor. For this, the observed difference in length growth between the 2 spp. was included in the model. Based on the simulation results it could be concluded that light interception is probably the most important competition factor between the 2 spp. Simulating a series of 7, 21 and 31 days earlier germination for (b) showed that the critical period in which (b) can just maintain itself in a mixture with (a) is c. 15 days. Attention is called to the fact that the result of a competition experiment carried out under controlled conditions in a climate room cannot be used without comment for predicting a value under field conditions. (Abstract retrieved from CAB Abstracts by CABI’s permission)